OBJECTIVE: The purpose of this study was to test the effect of high glycemic index (HGI) and low glycemic index (LGI) meals on blood glucose levels using continuous blood glucose monitoring in youths with type 1 diabetes. RESEARCH DESIGN AND METHODS: A total of 20 youths on basal-bolus regimens consumed macronutrient-matched HGI and LGI meals 1 day each in a controlled setting in varying order following consumption of a standardized evening meal. Medtronic MiniMed Continuous Glucose Monitoring Systems were used to assess blood glucose (BG) profiles. RESULTS: Participants demonstrated significantly lower daytime mean BG, BG area >180 mg/dl, and high BG index when consuming LGI meals but no differences for daytime BG area <70 mg/dl, daytime low BG index, or any nighttime values. Significantly more BG values <80 mg/dl were treated on LGI days. CONCLUSIONS: Findings indicate that consumption of an LGI diet may reduce glucose excursions, improving glycemic control.