Both Glimepiride and High-Dose Metformin Are Important for Sustained Glucose Lowering in Japanese Type 2 Diabetes Patients on Glimepiride–Sitagliptin–Metformin Therapy: Subanalysis of a Single-Center, Open-Label, Randomized Study

Background: In a previous single-center, open-label randomized 3-month study of triple oral antidiabetes drug (OAD) therapy, we investigated factors affecting the glycemic control afforded by sitagliptin, high-dose metformin, and low-dose glimepiride. Patients were prospectively assigned to either Group 1 (50% reduction in metformin) or Group 2 (discontinuation of glimepiride) and compared. The results showed that the glycated hemoglobin (HbA1c) levels of patients in Group 2 deteriorated more than those in Group 1, whereas HbA1c levels were maintained in some patients in both groups. Materials and Methods: To determine the factors associated with maintenance of HbA1c under this triple OAD regimen, data from the prospective study were further analyzed. Results: In both Groups 1 and 2, the baseline HbA1c level was higher in patients with HbA1c ≥7.0% after 3 months of treatment than those with an HbA1c level of <7.0%. A generalized linear model revealed that high-dose metformin was associated with a deterioration of HbA1c levels in Group 2. Conclusions: Together, the findings indicate that glimepiride and high-dose metformin are important for sustained glycemic control in triple OAD therapy with sitagliptin, metformin, and sulfonylurea.