OBJECTIVE To evaluate the effects of missed insulin boluses for snacks in youth with type 1 diabetes. RESEARCH DESIGN AND METHODS Three months of simultaneous continuous subcutaneous insulin infusion and continuous glucose monitoring data from nine subjects were retrospectively evaluated. Glucose excursions between 1330 and 1700 h were defined as relating to snacks with insulin or snacks with no insulin administered. Area under the curve >180 mg/dl (AUC >180), average Delta glucose, and rate of change were analyzed and compared within and between groups. RESULTS A total of 94 snacks without insulin and 101 snacks with insulin were analyzed. Snacks without insulin had significantly higher log (AUC >180 + 1) (1.26 vs. 0.44 mg/dl per event; P < 0.001), Delta glucose (114 vs. 52 mg/dl; P < 0.001), and average rate of change (1.3 vs. 1.1 mg/dl per minute; P < 0.001). CONCLUSIONS This study shows that afternoon snacks without insulin boluses are common and result in significantly higher glucose excursions than snacks with insulin administration.