Glycemic control and variability in association with body mass index and body composition over 18months in youth with type 1 diabetes.

AIMS: The impact of adiposity on glycemic control in type 1 diabetes patients has important implications for preventing complications. This study examined associations of glycemic outcomes with body mass index (BMI, kg/m(2)) and body composition in youth with type 1 diabetes.

METHODS: This is a secondary analysis of an 18-month randomized controlled dietary intervention trial (N=136, baseline age=12.3±2.5y, HbA1c=8.1±1.0% (65±11mmol/mol)). Measured height and weight every 3months were abstracted from medical records. Body composition was assessed by dual energy X-ray absorptiometry (DXA) at baseline, 12 and 18months. Glycated hemoglobin (HbA1c) and glycemic variability assessed by masked 3-day continuous blood glucose monitoring (CGM) were obtained every 3months. 1,5-Anhydroglucitol (1,5-AG) was assessed every 6months. Adjusted random effects models for repeated measures estimated associations of time-varying BMI and body composition with time-varying glycemic outcomes.

RESULTS: There was no treatment effect on glycemic outcomes. HbA1c was not associated with BMI or body composition indicators. 1,5-AG was inversely associated with BMI and adiposity indicators (%fat, trunk fat mass and trunk %fat), adjusting for developmental covariates. Adiposity indicators were positively associated with %glucose >180mg/dL and >126mg/dL when adjusting for developmental covariates, and %glucose >126mg/dL when additionally adjusting for diabetes-related covariates. Fewer consistent relationships were observed for 3-day mean glucose and %glucose <70.2mg/dL. BMI and body composition variables were not associated with standard deviation of glycemic values or mean amplitude of glycemic excursions.

CONCLUSIONS: The role of greater BMI and adiposity in diabetes management in youth with type 1 diabetes may relate specifically to increased hyperglycemic excursions.