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 (beta = -3 center dot 33, 95 % CI -6 center dot 28, -0 center dot 39, P = 0 center dot 03) and grams of soluble fibre (beta = -5 center dot 20, 95 % CI -9 center dot 81, -0 center dot 59, P = 0 center dot 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 (beta = 6 center dot 34, 95 % CI 2 center dot 78, 9 center dot 91, P <0 center dot 001) and HOMA-IR (beta = 28 center dot 77, 95 % CI 8 center dot 13, 49 center dot 40, P = 0 center dot 006). Serum cotinine concentrations at 16-17 years, indicating exposure to tobacco, were associated with large increases (beta = 15 center dot 43, 95 % CI 6 center dot 09, 24 center dot 77, P <0 center dot 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.