Research to date suggests that the selection of lower glycemic index foods, that is, foods provoking a slower, more sustained blood sugar response, may result in improved glycemic control in youth with diabetes. However, there is currently insufficient data to support practice recommendations. The purpose of this pilot study is to test the blood glucose response to low and high glycemic index meals in youth with diabetes using continuous blood glucose monitoring, and to determine whether the effect of glycemic index differs by regimen or diagnosis. In this pilot study up to 42 youth with type 1 diabetes or impaired glucose metabolism (elevated fasting glucose, insulin resistance, or type 2 diabetes) will participate in 5 days of continuous blood glucose monitoring during which they will receive both low and high glycemic index meals. Children will be provided with 1 full day of low glycemic index meals and 1 full day of high glycemic index meals in a supervised setting in randomized order. Each of these test days will be preceded by a standard evening meal and snack. Continuous blood glucose monitoring will also be conducted during regular food intake ad libidum away from the clinic, as well as during one day of instructed low glycemic meals at home. All food intake, insulin, and blood glucose self-monitoring will be recorded. While in the clinic, measures of satiety and acceptability of the food will also be obtained. Data analysis will include indices of blood glucose levels and variability.