- Has been treated by sulfonylurea (SU) alone, SU and biguanide, or SU and thiazolidinedione for at least 90 days prior to study start. In a patient receiving SU alone, the dose must be within the dose range from maximum maintenance dose to maximum approved dose. The patients with concomitant use of alpha glucosidase inhibitors (acarbose, voglibose or miglitol) or meglitinide derivatives (mitiglinide or nateglinide) can be included in this study, but these drugs must be discontinued at study start.