Glycemic Benefit of Insulin Degludec/Insulin Aspart Compared to Basal Insulin in Type 2 Diabetes Mellitus Associated with Impaired Glucagon-Like Peptide-1 Response: A Randomized Crossover Trial.

We aimed to confirm that once-daily insulin degludec/insulin aspart (IDegAsp) is superior to basal insulin therapy in participants with type 2 diabetes mellitus (T2DM) exhibiting signs of overbasalization. Additionally, we analyzed incretin profiles in relation to the benefits of IDegAsp, providing insights into the underlying mechanisms. A prospective study was conducted in participants receiving basal insulin therapy, with a fasting plasma glucose (FPG) level lower than predicted from their glycosylated hemoglobin (HbA1c). Participants were randomly assigned to either IDegAsp or insulin glargine (IGlar) in a 1:1 ratio. After 20 weeks of treatment, the insulins were switched in a crossover design. The primary endpoint was the change in HbA1c from baseline. Incretin profiles, hypoglycemic events, and continuous glucose monitoring (CGM) were also analyzed (Trial registration: www.cris.nih.go.kr; KCT0004597). The study included 55 participants (male 40%, mean age 65 years, FPG 103 mg/dL, and HbA1c 8.3%). HbA1c significantly decreased to 7.8%±0.8% with IDegAsp, compared to 8.0%±0.7% with IGlar. The mean estimated treatment difference of changes was -0.21% points (95% confidence interval, -0.39 to -0.02; P=0.031), favoring IDegAsp. Hypoglycemic events were comparable. CGM demonstrated significantly lower glucose measures during the daytime with IDegAsp compared to IGlar, and vice versa at dawn. The HbA1c benefit of IDegAsp over IGlar was associated with a low glucagon-like peptide-1 (GLP-1) ratio at 30 minutes relative to baseline (r=0.301, P=0.040), while not with glucose-dependent insulinotropic polypeptide. The greater reduction in HbA1c achieved with IDegAsp compared to IGlar in individuals with T2DM was associated with an impaired GLP-1 response, facilitating personalized insulin therapy.