Choice of urine sample predictive of microalbuminuria in patients with insulin-dependent diabetes mellitus

High-Density Lipoprotein Particle Concentration and Size Predict Incident Coronary Artery Disease Events in a Cohort With Type 1 Diabetes

BACKGROUND

The cholesterol efflux capacity of high density lipoprotein (HDL) is negatively associated with cardiovascular risk. Small HDL particles account almost quantitatively for cholesterol efflux capacity, perhaps mediated through efflux of cholesterol and outer leaflet plasma membrane phospholipids by ABCA1 (ATP binding cassette subfamily A member 1). People with type 1 diabetes are at increased coronary artery disease (CAD) risk despite normal HDL-cholesterol concentrations. We therefore tested the hypothesis that small HDL particles (HDL-P)-rather than HDL-cholesterol-predict incident CAD in type 1 diabetes.

METHODS AND RESULTS

Incident CAD (CAD death, myocardial infarction, or coronary revascularization) was determined in 550 individuals with childhood-onset type 1 diabetes. HDL-P was quantified by calibrated ion mobility analysis and cholesterol efflux capacity was quantified with validated assays. During a median follow-up of 26 years, 36.5% of the participants developed incident CAD, for an incidence density of 181.3 per 10 000 person-years. In multivariable Cox models, neither HDL-cholesterol nor apolipoprotein A1 concentration was significantly associated with CAD risk. In contrast, higher extra-small HDL-P concentrations were significantly associated with decreased CAD risk (hazard ratio [HR], 0.26 [95% CI, 0.14-0.50]). Weaker associations were observed for total HDL-P (HR, 0.88 [95% CI, 0.83-0.93]), small HDL (HR, 0.83 [95% CI, 0.68-1.02]), medium HDL (HR, 0.79 [95% CI, 0.71-0.89]), and large HDL (HR, 0.72 [95% CI, 0.59-0.89]). Although cholesterol efflux capacity was negatively associated with incident CAD, this association was no longer significant after adjustment for total HDL-P.

CONCLUSIONS

Lower concentrations of total HDL-P and HDL subpopulations were positively associated with incident CAD independently of HDL-cholesterol, apolipoprotein A1, and other common CVD risk factors. Extra-small HDL was a much stronger predictor of risk than the other HDLs. Our data are consistent with the proposal that extra-small HDL plays a critical role in cardioprotection in type 1 diabetes, mediated by macrophage cholesterol efflux by the ABCA1 pathway.

HDL Particle Concentration and Size Predict Incident Coronary Artery Disease Events in People with Type 1 Diabetes

Background

Cholesterol efflux capacity (CEC) negatively correlates with cardiovascular disease risk. Small HDL particles account almost quantitively for CEC, perhaps mediated through efflux of outer leaflet plasma membrane phospholipids by ABCA1. People with type 1 diabetes (T1D) are at increased risk of coronary artery disease (CAD) despite normal levels of HDL-cholesterol (HDL-C). We therefore tested the hypotheses that small HDL particles (HDL-P)-rather than HDL-C levels-predict incident CAD in T1D.

Methods

Incident CAD (CAD death, myocardial infarction, and/or coronary revascularization) was determined in a cohort of 550 participants with childhood-onset T1D. HDL-P was quantified by calibrated ion mobility analysis. CEC and phospholipid efflux were quantified with validated assays.

Results

During a median follow-up of 26 years, 36.5% of the participants developed incident CAD. In multivariable Cox models, levels of HDL-C and apolipoprotein A-I (APOA1) did not predict CAD risk. In contrast, extra-small HDL particle levels strongly and negatively predicted risk (hazard ratio [HR]=0.25, 95% confidence interval [CI]=0.13-0.49). An increased concentration of total HDL particles (T-HDL-P) (HR=0.87, CI=0.82-0.92) and three other HDL sizes were weaker predictors of risk: small HDL (HR=0.80, 0.65-0.98), medium HDL (HR=0.78, CI=0.70-0.87) and large HDL (HR=0.72, CI=0.59-0.89). Although CEC negatively associated with incident CAD, that association disappeared after the model was adjusted for T-HDL-P. Isolated small HDLs strongly promoted ABCA1-dependent efflux of membrane outer leaflet phospholipids.

Conclusions

Low concentrations of T-HDL-P and all four sizes of HDL subpopulations predicted incident CAD independently of HDL-C, APOA1, and other common CVD risk factors. Extra-small HDL was a much stronger predictor of risk than the other HDLs. Our data are consistent with the proposal that small HDLs play a critical role in cardioprotection in T1D, which might be mediated by macrophage plasma membrane outer leaflet phospholipid export and cholesterol efflux by the ABCA1 pathway.

Joint 30-year HbA1c and lipid trajectories and mortality in type 1 diabetes

AIMS

Higher HbA1c has been associated with dyslipidemia in type 1 diabetes, but it is unknown whether there is heterogeneity in this association. Thus we assessed the longitudinal association between HbA1c and lipids over 30 years in a type 1 diabetes cohort and examined whether variation in such longitudinal patterns was associated with total and cause-specific mortality.

METHODS

Data were from the Pittsburgh Epidemiology of Diabetes Complications study (n = 581 with ≥2 visits, 51% male, baseline mean age 27, diabetes duration 19 years). Longitudinal associations between HbA1c and lipids were assessed in mixed models. Group-based multi-trajectory models identified simultaneous trajectories of HbA1c and lipids.

RESULTS

Longitudinal HbA1c was associated with Non-HDLc (p < 0.0001) and triglycerides (p < 0.0001), but not HDLc (men: p = 0.72, women: p = 0.76). There was heterogeneity in the HbA1c-Non-HDLc association only, with five HbA1c-Non-HDLc groups identified. One group (20%) had an unexpected combination of high HbA1c but normal Non-HDLc and had only moderately increased cardiovascular mortality (rate ratio [RR] = 2.80, 95% CI 1.31-6.00) and kidney disease mortality (RR = 2.30, 95% CI 0.97-5.50) compared to Low HbA1c-Normal Non-HDLc.

CONCLUSIONS

These results suggest there is a subgroup with type 1 diabetes who, despite poor glycemic control, has a relatively good prognosis, perhaps related to good Non-HDLc.

30-Year Cardiovascular Disease in Type 1 Diabetes: Risk and Risk Factors Differ by Long-term Patterns of Glycemic Control

OBJECTIVE

We hypothesized that there is heterogeneity in long-term patterns of glycemic control with respect to cardiovascular disease (CVD) development in type 1 diabetes and that risk factors for CVD differ by glycemic control pattern. Thus, we estimated associations between data-derived latent HbA1c trajectories and 30-year CVD risk in the Pittsburgh Epidemiology of Diabetes Complications (EDC) study of childhood-onset (<17 years old) type 1 diabetes.

RESEARCH DESIGN AND METHODS

Participants (n = 536 with two or more HbA1c measurements [median 6] and CVD-free at baseline; mean age 27 and diabetes duration 18 years) were followed from 1986 to 1988 to 2016 to 2018 to ascertain CVD incidence (CVD death, myocardial infarction, stroke, coronary revascularization or blockage ≥50%, ischemic electrocardiogram, or angina). Latent HbA1c trajectories and their association with time-to-CVD incidence were simultaneously assessed using joint latent class mixed models.

RESULTS

Two HbA1c trajectories with respect to differential CVD risk were identified: low (HbA1c ∼8% [64 mmol/mol] and improving over follow-up, 76% of cohort) and high (HbA1c ∼10% [86 mmol/mol] and stable, 24%). Overall, 30-year CVD incidence was 47.4% (n = 253); major adverse cardiovascular event incidence was 31.0% (n = 176). High HbA1c was associated with threefold increased CVD risk versus low HbA1c. Both groups had similar age and diabetes duration. Non-HDL cholesterol and estimated glomerular filtration rate were associated with CVD risk only in low HbA1c; albumin excretion rate was associated with CVD risk only in high HbA1c.

CONCLUSIONS

These risk factor differences suggest that pathways to CVD may differ by glycemic control, potentially resulting in important implications for prognosis in type 1 diabetes.

Predictors of Change in Skin Intrinsic Fluorescence in Type 1 Diabetes: The Epidemiology of Diabetes Complications Study

BACKGROUND

Skin intrinsic fluorescent (SIF) scores are indirect measures of advanced glycation end-products (AGEs). SIF scores are cross-sectionally associated with type 1 diabetes (T1D) complications such as increased albumin excretion rate (AER), coronary artery calcification (CAC) and neuropathy. We assessed predictors of SIF score change in those with T1D.

METHODS

Data from the 30-year longitudinal Epidemiology of Diabetes Complications (EDC) study of childhood-onset T1D were used to assess AGEs measured with a SIF score produced by the SCOUT DS® device. SIF scores were assessed twice in 83 participants: between 2007-08 and again between 2010-14. Regression analyses were used to assess independent predictors of SIF score change.

RESULTS

At baseline, mean age was 47.9 ± 6.9 years, diabetes duration was 36.7 ± 6.4 years, and median glycosylated hemoglobin (HbA1c) was 7.1 (interquartile range: 6.5, 8.5). During a mean follow-up of 5.2 ± 0.9 years, mean change in SIF score was 2.9 ± 2.8 arbitrary units. In multivariable linear regression models, log HbA1c (P < 0.001), log estimated glomerular filtration rate (eGFR) (P < 0.001), overt nephropathy (defined as AER ≥ 200 µg/min, P = 0.06), and multiple daily insulin shots/pump use (MDI) exposure years (P = 0.02) were independent predictors of SIF score change.

CONCLUSIONS

Increases in SIF score over 5 years were related to increased glycemic levels and decreased kidney function (eGFR). MDI and glomerular damage were related to a decreased SIF score. This is one of the first studies with repeated SIF assessments in T1D and provides unique, albeit preliminary, insight about these associations.

Predictors of the age at which natural menopause occurs in women with type 1 diabetes: the Pittsburgh Epidemiology of Diabetes Complications (EDC) study

OBJECTIVE

Women with type 1 diabetes (T1D) are thought to experience menopause earlier than women without diabetes, although not all studies agree. We assessed metabolic predictors of the age at which natural menopause occurs among women with T1D participating in the Epidemiology of Diabetes Complications study.

METHODS

Women with childhood-onset (<17 y) of T1D who underwent natural menopause without use of hormone therapy during their menopausal transition were included in the analysis (n = 105; mean baseline age, 29.5 and diabetes duration, 20.2 y). Self-reported reproductive history and the Women's Ischemia Syndrome Evaluation hormonal algorithms were used to determine menopause status. Linear regression was used to ascertain whether time-weighted metabolic factors (eg, BMI, lipids, HbA1c, insulin dose, albumin excretion rate [AER]) were associated with age at natural menopause.

RESULTS

Univariately, only insulin dose (β = -4.87, P = 0.04) and log (AER) (β = -0.62, P = 0.02) were associated (negatively) with age at natural menopause. Adjusting for BMI, smoking status, lipids, HbA1c, number of pregnancies, and oral contraceptive use, each 0.1 unit increase in the daily dose of insulin per kilogram body weight was associated with 0.64 years younger age at natural menopause (P = 0.01), while for every 30% increase in AER, age at natural menopause decreased by 0.18 years (P = 0.03).

CONCLUSION

Higher average levels of insulin dose and AER over time were significantly associated with a younger age at which natural menopause occurred among women with T1D. The biologic mechanisms underlying the observed associations between exogenous insulin dose and AER on reproductive health should be investigated among women with T1D.

Association of age at diabetes complication diagnosis with age at natural menopause in women with type 1 diabetes: The Pittsburgh Epidemiology of Diabetes Complications (EDC) Study

OBJECTIVE

Vascular damage is thought to have a role in premature ovarian aging. We thus assessed the association between the presence, and age at onset of, vascular diabetes complications and age at natural menopause in women with type 1 diabetes.

METHODS

Female participants of the Epidemiology of Diabetes Complications study with type 1 diabetes who experienced natural menopause and who never received hormone therapy during their menopausal transition were included in the analysis (n=105). Microalbuminuria (MA), overt nephropathy, proliferative retinopathy, confirmed distal symmetric polyneuropathy, and coronary artery disease, were assessed during biennial clinical exanimations for the first 10 years of follow-up and at year 18, 25 and 30. Menopausal status was determined via self-report and sex hormone data. For each complication, separate linear regression models were used to assess whether, compared with women without the complication of interest, an earlier age at complication development (i.e., <30 years of age) was associated with an earlier age at natural menopause.

RESULTS

Although results from multivariable linear regression models suggested a similar age at menopause between women with normo-albuminuria and those diagnosed with MA after 30 years of age, menopause occurred 2.06 years earlier (β±SE=-2.06±1.08) among women diagnosed with MA before age 30 (p=0.06). No significant association was observed for other complications.

CONCLUSION

Among women with type 1 diabetes, menopause appears to occur earlier in those diagnosed with MA before age 30 compared to those with normo-albuminuria, suggesting that vascular dysfunction associated with early microvascular disease may affect ovarian aging.

Skin intrinsic fluorescence scores are a predictor of all-cause mortality risk in type 1 diabetes: The Epidemiology of Diabetes Complications study

AIMS

We assessed the association of skin intrinsic fluorescence (SIF) scores, as a measure of advanced glycation end-products (AGE), with all-cause mortality in type 1 diabetes (T1D).

METHODS

This is an observational retrospective study of a convenience sample from the Epidemiology of Diabetes Complications (EDC) study. AGEs were measured with a SIF score between 2007 and 2014; vital status was assessed in 2020.

RESULTS

Among 245 participants, mean age was 48.6 ± 7.4 years, median diabetes duration was 39.5 years (IQR: 34.2, 44.9), and 53.5% were female. Compared to survivors, the deceased (n = 20) were older, with higher SIF scores, longer diabetes duration, lower body mass index (BMI), and an adverse risk factor profile (all p≤0.05). Univariate Cox regression showed a marginal association between SIF score and mortality (HR: 1.1, 95% CI 0.9-1.2, p = 0.06), which persisted after adjustment for multiple daily insulin shots/pump (MDI) use (HR: 1.1, 95% CI 1.0-1.2, p = 0.04). This association was attenuated after adjustment for T1D duration, A_1c months, or estimated glomerular filtration rate (eGFR).

CONCLUSIONS

In individuals with long duration T1D, SIF scores adjusted for MDI predicted all-cause mortality, although this association was attenuated after adjustments. Given the nature of sampling and small number of events, our findings require replication.

High-Sensitivity Cardiac Troponin-T and N-Terminal Prohormone of B-Type Natriuretic Peptide in Relation to Cardiovascular Outcomes in Type 1 Diabetes

OBJECTIVE

High-sensitivity cardiac troponin-T (hs-cTnT) and N-terminal prohormone of B-type natriuretic peptide (NT-proBNP), biomarkers of cardiovascular disease (CVD) and heart failure, respectively, have not been widely studied in type 1 diabetes (T1D). We evaluated whether their assessment in T1D enhances the prediction of CVD and major adverse cardiovascular events (MACE).

RESEARCH DESIGN AND METHODS

hs-cTnT and NT-proBNP were analyzed on the Roche Cobas E601 using the first available stored specimen (n = 581; mean age 29 years and diabetes duration 21 years). CVD was defined as CVD death, myocardial infarction, coronary revascularization, angina, ischemia, or stroke, and MACE as CVD death, myocardial infarction, or stroke.

RESULTS

Median hs-cTnT (5.0 ng/L; interquartile range <3.0, 10.0) was higher among men (P < 0.0001), whereas median NT-proBNP (22.0 ng/L; 7.0, 61.0) did not differ by sex. In Cox models, log hs-cTnT (hazard ratio [HR] 1.38, P = 0.0006) and log NT-proBNP (HR 1.24, P = 0.0001) independently predicted CVD during 21 years of follow-up. However, their addition to models, singly or together, did not significantly improve CVD prediction. Furthermore, a marginally significant sex interaction was observed (P = 0.06), indicating that the hs-cTnT prediction was limited to men. hs-cTnT and NT-proBNP also predicted MACE, although only NT-proBNP remained significant (HR 1.27, P = 0.0009) when the biomarkers were included in a model simultaneously. Nonetheless, their addition to multivariable models did not enhance MACE prediction.

CONCLUSIONS

Sex differences were observed in the concentration and predictive ability of hs-cTnT and NT-proBNP in T1D. Overall, their addition to traditional risk factor models increased the area under the curve for neither CVD nor MACE.

Costs and outcomes of "intermediate" vs "minimal" care for youth-onset type 1 diabetes in six countries

OBJECTIVE

Data are needed to demonstrate that providing an "intermediate" level of type 1 diabetes (T1D) care is cost-effective compared to "minimal" care in less-resourced countries. We studied these care scenarios in six countries.

METHODS

We modeled the complications/costs/mortality/healthy life years (HLYs) associated with "intermediate" care including two blood glucose tests/day (mean HbA1c 9.0% [75 mmol/mol]) in three lower-gross domestic product (GDP) countries (Mali, Tanzania, Pakistan), or three tests/day (mean HbA1c 8.5% [69 mmol/mol]) in three higher-GDP countries (Bolivia, Sri Lanka, Azerbaijan); and compared findings to "minimal" care (mean HbA1c 12.5% [113 mmol/mol]). A discrete time Markov illness-death model with age and calendar-year-dependent transition probabilities was developed, with inputs of 30 years of complications and Standardized Mortality Rate data from the youth cohort in the Pittsburgh Epidemiology of Diabetes Complications Study, background mortality, and costs determined from international and local prices.

RESULTS

Cumulative 30 years incidences of complications were much lower for "intermediate care" than "minimal care", for example, for renal failure incidence was 68.1% (HbA1c 12.5%) compared to 3.9% (9%) and 2.4% (8.5%). For Mali, Tanzania, Pakistan, Bolivia, Sri Lanka, and Azerbaijan, 30 years survival was 50.1%/52.7%/76.7%/72.5%/82.8%/89.2% for "intermediate" and 8.5%/10.1%/39.4%/25.8%/45.5%/62.1% for "minimal" care, respectively. The cost of a HLY gained as a % GDP/capita was 141.1%/110.0%/52.3%/41.8%/17.0%/15.6%, respectively.

CONCLUSIONS

Marked reductions in complications rates and mortality are achievable with "intermediate" T1D care achieving mean clinic HbA1c of 8.5% to 9% (69-75 mmol/mol). This is also "very cost-effective" in four of six countries according to the WHO "Fair Choices" approach which costs HLYs gained against GDP/capita.

Risk factors differ by first manifestation of cardiovascular disease in type 1 diabetes

AIMS

We compared risk factors for three CVD manifestations and a composite outcome over 25 years' follow-up in the Pittsburgh Epidemiology of Diabetes Complications (EDC) prospective cohort study of childhood-onset (<17 years) type 1 diabetes (n = 658).

METHODS

First CVD manifestations examined were: (1) major atherosclerotic cardiovascular event (MACE, i.e. CVD death, myocardial infarction, stroke), (2) coronary revascularization, (3) soft coronary artery disease (CAD, i.e. ischemia ECG, angina), and a (4) composite (MACE + revascularization) outcome. Baseline and time-varying mean and current risk factors, including medication use, were assessed, in diabetes duration-adjusted models.

RESULTS

MACE (n = 107) was predicted by ln(albumin excretion rate) (AER, HR = 1.3, p < 0.0001), systolic BP (SBP, HR = 1.03, p < 0.0001), white blood cell count (WBC, HR = 1.2, p < 0.0001), HbA1c (HR = 1.2p = 0.03), LDLc (HR = 1.01, p = 0.03). Soft CAD (n = 91) was predicted by ln(AER) (HR = 1.2, p = 0.004), SBP (HR = 1.03, p = 0.0002), WBC (HR = 1.2, p = 0.0003), HbA1c (HR = 1.2, p = 0.005). Revascularization (n = 38) was predicted by LDLc (HR = 1.03, p < 0.0001), eGFR (HR = 0.98, p = 0.002), HbA1c (HR = 1.3, p = 0.03). Adding revascularization to MACE enhanced the role of LDLc, while diminishing that of HbA1c, compared to MACE alone.

CONCLUSIONS

Important risk factor associations may be affected by examining composite CVD outcomes. More research is needed to determine how to best incorporate revascularization into composite CVD definitions.

Mediation analysis for estimating cardioprotection of longitudinal RAS inhibition beyond lowering blood pressure and albuminuria in type 1 diabetes

PURPOSE

We assessed the extent of cardiovascular benefit of renin-angiotensin system (RAS) inhibition beyond lowering blood pressure (BP) and albuminuria in type 1 diabetes (T1D).

METHODS

This cohort study included 605 T1D participants from the Pittsburgh Epidemiology of Diabetes Complications study without baseline coronary artery disease (CAD). Participant follow-up extended through 25 years. We implemented marginal structural models to estimate total effect of and controlled direct effect by isolating the role of BP or albuminuria in mediating the relation between RAS inhibitors and CAD.

RESULTS

Total effect of longitudinal RAS inhibition treatment was associated with 38% decreased CAD risk (HR [95% CI]: 0.62 [0.23, 1.77]). The controlled direct effect of RAS inhibition was a 27% risk reduction (HR: 0.73 [0.20, 2.59]) when isolating the role of BP and 26% risk reduction (HR: 0.74 [0.16, 3.35]) when isolating the role of albuminuria. The mediation proportion for each 10 mm Hg systolic BP and each 1 log unit of albumin excretion rate were 34% and 37%, respectively.

CONCLUSION

Our findings suggest that BP regulation and albuminuria reduction can only partially explain cardiovascular benefit of RAS inhibition on CAD in T1D, supporting the assertion that RAS inhibitors provide additional cardioprotection beyond lowering BP and albuminuria.

Prognostic Significance of Pulse Pressure and Other Blood Pressure Components for Coronary Artery Disease in Type 1 Diabetes

BACKGROUND

To compare in individuals with type 1 diabetes the prediction of incident coronary artery disease (CAD) by components of resting blood pressure-systolic, diastolic, pulse pressure, and mean arterial pressure.

METHODS

In 605 participants without known CAD at baseline and followed sequentially for 25 years, we used Cox modeling built for each blood pressure component associated with incident CAD, overall and stratified by age (<35 and ≥35 years) or hemoglobin A1c (HbA1c) (<9% and ≥9%).

RESULTS

Baseline mean age and diabetes duration were 27 and 19 years, respectively. We observed an early asymptote and then fall in diastolic blood pressure in their late 30s and early 40s in this group of type 1 diabetes individuals, followed by an early rise of pulse pressure. Adjusted hazard ratios (HR) (95% con) for CAD associated with 1 SD pressure increase were 1.35 (1.17, 1.56) for systolic pressure; 1.30 (1.12, 1.51) for diastolic pressure; 1.20 (1.03, 1.39) for pulse pressure; and 1.35 (1.17, 1.56) for mean arterial pressure. Pulse pressure emerged as a strong predictor of CAD at age ≥ 35 years (HR: 1.49 [1.15, 1.94]) and for HbA1c ≥ 9% (HR: 1.32 [1.01, 1.72]).

CONCLUSIONS

Individuals with type 1 diabetes may manifest early vascular aging by an early decline in diastolic blood pressure and rise in pulse pressure, the latter parameter becoming a comparable to systolic blood pressure in predictor incident CAD in those aged over 35 years and those with poor glycemic control.

Optimal Blood Pressure Thresholds for Minimal Coronary Artery Disease Risk in Type 1 Diabetes

OBJECTIVE

We aimed to determine optimal blood pressure (BP) thresholds for minimizing coronary artery disease (CAD) risk in people with childhood-onset type 1 diabetes.

RESEARCH DESIGN AND METHODS

The Pittsburgh Epidemiology of Diabetes Complications (EDC) Study participants without known CAD at baseline (n = 605) were included and followed for 25 years. The associations of time-weighted BP measures (systolic BP [SBP], diastolic BP [DBP], and mean arterial pressure) with incident CAD were examined by using Cox models. Areas under the receiver operating characteristic curve (AUC) were summarized by different cut points of time-weighted BPs. Risk stratification analyses were then performed on the basis of BP (<120/80 vs. ≥120/80 mmHg) and HbA1c (<8% vs. ≥8%).

RESULTS

Baseline mean age was 27 years. Half of the cohort were women and 98% were white. A dose-gradient association was observed for categorized time-weighted BPs and CAD. According to AUC, the optimal cut point for SBP was 120 mmHg and for DBP was 80 mmHg. BP ≥120/80 mmHg was associated with a 1.9 times (95% CI 1.4, 2.6) greater risk of developing CAD than that for BP <120/80 mmHg. Participants with good control of both BP and HbA1c had BP <120/80 mmHg and HbA1c <8%. Those with only high BP (hazard ratio [HR] 2.0 [95% CI 1.1, 3.9]) carried a similar risk of developing CAD as those with only high HbA1c (HR 1.6 [95% CI 0.97, 2.8]).

CONCLUSIONS

The optimal BP threshold associated with minimal CAD risk is 120/80 mmHg in young adults with childhood-onset type 1 diabetes.

Persistent C-peptide levels and microvascular complications in childhood onset type 1 diabetes of long duration

AIMS

The aim was to determine if persistent c-peptide in long duration childhood onset (<17 years) type 1 diabetes (T1D) related to microvascular complications.

METHODS

Pittsburgh Epidemiology of Diabetes Complications (EDC) participants (n = 185) had serum c-peptide levels measured by Mercodia ultra-sensitive ELISA at the 25-year follow-up exam. Microvascular complications between those with and without detectable c-peptide were compared.

RESULTS

Eighteen (9.7%) participants had detectable median c-peptide levels of 3.8 (2.6, 12.2) pmol/L and did not differ from those without detectable levels. No differences in microalbuminuria, confirmed distal symmetric polyneuropathy, renal failure, or between those with one or more complications were found between the two groups. Proliferative retinopathy (PR) was marginally lower in those with detectable c-peptide (33.3% vs 55.1%, p = 0.08). However, those with c-peptide were somewhat less likely to have fasted for a full 8-h (66.7% vs. 84.9%, p = 0.09). Excluding those not fully fasted, PR no longer approached significance but macroalbuminuria became marginally lower in those with detectable levels (23.4% vs 0%, p = 0.07).

CONCLUSIONS

Low levels of c-peptide in T1D patients of long duration were detected but were not strongly related to microvascular complications.

Periodontal disease, smoking, cardiovascular complications and mortality in type 1 diabetes

AIM

To assess the role of periodontal disease (PD) as a predictor of coronary artery disease (CAD) and mortality in a prospective type 1 diabetes (T1D) cohort and to evaluate the role of smoking in this relationship.

METHODS

Data were based on 320 participants of the Pittsburgh Epidemiology of Diabetes Complications study of T1D who, during 1992-94, received a partial mouth periodontal exam, and who were followed for up to 19 years to ascertain complication incidence. PD was defined as clinical attachment loss of ≥4 mm for at least 10% of the examined sites. Predictors of all-cause mortality; Hard CAD (CAD death, myocardial infarction or revascularization), and Total CAD (Hard CAD, angina, ischemic ECG) were assessed using Cox models.

RESULTS

During 19 years of follow-up, 33.7% (97/288) developed CAD, 27.3% (83/304) developed Hard CAD, and 16.9% (54/320) died. Among current smokers, 46.4% (26/56) developed CAD, 42.7% (24/56) developed Hard CAD and 29.5% (18/61) died. PD was not associated with all-cause mortality, although it was a significant predictor of both CAD (HR = 1.12, CI = 1.01-1.23) and Hard CAD (HR = 1.30, CI = 1.11-1.51). As smoking modified the PD-CAD and PD-Hard CAD associations, analyses were stratified by smoking status. PD was associated with an increased risk of CAD (HR = 1.25, CI = 1.03-1.50) and Hard CAD (HR = 1.85, CI = 1.17-2.93) only among smokers.

CONCLUSION

PD was a significant predictor of CAD and Hard CAD among current smokers with T1D.

Recent trends over time in vascular disease in type 1 diabetes: insights from the Pittsburgh Epidemiology of Diabetes Complications study

Aims

To evaluate recent trends, by diagnosis year, in the cumulative incidence of vascular type 1 diabetes (T1D) complications and their risk factors up to 35 years duration.

Methods

Participants from the Epidemiology of Diabetes Complications study of childhood-onset T1D were categorized into three calendar year onset cohorts: 1965-69, 1970-74, and 1975-80. All-cause, cardiovascular and renal mortality were determined both on the complete cohort (n=440) as well as in the subset with clinical examinations (n=363). Coronary artery disease (CAD, CAD death, myocardial infarction, revascularization, angina and ischemic ECG abnormalities); lower extremity arterial disease (LEAD, abnormal Ankle Brachial Index/amputation/intermittent claudication); distal symmetric polyneuropathy (DSP, clinical exam); cardiac autonomic neuropathy (CAN, abnormal heart rate response to deep breathing); overt nephropathy (ON, albumin excretion rate>200 μg/min) and proliferative retinopathy (PR, fundus photography) were assessed on the subset with clinical examinations.

Results

While all-cause, cardiovascular and renal mortality improved with a more recent diagnosis in the overall cohort, no univariate differences were observed for complications requiring examination (CAD, DSP, CAN, ON), although a borderline trend toward improved complication-free survival with a more recent onset was observed for PR (p=0.06). LEAD incidence showed an anomalous pattern, being highest in the 1975-80 and lowest in the 1970-74 cohort (p=0.009). Allowing for risk factors over time did not materially change these results.

Conclusions

Despite declines in all-cause, cardiovascular and renal mortality in the total cohort, no improvements were observed in either mortality or complication incidence with a more recent onset in the examined cohort.

Risk Factor Modeling for Cardiovascular Disease in Type 1 Diabetes in the Pittsburgh Epidemiology of Diabetes Complications (EDC) Study: A Comparison With the Diabetes Control and Complications Trial/Epidemiology of Diabetes Interventions and Complications Study (DCCT/EDIC)

In a recent Diabetes Control and Complications Trial (DCCT)/Epidemiology of Diabetes Interventions and Complications (EDIC) study report, mean HbA_1c was the strongest predictor of cardiovascular disease (CVD) after age. In DCCT/EDIC, mean diabetes duration was 6 years (median 4) at baseline and those with high blood pressure or cholesterol were excluded. We now replicate these analyses in the Pittsburgh Epidemiology of Diabetes Complications (EDC) prospective cohort study of childhood-onset (at <17 years of age) type 1 diabetes, with similar age (mean 27 years in both studies) but longer diabetes duration (mean 19 years and median 18 years) and no CVD risk factor exclusion at baseline. CVD incidence (CVD death, myocardial infarction (MI), stroke, revascularization, angina, or ischemic electrocardiogram) was associated with diabetes duration, most recent albumin excretion rate (AER), updated mean triglycerides, baseline hypertension, baseline LDL cholesterol, and most recent HbA_1c Major atherosclerotic cardiovascular events (CVD death, MI, or stroke) were associated with diabetes duration, most recent AER, baseline systolic blood pressure, baseline smoking, and updated mean HbA_1c Compared with findings in DCCT/EDIC, traditional risk factors similarly predicted CVD; however AER predominates in EDC and HbA_1c in DCCT/EDIC. Thus, the relative impact of HbA_1c and kidney disease in type 1 diabetes varies according to diabetes duration.

The role of coronary artery calcification testing in incident coronary artery disease risk prediction in type 1 diabetes

AIMS/HYPOTHESIS

We sought to assess the role of coronary artery calcification (CAC) and its progression in predicting incident coronary artery disease (CAD) in individuals with type 1 diabetes using data from the Pittsburgh Epidemiology of Diabetes Complications (EDC) Study.

METHODS

The present study examined 292 participants who had at least one CAC measure and were free from CAD at baseline; 181 (62%) had repeat CAC assessments 4-8 years later and did not develop CAD between the two CAC measures. The HRs of incident CAD events were estimated using Cox models in categorised or in appropriately transformed CAC scores. C statistics and net reclassification improvement (NRI) were used to assess the added predictive value of CAC for incident CAD.

RESULTS

At baseline, the mean age of participants was 39.4 years and the mean diabetes duration was 29.5 years. There were 76 participants who experienced a first incident CAD event over an average follow-up of 10.7 years. At baseline, compared with those without CAC (Agatston score = 0), the adjusted HR (95% CI) in groups of 1-99, 100-399 and ≥400 was 3.1 (1.6, 6.1), 4.4 (2.0, 9.5) and 4.8 (1.9, 12.0), respectively. CAC density was inversely associated with incident CAD in those with CAC volume ≥100 (HR 0.3 [95% CI 0.1, 0.9]) after adjusting for volume score. Among participants with repeated CAC measures, annual CAC progression was positively associated with incident CAD after controlling for baseline CAC. The HR (95% CI) for above vs below the median annual CAC volume progression was 3.2 (1.2, 8.5). When compared with a model that only included established risk factors, the addition of CAC improved the predictive ability for incident CAD events in the whole group.

CONCLUSIONS/INTERPRETATION

CAC is strongly associated with incident CAD events in individuals with type 1 diabetes; its inclusion in CAD risk models may lead to improvement in prediction over established risk factors.

Greater progression of coronary artery calcification is associated with clinically relevant cognitive impairment in type 1 diabetes

BACKGROUND AND AIMS

We assessed the predictive role of coronary artery calcification (CAC) in clinically relevant cognitive impairment in 148 middle-aged individuals with childhood-onset type 1 diabetes (T1D) from the Pittsburgh Epidemiology of Diabetes Complications (EDC) Study.

METHODS

Baseline CAC was measured in 1996-98 and repeated 4-8 years later. Per extensive neuropsychological testing in 2010-15, 28% (41/148) of participants met the study definition of clinically relevant cognitive impairment (two or more of 7 select test scores ≥1.5SD worse than demographically appropriate published norms). Logistic regression models with backward selection were constructed for statistical analysis.

RESULTS

Mean age and T1D duration at first CAC measure were 37 and 29 years, respectively. A greater burden of initial CAC was associated with cognitive impairment determined 14 years later. Compared to Agatston score = 0, odds ratio (OR) and 95% confidence intervals (CI) of 0<-100, 100<-300 and >300 were 1.4 (0.6, 3.6), 2.3 (0.6, 9.7), and 7.9 (1.6, 38.5), respectively. With both initial and progression of CAC in the multivariable model, backward selection retained only CAC progression, showing it was significantly associated with cognitive impairment (OR [95% CI]: 1.7 [1.1, 2.9]). In those with an initial CAC>0, CAC density was marginally, inversely, associated with cognitive impairment when controlling for CAC volume (OR [95%CI]: 0.3 (0.1, 1.2), p value = 0.078).

CONCLUSIONS

Greater CAC burden was associated with clinically relevant cognitive impairment in middle-aged adults with childhood-onset T1D. CAC progression appears to be a more powerful predictor than initial calcification.

Celiac Autoimmunity Is Associated With Lower Blood Pressure and Renal Risk in Type 1 Diabetes

CONTEXT

Though the long-term consequences of celiac disease (CD) in type 1 diabetes are unclear, CD has been associated with increased prevalence of end-stage renal disease (ESRD) independent of type 1 diabetes.

OBJECTIVE

We evaluated whether celiac autoimmunity is related to the cumulative incidence of microalbuminuria [albumin excretion rate (AER) 20 to 200 µg/min], macroalbuminuria (AER >200 µg/min), and ESRD.

DESIGN, PATIENTS, AND METHODS

In the prospective follow-up of the Pittsburgh Epidemiology of Diabetes Complications study of childhood-onset type 1 diabetes, 618 participants were screened for tissue transglutaminase (tTG) antibodies with a clinical assay. Nephropathy outcomes were determined at 25 years of diabetes duration.

RESULTS

Overall, the 33 subjects (5.3%) with strongly positive tTG levels (≥3 times the upper limit of normal) or a reported clinical history of CD had lower baseline blood pressure and lipid values. At 25 years of diabetes duration, a lower cumulative incidence of macroalbuminuria in strongly positive subjects compared with those with negative serology (3.6% vs 30.0%; P = 0.003) remained significant after adjustment for age, HbA1c, lipid measures, and blood pressure (adjusted P = 0.004). No considerable differences between these subjects and tTG-negative groups were found for microalbuminuria (40.0% vs 57.1%) or ESRD (0 vs 4.1%).

CONCLUSIONS

These findings show that strongly positive celiac autoimmunity status in individuals with childhood-onset type 1 diabetes is associated with lower baseline blood pressure and cholesterol measurements as well as lower macroalbuminuria risk after 25 years of type 1 diabetes duration with no increase in the risk of microalbuminuria or ESRD.

Hemoglobin A1c Level and Cardiovascular Disease Incidence in Persons With Type 1 Diabetes: An Application of Joint Modeling of Longitudinal and Time-to-Event Data in the Pittsburgh Epidemiology of Diabetes Complications Study

Type 1 diabetes (T1D) is associated with increased risk of cardiovascular disease (CVD), but hyperglycemia (measured by hemoglobin A1c (HbA1c) level), which characterizes T1D, has itself been an inconsistent predictor of CVD incidence. However, only baseline HbA1c or a summary measure (e.g., mean level over follow-up) is usually analyzed. Joint models allow simultaneous modeling of repeatedly measured longitudinal covariates, using random effects, and time-to-event data. We evaluated data from the Pittsburgh Epidemiology of Diabetes Complications Study, an ongoing prospective cohort study of childhood-onset T1D that has followed participants since 1986-1988 and has repeatedly found little association between baseline HbA1c or mean follow-up HbA1c and coronary artery disease incidence. Of 561 participants without CVD at baseline, 263 (46.9%) developed CVD over a period of 25 years (1986-2014). In joint models, each 1% unit increase in HbA1c trajectory was associated with a 1.26-fold increased risk of CVD (95% confidence interval: 1.07, 1.45), after adjustment for baseline levels of other CVD risk factors, and a 1.13-fold increased risk (95% confidence interval: 0.99, 1.32) after adjustment for updated mean levels of other CVD risk factors. These findings, which support the need for good glycemic control to prevent CVD in persons with T1D, underscore the importance of utilizing methods incorporating within-subject variation over time when analyzing and interpreting longitudinal cohort study data.

Left ventricular systolic dysfunction predicts long-term major microvascular complication outcomes in type 1 diabetes. The Pittsburgh Epidemiology of Diabetes Complications (EDC) study of childhood onset diabetes

OBJECTIVES

We aimed to assess association between abnormal LVEF, in the absence of coronary artery disease (CAD), and 25-year incidence of major outcomes of diabetes (MOD) in a cardiology substudy of the Pittsburgh Epidemiology of Diabetes Complications cohort of childhood-onset type 1 diabetes.

METHODS

115 normotensive type 1 diabetes individuals without known CAD, underwent a baseline exercise radionuclide ventriculography. Abnormal LVEF was defined as a resting ejection fraction <50% or a failure to increase ejection fraction with exercise by >5% (men) or a fall in ejection fraction with exercise (women). Cox proportional hazards models were used to predict the composite endpoint of MOD (first instance of major CAD, stroke, end-stage renal disease, blindness, amputation or diabetes-related death).

RESULTS

Mean baseline age was 28 and diabetes duration 19 years. In a mean follow-up of 19 years, 50 MOD events were identified. Allowing for established risk factors at baseline, abnormal LVEF (n = 22) independently predicted MOD incidence (HR = 2.12, 95% CI: 1.12-4.00, p = 0.022) but not major CAD (HR = 1.33, 95% CI: 0.53-3.33, p = 0.539).

CONCLUSIONS

An abnormal LVEF may identify diabetic cardiomyopathy and predict long term risk of MOD (but not CAD alone) in type 1 diabetes individuals, consistent with it reflecting microvascular disease.

A Contemporary Estimate of Total Mortality and Cardiovascular Disease Risk in Young Adults With Type 1 Diabetes: The Pittsburgh Epidemiology of Diabetes Complications Study

OBJECTIVE

The degree to which mortality and cardiovascular disease (CVD) incidence remains elevated in young U.S. adults with type 1 diabetes (T1DM) is unclear. We determined contemporary rates for adults <45 years old with long-standing, childhood-onset T1DM from the Pittsburgh Epidemiology of Diabetes Complications (EDC) Study.

RESEARCH DESIGN AND METHODS

Members of the EDC Study cohort <45 years old during the 1996-2012 follow-up period (n = 502) were studied. Mortality and CVD rates were calculated for those aged 30-39 and 40-44 years. Data from the background Allegheny County, Pennsylvania, population were used to calculate age- and sex-matched standardized mortality (SMR) and incidence rate ratios (IRR).

RESULTS

In both age groups, the SMR for total mortality was ∼5 (95% CIs: 30-39-year-olds, 2.8, 7.2; 40-44-year-olds, 3.4, 7.8). CVD mortality SMRs ranged from 19 (95% CI 11, 32) to 33 (95% CI 17, 59). Hospitalized CVD IRR was ∼8 (95% CIs: 30-39-year-olds, 2.5, 18.9; 40-44-year-olds, 4.5, 12.8); revascularization procedures account for much of the increased risk. For all outcomes, the relative risk was larger in women. Participants aged 30-39 years had 6.3% (95% CI 3.8, 9.8) absolute 10-year CVD risk, approaching the American College of Cardiology/American Heart Association-recommended cut point of 7.5% for initiation of statin therapy in older adults.

CONCLUSIONS

Total and CVD mortality and hospitalized CVD are all significantly increased in this contemporary U.S. cohort of young adults with long-standing T1DM. These findings support more aggressive risk factor management in T1DM, especially among women.

Risk stratification for 25-year cardiovascular disease incidence in type 1 diabetes: Tree-structured survival analysis of the Pittsburgh Epidemiology of Diabetes Complications study

BACKGROUND

The formal identification of subgroups with varying levels of risk is uncommon in observational studies of cardiovascular disease, although such insight might be useful for clinical management.

METHODS

Tree-structured survival analysis was utilized to determine whether there are meaningful subgroups at varying levels of cardiovascular disease risk in the Pittsburgh Epidemiology of Diabetes Complications study, a prospective cohort study of childhood-onset (<17 years old) type 1 diabetes.

RESULTS

Of the 561 participants free of cardiovascular disease (coronary artery disease, stroke or lower extremity arterial disease) at baseline, 263 (46.9%) had an incident cardiovascular disease event over the 25-year follow-up. Tree-structured survival analysis revealed a range of risk groups, from 24% to 85%, which demonstrate that those with short diabetes duration and elevated non-high-density lipoprotein cholesterol have similar cardiovascular disease risk to those with long diabetes duration and that renal disease is a better discriminator of risk in men than in women.

CONCLUSION

Our findings suggest that subgroups with major cardiovascular disease risk differences exist in this type 1 diabetes cohort. Using tree-structured survival analysis may help to identify these groups and the interrelationships between their associated risk factors. This approach may improve our understanding of various clinical pathways to cardiovascular disease and help target intervention strategies.

Changing impact of modifiable risk factors on the incidence of major outcomes of type 1 diabetes: the Pittsburgh Epidemiology of Diabetes Complications Study

OBJECTIVE

The incidence of type 1 diabetes complications appears to be decreasing, but relative contributions of risk factors are unclear. We thus estimated the effect of modifiable risk factors on the incidence of a composite end point, major outcomes of diabetes (MOD).

RESEARCH DESIGN AND METHODS

The Pittsburgh Epidemiology of Diabetes Complications (EDC) Study was used to derive two cohorts based on diabetes diagnosis year (1960-1969 and 1970-1980). Baseline exam data in the current analysis for the 1960s group were collected in 1986-1988 and for the 1970s in 1996-1998. Each group was followed for 8 years for MOD incidence (diabetes-related death, myocardial infarction, revascularization procedure/blockage ≥50%, stroke, end-stage renal disease, blindness, and amputation). Assessed risk factors include the following: HbA1c, hypertension, microalbuminuria, BMI, hypercholesterolemia, and smoking. Accelerated failure time models were used to estimate the acceleration factor.

RESULTS

MOD incidence decreased in the 1970s cohort (15.8% [95% CI 11.6-21.4]) compared with the 1960s (22.6% [17.0-29.1]) over the 8-year follow-up (P = 0.06). Hypertension and microalbuminuria were associated with significantly accelerated MOD incidence in both cohorts (P < 0.01 for both). High HbA1c (P = 0.0005), hypercholesterolemia (P = 0.01), and current smoking (P = 0.003) significantly accelerated the incidence of MOD in the 1960s but not 1970s cohort. BMI was not associated with MOD in either cohort.

CONCLUSIONS

These results suggest that hypertension and microalbuminuria remain important predictors of complications that are not being adequately addressed.

Associations between socioeconomic status and major complications in type 1 diabetes: the Pittsburgh epidemiology of diabetes complication (EDC) Study

PURPOSE

To understand the effect of socioeconomic status (SES) on the risk of complications in type 1 diabetes (T1D), we explored the relationship between SES and major diabetes complications in a prospective, observational T1D cohort study.

METHODS

Complete data were available for 317 T1D persons within 4 years of age 28 (ages 24-32) in the Pittsburgh Epidemiology of Diabetes Complications Study. Age 28 was selected to maximize income, education, and occupation potential and to minimize the effect of advanced diabetes complications on SES.

RESULTS

The incidences over 1 to 20 years' follow-up of end-stage renal disease and coronary artery disease were two to three times greater for T1D individuals without, compared with those with a college degree (p < .05 for both), whereas the incidence of autonomic neuropathy was significantly greater for low-income and/or nonprofessional participants (p < .05 for both). HbA(1c) was inversely associated only with income level. In sex- and diabetes duration-adjusted Cox models, lower education predicted end-stage renal disease (hazard ratio [HR], 2.9; 95% confidence interval [95% CI], 1.1-7.7) and coronary artery disease (HR, 2.5, 95% CI, 1.3-4.9), whereas lower income predicted autonomic neuropathy (HR, 1.7; 95% CI, 1.0-2.9) and lower-extremity arterial disease (HR, 3.7; 95% CI, 1.1-11.9).

CONCLUSIONS

These associations, partially mediated by clinical risk factors, suggest that lower SES T1D individuals may have poorer self-management and, thus, greater complications from diabetes.

Association of socioeconomic status with mortality in type 1 diabetes: the Pittsburgh epidemiology of diabetes complications study

PURPOSE

Socioeconomic status (SES) as a risk factor for mortality in type 1 diabetes (T1D) has not been adequately studied prospectively.

METHODS

Complete clinical and SES (income, education, occupation) data were available for 317 T1D participants in the Pittsburgh Epidemiology of Diabetes Complications Study within 4 years of age 28 (chosen to maximize income, education, and occupational potential, and to minimize the SES effect of advanced diabetes complications). Vital status was determined as of 1/1/2008.

RESULTS

Over a median 16 years of follow-up, 34 (10.7%) deaths occurred (standardized mortality ratios [SMRs] = 4.1, 95% confidence interval [CI]: 2.7-5.5). SMRs did not differ from the general population for those in the highest education and income groups, whereas in those with low SES, SMRs were increased. Mortality rates were three times lower for individuals with a college degree versus without a college degree (p = 0.004) and nearly four times lower for the highest income versus lower income groups (p = 0.04). In Cox models adjusting for diabetes duration and sex, education was the only SES measure predictive of mortality (hazard ratio [HR] = 3.0, 95% CI: 1.2-7.8), but lost significance after adjusting for HbA(1c), non-HDL cholesterol, hypertension, and microalbuminuria (HR = 2.1, 95% CI: 0.8-5.6).

CONCLUSIONS

The strong association of education with mortality in T1D is partially mediated by better glycemic, lipid, and blood pressure control.

Sex differences in the development of kidney disease in individuals with type 1 diabetes mellitus: a contemporary analysis

BACKGROUND

Kidney disease in patients with type 1 diabetes historically has been believed to be more prevalent in men. Because recent data do not reflect this pattern, we evaluated whether a sex difference persists.

STUDY DESIGN

Prospective cohort study.

SETTING & PARTICIPANTS

We used 18-year follow-up data from the Pittsburgh Epidemiology of Diabetes Complications Study (n = 788; baseline mean age, 27 years; diabetes duration, 19 years).

PREDICTOR OR FACTOR

Sex and diagnosis interval (1950-1964 or 1965-1980).

OUTCOMES

Cumulative incidences of macroalbuminuria (albumin excretion rate >200 μg/min) and end-stage renal disease (ESRD; kidney failure, dialysis, or transplant) were evaluated at 20, 25, and 30 years of diabetes duration. To address potential survival bias, death certificate information was included in determining ESRD for those who died before baseline (n = 145). Analyses were stratified by diagnosis year (1950-1964 or 1965-1980).

OTHER MEASUREMENTS

Kidney disease risk factor information was available.

RESULTS

A significant interaction was noted between sex and diagnosis cohort for ESRD incidence by 25 (P = 0.002) and 30 (P < 0.001) years' duration. Thus, within the 1950-1964 cohort (210 men and 180 women), ESRD incidence was higher in men compared with women by 25 (30.6% vs 18.0%, respectively) and 30 (43.4% vs 24.6%, respectively) years' duration of type 1 diabetes. However, in the 1965-1980 cohort (260 men and 283 women), the incidence was higher in women (7.6% vs 13.8% by 25 years [P = 0.04] and 13.7% vs 21.0% by 30 years' duration [P = 0.09] in men vs women, respectively). Results were similar for macroalbuminuria.

LIMITATIONS

Study participants were not followed up from the onset of diabetes; thus, risk-factor data from that period are lacking.

CONCLUSIONS

Our data suggest that the male excess of type 1 diabetic kidney disease cases observed in the earlier cohort has been eliminated in the younger cohort. The reason for this dramatic change presently is unclear, but should be addressed in subsequent studies.

In the absence of renal disease, 20 year mortality risk in type 1 diabetes is comparable to that of the general population: a report from the Pittsburgh Epidemiology of Diabetes Complications Study

AIMS/HYPOTHESIS

The FinnDiane Study has reported that mortality in type 1 diabetes is not increased over a 7 year follow-up in the absence of renal disease (RD). Using the Pittsburgh Epidemiology of Diabetes Complications (EDC) Study population (n = 658) of childhood-onset type 1 diabetes (age <17 years), the present study sought to replicate and expand these findings to a 20 year follow-up (as of 1 January 2008) and examine cause of death by renal status.

METHODS

At baseline (1986-1988), mean age and duration of diabetes were 28 and 19 years, respectively. RD was defined as an albumin excretion rate ≥20 μg/min from multiple samples and grouped as microalbuminuria (MA; 20-200 μg/min), overt nephropathy (ON; >200 μg/min), or end stage renal disease (ESRD; dialysis or renal transplantation).

RESULTS

At baseline, 311 (47.3%) individuals had RD (MA 21.3%, ON 22.2% and ESRD 3.8%). During a median 20 year follow-up, there were 152 deaths (23.1%). Mortality was 6.2 (95% CI 5.2-7.2) times higher than expected, with standardised mortality ratios of 2.0 (1.2-2.8) for normoalbuminuria (NA); 6.4 (4.4-8.4) for MA; 12.5 (9.5-15.4) for ON; and 29.8 (16.8-42.9) for ESRD. Excluding those (n = 64) with NA who later progressed to RD, no significant excess mortality was observed in the remaining NA group (1.2, 0.5-1.9), whose deaths were largely unrelated to diabetes.

CONCLUSIONS/INTERPRETATION

These data confirm the importance of RD, including persistent microalbuminuria, as a marker of mortality risk and suggest that type 1 diabetes patients without renal disease achieve long-term survival comparable to the general population.

Augmentation pressure and subendocardial viability ratio are associated with microalbuminuria and with poor renal function in type 1 diabetes

In this report we explore the hypothesis that arterial stiffness indices, which predict cardiovascular disease, might also correlate with microalbuminuria (MA) in type 1 diabetes (T1D), and thus have potential for risk assessment. Three pulse wave analysis (PWA) indices, measured using the SphygmoCor device, were evaluated on 144 participants with childhood-onset T1D. These variables, augmentation index (AIx), augmentation pressure (AP) and subendocardial viability ratio (SEVR, an estimate of myocardial perfusion) (an estimate of myocardial perfusion), were each analysed cross-sectionally in relation to both prevalent MA (defined as albuminuria excretion rate (AER) = 20-199 microg/min) and renal function (assessed by both eGFR and serum cystatin C). AP and SEVR were each univariately associated with AER, estimated glomerular filtration rate (eGFR) and cystatin C. Lower SEVR was also independently related to the presence of MA and degree of albuminuria within normo- and microalbuminuric participants. SEVR, not AP, was independently and negatively associated with both measures of renal function. SEVR is a better predictor of AER than brachial blood pressure measures in those without clinical proteinuria, indicating a potential use for PWA in the early detection of individuals at risk for cardiovascular and renal complications of T1D.

Development and progression of renal insufficiency with and without albuminuria in adults with type 1 diabetes in the diabetes control and complications trial and the epidemiology of diabetes interventions and complications study

OBJECTIVE

This multicenter study examined the impact of albumin excretion rate (AER) on the course of estimated glomerular filtration rate (eGFR) and the incidence of sustained eGFR <60 ml/min/1.73 m(2) in type 1 diabetes up to year 14 of the Epidemiology of Diabetes Interventions and Complications (EDIC) study (mean duration of 19 years in the Diabetes Control and Complications Trial [DCCT]/EDIC).

RESEARCH DESIGN AND METHODS

Urinary albumin measurements from 4-h urine collections were obtained from participants annually during the DCCT and every other year during the EDIC study, and serum creatinine was measured annually in both the DCCT and EDIC study. GFR was estimated from serum creatinine using the abbreviated Modification of Diet in Renal Disease equation.

RESULTS

A total of 89 of 1,439 subjects developed an eGFR <60 ml/min/1.73 m(2) (stage 3 chronic kidney disease on two or more successive occasions (sustained) during the DCCT/EDIC study (cumulative incidence 11.4%). Of these, 20 (24%) had AER <30 mg/24 h at all prior evaluations, 14 (16%) had developed microalbuminuria (AER 30-300 mg/24 h) before they reached stage 3 chronic kidney disease, and 54 (61%) had macroalbuminuria (AER >300 mg/24 h) before they reached stage 3 chronic kidney disease. Macroalbuminuria is associated with a markedly increased rate of fall in eGFR (5.7%/year vs. 1.2%/year with AER <30 mg/24 h, P < 0.0001) and risk of eGFR <60 ml/min/1.73 m(2) (adjusted hazard ratio 15.3, P < 0.0001), whereas microalbuminuria had weaker and less consistent effects on eGFR.

CONCLUSIONS

Macroalbuminuria was a strong predictor of eGFR loss and risk of developing sustained eGFR <60 ml/min/1.73 m(2). However, screening with AER alone would have missed 24% of cases of sustained impaired eGFR.

Haptoglobin genotype and renal function decline in type 1 diabetes

OBJECTIVE

Haptoglobin (Hp) binds free Hb, inhibiting Hb-induced oxidative damage. As oxidative stress has been associated with microvascular complications, we evaluated the relationship between Hp genotype and microalbuminuria, macroalbuminuria, end-stage renal disease (ESRD), and early renal function decline in type 1 diabetes.

RESEARCH DESIGN AND METHODS

Participants from the Epidemiology of Diabetes Complications Study with DNA available were studied for the incidence of microalbuminuria (albumin excretion rate [AER] 20-200 microg/min), macroalbuminuria (AER >200 microg/min), ESRD (renal dialysis or transplantation), and renal function decline (a decline > or =30 ml/min per 1.73 m(2) from baseline estimated [by the Cockcroft-Gault equation] glomerular filtration rate [eGFR] in those with baseline eGFR >60 ml/min per 1.73 m(2)).

RESULTS

The proportions with the Hp 2/2, 2/1, and 1/1 genotype were 43.4, 44.4, and 12.1%, respectively. During 18 years of follow-up, the incidence of eGFR decline, microalbuminuria, macroalbuminuria, and ESRD was 42.0, 40.5, 16.7, and 12.2%, respectively. No significant univariate differences were observed by Hp genotype. However, in multivariable Cox models, an approximately twofold increased risk was observed for the Hp 2/2 compared with the Hp 1/1 genotype for eGFR decline (hazard ratio 1.79 [95% CI 1.06-3.00]) and ESRD (2.74 [1.17-6.45]); no significant associations were observed for microalbuminuria or macroalbuminuria.

CONCLUSIONS

These data suggest that although Hp genotype is not associated with albuminuria per se, it may be an independent determinant of early renal function decline and progression to ESRD. Understanding these apparent contradictory findings may provide further insight into the pathogenesis of renal disease in type 1 diabetes.

Sequence of progression of albuminuria and decreased GFR in persons with type 1 diabetes: a cohort study

BACKGROUND

The sensitivity of albuminuria in predicting loss of kidney function has been questioned. We determined the sequence of kidney disease stages (microalbuminuria, macroalbuminuria, low estimated glomerular filtration rate [eGFR], and end-stage renal disease [ESRD]) and characterized those without albuminuria before a low eGFR.

STUDY DESIGN

The Pittsburgh Epidemiology of Diabetes Complications Study is a prospective cohort investigation of childhood-onset type 1 diabetes.

SETTING & PARTICIPANTS

480 study participants with eGFR greater than 60 mL/min/1.73 m(2) (mean age, 27 years; diabetes duration, 19 years at study entry) were prospectively followed up for 16 years.

OUTCOMES & MEASUREMENTS

Low eGFR was defined as creatinine clearance less than 60 mL/min/1.73 m(2) from timed urine collections; microalbuminuria, as albumin excretion rate between 20 to 200 microg/min (30 to 300 mg/24 h); macroalbuminuria, as albumin excretion rate greater than 200 microg/min (>300 mg/24 h); and ESRD, as dialysis or renal transplantation.

RESULTS

The 33 of 480 individuals (7%) who developed ESRD had prior albuminuria. 71 of 480 (15%) individuals developed low eGFR. 66 of 71 (93%) had prior/concurrent albuminuria, and 5 of 71 (7%) did not. Incident low eGFR values in the 5 patients were: (1) 54, (2) 58, (3) 59, (4) 59.7, and (5) 59.8 mL/min/1.73 m(2). 3 of 5 (60%; patients 1, 4, and 5) subsequently developed albuminuria. Final eGFRs in the 5 patients were: (1) 94, (2) 86, (3) 60, (4) 65, and (5) 54 mL/min/1.73 m(2), respectively.

LIMITATIONS

GFR and insulin sensitivity were not measured, but estimated. Incident decreased eGFR in patients without preceding/concurrent albuminuria may be caused by misclassification or a temporary eGFR decrease.

CONCLUSIONS

Moderately decreased eGFR may occur rarely in patients with type 1 diabetes without preceding albuminuria.

Progression of coronary artery calcium in type 1 diabetes mellitus

Coronary artery calcium (CAC) has been previously associated with atherosclerotic plaque disease and coronary events. Thus, identifying predictors of CAC progression may provide new insights for early risk-factor intervention and subsequent reduction of the rates of more severe atherosclerotic disease. The aim of this study was to identify risk factors for CAC progression and evaluate whether risk-factor change was related to CAC progression in a cohort of patients with type 1 diabetes mellitus (DM). Participants in the Pittsburgh EDC Study, a prospective investigation of childhood-onset type 1 DM, who underwent 2 electron beam tomographic screenings 4 years apart were selected for study (n = 222). CAC was calculated using the Agatston method of scoring, and progression was defined as an increase >2.5 in the square root-transformed CAC score. Adjusting for DM duration and initial CAC score, body mass index (BMI; odds ratio [OR] 1.13, 95% confidence interval [CI] 1.01 to 1.26), non-high-density lipoprotein cholesterol (OR 1.01, 95% CI 1.003 to 1.03), and albumin excretion rate (OR 1.30, 95% CI 1.03 to 1.63) were associated with CAC progression. When considering change in risk factors, an increase in BMI (OR 1.38, 95% CI 1.10 to 1.72) was also associated with CAC progression after adjustment. In conclusion, in this cohort with type 1 DM, in addition to baseline BMI, non-high-density lipoprotein cholesterol, albumin excretion rate, and all known coronary artery disease risk factors, weight gain further added to the prediction of CAC progression. Thus, weight control, in addition to lipid and renal management, may help retard atherosclerosis progression in persons with type 1 DM.

Lower-extremity arterial calcification as a correlate of coronary artery calcification

Coronary artery calcification (CAC) has been used as a testing modality for coronary atherosclerosis burden. In diabetes, arterial calcification in the tunica media is common and predicts renal and cardiovascular mortality. It is unknown whether the 2 calcification processes are related. We identified risk factors associated with lower-extremity arterial calcification (LEAC) and determined its relationship to the presence of CAC 6 years later and the incidence of complications in type 1 diabetes mellitus. A random sample of 190 participants from the Pittsburgh Epidemiology of Diabetes Complications Study, a prospective cohort of childhood-onset type 1 diabetes mellitus, received radiographs of their ankles and feet at the 4-year follow-up examination (1990-1992) and was followed up for approximately 6 years. At the 10-year examination, 121 of these individuals received an electron beam tomography scan. Male sex (odds ratio [OR] = 12.72, P < .0001), diabetes duration (OR = 4.53, P < .0001), and autonomic neuropathy (AN; OR = 5.92, P = .007) independently increased the odds of LEAC. Controlling for other known risk factors (duration and high-density lipoprotein cholesterol), we found that LEAC correlated with the presence of CAC 6 years later (OR = 1.12, P = .03), although adjusting for neuropathy attenuated this relationship (P = .08). LEAC also independently predicted AN but not the onset of other diabetes complications. Although arterial calcification in the lower extremities and the heart share many of the same risk factors, LEAC is an independent correlate of the later presence of CAC and AN. Thus, factors related to the calcification process in addition to vascular risk factors may play a role in determining the extent of CAC.

Mortality in African-Americans with Type 1 diabetes: The New Jersey 725

AIM

To determine rates and risk factors for all-cause mortality in African-Americans with Type 1 diabetes from a 3-year observational follow-up study of 725 African-Americans with Type 1 diabetes conducted between 1 January 1999 and 31 December 2001.

METHODS

Date of death was ascertained either from telephone contact with the patient's family or from relatives or on line review of the US Social Security death index.

RESULTS

Since the initial examination, 131 (18.1%) patients, 60 (20%) men and 71 (17%) women, have died. At the time of death, the mean age of the men was 40.7 +/- 10.6 years and that of the women 39.4 +/- 10.5 years. The median duration of diabetes at the baseline examination was 8.04 years, interquartile range (IQR) 3.76-15.22 years for men and median 10.54, IQR 4.49-18.36 years for women. Three-year mortality rates were 7.1% for women and 10.6% for men. Age-adjusted mortality rates were not significantly different between men and women. Relative to the general US and the New Jersey African-American population, standardized mortality ratios of African-Americans with Type 1 diabetes were 12 and six times greater for women and men, respectively. Older age, low socio-economic status, low body mass index, high diastolic blood pressure, macroangiopathy, proteinuria, severe diabetic retinopathy and heavy alcohol consumption were independent risk factors for all-cause mortality. In patients with microproteinuria at initial examination, the mortality rate for men was twice that of women.

CONCLUSION

Microproteinuria and other potentially modifiable factors, including hypertension, macroangiopathy and heavy alcohol consumption, are independent risk factors for mortality in this ethnic group.

The 30-year natural history of type 1 diabetes complications: the Pittsburgh Epidemiology of Diabetes Complications Study experience

Declining incidences in Europe of overt nephropathy, proliferative retinopathy, and mortality in type 1 diabetes have recently been reported. However, comparable data for the U.S. and trend data for neuropathy and macrovascular complications are lacking. These issues are addressed using the prospective observational Pittsburgh Epidemiology of Childhood-Onset Diabetes Complications Study. Participants were stratified into five cohorts by diagnosis year: 1950-1959, 1960-1964, 1965-1969, 1970-1974, and 1975-1980. Mortality, renal failure, and coronary artery disease (CAD) status were determined on the complete cohort (n = 906) at 20, 25, and 30 years. Overt nephropathy, proliferative retinopathy, and neuropathy were assessed at 20 and 25 years on the subset of participants with a clinical examination. There was a decreasing trend by diagnosis year for mortality, renal failure, and neuropathy across all time intervals (P < 0.05), with the 1950-1959 cohort having a fivefold higher mortality at 25 years than the 1970s' cohorts. Proliferative retinopathy and overt nephropathy showed nonsignificant declines at 20 years (P < 0.16 and P < 0.13, respectively) and no change at 25 years. CAD event rates, which were lower than the other complications, also showed no trend. Although some type 1 diabetes complications (mortality, renal failure, and neuropathy) are declining, others (CAD, overt nephropathy, and proliferative retinopathy) show less favorable changes by 30 years.

Late diabetes complications and non-dipping phenomenon in patients with Type 1 diabetes

BACKGROUND

Cardiovascular autonomic neuropathy (CAN) has been thought to underlie the loss of normal nocturnal blood pressure dipping, which is associated with a higher risk for nephropathy in Type 1 diabetes. Previous analyses also suggest however that nephropathy is a major predictor of subsequent CAN.

OBJECTIVE

To investigate links between non-dipping phenomenon (NDP) and complications, particularly CAN and nephropathy.

METHODS

24-h ambulatory blood pressure monitoring was performed on 61 consecutively recruited subjects (mean age: 38.5+/-8.1, mean duration: 29.5+/-8.2 years) from the Pittsburgh Epidemiology of Diabetes Complications cohort (658 subjects with childhood onset Type 1 diabetes diagnosed between 1950 and 80). NDP was diagnosed if nocturnal fall of both systolic and diastolic blood pressure was <10% of the average daytime blood pressure. CAN was detected by abnormal (<or=1.1) expiration/inspiration heart rate ratio. Proteinuria was established by abnormal (>20 microg/min) albumin excretion rate (AER) in at least two of three timed urines.

RESULTS

Non-dippers (n=17) had greater LDLc (p=0.012) and AER (p=0.052) and a higher frequency of nephropathy (OR=3.6, 95% CI=1.0-12.6) and proliferative retinopathy (OR=5.1, 95% CI=1.3-20.3) compared to the 44 dippers. CAN and NDP were not associated. In multivariate analyses, adjusting for CAN, proteinuria was significantly related to NDP (OR=3.6, 95% CI=1.0-12.6), an association that further modeling suggests was related to interactions between nephropathy, LDLc and hypertension.

CONCLUSIONS

These data suggest a strong link between NDP and proteinuria which is independent of CAN and may be modified by LDLc and hypertension.

The prospective association between adiponectin and coronary artery disease among individuals with type 1 diabetes. The Pittsburgh Epidemiology of Diabetes Complications Study

AIMS/HYPOTHESIS

Recent findings suggest the potential involvement of adiponectin in obesity, diabetes and cardiovascular disease. We assessed the prospective association between adiponectin concentration and coronary artery disease in individuals with type 1 diabetes.

METHODS

Participants were identified from the Pittsburgh Epidemiology of Diabetes Complications cohort, a prospective follow-up study of childhood-onset type 1 diabetes. At baseline, subjects had a mean age of 28 years, and a mean diabetes duration of 19 years. Cases (determined by physician-diagnosed angina, confirmed myocardial infraction, stenosis >or=50%, ischemic ECG or revascularization) were matched to the control subjects with respect to sex, age and diabetes duration. Samples and risk factors for analyses were identified from the earliest exam prior to incidence in cases. Sera and information on all covariates were available for 28 cases and 34 control subjects. Proportional hazards models were constructed including matching variables.

RESULTS

Compared with those in men, adiponectin concentrations were elevated in females (p=0.009) and among individuals with macroalbuminuria (p=0.04). In multivariable analyses (adjusting for standard risk factors as well as lipoprotein measurements determined by nuclear magnetic resonance spectroscopy, E-selectin or antioxidants), adiponectin inversely predicted the incidence of coronary artery disease (hazard ratio=0.37 per 1 SD increase, 95% CI 0.19-0.73, p=0.004).

CONCLUSIONS/INTERPRETATION

The results suggest that increased adiponectin concentration is prospectively associated with a lower risk of coronary artery disease type 1 diabetes. The potential of adiponectin determination as a useful marker of, and potential therapeutic target for, coronary artery disease prevention in type 1 diabetes should be further explored.

Proteinuria in African Americans with type 1 diabetes

AIMS

African Americans with type 1 diabetes are at a high risk for end-stage renal disease (ESRD). Factors associated with the presence of (any) proteinuria were examined in this ethnic group.

METHODS

Proteinuria and creatinuria were measured in both first-voided and 4-h timed urine specimens in African Americans with type 1 diabetes (N=717). Other evaluations included clinical interview, ocular examination, fundus photography, blood pressure, and glycosylated hemoglobin measurements.

RESULTS

Of the 717 patients, 357 (49.8%) had any proteinuria. Frequency of any proteinuria increased significantly with (a). age, from 34.2% of patients 20-30 years of age to 84.7% in those >or=45 years of age, and (b). duration of diabetes from 24.1% in those with 0-4 years of diabetes to 77.5% in those with >or=25 years of diabetes. Multivariate logistic regression showed that any proteinuria was significantly and independently associated with male sex, systemic hypertension, poor glycemic control, and longer duration of diabetes.

CONCLUSION

Proteinuria is common in African Americans with type 1 diabetes. Risk factors include male sex, systemic hypertension, poor glycemic control, and longer duration of diabetes. Whether early protection of renal function, in addition to glycemic control, may prevent such morbidity in this ethnic group requires study.

Tissue factor pathway inhibitor (TFPI) release after heparin stimulation is increased in Type 1 diabetic patients with albuminuria

AIMS

To study heparin-stimulated TFPI release in relation to complications in Type 1 diabetic patients.

SUBJECTS AND METHODS

Nineteen uncomplicated Type 1 diabetic patients (group I) were compared with 18 patients with retinopathy (group II), and nine patients with retinopathy and albuminuria (group III). Blood samples were taken before (basal) and till 30 min after 5000 IU of heparin i.v. (post-heparin). TFPI activity was measured chromogenically. Von Willebrand factor, tissue plasminogen activator (t-PA), plasminogen activator inhibitor-1 (PAI-1) and thrombomodulin were also measured.

RESULTS

Basal TFPI activity was higher in group III (121 +/- 10%) compared with group II (111 +/- 8%) or group I (110 +/- 13%) (P < 0.05), and strongly correlated with albuminuria (r = 0.66, P < 0.05). At all time points after heparin administration, TFPI activity in group III was significantly higher than in group I. TFPI activity was also higher in group III than in group II 5-30 min post-heparin. The increase in post-heparin TFPI activity, measured as the incremental area under the curve, was higher in group III compared with group I (65 +/- 7 vs. 59 +/- 4; P < 0.05). Of the other parameters, only thrombomodulin was higher in group III (44 +/- 24 vs. 26 +/- 7 (group II) and 28 +/- 9 ng/ml (group I); P < 0.01).

CONCLUSIONS

We conclude that basal and post-heparin TFPI activity is increased in albuminuric patients. The increase in heparin-stimulated TFPI release in patients with albuminuria is higher than in patients with retinopathy or without complications. This could be the result of altered endothelial glycosaminoglycan characteristics.

Diabetic nephropathy in KK and KK-Ay mice

KK mice and KK-Ay mice were examined for age related changes in blood and urinary biophysiological parameters. Blood hemoglobin A1c levels were significantly higher in KK-Ay and KK mice as compared to non-diabetic ddY mice. In both diabetic mice, especially KK-Ay mice, plasma insulin levels markedly increased at 2 to 4 months of age, and the urinary glucose and microalbumin levels and albumin-to-creatinine ratios increased dependent on age. Plasma thrombomodulin levels significantly increased at 2 to 4 months of age in both KK and KK-Ay mice. Mild enlargement of mesangial matrix and segmental proliferative glomerular nephritis were revealed in KK and KK-Ay mice, respectively, at 4 months of age. KK-Ay mice with insulin resistance and high urine mAlb level might be useful as models for the early stage of diabetic nephropathy.

Type 1 diabetes mellitus, xerostomia, and salivary flow rates

OBJECTIVE

The Oral Health Science Institute at the University of Pittsburgh has completed a cross-sectional epidemiologic study of 406 subjects with type 1 diabetes and 268 control subjects without diabetes that assessed the associations between oral health and diabetes. This report describes the prevalence of dry-mouth symptoms (xerostomia), the prevalence of hyposalivation in this population, and the possible interrelationships between salivary dysfunction and diabetic complications.

STUDY DESIGN

The subjects with diabetes were participants in the Pittsburgh Epidemiology of Diabetes Complications study who were enrolled in an oral health substudy. Control subjects were spouses or best friends of participants or persons recruited from the community through advertisements in local newspapers. Assessments of salivary function included self-reported xerostomia measures and quantification of resting and stimulated whole saliva flow rates.

RESULTS

Subjects with diabetes reported symptoms of dry mouth more frequently than did control subjects. Salivary flow rates were also impaired in the subjects with diabetes. Regression models of potential predictor variables were created for the 3 self-reported xerostomia measures and 4 salivary flow rate variables. Of the medical diabetic complications studied (ie, retinopathy, peripheral and autonomic neuropathy, nephropathy, and peripheral vascular disease), only neuropathy was found to be associated with xerostomia and decreased salivary flow measures. A report of dry-mouth symptoms was associated with current use of cigarettes, dysgeusia (report of a bad taste), and more frequent snacking behavior. Xerogenic medications and elevated fasting blood glucose concentrations were significantly associated with decreased salivary flow. Resting salivary flow rates less than 0.01 mL/min were associated with a slightly higher prevalence of dental caries. Subjects who reported higher levels of alcohol consumption were less likely to have lower rates of stimulated salivary flow.

CONCLUSIONS

Subjects with type 1 diabetes who had developed neuropathy more often reported symptoms of dry mouth as well as symptoms of decreased salivary flow rates. Because of the importance of saliva in the maintenance and the preservation of oral health, management of oral diseases in diabetic patients should include a comprehensive evaluation of salivary function.

Lipid modulation in insulin-dependent diabetes mellitus: effect on microvascular outcomes

Although hyperlipidemia is associated with the development of diabetes complications, the effect of lipid reduction on microvascular complications is unknown. We initiated a 2-year, randomized, double-blinded placebo-controlled pilot trial of simvastatin/diet vs. diet alone in Type 1 diabetic patients without overt nephropathy. Thirty-nine patients with LDL cholesterol 100-160 mg/dl, >10 year duration of diabetes and an albumin excretion rate (AER) <200 microg/min were recruited for study. The primary end-point was change in AER. Secondary end-points were change in ankle-brachial index, progression of retinopathy status, change in vibratory threshold, and development of new clinical neuropathy. Nineteen patients were treated with simvastatin and twenty with placebo. However, because of the lowering of drug initiation levels by the American Diabetes Association, the trial was terminated early with 2 subjects reaching 2 years, 17 reaching 18 months, 36 reaching 1 year, and all 6 months. Simvastatin significantly reduced total cholesterol (mean on treatment 173.4 vs. 191.4, P=.020) and LDL cholesterol (mean on treatment 105.0 vs. 127.7, P<.001). Simvastatin therapy was associated with a slower rise in AER compared to placebo, though the result was not statistically significant (median rate of change/month 0.004 vs. 0.029). There was a trend towards slower progression of neuropathy as measured by vibratory threshold (median change at 1 year 0.03 simvastatin vs. 0.94, P=.07). There was no difference in change in ankle-brachial index, clinical neuropathy status, or retinopathy status. In conclusion, treatment with simvastatin may have a beneficial effect on early nephropathy and diabetic neuropathy, justifying a fully powered trial. However, this would be difficult under current treatment guidelines.

Effect of lipid reduction on the progression of renal disease: a meta-analysis

BACKGROUND

It has been proposed that hyperlipidemia contributes to the progression of renal disease. A large trial has not been performed; however, a number of small, controlled trials have been reported. We examined the effects of antilipemic agents on glomerular filtration rate and proteinuria or albuminuria in patients with renal disease.

METHODS

We used Medline, abstracts from scientific meetings, and bibliographies from recent reviews and scientific reports to locate pertinent studies. Thirteen prospective controlled trials examining the effects of antilipemic agents on renal function, proteinuria, or albuminuria were included. Studies were published as full reports or abstracts and were at least three months in duration. For five of the studies, individual patient data were obtained. Other summary data were independently extracted from the published reports by two investigators and included study quality, subject characteristics, cause of renal disease, change in serum cholesterol, blood pressure, glomerular filtration rate, proteinuria, and albuminuria.

RESULTS

There was a lower rate of decline in glomerular filtration rate with treatment compared with controls (treated controls, 0.156 mL/min/month; 95% CI, 0.026 to 0. 285 mL/min/month, P = 0.008). The study results were statistically homogeneous, and in a regression analysis, the effect of treatment on glomerular filtration rate did not correlate with study quality, the percentage change in cholesterol, the type of lipid-lowering agent, or the cause of renal disease. However, longer follow-up correlated with the amount of improvement in glomerular filtration rate from treatment (P = 0.007). There was a tendency for a favorable effect of treatment on protein or albumin excretion [Ln (treatment) - Ln (control) = -0.248, 95% CI, -0.562 to 0.064, P = 0. 077]. However, these results were statistically heterogeneous between studies (P < 0.001). No obvious explanation for this heterogeneity was apparent in a regression analysis examining potential reasons for differences in study results.

CONCLUSIONS

Lipid reduction may preserve glomerular filtration rate and may decrease proteinuria in patients with renal disease.

Are predictors of coronary heart disease and lower-extremity arterial disease in type 1 diabetes the same? A prospective study

In the Type 1 diabetes population, coronary heart disease (CHD) and lower-extremity arterial disease (LEAD) are the two common macrovascular complications leading to early mortality and morbidity. However, it is not clear if these two complications share the same risk factors. The Pittsburgh Epidemiology of Diabetes Complications (EDC) Study prospectively examined and compared the risk factors for LEAD and CHD (including CHD morbidity and mortality). EDC subjects (332 men and 325 women), all diagnosed at Children's Hospital of Pittsburgh between 1950 and 1980, were first examined at baseline (1986-1988), and then biennially, for diabetes complications and their risk factors. Data used in the current analysis were from the first 6 years of follow-up, 98% provided at least some follow-up data for these analyses. CHD was defined as the presence of angina (diagnosed by the EDC examining physician) or a history of confirmed myocardial infarction or CHD death. An ankle-to-arm ratio of less than 0.9 at rest was considered to be evidence of LEAD. Among 635 subjects without CHD at baseline, 57 developed CHD (1.69/100 person-years), and among 579 without LEAD at baseline, 70 developed LEAD (2.31/100 person-years). CHD incidence rate was slightly higher in males, while LEAD incidence rate was slightly higher in females. Compared to non-incident cases, subjects who developed either complication were older, had a longer diabetes duration, higher LDL and total cholesterol, and were more likely to be hypertensive. In multivariate analyses, hypertension, low HDL cholesterol level, high white cell count, depression, and nephropathy were the independent risk factors for CHD (including morbidity and mortality). For LEAD, higher HbA1 level, higher LDL cholesterol level and smoking were the important contributing factors. In conclusion, the risk factor patterns differ between the two vascular complications. Glycemic control does not predict CHD overall but does predict LEAD, while hypertension and inflammatory markers are more closely related to CHD than to LEAD.

Cardiovascular autonomic neuropathy (expiration and inspiration ratio) in type 1 diabetes. Incidence and predictors

The pathogenesis of diabetic neuropathy is poorly understood. In this prospective study, we investigated the incidence rate and potential predictors for cardiovascular autonomic neuropathy (CAN) in a cohort of childhood-onset type 1 diabetic patients. Subjects from the Epidemiology of Diabetes Complications Study were examined at baseline and then biennially. CAN was diagnosed by abnormal (</=1. 1) expiration/inspiration ratio during deep breathing. During the 4. 7-year mean follow-up period, CAN developed in 104 patients from the 373 subjects who were free of CAN at baseline and provided follow-up data, an incidence-density of 5.9 cases/100 person-years. Cox proportional hazard modeling showed age (relative risk [RR]=2.15, p=0.0001), HbA1 (RR=1.50, p=0.0002) and nephropathy (albumin excretion >200 ug/min) (RR=2.46, p=0.0001) to be significant independent predictors. Hypertension was, however, predictive if nephropathy was not included in the model. We conclude that beyond age and poor glycemic control, nephropathy is a significant risk factor for CAN and this association may explain some of the increased mortality seen in CAN.

Microalbuminuria in essential hypertension

Urinary excretion of albumin exceeds normal values in 10 to 25% of patients with essential hypertension. The level of albuminuria is highly correlated with arterial pressure, and more closely with ambulatory arterial pressure. The interaction between albuminuria and arterial pressure is enhanced by overweight, smoking, protein intake, insulin resistance, lipid abnormalities, and possibly genotypes of the components of the renin-angiotensin system. The renal mechanisms of microalbuminuria are not well elucidated. Notably, an increase in filtration fraction suggestive of intraglomerular hypertension was observed in patients with hyperfiltration. Microalbuminuria may be a marker of diffuse vascular abnormalities predisposing to cardiovascular disease and/or hypertensive renal disease heralding future renal failure, but its predictive value needs to be tested in more long-term follow-up studies. Antihypertensive treatment has a varied influence on albuminuria; angiotensin-converting enzyme inhibitors may correct this abnormality (at least partially) better than other agents.

Low-density lipoprotein particle size and coronary artery disease in a childhood-onset type 1 diabetes population

Low-density lipoprotein (LDL) cholesterol has been widely recognized as a strong predictor of coronary artery disease (CAD). Recently, studies have examined the influence of LDL particle size (an integral part of the insulin resistance syndrome) on the development of CAD in the general population. This report examines the correlates of LDL particle size and its association with CAD in a type 1 diabetes population. We evaluated the interrelationships between LDL particle size and the presence of CAD in a cohort of childhood-onset type 1 diabetic subjects using the Pittsburgh Epidemiology of Diabetes Complications (EDC) study. LDL particle size was measured in 337 subjects (mean age, 35.6 years; mean diabetes duration, 27.2 years) who underwent the 8-year follow-up examination. LDL particle size was determined by vertical polyacrylamide gel (2% to 16%) electrophoresis. Subjects with the small dense LDL particle phenotype (<235.5 angstroms) [corrected] had a longer diabetes duration, higher cholesterol, triglyceride, LDL, fibrinogen, waist to hip ratio (WHR), and hemoglobin A1 (HbA1), and lower high-density lipoprotein (HDL) cholesterol compared with subjects with the large LDL particle phenotype (>257 angstroms) [corrected]. Males were also more likely to have an increased body mass index (BMI) and CAD, while females were more likely to have hypertension and a family history of type 2 diabetes (a potential marker of insulin resistance and CAD risk). The odds ratio ([OR] 95% confidence, interval [CI]) using logistic regression analysis for LDL particle size in association with CAD was 0.79 (0.60 to 1.04). Multivariate modeling indicated that the duration of type 1 diabetes, depressive symptomatology, and triglycerides were independently associated with the presence of CAD. We conclude that although small dense LDL particle size is associated with CAD in our type 1 diabetes population, its borderline association can largely be explained by the triglyceride concentration. However, as in the general population, LDL particle size is associated with many elements of the insulin resistance syndrome, including a family history of type 2 diabetes, and is likely an important element in the contribution of insulin resistance to the development of CAD in type 1 diabetes.