Timing of Meal Insulin Boluses to Achieve Optimal Postprandial Glycemic Control in Patients with Type 1 Diabetes

OBJECTIVE: This study determined the optimal timing of insulin bolus administration in relation to meal consumption in adolescents and adults with type 1 diabetes. STUDY DESIGN AND METHODS: Twenty-three subjects participated in this crossover study consisting of three treatment arms: delivering an insulin glulisine bolus by insulin pump 20 min prior to a meal ("PRE"), immediately before the meal ("START"), and 20 min after meal initiation ("POST"). Blood glucose levels were measured every 30 min for a total of 240 min post-meal initiation. Mean blood glucose levels at 1 and 2 h after meal initiation, blood glucose area under the curve (AUC), and maximum blood glucose levels were analyzed. RESULTS: At both 60 and 120 min after meal initiation, the PRE arm showed significantly lower glycemic excursions than the START arm (P = 0.0029 and 0.0294, respectively) and the POST arm (P = 0.001 and 0.0408, respectively). Glycemic AUC was significantly less in the PRE arm versus both the START and POST arms (159.5 +/- 58.9 mg/dL vs. 187.0 +/- 43.1 mg/dL P = 0.0297 and 184.5 +/- 33.2 mg/dL P = 0.0463, respectively). Peak blood glucose levels were significantly lower in the PRE arm compared to the START arm (P = 0.0039) and the POST arm (P = 0.0027). CONCLUSIONS: A bolus of rapid-acting insulin 20 min prior to a meal results in significantly better postprandial glucose control than when the meal insulin bolus is given just prior to the meal or 20 min after meal initiation.