Timing of Pre-meal Insulin Versus Accurate Carbohydrate Counting in Youth With Type 1 Diabetes

The investigators are hoping to figure out how youth with type 1 diabetes can best control their blood glucose levels after meals, by determining whether accurate carbohydrate dosing or the timing of the bolus is more important. There is evidence to suggest that each strategy is important for blood glucose control. Unfortunately, for some people, prebolusing is difficult, because they may not know how much they are going to eat. To give an exact dose of insulin 20 minutes before a meal can be difficult. In this study, the investigators would like to show that taking even just part of the insulin bolus 20 minutes before the meal is preferable to waiting until mealtime and taking the entire bolus. To do this, the investigators will have 24 patients in the study, who will each spend 4 mornings at The investigators clinic. The order of the visits will be selected randomly. The visits will include: taking full bolus at mealtime, taking full bolus 20 minute before mealtime, taking ½ bolus at mealtime, and taking ½ bolus 20 minutes before mealtime. At each visit, the person will eat the same meal, but the timing and amount of the bolus will be different. The investigators will measure the blood glucose levels with a blood glucose meter, and also with a laboratory test called YSI. The investigators will also be measuring the glucose levels under the person's skin with a continuous glucose monitor. The investigators will compare the area under the curve for the different visits, as well as the glucose levels at different points after the meal.

Inclusion Criteria: Ages 7-21, inclusive Diagnosis of type 1 diabetes for >1 year Using carbohydrate counting to dose mealtime insulin Using an insulin pump and continuous glucose monitor to control diabetes HbA1c <10% Exclusion Criteria: Celiac disease or other GI abnormality Severe hypoglycemia in the past 6 months Pregnancy Documented hypoglycemia unawareness