A Single Center, Open-label, Randomized Study Examining the Glycemic Effects of ID vs SC Bolus Dosing of Insulin Lispro in Patients With Type 1 Diabetes

Brief Summary

Detailed Description

Each patient will participate in 10 visits of which the first, Visit 1, is a Screening Visit. Visit 2 will consist of a brief isoglycemic clamp with a single IV insulin challenge to determine insulin sensitivity. A subsequent test meal and single SC insulin dose (off clamp) will be done to determine the nominal coverage dose of insulin for a mixed meal containing 60g of carbohydrate. This nominal dose will form the basis of insulin bolus dosing for the remainder of the study visits. For Visits 3-9, patients will come to the institute in the early morning 24 hours prior to the meal test for the application of a Continuous Glucose Monitor (Dexcom Seven Plus™, Dexcom, INC). Subjects will receive standardized meals during the day and their blood glucose will be stabilized overnight to a concentration of 115±15 mg/dL via IV insulin and/or glucose infusions. The next morning the subjects will start the experimental intervention. Immediately prior to standardized meals (2 minutes before eating) the patients will receive insulin by either the ID or SC route, followed by the breakfast (rapidly absorbed carb) meal at time point T0. Meal consumption will occur over a 10 to 15 min time interval. Blood glucose excursions will be observed in the 6 hours thereafter (until T= 360 min). Between hours 6 to 7, BG may be re-stabilized to starting values (115±15 mg/dL) by administration of IV insulin or glucose if necessary. At that time a second insulin injection (same dose as at time point T= -2 minutes) will be given and a second standardized lunch (mixed) meal will be administered. Blood glucose excursions will be followed for an additional 6 hours thereafter (T = 780 minutes) Conditions for Visits 3-8 will be: * Condition 1. Individualized Lispro ID dose (nominal dose based on prior insulin sensitivity testing and patient-specific insulin-to-carb ratio) given immediately (2min) prior to a breakfast meal containing predominantly rapidly absorbed carbohydrates (std 60 g CHO; approximately 70:15:15 CHO:protein:fat); a second lunch mixed meal given 7 hours later contains the same total number of carbohydrates (std 60 g mixed) but with a mixed composition between carbohydrate, protein, and fat (ratio approximately 35:25:40). * Condition 2. Equivalent insulin dose and meal regimen as Condition 1 but given by the SC route. * Conditions 3 and 4. The meal regimen from Condition 1, with ID and SC doses increased 30% above the nominal dose to simulate inappropriate carb counting. * Conditions 5 and 6. The meal regimen from Condition 1, with ID and SC doses decreased 30% below the nominal dose to simulate inappropriate carb counting. In addition during each meal challenge the subject will be maintained on an Animas pump intradermally delivering a combined bolus and basal profile of a placebo (5% dextrose for injection solution) during the study period to evaluate flow biomechanics. Visit 9 will examine a single earlier dose timing (determined by analysis of the glycemic profile dataset from the prior 8 visits) relative to the two meals for the ID route only, using the optimal target dose from conditions 1 and 2. Patients will have a final examination, Visit 10, immediately following Visit 9.

Primary Outcomes

Secondary Outcomes

• Insulin levels(12-14 hours)