Metformin as an adjunct therapy for the treatment of moderate to severe acne vulgaris: A randomized open-labeled study.

Insulin, insulin-like growth factor-1 (IGF-1) and essential amino acids activate the mechanistic target of rapamycin complex 1 (mTORC1), the main nutrient-sensitive kinase. Metformin, through inhibition of mTORC1 may improve acne. A 12-week, randomized, open-labeled study evaluated the efficacy and safety of metformin as an adjunct for moderate to severe facial acne. In total, 84 patients received either oral tetracycline 250 mg bd and topical benzoyl peroxide 2.5% with or without metformin 850 mg daily. Evaluations constituted lesion counts, the Cardiff Acne Disability Index (CADI), metabolic parameters and treatment success rate (Investigators Global Assessment score of 0 or 1 or improvement of two grades). Treatment success rates were higher in the metformin group (66.7% vs. 43.2%; p = .04). The mean percentage reduction from baseline in total lesion counts at Week 12 was greater in the metformin group (71.4% vs. 65.3%; p = .278). The CADI scores showed a greater mean reduction in the metformin group (4.82 vs. 4.22; p = .451). Metformin was equally efficacious in improving acne in lean and overweight subjects. Gastrointestinal symptoms were noted in 31.7% of subjects on metformin. This study presents favorable data for metformin as an adjunct for acne treatment. Further randomized placebo-controlled studies are required.