Masami Tanaka, Takeshi Nishimura, Risa Sekioka and Hiroshi Itoh
Objective: This retrospective cohort study aimed to investigate the significance of dipeptidyl peptidase-4 (DPP- 4) inhibitor switch therapy, which is currently not recommended by major diabetes guidelines. Methods: The subjects were 238 outpatients with type 2 diabetes who had been prescribed sitagliptin 50 mg daily, which was subsequently changed in one of three ways. Patients whose sitagliptin was switched to vildagliptin 50 mg twice daily were defined as the switched group. Patients whose sitagliptin was increased to 100 mg once daily were defined as the increased group. Patients who received an additional alfa-glucosidase inhibitor (α-GI) three times daily prior to meals and sitagliptin 50 mg once daily were defined as the added group. The primary endpoint was the glycated hemoglobin (HbA1c) value at 6 months after the medication change. Patients whose oral hypoglycemic agents were changed within 6 months after switching to vildagliptin, increasing sitagliptin, or adding α-GI were excluded from the full analysis set and the remaining patients were included in the per protocol analysis. Results: The per protocol analysis revealed that the HbA1c level decreased significantly in the switched group (n=71) and the added group (n=18) but did not change significantly in the increased group (n=69). Analysis of the full set showed that the HbA1c level decreased significantly in all three groups (switched [n=92], increased [n=88], and added [n=25]). Conclusion: Switching DPP-4 inhibitors can adequately reduce HbA1c compared with increasing original DPP- 4 inhibitor dose or adding an α-GI. When the original DPP-4 inhibitor did not significantly improve glycemic control, making a DPP-4 inhibitor switch, which is not recommended by major diabetes guidelines, can be an alternative strategy.