Genome wide identification of new genes and pathways in patients with both autoimmune thyroiditis and type 1 diabetes

Autoimmune thyroid diseases (AITD) and Type 1 diabetes (T1D) frequently occur in the same individual pointing to a strong shared genetic susceptibility. Indeed, the co-occurrence of T1D and AITD in the same individual is classified as a variant of the autoimmune polyglandular syndrome type 3 (designated APS3v). Our aim was to identify new genes and mechanisms causing the co-occurrence of T1D + AITD (APS3v) in the same individual using a genome-wide approach. For our discovery set we analyzed 346 Caucasian APS3v patients and 727 gender and ethnicity matched healthy controls. Genotyping was performed using the Illumina Human660W-Quad.v1. The replication set included 185 APS3v patients and 340 controls. Association analyses were performed using the PLINK program, and pathway analyses were performed using the MAGENTA software. We identified multiple signals within the HLA region and conditioning studies suggested that a few of them contributed independently to the strong association of the HLA locus with APS3v. Outside the HLA region, variants in GPR103, a gene not suggested by previous studies of APS3v, T1D, or AITD, showed genome-wide significance (p < 5 × 10(-8)). In addition, a locus on 1p13 containing the PTPN22 gene showed genome-wide significant associations. Pathway analysis demonstrated that cell cycle, B-cell development, CD40, and CTLA-4 signaling were the major pathways contributing to the pathogenesis of APS3v. These findings suggest that complex mechanisms involving T-cell and B-cell pathways are involved in the strong genetic association between AITD and T1D.

Change in adiposity minimally affects the lipid profile in youth with recent onset type 1 diabetes

OBJECTIVE

Dyslipidemia contributes to the increased risk of cardiovascular disease in persons with type 1 diabetes (T1D). Weight control is commonly recommended as a treatment for dyslipidemia. However, the extent to which decreases in weight affect the lipid profile in youth with T1D is not known. Therefore, we tested the hypothesis that decreases in body mass index z-score (BMIz) were associated with concomitant changes in the lipid profile in youth with T1D.

STUDY DESIGN

We studied 1142 youth with incident T1D, who had at least two fasting lipid measurements over 2 yr (initial visit mean: age = 10.8 ± 3.9 yr, BMIz = 0.55 ± 0.97, T1D duration = 10.7 ± 7.6 months; 47.5% female, 77.9% non-Hispanic white) in the SEARCH for Diabetes in Youth Study. Longitudinal mixed models were used to examine the relationships between changes in BMIz and changes in total, low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), non-HDL cholesterol, and log triglycerides (TG) adjusted for initial age, sex, race/ethnicity, clinical site, season of study visit, T1D duration, and glycated hemoglobin A1c (HbA1c).

RESULTS

We found that over 2 yr all lipid levels, except LDL-C, increased significantly (p < 0.05). Decreases in BMIz were associated with favorable changes in HDL-C and TG only and the magnitude of these changes depended on the initial BMIz value (interaction p < 0.05), so that greater improvements were seen in those with higher BMIz.

CONCLUSIONS

Our data suggest that weight loss may be an effective, but limited, therapeutic approach for dyslipidemia in youth with T1D.

Association of parental history of diabetes with cardiovascular disease risk factors in children with type 2 diabetes

AIMS

Determine if parental diabetes (DM) is associated with unhealthier cardiovascular disease (CVD) risk profiles in youth with type 2 diabetes (T2D), and whether associations differed by race/ethnicity.

METHODS

Family history was available for 382 youth with T2D from 2001 prevalent and 2002-2005 incident SEARCH for Diabetes in Youth cohorts. Parental DM was evaluated in two ways: two-category-any parent vs. no parent DM (evaluated overall and stratified by race/ethnicity); and four-category-both parents, mother only, father only, or no parent DM (evaluated overall only). Associations with hemoglobin A1c (HbA1c), fasting lipids, blood pressure (BP), and urine albumin:creatinine ratio (ACR) were examined using regression models.

RESULTS

Overall, sample characteristics included: 35.9% male, 19.1% non-Hispanic white (NHW), mean T2D duration 26.6±22.2months, mean HbA1c 7.9%±2.5% (62.6±27.8mmol/mol). Unadjusted two-category comparisons showed that youth with parental DM had higher HbA1c, higher DBP, and higher frequency of elevated ACR. Adjusted two-category comparisons showed associations remaining in non-stratified analysis for ACR [OR (95% CI)=2.3 (1.1, 5.0)] and in NHW youth for HbA1c [6.8%±0.4 vs. 8.0±0.4 (51.1±4.8 vs. 63.9±4.2mmol/mol), p=.015], DBP (67.7%±4.5 vs. 76.9±4.4mm Hg, p=.014) and lnTG (4.7±0.3 vs. 5.3±0.3, p=.008). There were no significant findings in the adjusted four-category evaluation.

CONCLUSIONS

Parental history of diabetes may be associated with unhealthier CVD risk factors in youth with T2D.

Insulin sensitivity and arterial stiffness in youth with type 1 diabetes: the SEARCH CVD study

AIMS

Decreased insulin sensitivity is a cardiovascular risk factor (CVRF) in youth with type 1 diabetes (T1D). Whether baseline insulin sensitivity is independently associated with changes in early arterial stiffness (pulse wave velocity (PWV)) over time in youth with T1D is not known.

METHODS

Two hundred ninety-eight youth with T1D in the SEARCH CVD study had PWV measured~five years apart. Insulin sensitivity and other CVRFs were measured at baseline. The association between baseline insulin sensitivity with PWV over time was explored using linear mixed models. Models were adjusted for baseline age, sex and race, with subsequent adjustment for CVRFs.

RESULTS

There was a significant interaction (p=0.0326) between baseline insulin sensitivity and time on PWV, independent of CVRFs, indicating that higher insulin sensitivity levels were associated with lower rate of change in PWV over time. Other significant predictors of PWV change were baseline age [β=0.007 (p=0.03) increase in logPWV/year increase in age] and mean arterial blood pressure (MAP) [β=0.005 (p<0.01) increase in logPWV/mmHg increase in MAP] and smoking status (current vs. never smoker).

CONCLUSIONS

Lower insulin sensitivity at baseline appears to be an important risk factor for increased arterial stiffness over time in youth with T1D. This identifies a potentially modifiable therapeutic target.

Cardiovascular health in adolescents with type 1 diabetes: the SEARCH CVD study

OBJECTIVE

In their Strategic Impact Goal Statement, the American Heart Association focused on primordial prevention of cardiovascular risk factors by defining metrics for ideal cardiovascular health (ICH). The prevalence of ICH among youth with type 1 diabetes is unknown. Youth with type 1 diabetes face an increased risk of cardiovascular disease (CVD) as they age. The purpose of this report was to examine the prevalence of ICH in a population of youth with type 1 diabetes and to examine the association of ICH with measures of cardiovascular structure and function.

RESEARCH DESIGN AND METHODS

This report is based on SEARCH CVD an ancillary study to the SEARCH for Diabetes in Youth. A total of 190 adolescents with type 1 diabetes had complete data on all of the ICH metrics at baseline and had measures of arterial stiffness [pulse wave velocity (PWV), brachial distensibility (BrachD), and augmentation index (AIx)] and carotid intima-media thickness completed at a follow-up visit [on average 5 yr after baseline (interquartile range 4-5)].

RESULTS

No subjects met the ICH criteria for all 7 metrics. Meeting an increasing number of ICH metrics was significantly associated with lower arterial stiffness [lower PWV of the trunk (β = -0.02 ±0.01; p = 0.004) and AIx (β = -2.2 ±0.66; p = 0.001), and increased BrachD (β = 0.14 ±0.07; p = 0.04)].

CONCLUSIONS

Increasing number of ICH metrics was significantly associated with decreased arterial stiffness, but prevalence of ICH in this population was low. Youth with type 1 diabetes could benefit from improvements in their cardiovascular health.

Shared decision-making among caregivers and health care providers of youth with type 1 diabetes

The present study aimed to examine perceptions of shared decision-making (SDM) in caregivers of youth with type 1 diabetes (T1D). Interview, survey data, and HbA1c assays were gathered from caregivers of 439 youth with T1D aged 3-18 years. Caregiver-report indicated high perceived SDM during medical visits. Multivariable linear regression indicated that greater SDM is associated with lower HbA1c, older child age, and having a pediatric endocrinologist provider. Multiple logistic regression found that caregivers who did not perceive having made any healthcare decisions in the past year were more likely to identify a non-pediatric endocrinologist provider and to report less optimal diabetes self-care. Findings suggest that youth whose caregivers report greater SDM may show benefits in terms of self-care and glycemic control. Future research should examine the role of youth in SDM and how best to identify youth and families with low SDM in order to improve care.

Smoking and arterial stiffness in youth with type 1 diabetes: the SEARCH Cardiovascular Disease Study

OBJECTIVE

To evaluate the effects of smoking on early markers of cardiovascular disease (arterial stiffness) in adolescents with and without type 1 diabetes (T1D) in the SEARCH Cardiovascular Disease Study.

STUDY DESIGN

Participants included 606 youth (18.9 ± 3.3 years, 83% non-Hispanic white; 50% male). Six groups were defined: (1) smokers with T1D (n = 80); (2) former smokers with T1D (n = 88); (3) nonsmokers with T1D (n = 232); (4) smokers without T1D (n = 40); (5) former smokers without T1D former (n = 51); and (6) nonsmokers without T1D (n = 115). Arterial stiffness measurements included pulse wave velocity (PWV), augmentation index, and brachial distensibility. Multivariate linear regression was used to assess the independent and joint effects of T1D and smoking on arterial stiffness.

RESULTS

Nearly 20% of both youth with and without T1D and T1D were smokers. In youth without T1D, smokers had higher trunk and arm PWV. After adjustment for potential confounders, T1D, but not smoking, was an independent predictor of PWV (P < .05). Moreover, smoking status did not modify the association between T1D and increased arterial stiffness.

CONCLUSIONS

We found a high prevalence of smoking among youth with and without T1D; however, smoking status was not independently associated with increased arterial stiffness in youth with T1D.

Prevalence of and disparities in barriers to care experienced by youth with type 1 diabetes

OBJECTIVE

To describe the prevalence of access and process barriers to health care and to examine their relationship to sociodemographic and disease factors in a large and diverse cohort of US youth with type 1 diabetes.

STUDY DESIGN

A cross-sectional analysis of 780 youth who participated in the SEARCH for Diabetes in Youth Study and were diagnosed with type 1 diabetes in 2002-2005. Experience of barriers to care was collected from parent report on questionnaires. Analyses included multivariate regression models to predict the presence of specific barriers to care.

RESULTS

Overall, 81.7% of participants reported at least one barrier; the 3 most common were costs (47.5%), communication (43.0%), and getting needed information (48.4%). Problems with access to care, not having a regular provider, and receiving contextual care (care that takes into account personal and family context) were associated with poorer glycated hemoglobin levels. Adjusted multivariate models indicated that barriers related to access (regular provider, cost) were most likely for youth with low family income and those without public health insurance. Barriers associated with the processes of quality care (contextual care, communication) were more likely for Hispanic youth and those whose parents had less education.

CONCLUSIONS

This study indicates that a large proportion of youth with type 1 diabetes experience substantial barriers to care. Barriers to access and those associated with processes of quality care differed by sociodemographic characteristics. Future investigators should expand knowledge of the systemic processes that lead to disparate outcomes for some youth with diabetes and assess potential solutions.

No association of dietary fiber intake with inflammation or arterial stiffness in youth with type 1 diabetes

AIM

To examine the association of dietary fiber intake with inflammation and arterial stiffness among youth with type 1 diabetes (T1D) in the US.

METHODS

Data are from youth ≥ 10 years old with clinically diagnosed T1D for ≥ 3 months and ≥ 1 positive diabetes autoantibody in the SEARCH for Diabetes in Youth Study. Fiber intake was assessed by food frequency questionnaire with measurement error (ME) accounted for by structural sub-models derived using additional 24-h dietary recall data in a calibration sample and the respective exposure-disease model covariates. Markers of inflammation, measured at baseline, included IL-6 (n=1405), CRP (n=1387), and fibrinogen (n=1340); markers of arterial stiffness, measured approximately 19 months post-baseline, were available in a subset of participants and included augmentation index (n=180), pulse wave velocity (n=184), and brachial distensibility (n=177).

RESULTS

Mean (SD) T1D duration was 47.9 (43.2) months; 12.5% of participants were obese. Mean (SD) ME-adjusted fiber intake was 15 (2.8) g/day. In multivariable analyses, fiber intake was not associated with inflammation or arterial stiffness.

CONCLUSION

Among youth with T1D, fiber intake does not meet recommendations and is not associated with measures of systemic inflammation or vascular stiffness. Further research is needed to evaluate whether fiber is associated with these outcomes in older individuals with T1D or among individuals with higher intakes than those observed in the present study.

Prediabetes: the effects on arterial thickness and stiffness in obese youth

OBJECTIVE

Adults with prediabetes are at increased risk to develop cardiovascular disease. Whether prediabetes in adolescents is associated with early markers of cardiovascular disease is not known. We sought to 1) compare the cardiovascular risk profiles among adolescents and young adults with prediabetes with those with normal glucose tolerance and 2) determine whether prediabetes is independently associated with noninvasive measures of arterial thickness and stiffness.

RESEARCH DESIGN AND METHODS

We studied 102 obese youth with prediabetes and 139 obese youth with normal glucose tolerance in a cross-sectional study. Prediabetes or at increased diabetes risk was diagnosed by a fasting blood glucose level of ≥100 to 125 mg/dL, 2-hour oral glucose tolerance test value of ≥140 to 199 mg/dL, or a hemoglobin A1c (HbA1c) value of ≥5.7% to 6.4%. Arterial thickness and stiffness were measured by carotid intima-media thickness (IMT), augmentation index, pulse wave velocity, and brachial distensibility (BrachD).

RESULTS

Nearly 50% of youth were diagnosed with prediabetes by HbA1c. Youth with prediabetes had worse metabolic profiles with higher BMI z score, systolic blood pressure, and fasting insulin; increased carotid IMT; and lower BrachD compared with normal glucose-tolerant youth (P < .05). Multivariate regression analysis found prediabetes was a significant determinant of internal carotid IMT and BrachD (P < .05). After excluding youth diagnosed by HbA1c, the prediabetes group was borderline significant for internal carotid IMT (.1 > P ≥ .05) only.

CONCLUSIONS

Youth with prediabetes have worse cardiometabolic risk factors and evidence of increased arterial thickness and stiffness. Interventions to prevent prediabetes are crucial to reduce the development of early arterial disease.

Diabetes self-management education patterns in a US population-based cohort of youth with type 1 diabetes

PURPOSE

The purpose of this study is to describe (1) the receipt of diabetes self-management education (DSME) in a large, diverse cohort of US youth with type 1 diabetes (T1DM), (2) the segregation of self-reported DSME variables into domains, and (3) the demographic and clinical characteristics of youth who receive DSME.

METHODS

Data are from the US population-based cohort SEARCH for Diabetes in Youth. A cross-sectional analysis was employed using data from 1273 youth <20 years of age at the time of diagnosis of T1DM. Clusters of 19 self-reported DSME variables were derived using factor analysis, and their associations with demographic and clinical characteristics were evaluated using polytomous logistic regression.

RESULTS

Nearly all participants reported receiving DSME content consistent with "survival skills" (eg, target blood glucose and what to do for low or high blood glucose), yet gaps in continuing education were identified (eg, fewer than half of the participants reported receiving specific medical nutrition therapy recommendations). Five DSME clusters were explored: receipt of specific MNT recommendations, receipt of diabetes information resources, receipt of clinic visit information, receipt of specific diabetes information, and met with educator or nutritionist. Factor scores were significantly associated with demographic and clinical characteristics, including race/ethnicity, socioeconomic status, and diabetes self-management practices.

CONCLUSIONS

Health care providers should work together to address reported gaps in DSME to improve patient care.

Cardiovascular risk factors are associated with increased arterial stiffness in youth with type 1 diabetes: the SEARCH CVD study

OBJECTIVE

To evaluate if presence of cardiovascular (CV) risk factors and their clustering as metabolic syndrome (MetS) is associated with increased arterial stiffness and accelerated progression over time among youth with type 1 diabetes.

RESEARCH DESIGN AND METHODS

Longitudinal study of 298 youth with type 1 diabetes (age 14.5 years; 46.3% female; duration 4.8 years), with two research visits conducted 5 years apart. CV factors included: waist circumference, blood pressure (BP), fasting lipids (HDL cholesterol, LDL cholesterol [LDL-c], triglycerides), albumin/creatinine ratio, and HbA1c. MetS was based on Adult Treatment Panel III criteria modified for youth. Pulse wave velocity (PWV) in the carotid-femoral segment was measured by tonometry. Mixed models were used to assess the rate of progression in PWV and the association between CV factors and PWV over time.

RESULTS

PWV increased significantly over time (0.145 m/s/year; P < 0.0001). MetS (P = 0.0035), large waist (P < 0.0001), and elevated BP (P = 0.0003) at baseline were each associated with worse PWV over time. These baseline factors, however, did not significantly influence the rate of progression. Increases in waist circumference (P < 0.0001), LDL-c levels (P = 0.0156), and declining glucose control (HbA1c; P = 0.0419) were independently associated with higher PWV over time.

CONCLUSIONS

Presence, clustering, and worsening of CV risk factors are associated with increased arterial stiffness over time in youth with type 1 diabetes. Whether improvement in CV risk factors early in life will slow the progression of arterial stiffness and reduce the burden of CV disease in this population requires further study.

Improving depression screening for adolescents with type 1 diabetes

OBJECTIVE

Depression is common among adolescents, but rates increase significantly in the presence of chronic health conditions. Outpatient screening for depression is recommended but rarely formally conducted due to barriers of implementation.

METHODS

To provide a model for depression screening of youth with chronic health conditions, a standard process using a self-administered electronic version of the Children's Depression Inventory (CDI) was developed. Quality improvement methodology and traditional analytic approaches were used to test the feasibility and outcomes of routine screening in patients 13 to 17 years of age with type 1 diabetes.

RESULTS

Of the 528 eligible adolescents, 509 (96%) received at least 1 depression screen during the first year. The process was tested and refined in over 1200 patient encounters, which resulted in an increase in depression screening rates from <5% to a median of 85% over the initial 12 months. Both patients and staff reported acceptance of screening on qualitative surveys. Elevated CDI scores (≥ 16) were found in 8% of the sample; moderate scores (10-15) in 12% of the sample. Low risk scores were found in 80% of the sample. Higher CDI scores correlated with lower blood glucose monitoring frequency and higher hemoglobin A1c, confirming the link between more depression symptoms and poorer diabetes management and control. Suicidal ideation was endorsed in 7% of the population.

CONCLUSIONS

Systematic depression screening in adolescents with type 1 diabetes can be reliably implemented with clinically significant results. A systematic approach, such as described in this study, can serve as a model for other chronic health conditions.

Digenic heterozygous HNF1A and HNF4A mutations in two siblings with childhood-onset diabetes

Monogenic diabetes due to mutations in the transcription factor genes hepatocyte nuclear factor 1A (HNF1A) and HNF4A is characterized by islet cell antibody negative, familial diabetes with residual insulin secretion. We report two sisters with childhood onset diabetes who are both heterozygous for the most common mutation in each of two transcription factors, HNF1A, and HNF4A. The proband was diagnosed with diabetes at 7 yr of age and treated with insulin for 4 yr. Her genetic diagnosis resulted in transition to sulfonylureas for one and a half years before insulin therapy was re-initiated due to declining glycemic control. Her sister was diagnosed with diabetes at 14 yr of age, treated initially with insulin but has been well controlled on oral sulfonylurea therapy for over 2 yr. Both sisters inherited the HNF4A gene mutation R127W from their mother and the HNF1A gene mutation P291fsinsC (c.872dup) from their father. The father was diagnosed with diabetes at 45 yr of age. Their brother is heterozygous for the HNF4A R127W mutation. Both the brother and mother have normal glucose tolerance at the ages of 16 and 46 yr, respectively. Digenic inheritance of HNF1A and HNF4A mutations is very rare and has only been reported in two families where conclusive evidence for the pathogenicity of their mutations was lacking. Follow-up studies in this family co-segregating the two most commonly reported HNF1A/HNF4A mutations will be informative for understanding the effect of digenic inheritance upon phenotypic severity and response to sulfonylurea therapy.

Prevalence, characteristics and clinical diagnosis of maturity onset diabetes of the young due to mutations in HNF1A, HNF4A, and glucokinase: results from the SEARCH for Diabetes in Youth

AIMS

Our study aims were to determine the frequency of MODY mutations (HNF1A, HNF4A, glucokinase) in a diverse population of youth with diabetes and to assess how well clinical features identify youth with maturity-onset diabetes of the young (MODY).

METHODS

The SEARCH for Diabetes in Youth study is a US multicenter, population-based study of youth with diabetes diagnosed at age younger than 20 years. We sequenced genomic DNA for mutations in the HNF1A, HNF4A, and glucokinase genes in 586 participants enrolled in SEARCH between 2001 and 2006. Selection criteria included diabetes autoantibody negativity and fasting C-peptide levels of 0.8 ng/mL or greater.

RESULTS

We identified a mutation in one of three MODY genes in 47 participants, or 8.0% of the tested sample, for a prevalence of at least 1.2% in the pediatric diabetes population. Of these, only 3 had a clinical diagnosis of MODY, and the majority was treated with insulin. Compared with the MODY-negative group, MODY-positive participants had lower FCP levels (2.2 ± 1.4 vs 3.2 ± 2.1 ng/mL, P < .01) and fewer type 2 diabetes-like metabolic features. Parental history of diabetes did not significantly differ between the 2 groups.

CONCLUSIONS/INTERPRETATION

In this systematic study of MODY in a large pediatric US diabetes cohort, unselected by referral pattern or family history, MODY was usually misdiagnosed and incorrectly treated with insulin. Although many type 2 diabetes-like metabolic features were less common in the mutation-positive group, no single characteristic identified all patients with mutations. Clinicians should be alert to the possibility of MODY diagnosis, particularly in antibody-negative youth with diabetes.

Effect of type 1 diabetes on carotid structure and function in adolescents and young adults: the SEARCH CVD study

OBJECTIVE

Type 1 diabetes mellitus causes increased carotid intima-media thickness (IMT) in adults. We evaluated IMT in young subjects with type 1 diabetes.

RESEARCH DESIGN AND METHODS

Participants with type 1 diabetes (N = 402) were matched to controls (N = 206) by age, sex, and race or ethnicity. Anthropometric and laboratory values, blood pressure, and IMT were measured. ANCOVA was used to assess differences controlling for demographic risk factors, cardiovascular risk factors, and HbA1c.

RESULTS

Subjects were 18.9 ± 3.3 years old (50% male, 82.7% non-Hispanic white). Youth with type 1 diabetes had thicker bulb IMT, which remained significantly different after adjustment for demographics and cardiovascular risk factors. Age, sex, adiposity, and systolic blood pressure were consistent significant determinants of IMT. Adjustment for HbA1c eliminated the difference, suggesting the difference was attributable to poor glycemic control.

CONCLUSIONS

Carotid IMT may be increased in youth with type 1 diabetes at high risk for cardiovascular disease. Better control of diabetes may be essential in preventing progression of atherosclerosis.

The effects of type 2 diabetes on lipoprotein composition and arterial stiffness in male youth

Recent studies suggest HDL exists as numerous subpopulations with distinct protein/lipid compositions that are not reflected in the HDL cholesterol (HDL-C) number. In this study, we sought to evaluate HDL subpopulations in adolescents with type 2 diabetes (T2D) to determine if changes in HDL composition are associated with early vascular disease. T2D (n = 10), lean (n = 9), and obese (n = 11) youth were recruited. Plasma was fractionated using gel-filtration chromatography, and lipid-associated proteins were identified using mass spectrometry. Concurrently, vascular stiffness was assessed using pulse wave velocity (PWV). We found youth with T2D exhibited decreased phospholipid content in fractions containing large HDL particles that was inversely associated with PWV (P < 0.001). No association was noted between HDL-C and PWV. Proteomic analysis revealed changes in 7 of 45 identified proteins in the T2D group, including apolipoprotein (apo) A-II, apoE, and paraoxonase-1 (P < 0.05). Our data demonstrate early changes in the lipid and protein compositions of specific HDL subspecies in adolescents with T2D that are related to early markers of arterial disease. These findings suggest that analyzing the composition of HDL, rather than HDL-C, may be useful in assessing cardiovascular risk in this population.

Reduced heart rate variability is associated with increased arterial stiffness in youth with type 1 diabetes: the SEARCH CVD study

OBJECTIVE

Reduced heart rate variability (HRV) and increased arterial stiffness (AS) are both present in youth with type 1 diabetes. However, it is unclear whether they are associated and whether their association is independent of cardiovascular disease (CVD) risk factors.

RESEARCH DESIGN AND METHODS

The SEARCH Cardiovascular Disease (SEARCH CVD) study explored the cross-sectional relationships between HRV and several measures of AS in youth with (n = 344) and without (n = 171) type 1 diabetes. The SphygmoCor device (AtCor Medical, Sydney, Australia) was used to measure HRV using SD of normal R-R interval (SDNN), as well as AS, using pulse wave velocity in the carotid to femoral segment (PWV-trunk) and augmentation index adjusted to a heart rate of 75 bpm (AIx75). Brachial distensibility (BrachD), another index of AS, was measured with a DynaPulse instrument (Pulse Metric, San Diego, CA). Multiple linear regression analyses explored the associations between HRV and each of the three AS measures, after adjusting for demographic characteristics and traditional CVD risk factors (blood pressure, lipids, obesity, microalbuminuria, and smoking) separately, for youth with and without type 1 diabetes.

RESULTS

Among youth with type 1 diabetes, lower SDNN was associated with peripheral AS (lower BrachD, P = 0.01; r(2) = 0.30) and central AS (higher PVW-trunk, P < 0.0001; r(2) = 0.37; and higher AIx75, P = 0.007; r(2) = 0.08). These associations were attenuated with adjustment for CVD risk factors, but remained statistically significant for BrachD and PWV-trunk. While a similar association between HRV and BrachD was present in control youth, lower HRV was not associated with increased central AS or with AIx75.

CONCLUSIONS

Longitudinal studies are needed to understand the pathways responsible for these associations.

Does eating during television viewing affect mealtimes in young children with type 1 diabetes mellitus?

This study looks for differences in mealtime characteristics and glycemic control for young children with type 1 diabetes who either eat with television (TV) viewing or without TV viewing. Sample size is 24 families (mean child age=5.2, SD=1.0 years). Meals with TV lasted 6 minutes longer than meals without TV. Meals with TV were associated with greater fat intake and higher average glucose levels, but not with greater intake of calories, carbohydrates, or more child bites. This study suggests relations between TV viewing and some negative outcomes for young children, but more research is needed to determine causation.

Identification of minimal clinically important difference scores of the PedsQL in children, adolescents, and young adults with type 1 and type 2 diabetes

OBJECTIVE

To establish minimal clinically important difference (MCID) scores representing the smallest detectable change in quality of life (QOL), using the Pediatric Quality of Life Inventory (PedsQL) Generic Core and Diabetes Module among youth with diabetes and their parents, and to identify demographic and clinical correlates of QOL change over 1 year.

RESEARCH DESIGN AND METHODS

Participants in the SEARCH for Diabetes in Youth Study aged >5 years and parents of youth aged <18 years completed PedsQL surveys at their initial and 12-month study visits. MCIDs for each PedsQL module were calculated using one standard error of measurement. Demographic and clinical characteristics associated with QOL change were identified through multiple linear and logistic regression analyses.

RESULTS

The sample comprised 5,004 youth (mean age, 12.5 ± 4.7 years; mean diabetes duration, 3.4 ± 3.7 years). Of 100 possible points, PedsQL total score MCIDs for youth with type 1 and type 2 diabetes, respectively, were Generic Core, 4.88, 6.27 (parent) and 4.72, 5.41 (youth); Diabetes Module, 4.54, 6.06 (parent) and 5.27, 5.96 (youth). Among 1,402 youth with a follow-up visit, lower baseline QOL, male sex, private insurance, having type 1 diabetes, longer diabetes duration, and better glycemic control predicted improvements in youth- and parent-reported PedsQL total scores over 1 year. Clinically meaningful (≥1 MCID) improvements in total score for at least one PedsQL module were predicted by private insurance, lower BMI, and lower A1C at baseline.

CONCLUSIONS

These diabetes-specific reference points to interpret clinically meaningful change in PedsQL scores can be used in clinical care and research for youth with type 1 and type 2 diabetes.

Dietary intake following experimentally restricted sleep in adolescents

STUDY OBJECTIVE

To examine the relationship between sleep and dietary intake in adolescents using an experimental sleep restriction protocol.

DESIGN

Randomized crossover sleep restriction-extension paradigm.

SETTING

Sleep obtained and monitored at home, diet measured during an office visit.

PARTICIPANTS

Forty-one typically developing adolescents age 14-16 years.

INTERVENTIONS

The 3-week protocol consisting of a baseline week designed to stabilize the circadian rhythm, followed randomly by 5 consecutive nights of sleep restriction (6.5 hours in bed Monday-Friday) versus healthy sleep duration (10 hours in bed), a 2-night washout period, and a 5-night crossover period.

MEASUREMENTS

Sleep was monitored via actigraphy and teens completed validated 24-hour diet recall interviews following each experimental condition.

RESULTS

Paired-sample t-tests examined differences between conditions for consumption of key macronutrients and choices from dietary categories. Compared with the healthy sleep condition, sleep-restricted adolescents' diets were characterized by higher glycemic index and glycemic load and a trend toward more calories and carbohydrates, with no differences in fat or protein consumption. Exploratory analyses revealed the consumption of significantly more desserts and sweets during sleep restriction than healthy sleep.

CONCLUSIONS

Chronic sleep restriction during adolescence appears to cause increased consumption of foods with a high glycemic index, particularly desserts/sweets. The chronic sleep restriction common in adolescence may cause changes in dietary behaviors that increase risk of obesity and associated morbidity.

Lipids and lipoprotein ratios: contribution to carotid intima media thickness in adolescents and young adults with type 2 diabetes mellitus

BACKGROUND

Dyslipidemia is common among adolescents with type 2 diabetes (T2D).

OBJECTIVE

To assess whether the lipoprotein ratios of low-density lipoprotein (LDL) cholesterol/high-density lipoprotein (HDL) cholesterol or triglycerides/HDL or non-HDL cholesterol are more useful than the traditional lipid panel to predict increased arterial thickness in adolescents and young adults with T2D.

METHODS

We evaluated 244 adolescents and young adults with T2D in a cross-sectional study (mean age 18 years; 56% African American; 65% female). Demographics, anthropometrics, and laboratory data were collected. Arterial thickness was assessed with carotid intima media thickness (IMT). Bivariate correlations and general linear models were used to determine the independent contributions of the various lipid parameters to carotid IMT.

RESULTS

Bivariate correlations showed LDL/HDL ratio was the strongest predictor of carotid IMT (P < .02). After adjustment for potential covariates LDL/HDL was no longer significant. HDL cholesterol was the only lipid to independently (negatively) contribute to carotid IMT. Other risk factors that were independently associated with carotid IMT included age, race, sex, body mass index z score, and hemoglobin A1c. Together these cardiovascular risk factors explained <20% of the variance in carotid IMT.

CONCLUSIONS

HDL cholesterol is the only lipid to independently associate with carotid IMT. Lipoprotein ratios and non-HDL did not provide additional information. The low variance in carotid IMT explained by traditional risk factors suggests nontraditional risk factors may be important to assess to better understand the contributors to early-stage atherosclerosis in adolescents and young adults with T2D.

Injury initiates unfavourable weight gain and obesity markers in youth

OBJECTIVE

The purpose of this study was to examine the association of knee injuries with subsequent changes in body mass index and body composition during maturation in young females.

METHODS

A prospective longitudinal study design was employed to evaluate young females active in soccer or basketball (N=862). Participants who completed at least 1-year follow-up to provide consecutive annual measures of BMIZ and %fat were included in the study analysis to determine the effect of knee injuries on the trajectory of these obesity markers in youth.

RESULTS

Of the 71 reported knee injuries, 12 (17%) occurred in athletes at the prepubertal stage, 24 (34%) in athletes at the pubertal stage, and 35 (49%) in postpubertal athletes. Controlling for the effects of maturation, female athletes who reported knee injury demonstrated a greater yearly increase in BMIZ (LS means and 95% CI for the injured group=0.039 (-0.012 to 0.089), for the non-injured group=-0.019 (-0.066 to 0.029), and group difference=0.057 (0.005 to 0.11), p=0.03) and in %body fat (LS means and 95% CI for the injured group=1.05 (0.45 to 1.65), for the non-injured group=0.22 (-0.21 to 0.064), and group difference=0.83 (0.21 to 1.45), p=0.009), compared to those without knee injuries. This indicates that the athletes with knee injuries will increase their body mass index percentile by up to 5 units more than someone of the same age without an injury, and in body fat by up to 1.5%, compared to their non-injured peers.

CONCLUSIONS

The present findings indicate that knee injury during the growing years may be associated with unfavourable changes in body composition.

Fructose intake and cardiovascular risk factors in youth with type 1 diabetes: SEARCH for diabetes in youth study

AIMS

High consumption of dietary fructose has been shown to contribute to dyslipidemia and elevated blood pressure in adults, but there are few data in youth, particularly those at greater risk of cardiovascular disease (CVD). The aim of this study was to examine the association between fructose intake and CVD risk factors in a diverse population of youth with type 1 diabetes (T1D).

METHODS

This was a cross-sectional analysis of data from the SEARCH for Diabetes in Youth study, including 2085 youth ages 10-22 years with T1D, of which 22% were racial/ethnic minority and 50% were female. A semi-quantitative food frequency questionnaire was used to assess intake.

RESULTS

Median daily fructose consumption was 7.9% of total calories. Fructose intake was positively associated with triglycerides (p<.01), but not with total cholesterol, LDL-cholesterol, HDL-cholesterol, or blood pressure after adjustment for physical activity and socio-demographic, clinical, and dietary covariates. An increase in fructose intake of 22 g (equivalent to a 12 oz can of soda) was associated with 23% higher odds of borderline/high versus low triglycerides (p<.005).

CONCLUSION

These data suggest that children with T1D should moderate their intake of fructose, particularly those with borderline or high triglycerides.

Permanent neonatal diabetes mellitus: prevalence and genetic diagnosis in the SEARCH for Diabetes in Youth Study

BACKGROUND

Neonatal diabetes mellitus (NDM) is defined as diabetes with onset before 6 months of age. Nearly half of individuals with NDM are affected by permanent neonatal diabetes mellitus (PNDM). Mutations in KATP channel genes (KCNJ11, ABCC8) and the insulin gene (INS) are the most common causes of PNDM.

OBJECTIVE

To estimate the prevalence of PNDM among SEARCH for Diabetes in Youth (SEARCH) study participants (2001-2008) and to identify the genetic mutations causing PNDM.

METHODS

SEARCH is a multicenter population-based study of diabetes in youth <20 yr of age. Participants diagnosed with diabetes before 6 months of age were invited for genetic testing for mutations in the KCNJ11, ABCC8, and INS genes.

RESULTS

Of the 15,829 SEARCH participants with diabetes, 39 were diagnosed before 6 months of age. Thirty-five of them had PNDM (0.22% of all diabetes cases in SEARCH), 3 had transient neonatal diabetes that had remitted by 18 months and 1 was unknown. The majority of them (66.7%) had a clinical diagnosis of type1 diabetes by their health care provider. Population prevalence of PNDM in youth <20 yr was estimated at 1 in 252 000. Seven participants underwent genetic testing; mutations causing PNDM were identified in five (71%), (two KCNJ11, three INS).

CONCLUSIONS

We report the first population-based frequency of PNDM in the US based on the frequency of PNDM in SEARCH. Patients with NDM are often misclassified as having type1 diabetes. Widespread education is essential to encourage appropriate genetic testing and treatment of NDM.