Fixed-dose combination therapy for type 2 diabetes: sitagliptin plus pioglitazone

Importance of the field: Type 2 diabetes is typically associated with insulin resistance and dysfunction of insulin-secreting pancreatic beta-cells. Addressing these defects often requires therapy with a combination of differently acting antidiabetic agents. A potential novel combination in development brings together the dipeptidyl peptidase-4 (DPP-4) inhibitor sitagliptin with the thiazolidinedione pioglitazone into a fixed-dose single-tablet combination. The former component acts mainly to increase prandial insulin secretion; the latter improves insulin sensitivity. Areas covered in this review: To date, clinical trials conducted in type 2 diabetes patients have used combinations of sitagliptin (100 mg/day) and pioglitazone (30 - 45 mg/day) as separate tablets. These trials have shown that the combinations offer additive efficacy in reducing blood glucose when given as initial antidiabetic therapy and as add-on therapy when pioglitazone alone fails to maintain glycemic control. What the reader will gain: Initial therapy with a combination of sitagliptin (100 mg/day) and pioglitazone (30 mg/day) reduced HbA1c by > 2% starting from a baseline > 9%. Adding sitagliptin (50 - 100 mg/day) to patients inadequately controlled on pioglitazone reduced HbA1c by 0.7 - 1.4% from a baseline of 8 - 8.5%. The combination did not increase the risk of hypoglycemia and produced similar or slightly more weight gain than pioglitazone alone when introduced as initial antidiabetic therapy. Take home message: The combination of sitagliptin and pioglitazone was well tolerated in these trials, and would appear to be suited to a fixed-dose single-tablet combination for once-daily administration.