Effect of 24-week treatment with ipragliflozin on proinsulin/C-peptide ratio in Japanese patients with type 2 diabetes.

Background: Chronic hyperglycemia has an adverse influence on beta-cell function, which is known as 'glucotoxicity'. Sodium-glucose cotransporter-2 (SGLT2) inhibitors lower the blood glucose concentration by enhancing urinary glucose excretion. This study was performed to clarify the influence of the SGLT2 inhibitor ipragliflozin on beta-cell function assessed from the plasma intact proinsulin/C-peptide ratio in Japanese patients with type 2 diabetes. Research design and methods: This was a 24-week, prospective, single-center, open-label, single-arm study. The subjects were 19 Japanese patients with type 2 diabetes. After a 4- to 8-week period of lifestyle modification, ipragliflozin (50 mg/d) was added to their existing treatment. At baseline and at 12 and 24 weeks after starting ipragliflozin treatment, a meal test was performed to evaluate the fasting and 2-hour proinsulin/C-peptide ratio. Results: After 24 weeks, the body mass index, fasting plasma glucose, and hemoglobin A1c were all decreased significantly. Both the fasting and 2-hour proinsulin/C-peptide ratio decreased significantly from 25.0 +/- 18.9 x 10(-3) to 14.3 +/- 9.0 x 10(-3) and from 23.2 +/- 14.9 x 10(-3) to 13.7 +/- 5.4 x 10(-3), respectively (both p < 0.01 vs. baseline). Conclusions: These findings indicate that ipragliflozin might have a beneficial effect on beta-cells.