Insulin dose reduction in dapagliflozin combination therapy for type 1 diabetes mellitus: the RISING-STAR study

To clarify the frequency of hypoglycemia in patients with type 1 diabetes mellitus receiving dapagliflozin combination therapy to reduce their basal insulin dose. Sixty subjects were assigned to two groups according to their basal insulin-to-total daily dose (TDD) ratio: group A (basal insulin/TDD <40%) and group B (>= 40%). Reduction of the basal insulin dose was instituted in group B, but not in group A. The number of hypoglycemic events per day and ketosis frequency were the primary and secondary endpoints, respectively. The hypoglycemia frequency before and after the intervention was 0.23 and 0.26 times/day in group A and 0.19 and 0.23 times/day in group B, respectively, with no significant difference between the groups. The total insulin dose reduction was approximately 10% in both groups. Ketosis frequency increased significantly after the intervention (from 0.013 to 0.086 times/day in group A and 0.013 to 0.059 times/day in group B). Time-in-range, mean amplitude of glycemic excursion, and glycated hemoglobin A1c improved in both groups. No significant difference in hypoglycemia frequency was observed between patients with and without reduction of the basal insulin dose. The combination therapy improved glycemic control and patient satisfaction regarding hyperglycemia. Nevertheless, adequate attention to ketosis is crucial.