Abstract

Objective: Postprandial glycemic excursions may contribute to the development of diabetes related complications. Meals of high and low glycemic index (GI) have distinct effects on postprandial glycemia (PPG). Insulin pump therapy offers the potential to tailor insulin delivery to meal composition, however optimal bolus types for meals of different glycemic loads have not been defined. We sought to compare the impact of GI combined with varying prandial bolus types on PPG.

Research Design and Methods: An open cross-over study examining the effects of four different meal and bolus-type combinations on 3 hour PPG (measured by CGMS) was conducted. Twenty young people aged 8-18yrs with type 1 diabetes using insulin pump therapy participated. Meals had equal macronutrient, energy and fibre content and differed only in GI (low vs high). Participants consumed meals of the same GI on consecutive days and were randomised to receive either a standard (100%) or dual-wave (DW- 50:50% over 2 hours) bolus each day. CGMS data from 10 healthy control participants established the ‘target’ response to each meal.

Results: A DW bolus before low GI meals decreased PPG area under curve (AUC) by up to 47% (p=0.004) and lowered the risk of hypoglycemia for the same pre-meal glucose (p=0.005), compared with standard bolus. High GI meals resulted in significant upward PPG excursions with greater AUC (p=0.45), regardless of bolus type.

Conclusion: This data supports the use of a DW bolus with low GI meals to optimize PPG in patients with Type 1 diabetes using insulin pump therapy.