The overall findings from the present study demonstrated the tolerability of metformin and its efficacy as adjuvant therapy to celecoxib in obese patients with knee osteoarthritis through its favorable effects on clinical outcome (WOMAC score) and biological markers involved in osteoarthritis (COMP, CTX-1 and IL-1β) and through reduction in body weight and BMI. This evidence concerns the gene IL1B and osteoarthritis.