Glycemic Variability in Type 1 Diabetes Compared with Degludec and Glargine on the Morning Injection: An Open-label Randomized Controlled Trial

Introduction: Optimal adjustment of basal insulin to overcome hypoglycemia and glycemic variability (GV) depends on its duration of action and peak-less profile. Owing to the ability of long-acting basal insulin to avoid hypoglycemia, we titrated pre-meal glucose to normal fasting blood glucose, 80–110 mg/dL (4.5–6.1 mmol/L), and post-meal glucose to 80–140 mg/dL (4.5–7.8 mmol/L). The purpose of this study was to evaluate two basal insulin analogues degludec (IDeg) and glargine (IGlar), injected in the morning, for GV using continuous glucose monitoring (CGM) in type 1 diabetes (T1DM). Methods: In this crossover study, 20 Japanese patients with T1DM (age 54 ± 16 years, disease duration 16 ± 8 years, BMI 24 ± 4 kg/m², HbA1c 7.4 ± 0.8%) were randomized into one of two different starting regimens, and CGM was conducted on three consecutive days during the last week of each 12-week titration period. Treatment satisfaction was assessed at the end of each treatment period using the Diabetes Therapy-Related Quality of Life Questionnaire (DTR-QOL). Results: There were no differences in HbA1c, total insulin dosage, body weight changes, and basal to bolus ratio between the IDeg and IGlar arms. The day-to-day variability in fasting interstitial GV on the CGM curves was significantly less in the IDeg than IGlar treatment period (25.9 ± 22.0 vs. 43.8 ± 30.1 mg/dl, p = 0.04). Other markers of GV, calculated by the EasyGV software, including mean amplitude of glycemic excursions (MAGE), J-index, total and nocturnal hypoglycemia were not different between the two treatment periods. The score of “satisfaction with treatment”, a subdomain of the DTR-QOL system, was higher in the IDeg period. Conclusion: Thus, the morning injection of the two long-acting insulin analogues seemed similar with regard to the magnitude of hypoglycemia in T1DM, but treatment with IDeg was associated with lower day-to-day variation in glucose level. These results suggest that IDeg is safe with minimal morning GV in patients with T1DM. Clinical trial registration: Japanese Clinical Trials Registry, UMIN000012358.