Safety and efficacy of insulin degludec/insulin aspart with bolus mealtime insulin aspart compared with standard basal-bolus treatment in people with Type 1 diabetes: 1-year results from a randomized clinical trial (BOOST T1).

Aims: To evaluate the long-term safety and efficacy of a simplified basal-bolus regimen of once-daily insulin degludec/insulin aspart (IDegAsp) with additional IAsp vs. a standard basal-bolus insulin regimen of insulin detemir (IDet) with IAsp in adults with Type 1 diabetes.

Methods: This was an open-label trial comprising a 26-week core phase followed by a 26-week extension phase. Participants were randomized to IDegAsp once daily at the main meal and IAsp at remaining meals (IDegAsp+IAsp), or IDet (once or twice daily) and IAsp at all meals (IDet+IAsp). Insulins were titrated to target plasma glucose of < 5 mmol/l (< 90 mg/dl) at pre-breakfast (IDegAsp and IDet) and at pre-meal (IAsp).

Results: After 52 weeks, the overall confirmed hypoglycaemia rate was 31.8 episodes/patient-years of exposure (PYE) with IDegAsp+Asp and 36.7 episodes/PYE with IDet+IAsp, and the rate of nocturnal confirmed hypoglycaemia was significantly lower with IDegAsp+Asp than with IDet+IAsp (3.1 vs. 5.4 episodes/PYE, respectively; P < 0.05). Adverse event rates were comparable between groups. Mean HbA decreased from baseline by 0.7% (IDegAsp+IAsp) and 0.6% (IDet+IAsp), achieving 60 or 61 mmol/mol (7.6% or 7.7%, respectively), at Week 52. The mean total daily insulin dose was lower with IDegAsp+IAsp than with IDet+IAsp (ratio: 0.87; 95% CI 0.79-0.95; P = 0.0026).

Conclusions: Once-daily treatment with IDegAsp and IAsp as bolus insulin for remaining meals was associated with significantly lower risk of nocturnal confirmed hypoglycaemia, improved glycaemic control and showed non-inferiority compared with IDet+IAsp, the standard of care in Type 1 diabetes.