A Pilot Study Evaluating Meal Timing, Macronutrient Composition, and Faster-Acting Insulin Aspart Versus Insulin Aspart on Postprandial Glycemia with the Medtronic Advanced Hybrid Closed-Loop System.

Background: This study compared postprandial glycemia with faster-acting insulin aspart (FiAsp) versus insulin aspart delivered by advanced hybrid closed loop (AHCL) according to varying meal composition, time of day, and premeal bolus dose estimation in adults with type 1 diabetes. Materials and Methods: Participants received 11 weeks of insulin aspart and FiAsp in sequence, delivered by the MiniMed™ 780G AHCL algorithm, and within each period ingested 12 standardized meals. Test meals, containing 60 g of carbohydrate but varying by fat and protein content (high fat low protein [HFLP], high fat high protein [HFHP], and low fat low protein [LFLP]), were each eaten in the morning and evening and with a full bolus or 50% reduction. The primary outcome was continuous glucose monitoring time in range (%TIR; 3.9-10.0 mmol/L) 4 h postmeal for FiAsp versus insulin aspart. Results: Twelve participants (mean [standard deviation or SD] age 48 (13) years; 58% male; HbA1c 6.7 (0.7)%/50 (7) mmol/mol) were recruited. When all meal types, timing, and bolus conditions were combined, FiAsp tended to have greater glucose TIR compared with insulin aspart (mean difference = 5.17% [-0.09, 10.43]; P = 0.054), with differences most apparent for morning meals. Insulin formulation did not impact outcomes with full versus 50% premeal bolus or meal composition. HFLP meals resulted in the greatest TIR, followed by HFHP and lowest for LFLP (83.7% [19.6] vs. 74.7% [26.9] vs. 62.0% [23.1], respectively, mean [SD], P < 0.01). Conclusions: For adults with type 1 diabetes who are susceptible to morning hyperglycemia, FiAsp delivered by AHCL and higher fat content of meals may help improve postprandial glycemic outcomes. Clinical Trial Registration: Australian New Zealand Clinical Trials Registry-ACTRN12619001340123.