1603-P: The Cardiovascular Impact of Appropriately-Timed Prandial Insulin in Type 1 Diabetes—A Randomized Crossover Study

Introduction & Objective: Appropriately-timed (i.e., ~15 minutes before meal intake) prandial insulin administration improves postprandial glycemic control, but the cardiovascular impact of this intervention is unknown. In this study, we tested whether appropriate prandial insulin timing improves insulin’s microvascular action in people with type 1 diabetes (T1D).

Methods: The primary outcome was change in myocardial microvascular perfusion (via contrast-enhanced ultrasound) and secondary outcome was change in skeletal muscle microvascular perfusion. Following overnight fast, participants underwent baseline measures of microvascular perfusion and then consumed a standardized liquid mixed meal (10 kcal/kg body weight). Vascular measurements were then repeated 120 minutes later. 18 participants with T1D completed two admissions with a randomized crossover design: (A) prandial insulin injected 15 minutes before meal intake and (B) prandial insulin injected 15 minutes after meal intake began. Plasma insulin and glucose were measured every 30 minutes. Repeated measures ANOVA compared changes in insulin and glucose while paired and unpaired t-tests compared changes in microvascular outcomes.

Results: Myocardial microvascular blood flow was similar at baseline between the two admissions. Change in plasma glucose was greater (p<0.01) and plasma insulin was higher (54.43 vs 41.42 µIU/mL; p<0.01) at the 120-minute mark in Admission B compared to Admission A. Myocardial microvascular blood flow increased (p=0.03) in Admission A while it modestly decreased (p=0.08) in Admission B. There were no changes in skeletal muscle microvascular perfusion during either admission.

Conclusion: Appropriately-timed prandial insulin administration improved glycemic control and myocardial microvascular perfusion two hours after meal intake. Future work could investigate whether such improvements, occurring repetitively, can improve cardiovascular health.