Endocrine Abstracts

Objective: Metformin was considered as a weight lowering agent in diabetes patients, while it remained unclear in simple obesity patients. We aimed to investigate if metformin is effective and safe in the therapy of normoglycemic obesity.

Methods: We systematically searched MEDLINE (1950–2011), EMBase (1950–2011), and CCTR (4th Issue 2011), and collected and screened all randomized controlled trials compared metformin and placebo in obese participants excluding hyperglycemia, hypertension, and other chronic diseases.

Results: Twelve trials with follow-up duration 3–24 months were included in our study, eight of which included adolescence as subjects. Compared with placebo, metformin can effectively reduce BMI (overall MD −1.14 kg/m², 95% CI −1.61 to −0.67 kg/m², P<0.00001) and body weight (overall MD −2.52 kg, 95% CI −3.84 to −1.20 kg, P=0.0002), especially in adolescent patients (BMI, overall MD −1.61 kg/m², 95% CI −2.61 to −0.61 kg/m², P=0.002; body weight, overall MD −3.11 kg, 95% CI −4.28 to −1.95 kg, P<0.00001). The overall fat mass (overall MD −1.77 kg, 95% CI −4.19 to 0.66 kg, P=0.15) and waist circumferential (overall MD 0.57 cm, 95% CI −1.33 to 0.20 cm, P=0.15) reduction due to metformin did not meet statistical significance, while waist circumference could be reduced by metformin in adolescent subgroup (overall MD −1.20 cm, 95% CI −2.18 to −0.22 cm, P=0.02). Furthermore, fasting insulin (overall MD −18.09 pmol/l, 95% CI −28.92 to −7.26 pmol/l, P=0.001) and HOMA-IR (overall MD −3.13, 95% CI −5.95 to −0.31, P=0.03) but not fasting blood glucose (overall MD −0.15 mmol/l, 95% CI −0.3 to 0.01 mmol/l, P=0.06) decreased significantly after metformin therapy compared with placeobo. Gastrointestinal adverse effects in metformin group were not significantly different from those in placebo.

Conclusion: Metformin could markedly reduce body weight and insulin resistance in the treatment of normoglycemic obesity, especially in adolescent patients.

Keywords: metformin, obesity, systematic review.

Declaration of interest: The authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project.

Funding: This research did not receive any specific grant from any funding agency in the public, commercial or not-for-profit sector.