Teneligliptin, a Dipeptidyl Peptidase-4 Inhibitor, Improves Early-Phase Insulin Secretion in Drug-Naïve Patients with Type 2 Diabetes

INTRODUCTION: It remains unknown whether dipeptidyl peptidase-4 (DPP-4) inhibitors improve early-phase insulin secretion in Japanese patients with type 2 diabetes (T2D), a disease characterized by impaired insulin secretion. We investigated the changes in insulin secretion before and after treatment with the DPP-4 inhibitor teneligliptin in patients with T2D with a low insulinogenic index (IGI) determined by the oral glucose tolerance test (OGTT). METHODS: An open-label, prospective clinical study was conducted. Thirteen drug-naïve patients (mean age 55.5 ± 3.9 years) with T2D underwent OGTT before and after teneligliptin 20 mg/day monotherapy. Plasma levels of glucose (PG), insulin, and C-peptide were measured at 0, 30, 60, 90, and 120 min after glucose loading in the OGTT. Homeostasis model assessment (HOMA)-β, IGI, and the total or incremental area under the curve (AUC) for PG and insulin were measured. AUC(120min) for the secretory units of islets in transplantation (SUIT) index was also measured. RESULTS: HbA1c significantly decreased from 8.3 ± 0.4 % at baseline to 6.3 ± 0.2 % after 12 weeks of teneligliptin treatment (p < 0.05). Incremental AUC(120min) PG also significantly decreased, and β-cell function assessed by IGI(30min), AUC(120min) insulin, and the AUC(120min) SUIT index significantly increased (0.16 ± 0.05 vs. 0.28 ± 0.06, 2692 ± 333 µU·2h/mL vs. 3537 ± 361 µU·2h/mL, and 4261 ± 442 vs. 8290 ± 1147, respectively; all p < 0.05). HOMA-β was unchanged. The reduction in incremental AUC(120min) PG was significantly associated with the augmentation of IGI(30min) and the AUC(120min) SUIT index. No severe adverse events were observed. CONCLUSIONS: Twelve weeks of teneligliptin treatment improved IGI(30min), AUC(120min), and the SUIT index in drug-naïve Japanese patients with T2D.