Objective: To assess the effect of metformin on weight, BMI, body fat, and insulin sensitivity in obese children and adolescents.
Methodology: The study was prospective, and included 21 patients with obesity (8 male, 13 female) with a mean age of 12.31 (3.87) years. Inclusion criteria were a fat mass percentage (FM%) of over 25% in males and over 30% in females, a BMI of greater than the 95th percentile, and a lack of response to nutritional and lifestyle changes over three months. Informed consent was obtained from children, parents and the treatment was approved by the hospital's Ethics Committee, and the Spanish health ministry. All subjects received treatment with metformin for six months and each month was instructed to follow nutritional and lifestyle changes. The oral glucose tolerance test (OGTT) was done for 95% of the patients.
Results: A decrease in weight-SDS (p< 0.001), BMI-SDS (p< 0.001), FM% (p = 0.002), waist/hip ratio (p = 0.141), HOMA (p = 0.198 and plasma glucose level at 120 min. (p = 0.008) was observed after six months of metformin therapy in association with nutritional and lifestyle changes. At the onset of the study, plasma glucose level at 120 min. was above 140 mg/dL in 38% (n = 8) of patients, and the HOMA index was above 3.8 in 42% (n = 9). Altogether, 11 patients had insulin resistance. Mean dose of metformin was built up to a maximum of 1275 mg/day. Twenty-four percent of the subjects complained of dyspepsia or diarrhea or both.
Conclusion: In this study, metformin, combined with diet and lifestyle changes, contributed to an improvement in BMI and to a loss of weight and body fat in children with obesity, whether or not that obesity was associated with insulin resistance.