OBJECTIVE:

To evaluate whether metformin, when added to a program of personal goal setting, improves weight loss and clinical status in obese adolescents.

STUDY DESIGN:

In a randomized double-blind placebo controlled trial, 85 adolescents with insulin resistance were randomized to receive metformin (70%) or placebo (30%), along with monthly goal setting for diet and exercise modification. Anthropometric measures, fasting blood analysis, and glucose tolerance tests were performed at baseline and 6 months.

RESULTS:

Mean age was 15.7 years. Mean body mass index (BMI) was 39.7 kg/m(2). 71% were female, 58% were Hispanic, and 34% were African-American. 76% of participants completed the study. Goal setting alone did not result in significant weight loss. In addition, there were no group differences between metformin and placebo in weight loss or measures of glucose metabolism. However, among females taking metformin, there was a significant decrease in BMI not seen in the placebo group. Furthermore, metformin adherence, when accompanied by lifestyle change, was a predictor of BMI decrease of 5% or more. 60% of 10 subjects who adhered to metformin and decreased portion size decreased BMI by >5%.

CONCLUSIONS:

In this group of predominately minority adolescents, monthly goal setting alone did not lead to weight loss. Although the addition of metformin had no effect on weight loss overall, the agent did significantly increase weight loss among females and weight loss was predicted by degree of metformin adherence. However, weight loss was only found in those participants also reporting lifestyle change, particularly a decrease in portion sizes. These results suggest that metformin may be a useful agent to promote short-term weight loss among girls making modest lifestyle changes.