Dietary risk factors for the development of insulin resistance in adolescent girls: a 3-year prospective study

Objective: Identifying risk factors for insulin resistance in adolescence could provide valuable information for early prevention. The study sought to identify risk factors for changes in insulin resistance and fasting blood glucose levels. Design Prospective cohort of girls participating in the National Heart, Lung, and Blood Institute Growth and Health Study. Setting: USA. Subjects: Adolescent girls (n 774) assessed at the ages of 16–17 and 18–19 years. Over a 3-year period, measurements of fasting blood glucose and insulin and serum cotinine were taken, and dietary intake (3 d food diary), smoking status and physical activity levels were self-reported. Results: Improvements in homeostasis model assessment of insulin resistance (HOMA-IR) were associated with increases in the percentage of energy intake from polyunsaturated fats (β = −3·33, 95 % CI −6·28, −0·39, P = 0·03) and grams of soluble fibre (β = −5·20, 95 % CI −9·81, −0·59, P = 0·03) between the ages of 16–17 and 18–19 years; with similar findings for insulin. Transitioning into obesity was associated with an increase in insulin (β = 6·34, 95 % CI 2·78, 9·91, P < 0·001) and HOMA-IR (β = 28·77, 95 % CI 8·13, 49·40, P = 0·006). Serum cotinine concentrations at 16–17 years, indicating exposure to tobacco, were associated with large increases (β = 15·43, 95 % CI 6·09, 24·77, P < 0·001) in fasting blood glucose concentrations. Conclusions: Increases in the percentage of energy from polyunsaturated fat and fibre, and avoidance of excess weight gain and tobacco exposure, could substantially reduce the risk of insulin resistance in late adolescence.