Carbohydrate and Insulin Requirements During Prolonged Fasted Exercise
Condition: Type 1 Diabetes
MeSH terms: Diabetes Mellitus, Type 1
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 management strategies for
      prolonged aerobic exercise: A) carbohydrate dose of 0.3g/kg/hr; B) A 50 percent basal rate
      reduction, performed 90-minutes in advance of exercise for the duration of the activity; and
      C) A 50 percent basal rate reduction, performed at exercise onset, with carbohydrate dose of
      0.3g/kg/hr
    

Detailed description: 
      This project focuses on the effectiveness of various exercise strategies on the time spent in
      target range during and after aerobic exercise in adults with type 1 diabetes (T1D) on
      continuous subcutaneous insulin infusion (CSII).

      The primary objective of the protocol is to determine if a moderate basal insulin reduction
      (-50 percent of basal), performed 90-minutes before a 120-minute aerobic exercise session
      (with 5-minute breaks every 30 minutes of exercise, and a ten minute break mid-exercise),
      improves the time in target range compared to either a carbohydrate consumption only strategy
      or insulin reduction (-50 percent) and carbohydrate consumption strategy both performed at
      the onset of exercise in patients with T1D on CSII therapy. The time in target will be
      determined for both the exercise period and during a 24-hour window after the end of
      exercise.

      In all three sessions, aerobic exercise (brisk walking) will be performed in the fasted state
      (minimum 8 hours after the last meal) in the early-morning. The exercise will consist of four
      30-minute bouts of walking at 40-50 percent of the participant's pre-determined aerobic
      capacity, separated by 5-10 minute breaks. The participants exercise intensity will be
      monitored continuously using heart rate and activity monitors. Blood glucose and blood ketone
      levels will be monitored throughout exercise.

      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 two days and
      participants will be expected to complete all sessions within ~ 12 weeks from the time of the
      baseline/screening visit. Participants will be instructed to apply a new continuous glucose
      monitor (CGM) sensor between 1-5 days prior, not to perform moderate-to-vigorous exercise 24
      hours prior and refrain from caffeine and alcohol 12 hours prior to each study visit.
      Participants are also instructed not to eat after 2330h the night before arriving to the
      laboratory and not to give bolus insulin or perform temporary basal rate changes after 0200h
      on the morning of the exercise visit. Participants are instructed to try to arrive at the
      laboratory with their blood glucose between 72-270 mg/dL, with no active bolus insulin
      according to personal CSII device, in the fasted state. If a bolus of insulin was given prior
      to the exercise session, the session was rescheduled. Females of reproductive capacity
      performed all three visits in the early follicular phase (days 1-6 of cycle). Participants
      arrived at the laboratory between 0600h and 1000h. Exercise start time was between 0700h and
      1045h, based on participants' choice, and the timing of exercise was kept consistent within
      participants.

      Following each exercise session, the participant will rest for 20-minutes and then leave the
      laboratory. The participants glucose will be monitored for 24-hours after the standardized
      exercise. They will also be instructed to perform a standardized basal insulin reduction
      overnight to help reduce the risk of post-exercise nocturnal hypoglycemia (-20 percent from
      bedtime for 6 hours).
    

Intervention name(s): Exercise strategies
Intervention type(s): Other
Intervention description(s): Strategies for exercise in type 1 diabetes to maintain glucose control
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 (50 percent reduction) with or without carbohydrate feeding.
Masking: None (Open Label)
Primary purpose: Other
Keywords: Physical Activity; Exercise; Carbohydrates; Hypoglycemia; Continuous Glucose Monitoring