Basal and Bolus Insulin Dose Changes after Switching Basal Insulin to Insulin Degludec in Patients with Type 1 Diabetes Mellitus: A Pilot Study

Background and objectives Ultra-long-acting insulin degludec (DEG) has a longer duration of action and less daily variability relative to other basal insulin (BI), and thus may benefit patients with type 1 diabetes mellitus (T1DM). We examined the impact of switching BI to DEG on glycemic control and insulin dose in T1DM. Methods T1DM patients ( n = 22; six male; mean age: 64.5 ± 12.6 years) receiving basal-bolus insulin therapy were included. Initially, the BI dose was replaced with DEG in a 1:1 ratio; 80–100% of the total dose was replaced with DEG for multiple basal insulin injections. DEG was titrated according to study protocol. Changes in HbA1c, daily insulin dose, glycemic self-monitored blood glucose variations, and hypoglycemia frequency were evaluated for 24 weeks. Results Once-daily DEG significantly decreased HbA1c levels when switched from once-daily BI (7.9 ± 0.8 vs. 7.5 ± 0.9%, p = 0.020) and maintained HbA1c when switched from twice-daily BI (8.5 ± 1.6 vs. 8.4 ± 1.2%, p = 0.457). The BI dose decreased by −7.8 ± 13.9% ( p = 0.017) and −16.6 ± 16.9% ( p = 0.050) when switched from once-daily BI and twice-daily BI, respectively. The total bolus insulin dose significantly decreased when switched from once-daily BI (21.7 ± 8.3 to 19.3 ± 8.8 U/day, p = 0.016) especially in the injection before breakfast and evening meal. Body weight and hypoglycemia frequency was not significantly different. Conclusion DEG improved glycemic control when switched from once-daily BI and maintained glycemic control when switched from twice-daily BI without increasing hypoglycemia.