Brain gray matter volume differences in obese youth with type 2 diabetes: a pilot study

BACKGROUND

Adults with type 2 diabetes (T2D) have significantly lower gray matter volume (GMV) compared to healthy peers. Whether GMV differences exist in youth with T2D remains unclear. Thus, we compared global and regional GMV between obese youth with T2D with age, race and sex similar healthy controls.

METHODS

In a cross-sectional study, 20 obese youth with T2D underwent T1-weighted brain magnetic resonance imaging (MRI). Comparisons were made to 20 age, race and sex similar controls. Differences in global and regional GMV between groups were identified using voxel-based morphometry (VBM).

RESULTS

Youth with T2D had a significantly lower global GMV-to-intracranial volume ratio (0.51±0.02 in T2D vs. 0.53±0.02 in controls, p=0.02, Cohen's d=0.85). There were 14 regions where GMV was significantly lower in the T2D group, and nine of these were found in either the temporal or occipital lobes. There were six regions with increased GMV in T2D. All regional differences were significant at p<0.05 after adjusting for multiple comparisons.

CONCLUSIONS

Results from this pilot study show obese youth with T2D have significantly lower global GMV and regional GMV differences, when compared to their age, race and sex similar peers. Future work is needed to determine whether these brain findings are a direct result of adolescent-onset T2D.

Arterial Thickness and Stiffness Are Independently Associated with Left Ventricular Strain

BACKGROUND

The aim of this study was to examine the association between myocardial strain and arterial thickness and stiffness in young adults. Increased common carotid artery intima media thickness and peripheral arterial stiffness are known to precede coronary artery disease and cardiovascular (CV) events such as myocardial infarction and congestive heart failure. However, subclinical cardiac dysfunction can be detected in high-risk adults by myocardial strain echocardiography. The authors hypothesized that increased carotid artery intima media thickness would be associated with abnormal myocardial strain in young subjects who had obesity and type 2 diabetes mellitus.

METHODS

CV risk factors were collected in 338 young adults participating in a prospective, cross-sectional study. The CV parameters collected included intima-media thickness, peripheral arterial stiffness by brachial distensibility, and myocardial strain and strain rate. General linear models were constructed to determine if vascular structure and function measures were independently associated with myocardial strain and strain rate.

RESULTS

A linear relationship was found between global longitudinal strain obtained from the four-chamber view and global strain rate in systole and carotid intima-media thickness (four-chamber global longitudinal strain: β = 3.0, CV risk factor-adjusted R2 = 0.34; global strain rate in systole: β = 0.0053, R2 = 0.21; P ≤ .0001) and between four-chamber global longitudinal strain and lower brachial distensibility (β = -0.42, R2 = 0.22; P < .001).

CONCLUSIONS

Adverse changes in vascular structure and function are simultaneously present with reduced myocardial systolic function.

Obesity and type 2 diabetes are associated with elevated PCSK9 levels in young women

BACKGROUND

Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a key regulator of low-density lipoprotein cholesterol and cardiovascular disease risk, and is an emerging therapeutic target.

OBJECTIVE

We compared serum PCSK9 levels in young adults, with and without type 2 diabetes.

SUBJECTS AND METHODS

Cross-sectional analysis was conducted in a cohort, aged 15 to 26 years, in Cincinnati, OH, from 2005 to 2010. Serum PCSK9 levels were measured in 94 youth with type 2 diabetes, 93 obese control subjects, and 99 lean control subjects. Correlative analyses were conducted to determine significant covariates of PCSK9 by group and sex, and multivariate linear regression models were used to study the independent determinants of PCSK9.

RESULTS

In females, PCSK9 levels were significantly increased in the obese and type 2 diabetes subjects relative to the lean controls (P < .01). Moreover, PCSK9 was positively correlated with multiple metabolic parameters in females: body mass index, systolic blood pressure, fasting glucose, fasting insulin, and C-reactive protein levels (P ≤ .02). In males, PCSK9 levels were decreased overall compared with females (P = .03), and did not differ between the lean, obese, or type 2 diabetes groups.

CONCLUSIONS

Obesity and type 2 diabetes were associated with significantly higher levels of PCSK9 in young women, but not in young men. These data suggest that sex could modify the effects of obesity and diabetes on PCSK9 in young adults.

Prevalence of and Risk Factors for Diabetic Peripheral Neuropathy in Youth With Type 1 and Type 2 Diabetes: SEARCH for Diabetes in Youth Study

OBJECTIVE

We assessed the prevalence of and risk factors for diabetic peripheral neuropathy (DPN) in youth with type 1 diabetes (T1D) and type 2 diabetes (T2D) enrolled in the SEARCH for Diabetes in Youth (SEARCH) study.

RESEARCH DESIGN AND METHODS

The Michigan Neuropathy Screening Instrument (MNSI) was used to assess DPN in 1,734 youth with T1D (mean ± SD age 18 ± 4 years, T1D duration 7.2 ± 1.2 years, and HbA_1c 9.1 ± 1.9%) and 258 youth with T2D (age 22 ± 3.5 years, T2D duration 7.9 ± 2 years, and HbA_1c 9.4 ± 2.3%) who were enrolled in the SEARCH study and had ≥5 years of diabetes duration. DPN was defined as an MNSI exam score of >2. Glycemic control over time was estimated as area under the curve for HbA_1c.

RESULTS

The prevalence of DPN was 7% in youth with T1D and 22% in youth with T2D. Risk factors for DPN in youth with T1D were older age, longer diabetes duration, smoking, increased diastolic blood pressure, obesity, increased LDL cholesterol and triglycerides, and lower HDL cholesterol (HDL-c). In youth with T2D, risk factors were older age, male sex, longer diabetes duration, smoking, and lower HDL-c. Glycemic control over time was worse among those with DPN compared with those without for youth with T1D (odds ratio 1.53 [95% CI 1.24; 1.88]) but not for youth with T2D (1.05 [0.7; 1.56]).

CONCLUSIONS

The high rates of DPN among youth with diabetes are a cause of concern and suggest a need for early screening and better risk factor management. Interventions in youth that address poor glycemic control and dyslipidemia may prevent or delay debilitating neuropathic complications.

Serum cystatin C in youth with diabetes: The SEARCH for diabetes in youth study

AIMS

We compared cystatin C in youth with versus without diabetes and determined factors associated with cystatin C in youth with type 1 diabetes (T1D) and type 2 diabetes (T2D).

METHODS

Youth (ages 12-19years) without diabetes (N=544) were ascertained from the NHANES Study 2000-2002 and those with T1D (N=977) and T2D (N=168) from the SEARCH for Diabetes in Youth Study. Adjusted means of cystatin C concentrations were compared amongst the 3 groups. Next, we performed multivariable analyses within the T1D and T2D SEARCH samples to determine the association between cystatin C and race, sex, age, diabetes duration, HbA1c, fasting glucose, and BMI.

RESULTS

Adjusted cystatin C concentrations were statistically higher in NHANES (0.85mg/L) than in either the T1D (0.75mg/L) or T2D (0.70mg/L) SEARCH groups (P<0.0001). Fasting glucose was inversely related to cystatin C only in T1D (P<0.001) and BMI positively associated only in T2D (P<0.01) while HbA1c was inversely associated in both groups.

CONCLUSIONS

Cystatin C concentrations are statistically higher in youth without diabetes compared to T1D or T2D, however the clinical relevance of this difference is quite small, especially in T1D. In youth with diabetes, cystatin C varies with BMI and acute and chronic glycemic control, however their effects may be different according to diabetes type.

Obesity is associated with an altered HDL subspecies profile among adolescents with metabolic disease

We aimed to determine the risk factors associated with the depletion of large HDL particles and enrichment of small HDL particles observed in adolescents with T2D. Four groups of adolescents were recruited: 1) lean insulin-sensitive (L-IS), normal BMI and no insulin resistance; 2) lean insulin-resistant (L-IR), normal BMI but insulin resistance (fasting insulin levels ≥ 25 mU/ml and homeostatic model assessment of insulin resistance ≥ 6); 3) obese insulin-sensitive (O-IS), BMI ≥ 95th percentile and no insulin resistance; and 4) obese insulin-resistant (O-IR), BMI ≥ 95th percentile and insulin resistance. Plasma was separated by using gel-filtration chromatography to assess the HDL subspecies profile and compared with that of obese adolescents with T2D (O-T2D). Large HDL subspecies were significantly lower across groups from L-IS > L-IR > O-IS > O-IR > O-T2D (P < 0.0001); small HDL particles were higher from L-IS to O-T2D (P < 0.0001); and medium-sized particles did not differ across groups. The contributions of obesity, insulin resistance, and diabetes to HDL subspecies profile were between 23% and 28%, 1% and 10%, and 4% and 9%, respectively. Obesity is the major risk factor associated with the altered HDL subspecies profile previously reported in adolescents with T2D, with smaller contributions from insulin resistance and diabetes.

Lipoprotein particle number and size predict vascular structure and function better than traditional lipids in adolescents and young adults

BACKGROUND

In adults, dyslipidemia is associated with higher carotid thickness and arterial stiffness, predictors of cardiovascular events. In young subjects, lipid concentrations have not been consistently associated with vascular measures.

OBJECTIVE

The objective of the study was to compare nuclear magnetic resonance (NMR) measures of lipoprotein particle number (low-density lipoprotein [LDL] particle, low-density lipoprotein [HDL] particle, very low-density lipoprotein [VLDL] particle) and size (LDL size, HDL size, and VLDL size) to determine if they were associated with vascular measures more strongly than lipid concentrations (LDL cholesterol, HDL cholesterol, and triglyceride [TG]).

METHODS

We evaluated 214 lean (L), 228 obese (O), and 214 diabetic (T2DM) subjects aged 10 to 24 years (33% male and 39% Caucasian). Cardiovascular risk factors, vascular structure, and arterial stiffness were measured. General linear models were constructed including demographics, risk factors, and traditional or NMR lipid parameters. A composite vascular function score was developed as the outcome in receiver operator characteristic scores for determining which lipid parameter was superior in predicting vascular damage.

RESULTS

Risk factors worsened from L to O to T. However, LDL cholesterol was similar in O and T, whereas LDL size differentiated the 3 groups (T > O > L, P ≤ .0001). Models demonstrated the superiority of NMR values, which entered for all but 1 vascular outcome and explained more of the variance than traditional lipid concentrations. Receiver operator characteristic curves demonstrated that NMR values were superior in predicting vascular outcomes. Models stratified by race were similar but cutpoints predicting vascular outcomes differed by race for TG, TG/HDL, and VLDL.

CONCLUSION

Lipoprotein particle number and size are more strongly related to vascular structure and function than traditional lipid values. NMR lipid measures may be a better indicator of risk for target organ damage than traditional lipid measures in adolescents and young adults.

Obese adolescents with type 2 diabetes perform worse than controls on cognitive and behavioral assessments

BACKGROUND

Children with type 1 diabetes demonstrate worse cognitive performance compared with their peers. Little is known regarding the cognitive and behavioral performance in obese adolescents with type 2 diabetes.

METHODS

Cross sectional evaluation of 20 obese adolescents with type 2 diabetes and 20 healthy adolescents was performed in Cincinnati, Ohio. Cognitive tests that included measures of processing speed, working memory, verbal and semantic fluency and parent reports of executive function and problem behavior were compared. Academic achievement and the relationship between cognitive/behavioral scores and diabetes duration and diabetes control (hemoglobin A1c) were assessed in the type 2 diabetes group only.

RESULTS

The type 2 diabetes group had mean duration of diabetes of 2.8 ± 2.2 yr and hemoglobin A1c of 7.9 ± 2.2%. Adolescents with type 2 diabetes scored lower than controls on tests of working and verbal memory and processing speed (all p < 0.05) and worse for Internalizing, Externalizing, and Total Problems behaviors on the Child Behavior Checklist (all p < 0.05). Adolescents with type 2 diabetes scored below the population mean in academic achievement, most notably calculation. Working memory and processing speed were negatively correlated with duration of diabetes (r = -0.50 and -0.47, respectively, p < 0.05).

CONCLUSIONS

Obese youth with type 2 diabetes score poorly compared with controls on multiple assessments of cognitive function and adaptive behavior. Further work is needed to determine if these effects are driven by obesity, diabetes or other demographic and socioeconomic risk factors.

Predictors of Dyslipidemia Over Time in Youth With Type 1 Diabetes: For the SEARCH for Diabetes in Youth Study

OBJECTIVE

Understanding the risk factors associated with progression and regression of dyslipidemia in youth with type 1 diabetes may guide treatments.

RESEARCH DESIGN AND METHODS

We studied 1,478 youth with type 1 diabetes (age 10.8 ± 3.9 years, 50% male, 77% non-Hispanic white, not on lipid-lowering medications) at baseline and at a mean follow-up of 7.1 ± 1.9 years in the SEARCH for Diabetes in Youth (SEARCH) study. Progression to dyslipidemia was defined as normal lipid concentrations at baseline and abnormal at follow-up (non-HDL-cholesterol [C] >130 mg/dL or HDL-C <35 mg/dL). Regression was defined as abnormal lipids at baseline and normal at follow-up. Multivariable logistic regression was used to evaluate factors associated with progression and regression compared with stable normal and stable abnormal, respectively. An area under the curve (AUC) variable was used for the time-varying covariates A1C and waist-to-height ratio (WHtR).

RESULTS

Non-HDL-C progressed, regressed, was stable normal, and stable abnormal in 19%, 5%, 69%, and 7% of youth with type 1 diabetes, respectively. Corresponding percentages for HDL-C were 3%, 3%, 94%, and 1%, respectively. Factors associated with non-HDL-C progression were higher A1C AUC and higher WHtR AUC in males. Non-HDL-C regression was associated with lower WHtR AUC, and HDL-C progression was associated with male sex and higher WHtR AUC. HDL-C regression was not modeled due to small numbers.

CONCLUSIONS

A1C and WHtR are modifiable risk factors associated with change in dyslipidemia over time in youth with type 1 diabetes.

High health satisfaction among emerging adults with diabetes: Factors predicting resilience

OBJECTIVE

This study was conducted to identify factors contributing to health satisfaction outcomes among emerging adults (ages 18-25) with diabetes.

METHOD

SEARCH for Diabetes in Youth study participants whose diabetes was prevalent in 2001 and were ≥18 years of age when they completed a 2008-2009 follow-up survey (n = 340) were included. We developed a health resilience model (HRM) to identify potentially modifiable factors (anticipatory guidance, social support, physical activity, quality of life) associated with health outcomes (satisfaction with health care, overall personal health, self-report of hemoglobin A1c [HbA1c]). Proportional odds logistic regression models were used to examine relationships between modifiable factors and health outcomes while adjusting for predetermined characteristics; linear regression models were used for reported HbA1c. Comparison of participants who reported HbA1c versus nonreporters was conducted.

RESULTS

A majority (70%) of participants rated satisfaction with health care ≥7 out of 10, and most (71%) rated overall health as good, very good, or excellent. Satisfaction with health care was independent of change in provider between the ages of 17 and 24. After controlling for predetermined characteristics, we found that the odds of increased satisfaction with health care and overall personal health were 1.3 and 1.2 greater, respectively, when participants discussed additional diabetes-related anticipatory guidance topics with a provider and 1.3 and 2.1, respectively, for each 10-unit change in quality of life score. Relationship between HbA1c level and modifiable factors was not significant; however, participants reporting HbA1c had higher ratings of health care and overall health versus nonreporters.

CONCLUSIONS

HRM describes relationships between modifiable factors and patient-reported outcomes of satisfaction with health care and overall personal health among a cohort of ethnically and racially diverse emerging adults with longstanding diabetes, over half of whom experienced a change in provider. HRM may discern candidate areas for intervention, such as effective anticipatory guidance that can impact satisfaction with health care and overall health, to promote positive health outcomes. (PsycINFO Database Record

Reexamining the Hypoglycemia Fear Survey for Parents of Young Children in a Sample of Children Using Insulin Pumps

BACKGROUND

We update the psychometric properties of the Hypoglycemia Fear Survey-Parents of Young Children (HFS-PYC), a 26-item measure of parents' hypoglycemia fear for young children using an insulin pump.

METHODS

We combined three similar datasets for the analyses. The data analyzed included parents' responses to the HFS-PYC and a demographic form. For a subset of children (n = 91), we also analyzed self-monitoring of blood glucose data. We used confirmatory factor analysis (CFA) to confirm the measure's original factor structure. Additional analyses examined reliability and validity of a revised HFS-PYC for parents of young children using pumps.

RESULTS

We analyzed data from 116 parents (93% mothers). Mean child age and HbA1c were 5.2 ± 1.3 years and 8.2% ± 1.1%, respectively. CFA identified a 22-item two-factor solution (χ² (208, n = 116) = 368.688, P < 0.001, root mean square error of approximation = 0.08, comparative fit index = 0.94, and Tucker-Lewis index = 0.93) with factors corresponding to the original subscales: worry and behavior. The revised subscales demonstrated at least adequate internal consistency (Cronbach's alpha >0.65). Correlations revealed significant negative associations between current HFS-PYC worry scores and children's mean daily blood glucose and percent of very high glucose levels per day, suggesting less fear among parents of young children with elevated glycemic levels. In addition, there was a positive association with the percent of glucose levels in target, suggesting greater hypoglycemia fear among parents of children who have better control.

CONCLUSIONS

Results provide preliminary evidence for the reliability and validity of a reduced 22-item HFS-PYC for parents of children using insulin pumps.

Associations between long chain polyunsaturated fatty acids and cardiovascular lipid risk factors in youth with type 1 diabetes: SEARCH Nutrition Ancillary Study

PURPOSE

In this longitudinal study we explored the relationships between plasma n-3 and n-6 polyunsaturated fatty acids (PUFAs) and Δ5 and Δ6 desaturase activities (D5D and D6D, respectively) and fasting lipids in youth with type 1 diabetes (T1D).

METHODS

Incident cases of T1D in youth <20years of age who were seen for a baseline study visit (N=914) and a 1-year follow-up visit (N=416) were included. Fasting blood samples were obtained at each visit and plasma phospholipid n-6 PUFAs were measured, which included linoleic acid (LA), dihomo-γ-linolenic acid (DGLA) and arachidonic acid (AA); n-3 PUFAs included α-linolenic acid (ALA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA). Estimated D5D and D6D were calculated as FA product-to-precursor ratios, where D5D=AA/DGLA and D6D=DGLA/LA. To examine the longitudinal relationships between long chain PUFAs, desaturase activities and fasting plasma lipids in youth with T1D mixed effects models were used for each individual PUFAs, D5D and D6D, adjusted for demographics, clinic site, diabetes duration, insulin regimen, insulin dose/kg, HbA1c, insulin sensitivity score, and body mass index with random effects to account for the repeated measurements.

FINDINGS

Favorable lipid associations were found between LA and low-density lipoprotein (LDL) cholesterol (β=-0.58, p<0.05); AA, plasma triglycerides (TG) (β=-0.04, p<0.05) and TG/high-density lipoprotein (HDL)-C ratio (β=-0.04, p<0.05); and D5D, plasma TG (β=-0.2, p<0.05) and TG/HDL-cholesterol ratio (β=-0.23, p<0.05). Findings were mixed for the n-3 PUFAs and DGLA: ALA was positively associated with plasma TG (β=0.33, p<0.05) and HDL cholesterol (β=9.86, p<0.05); EPA was positively associated with total cholesterol (β=8.17, p<0.05), LDL cholesterol (β=5.74, p<0.01) and HDL cholesterol (β=2.27, p<0.01); and DGLA was positively associated with TG/HDL-cholesterol ratio (β=0.05, P<0.05).

CONCLUSION

Findings suggest that the most abundant PUFA, LA as well as its metabolic bi-product AA, may be important targets for CVD lipid risk factor reduction in youth with T1D.

Predictors of Increased Carotid Intima-Media Thickness in Youth With Type 1 Diabetes: The SEARCH CVD Study

OBJECTIVE

Youth with type 1 diabetes have worse cardiovascular (CV) risk factors and higher carotid intima-media thickness (IMT) than their peers without diabetes. Whether the burden of CV risk factors over time is associated with carotid IMT at follow-up in youth with type 1 diabetes is not known.

RESEARCH DESIGN AND METHODS

Two hundred ninety-eight youth with type 1 diabetes (mean age 13.3 ± 2.9 years, 87.6% non-Hispanic white, 53.7% male) had two study visits 5 years apart. CV risk factors, including BMI, lipids, blood pressure, hemoglobin A(1c), and smoking status, were assessed at both visits, and carotid IMT was measured at follow-up using B-mode ultrasonography. Linear regression models with an area under the curve measurement that incorporated the baseline and follow-up CV risk factors were used to evaluate the relationship with carotid IMT at follow-up.

RESULTS

All CV risk factors worsened significantly over time (except LDL cholesterol) (P < 0.05). From baseline to follow-up, the number of abnormal CV risk factors also increased (P < 0.05). Predictors of carotid IMT were older age, male sex, and higher BMI z score area under the curve (all P < 0.05).

CONCLUSIONS

The CV risk factor burden increases over time in youth with type 1 diabetes. BMI z score was the only modifiable CV risk factor that predicted carotid IMT. This study highlights the critical need to better understand the risk factors that influence carotid IMT early in the course of type 1 diabetes.

Adiposity has no direct effect on carotid intima-media thickness in adolescents and young adults: Use of structural equation modeling to elucidate indirect & direct pathways

BACKGROUND

Carotid intima-media thickness (cIMT) is associated with CV events in adults. Thicker cIMT is found in youth with CV risk factors including obesity. Which risk factors have the most effect upon cIMT in youth and whether obesity has direct or indirect effects is not known. We used structural equation modeling to elucidate direct and indirect pathways through which obesity and other risk factors were associated with cIMT.

METHODS

We collected demographics, anthropometrics and laboratory data on 784 subjects age 10-24 years (mean 18.0 ± 3.3 years). Common, bulb and internal carotid cIMT were measured by ultrasound. Multivariable regression analysis was performed to assess independent determinants of cIMT. Analyses were repeated with structural equation modeling to determine direct and indirect effects.

RESULTS

Multivariable regression models explained 11%-22% of variation of cIMT. Age, sex and systolic blood pressure (BP) z-score were significant determinants of all cIMT segments. Body mass index (BMI) z-score, race, presence of type 2 diabetes mellitus (T2DM), hemoglobin A1c (HbA1c) and non-HDL were significant for some segments (all p = 0.05). The largest direct effect on cIMT was age (0.312) followed by BP (0.228), Blood glucose control (0.108) and non-HDL (0.134). BMI only had a significant indirect effect through blood glucose control, BP & non-HDL. High sensitivity C-reactive protein (CRP) had a small indirect effect through blood glucose control (all p = 0.05).

CONCLUSIONS

Age and BP are the major factors with direct effect on cIMT. Glucose and non-HDL were also important in this cohort with a high prevalence of T2DM. BMI only has indirect effects, through other risk factors. Traditional CV risk factors have important direct effects on cIMT in the young, but adiposity exerts its influence only through other CV risk factors.

Superiority of lipoprotein particle number to detect associations with arterial thickness and stiffness in obese youth with and without prediabetes

BACKGROUND

The nuclear magnetic resonance (NMR) lipoprotein profile provides additional cardiovascular risk information beyond traditional lipids in high-risk adults. Similar studies have not been conducted in youth.

OBJECTIVE

To evaluate the relationship between the NMR profile and preclinical vascular measures in youth.

METHODS

We studied 96 obese youth with prediabetes (mean age = 18.1 ± 3.6 years, 63% female, 78% African American) and 118 obese normoglycemic controls (mean age = 18.0 ± 3.1 years, 75% female, 62% African American) cross sectionally. Traditional lipids (triglycerides, total, high-density lipoprotein [HDL], and low-density lipoprotein [LDL] cholesterol), NMR particle size (particle concentration [P] and size) and vascular thickness (carotid IMT) and stiffness (pulse wave velocity [PWV]) were measured. Independent associations between lipoproteins with carotid IMT and PWV after adjustment for group, age, race, sex, BMI z score, blood pressure, HOMA-IR, and A1c were studied.

RESULTS

NMR analysis revealed youth with prediabetes exhibited a more atherogenic profile with higher levels of small LDL-P and HDL-P and lower levels of intermediate and large HDL-P (P < .03). In addition, lower intermediate HDL-P was associated with a higher carotid IMT, whereas higher small HDL-P was associated with a higher PWV (P < .01). Traditional lipids were not significantly different between groups and were not associated with either vascular outcome.

CONCLUSIONS

NMR lipoprotein subclasses have improved sensitivity compared to traditional lipids to detect lipoprotein abnormalities in normoglycemic and prediabetic obese youth and are independently associated with preclinical vascular thickness and stiffness. NMR lipids may enhance cardiovascular risk assessment in youth.

Comparison of mercury sphygmomanometry blood pressure readings with oscillometric and central blood pressure in predicting target organ damage in youth

OBJECTIVE

Hypertension (HT) is an important risk factor for target organ damage (TOD). New methods for measuring BP are replacing mercury sphygmomanometry in many clinics. We examined the utility of different BP measurement techniques in predicting subclinical TOD in adolescents and young adults.

METHODS

Participants in a study of the cardiovascular effects of obesity and type 2 diabetes were evaluated (N=677, 18±3.3 years, 35% male, 60% non-White, 30% with type 2 diabetes). We measured adiposity, laboratory data, left ventricular mass, carotid intima-media thickness, and pulse wave velocity. BP was measured three times by mercury sphygmomanometry (BPm), using an oscillometric device (BPo), and by arterial tonometry to measure central aortic BP (BPc). Participants were stratified as normotensive, prehypertensive, or hypertensive.

RESULTS

The prevalence of HT in this cohort with a mean BMI of 31 was the highest on BPo measurement (16%), followed by BPm (11%) and BPc (9%; P≤0.001) measurements. BPm was the most consistent in differentiating left ventricular mass and pulse wave velocity among participants in the prehypertensive group as compared with the normotensive and hypertensive groups. Mercury BP measurement was also more sensitive and specific at predicting greater left ventricular mass, pulse wave velocity, and carotid thickness compared with other BP measurement techniques in logistic regression.

CONCLUSION

We conclude that mercury sphygmomanometry should remain the gold standard for evaluation of HT and the risk for TOD in adolescents and young adults.

Insulin pump use and glycemic control in adolescents with type 1 diabetes: Predictors of change in method of insulin delivery across two years

Few studies have explored durability of insulin pump use, and none have explored the link between depression and pump discontinuation. To examine the relationship between depressive symptoms [measured by the Children's Depression Inventory (CDI)], method of insulin delivery, and hemoglobin A1c (A1c), mixed models were used with data from 150 adolescents with type 1 diabetes (T1D) and visits every 6 months for 2 years. Of the 63% who used a pump, compared with multiple daily injections (MDI) at baseline, there were higher proportions who were non-minorities, had caregivers with a college degree, private insurance, and two caregivers in the home (p ≤ 0.01). After adjusting for time, sex, age, T1D duration, frequency of blood glucose monitoring, ethnicity, insurance, and caregiver number and education, baseline pump use was associated with -0.79% lower mean A1c [95% confidence interval (CI): -1.48, -0.096; p = 0.03]. For those using a pump at baseline, but switching to MDI during the study (n = 9), mean A1c was 1.38% higher (95% CI: 0.68, 2.08; p < 0.001) than that for those who did not switch method of delivery. A 10-point increase in CDI was associated with a 0.39% increase in A1c (95% CI: 0.16, 0.61; p = 0.001), independent of pump use. Regarding the temporal relationship between CDI score and changing method of insulin delivery, prior higher CDI score was associated with switching from pump to MDI (odds ratio = 1.21; 95% CI: 1.05, 1.39; p = 0.007). Clinicians should be aware of the associations between depressive symptoms, change in insulin delivery method, and the effect on glycemic control.

Insulin Sensitivity and β-Cell Function Improve after Gastric Bypass in Severely Obese Adolescents

OBJECTIVE

To test the hypothesis that insulin secretion and insulin sensitivity would be improved in adolescents after Roux-en-Y gastric bypass (RYGB).

STUDY DESIGN

A longitudinal study of 22 adolescents and young adults without diabetes undergoing laparoscopic RYGB (mean age 17.1 ± 1.42 years; range 14.5-20.1; male/female 8/14; Non-Hispanic White/African American 17/5) was conducted. Intravenous glucose tolerance tests were done to obtain insulin sensitivity (insulin sensitivity index), insulin secretion (acute insulin response to glucose ), and the disposition index as primary outcome variables. These variables were compared over the 1 year of observation using linear mixed modeling.

RESULTS

In the 1-year following surgery, body mass index fell by 38% from a mean of 61 ± 12.3 to 39 ± 8.0 kg/m(2) (P < .01). Over the year following surgery, fasting glucose and insulin values declined by 54% and 63%, respectively. Insulin sensitivity index increased 300% (P < .01), acute insulin response to glucose decreased 56% (P < .01), leading to a nearly 2-fold increase in the disposition index (P < .01). Consistent with improved β-cell function, the proinsulin to C-peptide ratio decreased by 21% (P < .01).

CONCLUSIONS

RYGB reduced body mass index and improved both insulin sensitivity and β-cell function in severely obese teens and young adults. These findings demonstrate that RYGB is associated with marked metabolic improvements in obese young people even as significant obesity persists.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT00360373.

Assessing endothelial dysfunction in adolescents and young adults with type 1 diabetes mellitus using a non-invasive heat stimulus

BACKGROUND

Microvascular dysfunction is a key event in the development of atherosclerosis, which predates the clinical manifestations of vascular disease including stroke and myocardial infarction. Dysfunction of the microvasculature can be measured as a decreased microperfusion in response to heat.

OBJECTIVE

We sought to evaluate the microvasculature using heat among adolescents and young adults with type 1 diabetes (T1D) compared to healthy non-diabetic controls. We hypothesized that youth with T1D would have impaired microvascular function measured as decreased perfusion.

METHODS

We studied 181 adolescents and young adults with T1D and 96 age-, race-, and sex-matched healthy controls (mean age 19 yr). Patients were seen at an in-person study visit where demographics, anthropometrics, and laboratory data was obtained. Skin microvascular perfusion was measured on the volvar surface of the right forearm using a standard laser flow Doppler. Measurements were taken at baseline and after heating to 44° C.

RESULTS

Youth with T1D had decreased microvascular perfusion as measured by lower percent change of perfusion units (1870 ± 945 vs. 2539 ± 1255, p < 0.01) and percent change in area under the curve (1870 ± 945 vs. 2539 ± 1255, p < 0.01) compared to controls. Glycosylated hemoglobin A1c (HbA1c) was found to be an independent determinant of microvascular function (p < 0.05).

CONCLUSIONS

Adolescents and young adults with T1D have evidence of microvascular dysfunction that can be detected using heat, a non-invasive physiologic stimulus. HbA1c appears to play an independent role in determining microvascular perfusion suggesting tight glycemic control is probably important for the development of vascular disease.

Low Serum Vitamin D Levels Are Associated With Increased Arterial Stiffness in Youth With Type 2 Diabetes

OBJECTIVE

Adult studies demonstrate that low vitamin D (25[OH]D) is an independent risk factor for arterial stiffness. Similar studies have not been conducted in youth with type 2 diabetes mellitus (T2DM). The objective was to elicit the association between 25[OH]D and arterial stiffness in obese youth with and without T2DM. We hypothesized that 25[OH]D would be inversely correlated with arterial stiffness indices, including pulse wave velocity (PWV), augmentation index (AIx), and brachial distensibility (BrachD).

RESEARCH DESIGN AND METHODS

Cross-sectional analysis was conducted in Cincinnati, OH, from 2004 to 2010. 25[OH]D, PWV, AIx, and BrachD were measured in 190 youth with T2DM, 190 obese control subjects without T2DM, and 190 lean control subjects without T2DM. Multivariate analyses were conducted to elicit the independent association between 25[OH]D and arterial stiffness indices by group.

RESULTS

The mean age was 17.9 ± 3.4 years, 55% were African American, and 34% were male. The mean 25[OH]D levels were 21.27, 14.29, and 14.13 ng/mL in lean individuals, obese individuals, and obese individuals with T2DM, respectively (P < 0.01). PWV, AIx, and BrachD worsened from lean to obese to T2DM (P < 0.01). General linear models found that 25[OH]D level was independently associated with PWV in lean individuals and with AIx in the group with T2DM such that a 3 ng/mL increase in 25[OH]D was associated with an AIx decrease of 1% (baseline AIx = 5.7 ± 12.0%).

CONCLUSIONS

25[OH]D is inversely associated with some measures of arterial stiffness in lean adolescents and obese adolescents with T2DM but not in obese normoglycemic adolescents. Future studies are needed to determine if supplemental 25[OH]D is important for cardiovascular health.

Arterial stiffness in adolescents and young adults with and without type 1 diabetes: the SEARCH CVD study

BACKGROUND

Arterial stiffness is a useful parameter to predict future cardiovascular disease.

OBJECTIVE

We sought to compare arterial stiffness in adolescents and young adults with and without type 1 diabetes (T1D) and explore the risk factors associated with the differences observed.

SUBJECTS AND METHODS

Carotid-femoral pulse wave velocity (PWV), augmentation index (AI75), and brachial distensibility (BrachD) were measured in 402 adolescents and young adults with T1D (age 18.8 ± 3.3 yr, T1D duration 9.8 ± 3.8 yr) and 206 non-diabetic controls that were frequency-matched by age, sex, and race/ethnicity in a cross-sectional study. General linear models were used to explore variables associated with an increase in arterial stiffness after adjustment for demographic and metabolic covariates.

RESULTS

T1D status was associated with a higher PWV (5.9 ± 0.05 vs. 5.7 ± 0.1 m/s), AI75 (1.3 ± 0.6 vs. -1.9 ± 0.7%), and lower BrachD (6.2 ± 0.1 vs. 6.5 ± 0.1%Δ/mmHg), all p < 0.05. In multivariate models, age, sex, race, adiposity, blood pressure, lipids, and the presence of microalbuminuria were found to be independent correlates of increased arterial stiffness. After adjustment for these risk factors, T1D status was still significantly associated with arterial stiffness (p < 0.05).

CONCLUSIONS

Peripheral and central subclinical vascular changes are present in adolescents and young adults with T1D compared to controls. Increased cardiovascular risk factors alone do not explain the observed differences in arterial stiffness among cases and controls. Identifying other risk factors associated with increased arterial stiffness in youth with T1D is critical to prevent future vascular complications.

Severe Obesity in Adolescents and Young Adults Is Associated With Subclinical Cardiac and Vascular Changes

CONTEXT

Severe obesity is the fastest growing subgroup of obesity in youth.

OBJECTIVE

We sought to explore the association between severe obesity and subclinical measures of cardiac and vascular structure and function in adolescents and young adults.

DESIGN, SETTING, AND PARTICIPANTS

This was a cross-sectional comparison of 265 adolescents and young adults with severe obesity (defined as body mass index [BMI] ≥120% of the 95th percentile) to 182 adolescents and young adults with obesity (defined as BMI ≥100-119th of the 95th percentile) at tertiary medical center.

MAIN OUTCOMES

Noninvasive measures of cardiac and vascular structure and function were assessed.

RESULTS

Participants were a mean age of 17.9 years, 62% were non-Caucasian, and 68% were female. Systolic blood pressure, fasting insulin, C-reactive protein, IL-6, and frequency of type 2 diabetes were higher in participants with severe obesity (all P < .05). Arterial thickness and stiffness, cardiac structure, and diastolic function were also significantly worse in youth with severe obesity as measured by higher left ventricular mass index, worse diastolic function, higher carotid intima media thickness, and pulse wave velocity and lower brachial distensibility (all P < .05). Regression modeling showed that severe obesity (compared with obesity) was independently associated with each of the above outcomes after adjustment for age, race, sex, blood pressure, lipids, and inflammatory markers (P < .05).

CONCLUSIONS

Adolescents and young adults with severe obesity have a more adverse cardiovascular risk profile and worse cardiac and vascular structure and function. More importantly, severe obesity is independently associated with these subclinical cardiac and vascular changes.