Methotrexate, an immunosuppressant and antineoplastic drug [3, 4], promotes glucose uptake and lipid oxidation in skeletal muscle via activation of AMPK [5], alleviates glucose dysregulation in diabetic [6] and obese mice [7], and protects patients with rheumatoid and psoriatic arthritis against diabetes [8, 9]. This evidence concerns the gene PRKAA1 and diabetes mellitus.