Body Composition in Adolescents with Type 1 Diabetes : Aspects of Glycaemic Control and Insulin Sensitivity

Abstract: Excessive weight gain has frequently been reported in adolescents with type 1 diabetes, especially in girls. In general, puberty is associated with reduced insulin sensitivity that is further diminished by overweight. The causes and consequences of excessive weight gain in adolescents with type 1 diabetes are not fully understood. The studies described in this thesis addressed body composition in adolescents with type 1 diabetes and the relationships between physical activity, energy intake and changes in body composition. Furthermore, the effect of metformin as additional therapy on glycaemic control and insulin sensitivity was examined in a randomised placebo-controlled study. Body mass index (BMI) and percentage body fat (%BF) were significantly higher in girls with type 1 diabetes compared to healthy control girls. Mean HbA1c during puberty, but not mean insulin dose, was positively related to BMI at the age of 18 in girls with diabetes. A centralised fat distribution was associated with poor glycaemic control, increased daily dosage of insulin and elevated cholesterol and triglyceride levels. Neither total physical activity nor total energy intake differed between adolescent girls with type 1 diabetes and healthy age-matched control girls. A high dietary fat intake was positively related to gain in %BF in girls with type 1 diabetes. Additional therapy with metformin for three months improved glycaemic control and peripheral insulin sensitivity in adolescents with poorly controlled type 1 diabetes. The improvement in glycaemic control was related to insulin sensitivity at baseline, implying that the most insulin resistant subjects benefited most from the metformin therapy. It is concluded that the excessive weight gain observed in girls with type 1 diabetes is mainly attributable to an increased fat mass and that dietary fat intake is of importance for this gain in body fat. Additional treatment with metformin improves glycaemic control in adolescents with poorly controlled type 1 diabetes.