Aerobic vs Resistance Exercise in Post-menopausal Women With Type 1 Diabetes

Acute Glycemic Effects of Aerobic and Resistance Exercise in Post-menopausal Women With Type 1 Diabetes

Participants will be asked to wear a continuous glucose monitor for at least three days on three separate occasions. One testing session will be a no-exercise resting control session (90 minutes). One will be a moderate aerobic exercise session (30 minutes of exercise, 60 minutes of recovery), and the third will be a moderate weight-lifting session (~30 minutes of exercise, 60 minutes of recovery).The investigators will measure changes in blood glucose during exercise by drawing blood during and after exercise. Post-exercise glucose trends will be examined using continuous glucose monitoring.

Pre-test measures: Interested participants will be invited to either the Exercise Physiology laboratory the Augustana campus of the University of Alberta, or the Physical Activity and Diabetes Laboratory on the main campus of the University of Alberta. They will be asked questions related to menopause, PA levels, and medication. Blood pressure and heart rate will also be measured. Where participants are eligible, anthropometric characteristics will be measured using standard protocols. A blood sample will be drawn for assessment of HbA1c. Those who meet all eligibility criteria and complete informed consent forms will be asked to complete the initial exercise tests. Participants will perform a maximal aerobic capacity test with ECG monitoring, under the supervision of a certified exercise physiologist. Indirect calorimetry will be used to assess oxygen consumption and carbon dioxide production and will be used to extrapolate the participant's aerobic capacity. Participants will undergo a strength test for each of the ten exercises involved in the study, in order to estimate the their 1 repetition maximum. Participants will also be asked to undergo a dual energy x-ray absorptiometry (DXA) scan for body composition in the Clinical Research Unit at the Alberta Diabetes Institute. While this procedure generally requires proof of a negative pregnancy test, participants will be provided with a waiver in order to decline this test (in light of their menopausal status).

Testing sessions: Participants will be asked to arrive at the lab at around 4:00 pm for all three sessions, which will be randomly assigned. During the sessions, participants will be asked to perform one of the three activities: 1) seated rest 2) aerobic exercise (walking on a treadmill at 50% of the participant's pre-determined VO2max) or 3) resistance exercise consisting of 1 set of 10 repetitions of 10 different exercises with 90 seconds rest between sets. Blood samples will be drawn at baseline, after 10, 20 and 30 minutes of exercise, along with 30- and 60-minutes post-exercise via an IV catheter. Indirect calorimetry will be used to ensure that the participant is exercising at the appropriate intensity. 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. The investigators will provide them with log sheets to assist in this task. They 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, or on the back of the arm of the participant, approximately 2 days prior to the first testing session. The Dexcom G6 CGM receiver 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 return the receiver to enable the upload of their data to Dexcom Clarity by the study team.

Interviews: During the third and final testing session, study participants will be invited to answer questions about their study participation experience, exercise preferences, barriers to exercise, and other information they feel may improve their exercise experience. These interviews will be audio recorded and transcribed.

Inclusion Criteria:

• type 1 diabetes, diagnosed for at least one year
• post-menopause (at least one year since last menstrual period), or have had a hysterectomy and bilateral salpingo oophorectomy
• able to perform aerobic and resistance exercise
• able to visit the lab in Edmonton, Alberta (University of Alberta)

Exclusion Criteria:

• HbA1c > 9.9 %
• frequent and unpredictable hypoglycemia
• change in insulin management strategy within the last 2 months
• blood pressure > 140 / 95
• severe peripheral neuropathy
• history of cardiovascular disease
• musculoskeletal injuries interfering with exercise performance
• use of medications (other than insulin) that affect glucose metabolism
• BMI > 30 kg/m2
• smoking
• moderate to high alcohol intake (> 2 drinks/day)