Hypothesis:
The association of excess weight with an adverse cardiometabolic profile in patients with type 1 diabetes (T1D) is unclear. The purpose of this study was to test the hypothesis that increasing BMI and adiposity indicators in youth with T1D are adversely associated with glycemic control and cardiovascular biomarkers.
Methods:
Subjects were youth participants of a family-based randomized controlled dietary intervention (N=136, age=12.3±2.5y, baseline A1c=8.1±1.1%). Glycemic control (A1c and 1,5-Anhydroglucitol, 1,5-Ag), body mass index (BMI, from measured height and weight), serum lipids (total cholesterol, TC; HDL-cholesterol, HDL-C; LDL-cholesterol, LDL-C; triglycerides, TG), inflammation (c-reactive protein, CRP), oxidative stress (8-iso-prostaglandin F2alpha, 8-iso-PGF2α), adiponectin and blood pressure (systolic, SBP; diastolic, DBP) were assessed at baseline and every 6 months for 18 months. Total and truncal lean, fat-free mass and percent fat (%fat) were measured by Dual X-ray Absorptiometry (DXA) scan at baseline, 12 months and 18 months. Multi-level linear mixed effects regression models (with a random intercept and a random slope for time) were used to estimate associations of time-varying BMI and body composition with time-varying indicators of glycemic control and cardiometabolic health. Covariates included time, sex, height, baseline age, treatment assignment, baseline diabetes duration, insulin regimen, insulin dose/kg and physical activity. Probability values <0.05 were considered to indicate statistical significance.
Results:
Time-varying BMI and body composition indicators were differentially associated with time-varying glycemic control and cardiometabolic indicators. A1C was unrelated to BMI and body composition, although 1,5-Ag was inversely associated with total %fat; inverse associations of 1,5-Ag with BMI and trunk %fat approached statistical significance (p=0.07). LDL-C was positively associated with trunk fat and trunk %fat; TG and HDL-C were positively associated with BMI and trunk fat, and HDL-C was inversely associated with total lean and trunk lean mass. CRP was positively associated with BMI, and with total and truncal fat and %fat. SBP and DBP were positively associated with BMI, %fat, trunk fat and trunk %fat. TC, 8-iso-PGF2α and adiponectin were unrelated to BMI and body composition.
Discussion: In a sample of youth with moderately well-controlled T1D, time-varying BMI and indicators of body fat were not universally associated with time-varying glycemic control and cardiometabolic indicators over 18 months. Significant associations of adiposity indicators, particularly BMI and trunk fat, with hyperglycemic excursions (1,5-Ag), several blood lipids (TG, HDL-C, and LDL-C), and inflammation (8-iso-PGF2α) suggest a role of excess body weight in the development of cardiovascular risk in this sample.
Body Mass Index and Retinopathy in Type 1 Diabetic Patients