The Durability of Basal Insulin Affects Day-to-Day Glycemic Variability Assessed by Continuous Glucose Monitoring in Type 2 Diabetes Patients: A Randomized Crossover Trial

Background: Not only within-day glycemic variability but also day-to-day glycemic variability is a risk factor for diabetic patients. However, the ways of controlling day-to-day glycemic variability are unclear. We hypothesized that the durability of basal insulin plays an important role in controlling day-to-day glycemic variability in type 2 diabetes patients, and we therefore aimed to evaluate whether glargine U300, which exhibits prolonged absorption compared with glargine U100 but the same composition as glargine U100, would lead to improved day-to-day glycemic variability. Materials and Methods: This was a single-center, randomized, open-label, crossover study in type 2 diabetes patients using basal insulin therapy. After switching from 4 weeks of treatment with glargine U100 or U300, the patients performed continuous glucose monitoring (CGM) for 72 h in an environment with routine activities and mealtimes. The mean of daily difference (MODD) was assessed as day-to-day glycemic variability. Results: We enrolled 22 patients, and 17 patients completed the study. The MODD assessed as day-to-day glycemic variability was significantly lower with glargine U300 than with glargine U100 (1.8 +/- 0.6 mmol/L vs. 2.4 +/- 0.9 mmol/L, P = 0.006). No significant difference was observed in short-term glycemic variability between the two glargine formulations as measured by the standard deviation, coefficient of variation, mean amplitude of glucose excursion. Conclusions: Compared with glargine U100 treatment, glargine U300 treatment improved the MODD as assessed by CGM in type 2 diabetes patients. These findings suggest that the durability of basal insulin may be associated with day-to-day glycemic variability in type 2 diabetes patients.