Fuel metabolism in adult individuals with a wide range of body mass index: effect of a family history of type 2 diabetes.

Objective: To evaluate whether a family history of Type 2 diabetes mellitus (T2DM) is associated with changes of fuel metabolism in normal glucose tolerant men and women with a wide range of BMI. Design: Cross-sectional study of resting energy expenditure (REE) and substrate oxidation in adult individuals. Subjects: Ninety-seven normal weight, overweight, and obese men and women, aged 18-45 years: 44 (38 pre-menopausal women and 6 men) with a first-degree family history of T2DM (FH + ) and 53 (45 pre-menopausal women and 8 men) with no family history of T2DM (FH - ). Measurements: REE, fat-free mass (FFM)-adjusted REE (REE/Kg FFM), respiratory quotient (RQ), substrate oxidation (carbohydrates, lipids, and proteins), energy intake, anthropometric parameters, body composition (evaluated by BIA), blood pressure, insulin sensitivity (as calculated by Homeostatic Model Assessment) and metabolic variables (fasting levels of insulin, glucose, and lipids). Results: REE, REE/Kg FFM, and lipid oxidation were lower, whereas carbohydrate oxidation and RQ were higher in FH + than in FH - individuals. Conclusions: This study suggests that a family history of T2DM decreases REE, REE/Kg FFM and lipid oxidation, thus possibly contributing to the development of obesity and to the adverse metabolic profile of subjects with a genetic background for T2DM.