Use of metformin in obese adolescents with hyperinsulinemia: a 6-month, randomized, double-blind, placebo-controlled clinical trial.

AIM: To determine whether metformin treatment for 6 months is effective in reducing body weight and hyperinsulinemia and also ameliorating insulin sensitivity indices in obese adolescents with hyperinsulinemia.

METHODS: One hundred and twenty adolescents (age range 9-17 years) with BMI >95th percentile for age and sex were included (metformin group, n = 90 [45 females, 45 males]; placebo group, n = 30 [15 females, 15 males]). The groups received 500 mg metformin (n = 90) or placebo (n = 30) twice daily for 6 months, plus individually tailored diet, exercise and behavioral therapy. Hyperinsulinism and insulin sensitivity indices were defined from fasting samples. Oral glucose tolerance tests were performed before and after treatment.

RESULTS: Before treatment, there were no significant differences between the metformin group and control group in terms of anthropometric data and metabolic parameters. After metformin, there was a significant decline in body mass index (from 28.5 +/- 3.4 to 26.7 +/- 4 kg/m2, p < 0.001), fasting insulin (from 19.2 +/- 10.4 to 11.1 +/- 6.1 microU/ml, p < 0.001) and 120 min insulin levels (from 103.7 +/- 73.8 to 49.8 +/- 30.9 microU/ml, p < 0.001). FGIR increased significantly from 6.26 +/- 3.0 to 12.5 +/- 10.6 (p < 0.001) and HOMA-IR was reduced from 4.95 +/- 3.34 to 2.6 +/- 1.6 (p < 0.001) after treatment. QUICKI significantly increased from 031 +/- 0.02 to 034 +/- 0.03 (p < 0.001) in the metformin group. Moreover, in comparison of changes in insulin sensitivity indices between the metformin treated and control groups, the metformin treated group showed significantly improved metabolic control at the end of the study.

CONCLUSION: These data suggest that metformin treatment is effective in reducing insulin resistance and also ameliorating metabolic complications of insulin resistance syndrome in obese adolescents with hyperinsulinemia.