Insulin Management for Exercise in Patients With Type 1 Diabetes
Condition: Type 1 Diabetes; Hypoglycemia; Physical Activity
MeSH terms: Diabetes Mellitus; Diabetes Mellitus, Type 1; Hypoglycemia
Study type: Interventional

Summary: 
      The purpose of this study is to compare the time spent in glucose target range (4.0-10.0
      mmol/L) during exercise and in recovery using three different basal insulin management
      strategies for prolonged aerobic exercise: A) pump suspension for the duration of the
      activity, starting at the onset of exercise; B) A 50% basal rate reduction, performed
      90-minutes in advance of exercise for the duration of the activity; and C) An 80% basal rate
      reduction, performed 90-minutes in advance of exercise for the duration of the activity.
    

Detailed description: 
      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.

      The participant will be monitored for at least three hours after the standardized meal prior
      to discharge. Continuous glucose monitoring (CGM) low- and high-glucose 'alerts' will be
      activated. They will also be instructed to perform a standardized basal insulin reduction
      overnight to help reduce the risk of post-exercise nocturnal hypoglycemia (-20% from bedtime
      for 6 hours).

      CGM sensors will be removed the next day at home and patients will be instructed to perform
      data upload using the appropriate websites (i.e. Dexcom Share/Clarity). The participant will
      bring the device to the next visit or an investigator will arrange for pickup.
    

Intervention name(s): Change in their basal insulin rate
Intervention type(s): Other
Intervention description(s): Individual with type 1 diabetes on insulin pump therapy typically lower their basal insulin delivery for exercise. This study will compare 3 common strategies of basal insulin reductions for 75 minutes of aerobic exercise.
Intervention MeSH terms: Insulin
Allocation: Randomized
Intervention model: Crossover Assignment
Intervention model description: Patients with type 1 diabetes on insulin pump therapy will remain on their usual insulin regimen. However, we are testing percent basal rate reductions during exercise (e.g. 80% reduction, 50% reduction, and 100% reduction).
Masking: None (Open Label)
Primary purpose: Other
Keywords: Type 1 Diabetes; Exercise; Basal insulin; CSII; OmniPod; CGM