3. Glitazone, glinide, and sulfonylurea group: renal failure or renal impairment defined as estimated glomerular filtration rate <30 ml/min (severe renal impairment) at Visit 1, Biguanide group: renal failure or renal impairment defined as estimated glomerular filtration rate <60 ml/min (moderate renal impairment) at Visit 1