Metformin in obese children and adolescents: the MOCA trial

J Clin Endocrinol Metab. 2013 Jan;98(1):322-9. doi: 10.1210/jc.2012-2710. Epub 2012 Nov 21.


Context: Childhood obesity is increasingly associated with type 2 diabetes (T2D). Metformin reduces the risk for T2D in adult obese nondiabetic patients, but the evidence in obese children and young people is inconclusive.

Objective: The objective of the study was to assess the effect of metformin on body mass index sd score (BMI-SDS), metabolic risk factors, and adipokines.

Design: This was a prospective, randomized, double-blind, placebo-controlled trial.

Setting: The study was conducted at six pediatric endocrine centers in the United Kingdom.

Participants: One hundred fifty-one obese children and young people with hyperinsulinemia and/or impaired fasting glucose or impaired glucose tolerance (metformin: 74, placebo: 77). The study was comprised of 67.5% females, 65.6% postpubertal individuals, and 23.8% British Asian or Afro-Caribbean participants. The age range was 8-18 yr, the mean age was 13.7 (SD 2.3) yr, and the mean BMI-SDS was +3.4 (SD 0.5).

Interventions: The intervention included metformin 1 g in the morning and 500 mg in the evening vs. placebo for 6 months.

Main outcome measure: The main outcome measure was a reduction in BMI-SDS at 6 months. Secondary outcomes included insulin and glucose levels from oral glucose tolerance tests, alanine aminotransferase (ALT), and adiponectin to leptin ratio (ALR) at 3 and 6 months.

Results: Metformin was associated with a significant reduction in BMI-SDS compared with placebo at 6 months [mean difference -0.1 SD (95% confidence interval -0.18 to -0.02), P = 0.02]. Significant improvements at 3 months were found in the metformin group: fasting glucose, -0.16 mmol/liter (-0.31 to -0.00), P = 0.047; ALT, 19% (5-36%), P = 0.008; and ALR, 32% (4-67%), P = 0.02.

Conclusions: Metformin therapy has a beneficial treatment effect over placebo for BMI-SDS, fasting glucose, ALT, and ALR ratio at 3 months, with changes in BMI-SDS sustained at 6 months.

Publication types

  • Multicenter Study
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Age of Onset
  • Child
  • Diabetes Mellitus, Type 2 / etiology
  • Diabetes Mellitus, Type 2 / prevention & control
  • Double-Blind Method
  • Female
  • Follow-Up Studies
  • Humans
  • Hypoglycemic Agents / adverse effects
  • Hypoglycemic Agents / therapeutic use
  • Male
  • Medication Adherence / statistics & numerical data
  • Metformin / adverse effects
  • Metformin / therapeutic use*
  • Obesity / complications
  • Obesity / drug therapy*
  • Obesity / epidemiology
  • Placebos
  • Treatment Outcome


  • Hypoglycemic Agents
  • Placebos
  • Metformin