a1 Centre for the Development and Evaluation of Complex Interventions for Public Health Improvement, School of Medicine, Cardiff University, Heath Park, Cardiff CF14 4YS, UK
a2 Centre for Exercise, Nutrition & Health Sciences, School for Policy Studies, University of Bristol, Bristol, UK
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.
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.
(Received May 24 2012)
(Revised September 10 2012)
(Accepted September 14 2012)
(Online publication November 19 2012)