Effectiveness of Aerobic Exercise to Mitigate Hyperglycemia After Fasted Resistance Exercise
Condition: Type 1 Diabetes
MeSH terms: Hyperglycemia
Study type: Interventional

Summary: 
      Certain types and timings of exercise are known to cause hyperglycemia (high blood glucose)
      in people with type 1 diabetes. Hyperglycemia increases the risk of most long-term
      complications for individuals with this complication. However, using insulin corrections to
      treat post-exercise hyperglycemia can increase the risk of late-onset hypoglycemia (low-blood
      glucose).

      Anaerobic activities performed in a fasted state are known to cause increases in blood
      glucose and post-exercise hyperglycemia in most individuals with type 1 diabetes. This study
      proposes to examine the effect of a ten-minute aerobic cool down after resistance exercise on
      the blood glucose response to fasted exercise of individuals with type 1 diabetes. It is
      hypothesized that adding a short aerobic cool down at the end of a fasted resistance exercise
      session will attenuate post-exercise increases in blood glucose observed in previous studies,
      leading to less post-exercise hyperglycemia.
    

Detailed description: 
      Individuals with type 1 diabetes (T1D), are at elevated risk of low muscular strength, as
      well as accelerated decline in muscle strength and functional status with aging. Resistance
      exercise (RE) is a proven intervention that has been demonstrated to improve physical
      function, muscle mass, body composition, mental health, bone mineral density, insulin
      sensitivity, blood pressure, lipid profiles, and cardiovascular health for all adults.
      Clinical guidelines recommend that individuals with T1D perform RE twice weekly to optimally
      benefit from RE yet most individuals with T1D are unable to meet these recommendations. Two
      barriers to exercise responsible for this discrepancy are a fear of hypoglycemia from
      exercise, and a loss of control over diabetes. To limit barriers to exercise, much research
      has been done to identify exercise modalities that have minimal risk for hypoglycemia,
      including recent investigations demonstrating a blood glucose increase leading to
      hyperglycemia in response to RE while participants are fasted. Hyperglycemia frequency is
      directly related to the incidence of diabetes-related complications, so exercise
      recommendations should minimize risk of hyperglycemic and hypoglycemic responses. Clinical
      guidelines for post-exercise hyperglycemia recommend a corrective insulin dose or a brief
      aerobic cool down, however the efficacy of an aerobic cool down has yet to be empirically
      tested. Additionally, overcorrection of hyperglycaemia with insulin after exercise can result
      in an increased risk of severe late onset hypoglycaemia, which could even be fatal.

      The study will have a randomized, repeated measures design with two testing sessions (one
      with a cool down and one without a cool down) in addition to a baseline fitness assessment.
      Interested participants will be invited to the Physical Activity and Diabetes Laboratory on
      the main campus of the University of Alberta. Participants will be asked questions related to
      diabetes care, physical activity levels, and medication. Blood pressure and heart rate will
      also be measured. Where participants are eligible, anthropometric characteristics will be
      measured using standard protocols. Those who meet all eligibility criteria and complete
      informed consent forms will be asked to complete the initial exercise tests. Participants
      will perform a submaximal aerobic capacity test to extrapolate the participant's aerobic
      capacity. Participants will also undergo a strength test for each of the seven exercises
      involved in the study, in order to estimate the maximum weight they can move for 3 sets of 8
      repetitions (8RM). During this session the investigators will introduce participants to the
      activity monitor (accelerometer) that will be worn on the day before, the day of, and the day
      after each testing session. The accelerometer will provide information on background physical
      activity and sleep patterns that might act as confounders where the blood glucose responses
      to exercise are concerned.

      Testing sessions: Participants will be asked to arrive at the lab between 7:00 and 8:00 am
      for both sessions, which will be randomly assigned by tossing a fair coin. During the
      sessions, participants will be asked to perform a total of seven resistance exercises (leg
      press, chest press, leg curls, lat pulldowns, seated row, shoulder press, and abdominal
      crunches). The protocol will be 3 sets of 8 repetitions at the participant's 8 RM.
      Participants will be asked to match their daily food and insulin intake as closely as
      possible from one testing session to the next for the day before, day of and day after the
      testing session. During this time participants will also wear an accelerometer on their waist
      during the day, and on their non-dominant wrist at night. Participants will be provided with
      log sheets to assist in both of these tasks and will also be asked to avoid strenuous
      exercise and alcohol intake.

      A CGM sensor will be subcutaneously inserted by one of the investigators (trained by a group
      from the CGM manufacturer) into the anterior abdominal area of the participant approximately
      2 days prior to the first testing session. The Dexcom G6 CGM will store glucose data every 5
      minutes for up to 10 days. The participant will be instructed on how to remove their sensor
      at least 24 hours after the exercise session, and will be asked to upload their data to
      Dexcom Clarity to share with the study team. If the participant habitually uses their Dexcom
      G6 in their diabetes care, they will be provided with the option to start their own CGM for
      the study.
    

Intervention name(s): Resistance exercise only; Resistance exercise plus cool down
Intervention type(s): Behavioral; Behavioral
Intervention description(s): Participants will perform 3 sets of 8 repetitions of 7 different exercises while in a fasted state.; Participants will perform 3 sets of 8 repetitions of 7 different exercises while in a fasted state followed by a 10-minute light aerobic cool down
Intervention model: Single Group Assignment
Masking: None (Open Label)
Primary purpose: Treatment
Keywords: resistance exercise, aerobic exercise