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 30min 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 +/- 58.9mg/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.