Continuous relationships between non-diabetic hyperglycaemia and both cardiovascular disease and all-cause mortality: the Australian Diabetes, Obesity, and Lifestyle (AusDiab) study

Insulin degludec, an ultra-long-acting basal insulin, once a day or three times a week versus insulin glargine once a day in patients with type 2 diabetes: a 16-week, randomised, open-label, phase 2 trial

BACKGROUND

Insulin degludec is a new basal insulin that forms soluble multihexamer assemblies after subcutaneous injection, resulting in an ultra-long action profile. This study aimed to assess efficacy and safety of insulin degludec injected once a day or three times a week compared with insulin glargine once a day in insulin-naive people with type 2 diabetes, who were inadequately controlled with oral antidiabetic drugs.

METHODS

In this 16-week, randomised, open-label, parallel-group phase 2 trial, participants aged 18–75 years with type 2 diabetes and glycosylated haemoglobin (HbA(1C)) of 7·0–11·0% were enrolled and treated at 28 clinical sites in Canada, India, South Africa, and the USA. Participants were randomly allocated in a 1:1:1:1 ratio by computer-generated block randomisation to receive insulin degludec either once a day or three times a week or insulin glargine once a day, all in combination with metformin. Investigators were masked to data until database release. The primary outcome was HbA(1C) after 16 weeks of treatment. Analyses were done by intention to treat. This trial is registered with ClinicalTrials.gov, number NCT00611884.

FINDINGS

Of 367 patients screened, 245 were eligible for inclusion. 62 participants were randomly allocated to receive insulin degludec three times a week (starting dose 20 U per injection [1 U=9 nmol]), 60 to receive insulin degludec once a day (starting dose 10 U [1 U=6 nmol]; group A), 61 to receive insulin degludec once a day (starting dose 10 U [1 U=9 nmol]; group B), and 62 to receive insulin glargine (starting dose 10 U [1 U=6 nmol]) once a day. At study end, mean HbA(1C) levels were much the same across treatment groups, at 7·3% (SD 1·1), 7·4% (1·0), 7·5% (1·1), and 7·2% (0·9), respectively. Estimated mean HbA(1C) treatment differences from insulin degludec by comparison with insulin glargine were 0·08% (95% CI –0·23 to 0·40) for the three dose per week schedule, 0·17% (–0·15 to 0·48) for group A, and 0·28% (–0·04 to 0·59) for group B. Few participants had hypoglycaemia and the number of adverse events was much the same across groups, with no apparent treatment-specific pattern.

INTERPRETATION

Insulin degludec provides comparable glycaemic control to insulin glargine without additional adverse events and might reduce dosing frequency due to its ultra-long action profile.

FUNDING

Novo Nordisk.

Diagnosis of prediabetes

A rational approach to diagnosing prediabetes is essential to identify those who would benefit from entering diabetes prevention programs. Impaired fasting glucose and impaired glucose tolerance are similar in relation to their ability to identify those at risk of diabetes or cardiovascular disease; however, because they identify different segments of the at-risk population, there is value in undertaking glucose tolerance testing to ensure that both conditions can be diagnosed. Simple noninvasive diabetes risk scores offer a valuable entry point in the diagnosis of prediabetes, enabling the identification of those who need blood testing.

Mechanisms of vascular complications in prediabetes

Although the state of prediabetes is defined by its role as a diabetes risk factor, it also carries a significant risk of cardiovascular disease, independent of progression to diabetes. Typical diabetic microvascular complications also occur, albeit at low rates, in prediabetes. There is evidence that both glucose-related and glucose-independent mechanisms contribute to these vascular complications. Effective preventive strategies will likely require control of glycemia, as well as other metabolic risk factors. This article reviews some of the proposed mechanisms for the vascular complications of the prediabetic state.

Use of reclassification for assessment of improved prediction: an empirical evaluation

BACKGROUND

An increasing number of studies evaluate the ability of predictors to change risk stratification and alter medical decisions, i.e. reclassification performance. We examined the reported design and analysis of recent studies of reclassification and the robustness of their claims for improved reclassification.

METHODS

Two independent investigators searched PubMed and citations to the article that introduced the currently most popular reclassification metric (net reclassification index, NRI) to identify studies performing reclassification analysis (January 2006-January 2010). We focused on articles that included any analyses comparing the performance of a baseline predictive model vs the baseline model plus some additional predictor for a prospectively assessed outcome. We recorded information on the baseline model used, outcomes assessed, choice of risk thresholds and features of reclassification analyses.

RESULTS

Of 58 baseline models used in 51 eligible papers, only 14 (24%) were previously described, used as described and had same outcomes as originally intended. Calibration was examined in 53% of the studies. Sixteen studies (31%) provided a reference for the choice of risk thresholds and only six used the previously proposed categories or justified the use of alternative thresholds. Only 14 studies (27%) stated that the chosen risk thresholds had different therapeutic intervention implications. NRI was calculated in 38 studies and was smaller in studies with adequately referenced or justified risk thresholds vs others (P < 0.0001).

CONCLUSIONS

Reclassification studies would benefit from more rigorous methodological standards; otherwise claims for improved reclassification may remain spurious.

Evaluation of four novel genetic variants affecting hemoglobin A1c levels in a population-based type 2 diabetes cohort (the HUNT2 study)

BACKGROUND

Chronic hyperglycemia confers increased risk for long-term diabetes-associated complications and repeated hemoglobin A1c (HbA1c) measures are a widely used marker for glycemic control in diabetes treatment and follow-up. A recent genome-wide association study revealed four genetic loci, which were associated with HbA1c levels in adults with type 1 diabetes. We aimed to evaluate the effect of these loci on glycemic control in type 2 diabetes.

METHODS

We genotyped 1,486 subjects with type 2 diabetes from a Norwegian population-based cohort (HUNT2) for single-nucleotide polymorphisms (SNPs) located near the BNC2, SORCS1, GSC and WDR72 loci. Through regression models, we examined their effects on HbA1c and non-fasting glucose levels individually and in a combined genetic score model.

RESULTS

No significant associations with HbA1c or glucose levels were found for the SORCS1, BNC2, GSC or WDR72 variants (all P-values > 0.05). Although the observed effects were non-significant and of much smaller magnitude than previously reported in type 1 diabetes, the SORCS1 risk variant showed a direction consistent with increased HbA1c and glucose levels, with an observed effect of 0.11% (P = 0.13) and 0.13 mmol/l (P = 0.43) increase per risk allele for HbA1c and glucose, respectively. In contrast, the WDR72 risk variant showed a borderline association with reduced HbA1c levels (β = -0.21, P = 0.06), and direction consistent with decreased glucose levels (β = -0.29, P = 0.29). The allele count model gave no evidence for a relationship between increasing number of risk alleles and increasing HbA1c levels (β = 0.04, P = 0.38).

CONCLUSIONS

The four recently reported SNPs affecting glycemic control in type 1 diabetes had no apparent effect on HbA1c in type 2 diabetes individually or by using a combined genetic score model. However, for the SORCS1 SNP, our findings do not rule out a possible relationship with HbA1c levels. Hence, further studies in other populations are needed to elucidate whether these novel sequence variants, especially rs1358030 near the SORCS1 locus, affect glycemic control in type 2 diabetes.

Testosterone and modifiable risk factors associated with diabetes in men

OBJECTIVE

The role of endogenous testosterone in the pathogenesis of type 2 diabetes mellitus remains vague. We investigated whether associations between endogenous testosterone and diabetes prevalence in men could be partially explained by modifiable risk factors.

STUDY DESIGN

A random population-based cross-sectional study of 1195 men aged 35-80 years living in the north-west regions of Adelaide, Australia. Data collections occurred between 2002 and 2005, and response rate was 45.1%.

MATERIALS AND METHODS

Diabetes (non-specific) was classified by either: (1) self-report for doctor diagnosis of diabetes; (2) prescription medication for diabetes; (3) fasting plasma glucose ≥ 7 mmol/L; or (4) glycosylated haemoglobin ≥ 6.2%. Logistic regressions were used to estimate odds ratios (OR [with 95% confidence intervals]) for diabetes, with stepwise adjustments for demographic, lifestyle, and clinical factors.

RESULTS

Diabetes prevalence was positively associated with age groups 45-54 years (2.8 [1.4, 5.8]), 55-64 years (3.9 [1.9, 8.3]) and ≥ 65 years (4.0 [1.8, 8.9]), lowest income group (1.8 [1.0, 3.4]), ex-smoker (1.8 [1.2, 2.9]), lowest (3.2 [1.9, 5.5]) and middle (1.9 [1.1, 3.4]) alcohol tertiles, cardiovascular disease (1.9 [1.2, 2.8]), metabolic syndrome (4.0 [2.6, 6.1]), and lowest plasma total testosterone tertile (1.8 [1.1, 3.0]), but negatively associated with middle (0.5 [0.3, 0.8]) and highest (0.4 [0.3, 0.7]) sugar intake tertiles, arthritis (0.6 [0.3, 1.0]), and elevated LDL cholesterol (0.5 [0.3, 0.8]); ORs showed an inverted 'U' shape for middle and highest voiding lower urinary tract symptoms tertiles. Body composition, muscle strength, and cardio-metabolic factors partially explained the association between low plasma total testosterone and diabetes.

CONCLUSIONS

Plasma total testosterone was inversely and independently associated with diabetes prevalence, that might have been partially explained by several modifiable risk factors.

Cardiovascular risk in patients with fasting blood glucose levels within normal range

Fasting glucose levels elevated beyond the normal range have been associated with increased cardiovascular risk. However, it is unknown whether this association exists for variations of fasting glucose within the normal range. The present study was conducted using the computerized database of the Sharon-Shomron District of Clalit Health Services. Included in the present study were subjects with fasting glucose levels within the normal range (< 100 mg/dl). We excluded patients with a history of cardiovascular disease or diabetes. The primary outcome was the incidence of coronary revascularization with either percutaneous coronary intervention or coronary artery bypass grafting. The 28,263 participants (age 53.7 ± 12.2 years) were divided into quartiles according to the fasting glucose level (75.4 ± 4.5, 83.6 ± 1.7, 88.9 ± 1.4, and 95.1 ± 2.2 mg/dl). During a mean follow-up of 5.9 ± 0.7 years, 424 subjects required coronary revascularization. A progressive increase was seen in the risk of coronary revascularization as the fasting glucose levels increased within the normal range (hazard ratio 1.73, 95% confidence interval 1.3 to 2.3, p > 0.001, between the fourth and first quartiles). However, this association lost its statistical significance after adjustments for the conventional coronary risk factors (hazard ratio 1.17, 95% confidence interval 0.85 to 1.62, p = 0.328). In conclusion, elevated fasting glucose levels within the normal range were associated with an increased cardiovascular risk. This association was caused by the greater prevalence of the other conventional risk factors and not by the glucose level itself.

HbA1c as predictor of all-cause mortality in individuals at high risk of diabetes with normal glucose tolerance, identified by screening: a follow-up study of the Anglo-Danish-Dutch Study of Intensive Treatment in People with Screen-Detected Diabetes in Primary Care (ADDITION), Denmark

AIMS/HYPOTHESIS

Stepwise screening for type 2 diabetes will not only identify people with the disease or some other form of dysglycaemia (impaired fasting glucose or impaired glucose tolerance), but also many individuals who are phenotypically at high risk of developing diabetes, but currently have normal glucose tolerance (NGT). We therefore sought to assess whether HbA(1c) adds prognostic information in relation to all-cause mortality in people who have NGT and a high risk of type 2 diabetes mellitus.

METHODS

In a Danish population-based stepwise screening programme for type 2 diabetes mellitus in general practice, we identified 15,634 persons at high risk of type 2 diabetes, who had NGT and a recorded HbA(1c) measurement. As comparison groups, we included 1,401 people identified as having type 2 diabetes mellitus and 8,149 individuals characterised as being at low risk of diabetes. All individuals were followed from time of screening (April 2001 to December 2006) until death or 31 October 2009. Excess mortality was estimated using Cox proportional hazard models with all-cause mortality as the outcome measure.

RESULTS

Compared with individuals with NGT and HbA(1c) below 6.0%, adjusted hazard ratios were: 1.21 (95% CI 0.95-1.56) for individuals with NGT and HbA(1c) between 6.0% and 6.5%; 2.48 (95% CI 1.23-4.99) for individuals with NGT and HbA(1c) 6.5% or above (in this group there were eight deaths among 68 individuals); 1.73 (95% CI 1.40-2.13) for individuals with type 2 diabetes mellitus.

CONCLUSIONS/INTERPRETATION

HbA(1c) level in people with NGT and at high risk of diabetes was clearly associated with increased all-cause mortality.

Low hemoglobin A1c and risk of all-cause mortality among US adults without diabetes

BACKGROUND

Among individuals without diabetes, elevated hemoglobin A1c (HbA1c) has been associated with increased morbidity and mortality, but the literature is sparse regarding the prognostic importance of low HbA1c.

METHODS AND RESULTS

National Health and Nutrition Examination Survey III (NHANES III) participants, 20 years and older, were followed up to 12 years (median follow-up, 8.8 years) for all-cause mortality. Cox proportional hazards regression was used to calculate hazard ratios (HR) and 95% confidence intervals (CI) for the association between HbA1c levels and all-cause mortality for 14 099 participants without diabetes. There were 1825 deaths during the follow-up period. Participants with a low HbA1c (<4.0%) had the highest levels of mean red blood cell volume, ferritin, and liver enzymes and the lowest levels of mean total cholesterol and diastolic blood pressure compared with their counterparts with HbA1c levels between 4.0% and 6.4%. An HbA1c <4.0% versus 5.0% to 5.4% was associated with an increased risk of all-cause mortality (HR, 3.73; 95% CI, 1.45 to 9.63) after adjustment for age, race-ethnicity, and sex. This association was attenuated but remained statistically significant after further multivariable adjustment for lifestyle, cardiovascular factors, metabolic factors, red blood cell indices, iron storage indices, and liver function indices (HR, 2.90; 95% CI, 1.25 to 6.76).

CONCLUSIONS

In this nationally representative cohort, low HbA1c was associated with increased all-cause mortality among US adults without diabetes. Additional research is needed to confirm these results and identify potential mechanisms that may be underlying this association.

Predictive modeling of health care costs: do cardiovascular risk markers improve prediction?

BACKGROUND

To investigate the ability of multiple cardiovascular disease (CVD) markers to predict future health care costs. CVD markers included traditional risk factors (smoking status, body mass index, waist circumference, alcohol intake, diabetes, total : high-density lipoprotein cholesterol ratio, actual hypertension, physical activity) and newer markers (carotid intima-media thickness, hemoglobin A1c, apolipoprotein B : apolipoprotein A-1 ratio, lipoprotein (a), leukocyte count, high-sensitive C-reactive protein, plasma fibrinogen, estimated glomerular filtration rate, urinary albumin : creatinine ratio).

DESIGN AND METHODS

The study sample consisted of 2233 participants without history of myocardial infarction, stroke, heart failure, and angina pectoris at baseline (50.6% women; mean age 60.9 years; age range 45-81 years) from the cohort Study of Health in Pomerania, Germany (median follow-up 5 years).

RESULTS

Predictive modeling revealed that a basic model with sex, age, years of school education, insurance status, and income explained 0.9% in baseline total cost variation and 1.5% in total cost variation at 5-year follow-up. The incorporation of a combination of significant CVD markers resulted in an increase in the R2 for total costs of 70% at baseline and 69% after 5 years, with a final R2 of 0.030 at baseline and an R2 of 0.048 at 5-year follow-up.

CONCLUSION

Our data suggest that for individuals without history of CVD, the simultaneous addition of several CVD risk markers improves predictive modeling of future health care costs beyond that of a model that is based on established health care predictors.

Cardiovascular disease mortality in Europeans in relation to fasting and 2-h plasma glucose levels within a normoglycemic range

OBJECTIVE

To study mortality in relation to fasting plasma glucose (FPG) and 2-h plasma glucose levels within the normoglycemic range.

RESEARCH DESIGN AND METHODS

Data from 19 European cohorts comprising 12,566 men and 10,874 women who had FPG <6.1 mmol/l and 2-h plasma glucose <7.8 mmol/l at baseline examination were analyzed. Multivariate-adjusted hazard ratios (HRs) and 95% CIs for deaths from cardiovascular disease (CVD), non-CVD, and all causes were estimated for individuals whose 2-h plasma glucose > FPG (group II) compared with those whose 2-h plasma glucose ≤ FPG (group I).

RESULTS

A total of 827 (246) CVD and 611 (351) non-CVD and 1,438 (597) all-cause deaths occurred in men (women). Group II was older and had higher BMI, blood pressure, and fasting insulin than group I. The multivariate-adjusted HRs (95% CIs) for CVD, non-CVD, and all-cause mortality were 1.22 (1.05-1.41), 1.09 (0.92-1.29), and 1.16 (1.04-1.30) in men and 1.40 (1.03-1.89), 0.99 (0.79-1.25), and 1.13 (0.94-1.35) in women, respectively, for group II as compared with group I. HRs were 1.25 (1.05-1.50), 1.09 (0.89-1.34), and 1.18 (1.03-1.35) in men and 1.60 (1.03-2.48), 1.05 (0.78-1.42), and 1.18 (0.93-1.51) in women, respectively, after additional adjustment for fasting insulin in a subgroup of individuals.

CONCLUSIONS

In individuals with both FPG and 2-h plasma glucose within the normoglycemic range, high 2-h plasma glucose was associated with insulin resistance and increased CVD mortality.

A1C between 5.7 and 6.4% as a marker for identifying pre-diabetes, insulin sensitivity and secretion, and cardiovascular risk factors: the Insulin Resistance Atherosclerosis Study (IRAS)

OBJECTIVE

A1C is an optional method for diagnosing diabetes and also for detecting individuals at increased risk of the disease. However, how A1C compares with fasting (FPG) and 2-h plasma glucose for detecting at-risk individuals is not well known.

RESEARCH DESIGN AND METHODS

A 2-h glucose tolerance test, frequently sampled intravenous glucose tolerance test, and A1C were obtained at the follow-up examination in 855 participants in the Insulin Resistance Atherosclerosis Study (IRAS). For this report, 385 individuals were at increased risk of diabetes as defined by A1C between 5.7 and 6.4%, impaired glucose tolerance (IGT), and/or impaired fasting glucose (IFG).

RESULTS

IFG and IGT identified 69.1 and 59.5% of all individuals at increased risk of diabetes, respectively. A1C 5.7-6.4% detected 23.6% of all at-risk individuals, although more African Americans (31.4%) and Hispanics (35.2%) than non-Hispanic whites (9.9%). Relative to A1C, FPG was more strongly related to fasting insulin (r = 0.38 vs. 0.26; P < 0.01), acute insulin response (r = - 0.20 vs. - 0.09; P < 0.01), and waist circumference (r = 0.43 vs. 0.25; P < 0.001) by the Spearman correlation test. Similarly, 2-h plasma glucose was more strongly related to Si (r = - 0.40 vs. - 0.27; P < 0.01) and triglycerides (r = 0.30 vs. 0.08; P < 0.001).

CONCLUSIONS

A1C 5.7-6.4% is less sensitive for detecting at-risk individuals than IFG and IGT, particularly among non-Hispanic whites. Single determinations of FPG and 2-h plasma glucose seem to be more precise correlates of insulin resistance and secretion than A1C and, in general, better for other metabolic disorders.

Intensive glucose control and cardiovascular outcomes in type 2 diabetes

Numerous observational studies have clearly shown a relationship between hyperglycaemia and cardiovascular (CV) disease. However, the United Kingdom Prospective Diabetes Study (UKPDS), which involved subjects with newly diagnosed type 2 diabetes, just failed to show that intensive glucose control significantly reduces CV events. The results of three subsequent large randomised controlled trials, the Action to Control Cardiovascular Risk in Diabetes (ACCORD), Action in Diabetes and Vascular Disease Preterax and Diamicron Modified Release Controlled Evaluation (ADVANCE) and the Veterans Administration Diabetes Trial (VADT), that involved approximately 25,000 subjects with established type 2 diabetes also failed to show that intensive glucose control, aiming for a glycated haemoglobin (HbA(1c)) level<7%, significantly reduces CV events. The ACCORD trial even suggested that under certain circumstances, intensive glucose control is associated with an increased risk for CV and all-cause mortality. Although the exact mechanisms responsible for an increase in mortality in the ACCORD trial remain unknown, there was an association between increased rates of mortality with higher rates of severe hypoglycaemia in the intensive glucose control group. In contrast, a 10-year post-randomisation follow-up study of the tight glucose intervention arm of the UKPDS showed that intensive glucose control was associated with a significant reduction in the risk for myocardial infarction (MI), diabetes-related deaths and all-cause mortality. This suggests that early strict glucose control generates a legacy effect that is eventually translated into protection from CV events. Recent meta-analyses of the above randomised trails have also shown that intensive glucose control is associated with a reduced risk of MI, without a clear benefit on other CV diseases such as stroke. Furthermore, these analyses have also shown that intensive glucose control is associated with increased rates of severe hypoglycaemia but not increased rates of CV or all-cause mortality. Aiming for HbA(1c) levels of <7.0% still remains the general target for good glucose control. Under certain circumstances, aiming for lower HbA(1c) levels may be appropriate. This applies in the setting of newly diagnosed diabetes in relatively young individuals without significant co-morbidities and in patients treated with agents that minimise the risk of severe hypoglycaemia such as metformin. Whether this also applies to newer glucose-lowering agents that target the incretin system will depend on CV outcomes of long-term studies which are in progress.

One-hour postload plasma glucose levels are associated with kidney dysfunction

BACKGROUND AND OBJECTIVES

A cutoff of 155 mg/dl for 1-hour postload plasma glucose (1hPG) during the oral glucose tolerance test (OGTT) is able to identify patients who are at high risk for type 2 diabetes and vascular atherosclerosis. We aimed to examine whether individuals with 1hPG ≥155 mg/dl are also at increased risk for chronic kidney disease (CKD).

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Atherosclerosis risk factors, OGTT, and estimated GFR by Chronic Kidney Disease Epidemiology Collaboration equation were analyzed in 1075 white individuals without diabetes.

RESULTS

The area under the receiver operating characteristic curve for 1hPG was the highest (0.700) compared with the areas under the receiver operating characteristic curve of 0, 30-minute, and 2-hour glucose concentrations. Individuals with 1hPG ≥155 mg/dl had a worse cardiometabolic risk profile, exhibiting significantly higher body mass index, BP, triglycerides, and fasting insulin levels and lower HDL, IGF-1 levels, and insulin sensitivity, than individuals with 1hPG <155 mg/dl. Estimated GFR was significantly lower in individuals with 1hPG ≥155 mg/dl. In a logistic regression model adjusted for age and gender, individuals with 1hPG ≥155 mg/dl showed an increased risk for CKD compared with individuals with 1hPG <155 mg/dl. When the logistic regression analysis was restricted to individuals who had normal glucose tolerance, those with 1hPG ≥155 mg/dl showed a higher risk for CKD compared with individuals with 1hPG <155 mg/dl.

CONCLUSIONS

These data suggest that a cutoff point of 155 mg/dl for the 1hPG during OGTT may be helpful in the identification of individuals who are at increased risk for CKD.

Do the Joint British Society (JBS2) guidelines on prevention of cardiovascular disease with respect to plasma glucose improve risk stratification in the general population? Prospective cohort study

AIMS

British guidelines on vascular disease prevention recommend adding a random (casual) blood glucose measurement to a lipid profile in those aged > or = 40 years. To assess this recommendation, we compared the predictive value of a risk model based on the Framingham risk score alone to one which additionally included information on fasting blood glucose, with respect to incident coronary heart disease (CHD) over 11 years.

METHOD

Men and women aged 40-63 years in Whitehall II were followed up for incident CHD: death/non-fatal myocardial infarction; angina confirmed by doctor diagnosis or electrocardiogram (ECG) and all first events. Fasting blood glucose was specified as a continuous variable or categorized by World Health Organization (WHO) 1999 glycaemic status (normal glucose tolerance, impaired fasting glucose or newly diagnosed diabetes).

RESULTS

The hazard ratio for incident CHD was 1.10 (95%CI 1.09; 1.12) in men and 1.13 (1.10; 1.17) in women per percentage point increase in Framingham risk. The excess risk remained unchanged in models which added glycaemic status or continuous fasting glucose. The area under the receiver operating characteristic (ROC) curve for the Framingham score and incident coronary heart disease [0.70 (0.68; 0.73)] did not change when glycaemic status or fasting glucose was added to the prediction model. Reclassification with these modified models improved discrimination based on the Framingham score alone when glycaemic status was added, net reclassification improvement 2.4% (95% CI 0.2%; 4.6%), but not when fasting glucose was added.

CONCLUSION

Better detection of unrecognized diabetes is a valuable consequence of including a random blood glucose in a vascular risk profile. Our results suggest that this strategy is unlikely to improve risk stratification for CHD.

Fasting plasma glucose in non-diabetic participants and the risk for incident cardiovascular events, diabetes, and mortality: results from WOSCOPS 15-year follow-up

AIMS

The evidence base for fasting plasma glucose (FPG) in the non-diabetic range as a risk factor for cardiovascular disease (CVD) is inconclusive. We investigated this question in the West of Scotland Coronary Prevention Study (WOSCOPS).

METHODS AND RESULTS

In WOSCOPS, we related FPG in 6447 men (mean age 55 years) with hypercholesterolaemia, but no history of CVD or diabetes, to the risk of cardiovascular events and mortality over 14.7 years of follow-up; 2381 non-fatal/fatal cardiovascular events and 1244 deaths occurred. Participants were divided into fifths of baseline FPG, Q1 (< or =4.3 mmol/L) to Q5 (>5.1-6.9 mmol/L). Q2 was designated the referent based on previous studies which have suggested a J-shaped relationship between FPG and CVD. Compared with Q2 (>4.3-4.6 mmol/L), men in Q5 had no elevated risk for cardiovascular events [hazard ratio (HR) 0.95 (0.83-1.08)], or all-cause mortality [HR 0.96 (0.80-1.15)] in fully adjusted analyses despite a significant risk for incident diabetes [HR 22.05 (10.75-45.22)]. After further dividing Q5 into fifths, Q5a-e, individuals in Q5e (FPG 5.8-6.9 mmol/L) were also not at increased risk of cardiovascular events [HR 1.05 (0.82-1.35)] or other endpoints compared with Q2. All results were similar using Q1 as the referent.

CONCLUSION

Elevations in FPG in the non-diabetic range were not associated with long-term risk of cardiovascular events in middle-aged men in WOSCOPS. These data suggest that the current FPG cutoff for diagnosing diabetes also appropriately identifies western men at risk of CVD.

Fasting plasma glucose and Type 2 diabetes risk: a non-linear relationship

AIMS

The current definition of impaired fasting glucose (IFG, >or=100 mg/dl) has been criticized as being too low for selective identification of individuals at risk for Type 2 diabetes. Furthermore, it is unclear whether any cut-off is justifiable from the shape of association between fasting plasma glucose (FPG) and diabetes. We therefore evaluated the association between FPG and incidence of Type 2 diabetes in a prospective, population-based study.

METHODS

A case-cohort study within the European Prospective Investigation into Cancer and Nutrition (EPIC)-Potsdam cohort study involved 589 fasted participants in a randomly selected subcohort and 153 incident cases. Restricted cubic spline regression was used to examine non-linearity of associations and we calculated pairs of sensitivities and specificities for different cut-offs of FPG.

RESULTS

Spline regression with adjustment for age, sex, body mass index, waist circumference, education, physical activity, alcohol consumption, and plasma levels of triglycerides, high-density lipoprotein cholesterol and gamma-glutamyltransferase indicated that FPG was associated with risk in a non-linear fashion. Risk with higher FPG increased only above approximately 84 mg/dl. FPG>or=84 mg/dl yielded a sensitivity of 95.4% at a false-positive rate of 86.8%. In comparison, FPG>or=100 and>or=110 mg/dl yielded sensitivities of 78.4 and 42.5% and false-positive rates of 27.8 and 6.8%, respectively. The optimal cut-off of FPG was at approximately 102 mg/dl (sensitivity: 75.8%, false-positive rate: 20.7%).

CONCLUSIONS

Although our study suggests a threshold for increasing diabetes risk at 84 mg/dl, this cut-off would classify the vast majority of the population as at risk. The statistically optimal cut-off supports the current definition of IFG (>or=100 mg/dl).

Performance of an A1C and fasting capillary blood glucose test for screening newly diagnosed diabetes and pre-diabetes defined by an oral glucose tolerance test in Qingdao, China

OBJECTIVE The study's goal was to evaluate the performance of A1C and fasting capillary blood glucose (FCG) tests as mass screening tools for diabetes and pre-diabetes, as determined by the standard oral glucose tolerance test (OGTT). RESEARCH DESIGN AND METHODS Data from 2,332 individuals aged 35-74 years who participated in a population-based cross-sectional diabetes survey in Qingdao, China, were analyzed. A 2-h 75-g OGTT was used to diagnose diabetes. The performance of A1C and FCG was evaluated against the results of the OGTTs by using receiver operating characteristic curve (ROC) analysis. RESULTS The prevalence of newly diagnosed diabetes and pre-diabetes (impaired fasting glucose and/or impaired glucose tolerance) was 11.9 and 29.5%, respectively. For subjects with newly diagnosed diabetes, the area under the ROC curve was 0.67 for A1C and 0.77 for FCG (P < 0.01) in men and 0.67 and 0.75 (P < 0.01) in women, whereas for pre-diabetes, these values were 0.47 and 0.64 (P < 0.001) in men and 0.51 and 0.65 (P < 0.001) in women. At the optimal A1C cutoff point of > or =5.6% for newly diagnosed diabetes, sensitivities (specificities) were 64.4% (61.6%) for men and 62.3% (63.3%) for women. CONCLUSIONS As a screening tool for newly diagnosed diabetes and pre-diabetes, the FCG measurement performed better than A1C in this general Chinese population.

Performance characteristics of the new definition of diabetes: the insulin resistance atherosclerosis study

OBJECTIVE

A1C > or =6.5% has been recently proposed as the defining criterion for diabetes. However, performance characteristics of this definition have not been described.

RESEARCH DESIGN AND METHODS

In the Insulin Resistance Atherosclerosis Study, we compared new to previous definitions of diabetes: 1999 World Health Organization (DM(1999WHO)) and 2003 American Diabetes Association based on fasting glucose alone (DM(FPG126)).

RESULTS

Participants with A1C > or =6.5%, DM(1999WHO), and DM(FPG126) were 44 (5.2%), 132 (15.4%), and 61 (7.1%), respectively. In individuals with DM(1999WHO), mean, median, and interquartile range of A1C were 6.3, 5.9, and 5.5-6.6%, respectively; in individuals with DM(FPG126), mean, median, and interquartile range of A1C were 7.0, 6.6, and 6.0-7.1%.

CONCLUSIONS

A1C > or =6.5% identifies fewer individuals than DM(1999WHO) or DM(FPG126). Studies are needed to determine that A1C > or =6.5% compromises neither blood pressure and lipid management in early diabetes nor the implementation of lifestyle interventions for diabetes prevention.

Could pre-diabetes be considered a clinical condition? opinions from an endocrinologist and a cardiologist

The prevalence of pre-diabetes is increasing worldwide and may start 7 to 10 years before the clinical diagnosis of diabetes. In this stage the presence and accumulation of risk factors is common and already implies an increase in cardiovascular risk. Likewise, the onset of cardiovascular diseases (CVD), mainly coronary artery disease (CAD), peripheral vascular disease and cerebrovascular disease can also take place, all of which account for high rates of morbidity and mortality worldwide. Considering pre-diabetes as a clinical entity, non-pharmacological and pharmacological treatments are indicated with drugs which have shown clinical benefits related to reduction in morbidity and mortality. However, there is still need for new long-term studies to assess the real benefits of several new therapeutical approaches, as well as its cost-effectiveness.

Relationship between A1C and glucose levels in the general Dutch population: the new Hoorn study

OBJECTIVE

To investigate the relationship among A1C, fasting plasma glucose (FPG), and 2-h postload plasma glucose in the Dutch general population and to evaluate the results of using A1C for screening and diagnosis of diabetes.

RESEARCH DESIGN AND METHODS

In 2006-2007, 2,753 participants of the New Hoorn Study, aged 40-65 years, who were randomly selected from the population of Hoorn, the Netherlands, underwent an oral glucose tolerance test (OGTT). Glucose status (normal glucose metabolism [NGM], intermediate hyperglycemia, newly diagnosed diabetes, and known diabetes) was defined by the 2006 World Health Organization criteria. Spearman correlations were used to investigate the agreement between markers of hyperglycemia, and a receiver operating characteristic (ROC) curve was calculated to evaluate the use of A1C to identify newly diagnosed diabetes.

RESULTS

In the total population, the correlations between fasting plasma glucose and A1C and between 2-h postload plasma glucose and A1C were 0.46 and 0.33, respectively. In patients with known diabetes, these correlations were 0.71 and 0.79. An A1C level of > or =5.8%, representing 12% of the population, had the highest combination of sensitivity (72%) and specificity (91%) for identifying newly diagnosed diabetes. This cutoff point would identify 72% of the patients with newly diagnosed diabetes and include 30% of the individuals with intermediate hyperglycemia.

CONCLUSIONS

In patients with known diabetes, correlations between glucose and A1C are strong; however, moderate correlations were found in the general population. In addition, based on the diagnostic properties of A1C defined by ROC curve analysis, the advantage of A1C compared with OGTT for the diagnosis of diabetes is limited.

HOMA insulin sensitivity index and the risk of all-cause mortality and cardiovascular disease events in the general population: the Australian Diabetes, Obesity and Lifestyle Study (AusDiab) study

AIMS/HYPOTHESIS

We assessed whether the relationships between insulin sensitivity and all-cause mortality as well as fatal or non-fatal cardiovascular disease (CVD) events are independent of elevated blood glucose, high blood pressure, dyslipidaemia and body composition in individuals without diagnosed diabetes.

METHODS

Between 1999 and 2000, baseline fasting insulin, glucose and lipids, 2 h plasma glucose, HbA(1c), anthropometrics, blood pressure, medication use, smoking and history of CVD were collected from 8,533 adults aged >35 years from the population-based Australian Diabetes, Obesity and Lifestyle study. Insulin sensitivity was estimated by HOMA of insulin sensitivity (HOMA-%S). Deaths and fatal or non-fatal CVD events were ascertained through linkage to the National Death Index and medical records adjudication.

RESULTS

After a median of 5.0 years there were 277 deaths and 225 CVD events. HOMA-%S was not associated with all-cause mortality. Compared with the most insulin-sensitive quintile, the combined fatal or non-fatal CVD HR (95% CI) for quintiles of decreasing HOMA-%S were 1.1 (0.6-1.9), 1.4 (0.9-2.3), 1.6 (1.0-2.5) and 2.0 (1.3-3.1), adjusting for age and sex. Smoking, CVD history, hypertension, lipid-lowering medication, total cholesterol and waist-to-hip ratio moderately attenuated this relationship. However, the association was rendered non-significant by adding HDL. Fasting plasma glucose, but not HOMA-%S significantly improved the prediction of CVD, beyond that seen with other risk factors.

CONCLUSIONS/INTERPRETATION

In this cohort, HOMA-%S showed no association with all-cause mortality and only a modest association with CVD events, largely explained by its association with HDL. Fasting plasma glucose was a better predictor of CVD than HOMA-%S.