Comparison of Glycemic Variability by Using Insulin Glargine and Insulin Degludec in Japanese Patients With Type 1 Diabetes, Monitored by Continuous Glucose Monitoring: A Preliminary Report

Background: Insulin degludec is a novel ultra-long-acting basal insulin, which is used clinically first in Japan. We aimed to study efficacy of insulin degludec compared with insulin glargine in patients with type 1 diabetes, by using continuous glucose monitoring (CGM). Methods: Patients studied were 4 Japanese patients with type 1 diabetes treated by the basal-bolus insulin therapy. We studied the influences of switching from insulin glargine to insulin degludec on parameters for glycemic variability using CGM for consecutive three days. Parameters studied for glycemic variability include the 24 h mean glucose levels, standard deviation (SD) values of 24 h glucose levels, M-values, mean amplitude of glycemic excursions (MAGE) values, 24 h area under the glucose curve (AUC), time in hypoglycemia and time in hyperglycemia. We compared these CGM data using insulin glargine with those using insulin degludec. Results: Although a statistically significant difference was not obtained, 24 h mean glucose levels, 24 h AUC, SD values of 24 h glucose levels, MAGE values and time in hyperglycemia were smaller in the insulin degludec treatment as compared with those in the insulin glargine treatment. M-values in the insulin degludec treatment were significantly smaller than those in the insulin glargine treatment. Although a significant difference was not observed in time in hypoglycemia, hypoglycemia was developed in the patient during the treatment using insulin degludec. Conclusions: The present study showed that the switching from in-sulin glargine to insulin degludec as basal insulin improved glycemic variability in patients with type 1 diabetes. To our knowledge, this is the first to report efficacy of insulin degludec compared with insulin glargine in patients with type 1 diabetes by using CGM.