This clinical study designed to investigate the efficacy of metformin as adjuvant therapy in obese knee OA patients, using the western ontario and McMaster universities arthritis index (WOMAC) score (McConnell et al. 2001) and by evaluating serum levels of cartilage oligomeric matrix protein (COMP), C-terminal cross-linked telopeptide of type I collagen (CTX-1), and Interleukin 1-beta (IL-1β). The gene discussed is COMP; the disease is Arthritis.