The Effect of Eighteen-Month Metformin Treatment in Obese Adolescents: Comparison of Results Obtained in Daily Practice with Results from a Clinical Trial

Background. In a recent randomized controlled trial (RCT) in obese adolescents, 18 month-treatment with metformin versus placebo was reported to lead to stabilisation of the BMI. This study aimed to compare the effect of metformin on BMI in obese adolescents in daily practice versus results obtained in an RCT. Methods. Obese adolescents treated off label with metformin in daily practice in an outpatient clinic with a follow-up of ≥18 months were identified. Anthropometric and biochemical data were collected at baseline and at 18 months. Patients treated with metformin for 18 months in an RCT were used for comparison. BMI was compared between the two groups. Results. Nineteen patients (median age 14.3 (interquartile range 11.7-15.7) years, BMI 31.3 (28.8-33.8) kg/m2) treated in daily practice were compared to 23 patients receiving metformin in the RCT (age 13.6 (12.6-15.3) years, BMI 29.8 (28.1-34.5) kg/m2). BMI change after 18 months was -0.36 (-2.10-1.58) versus +0.22 (-2.87-1.27) kg/m2 for the two groups, respectively. In the multivariable model, BMI change was not statistically significantly different between the two groups (p = 0.61). Conclusion. Treatment with metformin in obese adolescents in daily practice resulted in a comparable change in BMI as observed in an RCT. This trial is registered with ClinicalTrials.gov number: NCT01487993.