OBJECTIVE -The purpose of this study was to quantify the effects of glycemic index on postprandial glucose excursion (PPGE) in children with type 1 diabetes receiving multiple daily injections and to determine optimal insulin therapy for a low-glycemic index meal.RESEARCH DESIGN AND METHODS -Twenty subjects consumed test breakfasts with equal macronutrient contents on 4 consecutive days; high-and low-glycemic index meals (glycemic index 84 vs. 48) were consumed with preprandial ultra-short-acting insulin, and the low-glycemic index meal was also consumed with preprandial regular insulin and postprandial ultra-short-acting insulin. Each child's insulin dose was standardized. Continuous glucose monitoring was used.RESULTS -The PPGE was significantly lower for the low-glycemic index meal compared with the high-glycemic index meal at 30 -180 min (P Ͻ 0.02) when preprandial ultra-shortacting insulin was administered. The maximum difference occurred at 60 min (4.2 mmol/l, P Ͻ 0.0001). Regular insulin produced a 1.1 mmol/l higher PPGE at 30 min compared with ultrashort-acting insulin (P ϭ 0.015) when the low-glycemic index meal was consumed. Postprandial ultra-short-acting insulin produced a higher PPGE at 30 and 60 min compared with preprandial administration when the low-glycemic index meal was consumed. The maximum difference was 2.5 mmol/l at 60 min (P Ͻ 0.0001).CONCLUSIONS -Low-glycemic index meals produce a lower PPGE than high-glycemic index meals. Preprandial ultra-short-acting insulin is the optimal therapy for a low-glycemic index meal.

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