OmniPod®-Type 1 Diabetes Insulin Management for Exercise Study

This project focuses on the effectiveness of various basal insulin reductions on the time spent in target range during and after aerobic exercise in adults with type 1 diabetes (T1D) on OmniPod® insulin pump therapy. The OmniPod® is a Health Canada approved tubing-free insulin pump device that uses an insulin delivery 'pod' and a Personal Diabetes Manager (PDM). The PDM is a wireless handheld device that programs the pod, captures diabetes management events (food, exercise, etc.), and acts as a glucose meter.

The primary objective of the protocol is to determine if a moderate basal insulin reduction (-50% of basal), performed 90-minutes before a 75-minute aerobic exercise session (with three 5-minute breaks), improves the time in target range compared to either a more aggressive basal rate reduction (-80%) or complete pump suspension at the onset of exercise in patients with T1D on continuous subcutaneous insulin infusion (CSII) therapy. The time in target will be determined for both the exercise period and during a three-hour window after a standardized meal ingestion performed 30-minutes after the end of exercise.

In all three sessions, aerobic exercise (brisk walking/light jogging) will be performed in the post-absorptive state, ~ four hours after the last meal with their usual bolus insulin given. The exercise will consist of four 15-minute bouts of jogging at 50-60% of the participant's pre-determined aerobic capacity, separated by three 5-minute breaks (to simulate what is typically done in most team and individual workouts and sports). The subjects exercise intensity will be monitored continuously using heart rate and activity monitors.

Each participant will be assigned to a sequence of the three experimental visits through a randomization process. Each exercise session will be separated by at least three days and participants will be expected to complete all sessions within ~ 12 weeks from the time of the baseline/screening visit. Participants will be advised to avoid any vigorous exercise within 24 hours before or after the laboratory-based exercise tests. Subjects will be asked about activity during each clinic visit and phone call to monitor adherence to these recommendations.

Following each exercise session, the participant will rest for 30-minutes and then consume a standardized meal (50 g of carbohydrate, ~17g protein and ~8g of fat, Lean Cuisine). The amount of bolus insulin given at the post-exercise meal will be based on the carbohydrate content of the meal and the patient's own individualized insulin to carbohydrate ratio, and insulin sensitivity index and glycemic targets on their OmniPod® PDM, corrected to 75% of total dose to account for the increase in insulin sensitivity post-exercise. Insulin "corrections" will be given based on the patient's own OmniPod® settings (i.e. usual care). Insulin will be administered 10-minutes before the start of consuming the meal. If hypoglycemia occurs prior to the meal (blood glucose ≤ 3.9 mmol/L), subjects will be treated with 16 grams of fast-acting carbohydrates (Dex4, AMG Medical) prior to meal consumption.