Female participants with type 1 diabetes using oral contraceptives will be asked to wear a continuous glucose monitor for at least three days on two separate occasions (once during the last week of active pills and once during the no pill/placebo pill phase of the menstrual cycle). An exercise session (45 minutes of aerobic exercise at 60% VO2peak on a cycle ergometer) will take place at 5 pm on the second day of glucose monitoring.
Pre-test measures: Interested participants will be invited to the Physical Activity and Diabetes Laboratory on the main campus of the University of Alberta. They will be asked questions related to their menstrual cycle, physical activity levels and medication. Blood pressure will also be measured to assess their eligibility. Where participants are eligible, anthropometric characteristics will be measured using standard protocols. A blood sample will be drawn for assessment of HbA1c. Participants will perform an incremental treadmill test to volitional exhaustion. Indirect calorimetry will be used to assess oxygen consumption and carbon dioxide production to determine the participant's aerobic capacity. Testing sessions: Participants will perform two testing sessions separated by at least 5 days. One session will take place during the last week of active pill consumption of monophasic hormonal contraceptives. The second session will take place during the placebo pill consumption phase (i.e. menses). Participants will be asked to arrive at the lab at around 4:00 pm for both sessions, which will be randomly assigned. During the sessions, participants will be asked to perform 45 minutes of aerobic exercise on an ergonomic cycle ergometer at 60% of the participant's pre-determined aerobic capacity. Blood samples will be drawn at baseline, at the end of exercise, and an hour post-exercise via an IV catheter. 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. They will also be asked to avoid strenuous exercise and alcohol intake. A continuous glucose monitor (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 in the morning of the day prior to each testing session. The participant will wear the CGM for at least 24 hours before the exercise session, and at least 24 hours after the exercise session.
Study Type
INTERVENTIONAL
Allocation
NA
Purpose
OTHER
Masking
NONE
Enrollment
15
Participants will perform 45 minutes of moderate (60% VO2peak) aerobic exercise on a cycle ergometer during the last week of active pill consumption.
Participants will perform 45 minutes of moderate (60% VO2peak) aerobic exercise on a cycle ergometer within 5 days of starting their menses.
Alberta Diabetes Institute
Edmonton, Alberta, Canada
RECRUITINGBlood glucose
Change in blood glucose, with samples drawn via IV catheter
Time frame: Pre-exercise (0 minutes), post-exercise (45 minutes) and 1 hour post-exercise
Interstitial glucose (continuous glucose monitoring)
Mean CGM glucose
Time frame: 6 hours, 12 hours, overnight (midnight to 6 am) and 24 hours post-exercise
coefficient of variation (CV)
measure of variability for continuous glucose monitoring data
Time frame: 6 hours, 12 hours, overnight (midnight to 6 am) and 24 hours post-exercise
standard deviation (SD)
measure of variability for continuous glucose monitoring data
Time frame: 6 hours, 12 hours, overnight (midnight to 6 am) and 24 hours post-exercise
frequency of hypoglycemia
number of times that CGM glucose is equal to or lower than 3.9 mmol/L
Time frame: 6 hours, 12 hours, overnight (midnight to 6 am) and 24 hours post-exercise
frequency of hyperglycemia
number of times that CMG glucose is equal to or greater than 10.0 mmol/L
Time frame: 6 hours, 12 hours, overnight (midnight to 6 am) and 24 hours post-exercise
percent of time in range
percent of time with CGM glucose between 4.0 and 9.9 mmol/L
Time frame: 6 hours, 12 hours, overnight (midnight to 6 am) and 24 hours post-exercise
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percent of time in hypoglycemia
amount of time spent with CGM glucose equal to or less than 3.9 mmol/L
Time frame: 6 hours, 12 hours, overnight (midnight to 6 am) and 24 hours post-exercise
percent of time in hyperglycemia
amount of time spent with CGM glucose equal to or greater than 10.0 mmol/L
Time frame: 6 hours, 12 hours, overnight (midnight to 6 am) and 24 hours post-exercise