- Currently taking an antidiabetic/glucose-lowering agent. Antidiabetic agents that are prohibited include insulin, rosiglitazone, metformin, sitagliptin, sulfonylureas (e.g. glyburide, glipizide, glimepiride), non-sulfonylurea secretagogues (e.g. repaglinide, nateglinide), incretins (e.g. exenatide), and α-glucosidase inhibitors (e.g. acarbose, miglitol).