A low-glycemic index (GI) diet may lower postprandial hyperglycemia and decrease the risk for postabsorptive hypoglycemia in people with type 1 diabetes. However, insufficient evidence exists on the efficacy of a low-GI diet to support practice recommendations. The goal of this study was to examine the blood glucose response to and the macronutrient composition of low-GI meals vs usual meals consumed ad libitum at home in children with type 1 diabetes. A within-subject, crossover design was employed. Twenty-three participants were recruited between June and August 2006. Participants wore a continuous blood glucose monitoring system and completed diet diaries on 2 days. On 1 day, participants consumed their usual meal; on another day, participants consumed low-GI meals ad libidum. Order of the 2 days was counterbalanced. The mean GI was 34+/-6 for the low-GI day and 57+/-6 for the usual meal day (P<0.0001). During the low-GI day, mean daytime blood glucose values (125+/-28 mg/dL [6.9+/-1.5 nmol/L] vs 185+/-58 mg/dL [10.3+/-3.2 nmol/L], P<0.001), blood glucose area above 180 mg/dL (4,486+/-6,138 vs 26,707+/-25,038, P<0.006), and high blood glucose index (5.1+/-5.1 vs 13.6+/-7.6, P<0.001) were lower compared to the usual mean day. During the low-GI day, subjects consumed more fiber (24.5+/-12.3 g vs 14.5+/-6.1 g, P<0.007) and less fat (45.7+/-12.2 g vs 76.8+/-32.4 g, P<0.005); however, there were no differences in energy, carbohydrate, or protein intake. In this pilot study, a low-GI diet was associated with improved diet quality and a reduction in hyperglycemia.