Effects of short‐term tofogliflozin treatment on the insulin secretory capacity of people with type 2 diabetes: A randomized controlled trial, the TOP ‐ ELM study

AIMS/INTRODUCTION: We aimed to explore the short-term effects of tofogliflozin on the insulin secretory capacity of people with type 2 diabetes. MATERIALS AND METHODS: We performed a multicenter, prospective, randomized, active-controlled, open-label, parallel-group comparison study of people with type 2 diabetes aged 20-89 years, with hemoglobin A1c (HbA1c) 6.5%-9.0%, not previously treated with antihyperglycemic agents. The participants were randomly assigned to a group that received 20 mg tofogliflozin per day or a group that received 500 mg metformin per day for 4 weeks. Fasting blood samples were obtained and oral glucose tolerance testing was performed before and after treatment. The changes from baseline to week 4 in glucose tolerance and insulin secretory capacity were compared. RESULTS: Thirty participants in the metformin group and 35 in the tofogliflozin group completed the study. After 4 weeks, the HbA1c, glycated albumin, and fasting plasma glucose concentrations had significantly decreased in both groups, with no significant differences between the two groups. The fatty liver index improved significantly more in the tofogliflozin group. The disposition index (DI) did not significantly increase in either group, and there was no difference between the groups. However, in the tofogliflozin group, the DI improved in participants with poorer glucose tolerance at baseline or larger improvements after treatment, but not in the metformin group. CONCLUSION: Short-term tofogliflozin therapy did not improve the insulin secretory capacity of treatment-naïve people with type 2 diabetes. However, tofogliflozin may facilitate the early recovery of insulin secretory capacity in individuals with poor glucose tolerance.