The AMPK modulator metformin as adjunct to methotrexate in patients with rheumatoid arthritis: A proof-of-concept, randomized, double-blind, placebo-controlled trial

•The co-administration of metformin to rheumatoid patients has reduced the disease activity.•Metformin treatment decreases the expression of inflammatory cytokines.•Metformin adjunctive short-term approach is an effective and safe for nondiabetic rheumatic patients.•Metformin could be used preferentially for diabetic patients with rheumatoid arthritis.