None listed
Conditions
Brief summary
Background Blood glucose control is fundamental to the management of type 1 diabetes (T1D) to reduce rates of diabetes complications. Exercise studies have not been able to show a consistent benefit on blood glucose control in people with T1D. High-intensity interval training has been found to improve long term blood glucose control (HbA1c level) in people with type 2 diabetes. To our knowledge, there are no adequately-powered studies looking at the effect of HIIT exercise on HbA1c in people with T1D. Research Question In adults with type 1 diabetes who are overweight or obese, will 12-weeks of high-intensity interval training improve blood glucose control (HbA1c), cardiovascular risk factors and diabetes complications? Study aim This study will potentially show the first evidence that HIIT exercise can improve HbA1c without excess risk of hypoglycaemia (low glucose) in adults with T1D. Also, such exercise intervention may improve cardiovascular risk factors, and some aspects of traditional and novel diabetes complications including measures of non-alcoholic fatty liver disease, diabetic cardiomyopathy and cardiac autonomic neuropathy. Research design and methods In a randomised controlled trial (study period 1; 12 weeks) with subsequent partial cross-over (study period 2; 12 weeks), 30 sedentary adults with T1D who are overweight or obese will be randomised to the intervention group (12 weeks of supervised high-intensity interval training (HIIT) exercise, and then 12 weeks of unsupervised exercise) or the control group (12 weeks of usual care, and then 12 weeks of supervised HIIT exercise). The primary outcome will be HbA1c blood test at the end of the randomised controlled trial period (12 weeks exercise vs usual care), with a secondary outcome being to compare HbA1c with all 30 participants’ own baseline. The partial cross-over design allows all participants to benefit from undertaking the supervised HIIT, and has the advantage of increasing statistical power to secondary outcome measures. Further secondary outcomes include measurement of hypoglycaemia, hyperglycaemia and glucose variability using a glucose sensor, cardiorespiratory fitness using a treadmill fitness test, and cardiovascular risk factors such as blood pressure, cholesterol levels, weight, and body composition with a DEXA scan. Several diabetic complications will be examined for improvements after exercise, including diabetic cardiomyopathy and non-alcoholic fatty liver disease with cardiac and liver MRI, and cardiac autonomic neuropathy with bedside electrocardiography (ECG) testing. Importantly, changes in quality of life and fear of hypoglycaemia will be measured with validated diabetes-specific questionnaires.
Interventions
Randomised controlled trial (12 weeks) with subsequent partial cross-over (12 weeks)
Baseline study period and randomisation (Weeks 1-2):
Study participants will have initial baseline cardiorespiratory fitness assessment in a graded exercise test on treadmill with breath-by-breath gas analysis to determine individual peak heart rate and VO2peak in the Royal Prince Alfred Charles Perkins Centre clinic and gym. Participants will have a baseline HbA1c and a 2-week continuous glucose recording wi
Randomised controlled trial (12 weeks) with subsequent partial cross-over (12 weeks) Baseline study period and randomisation (Weeks 1-2): Study participants will have initial baseline cardiorespiratory fitness assessment in a graded exercise test on treadmill with breath-by-breath gas analysis to determine individual peak heart rate and VO2peak in the Royal Prince Alfred Charles Perkins Centre clinic and gym. Participants will have a baseline HbA1c and a 2-week continuous glucose recording with FreeStyle Libre Pro flash glucose monitor. Participants will then be randomised to either intervention or control groups. Study Period 1: “Randomised controlled trial” (Weeks 3-14): Intervention group: High-intensity interval training Participants will undertake 3 sessions/week of high-intensity interval training (HIIT) exercise for 12 weeks: consisting of 2 sessions/week on a cycle ergometer or treadmill in the Royal Prince Alfred Charles Perkins Centre gym supervised by a study investigator (Endocrinologist and/or Accredited Exercise Physiologist), and 1 session/week unsupervised walking/jogging at home. The HIIT exercise session will last 33 minutes consisting of: 5 minutes of warm-up at approximately 60% peak heart rate, then 4 bouts of 4-minute high-intensity intervals at 85-95% peak heart rate interspersed with 3 bouts of 3-minute recovery intervals at 50-70% peak heart rate, and concluding with 3 minutes of cool-down at approximately 50% peak heart rate. Participants will have their exercise individually progressed over the initial 2 weeks (by the supervising Endocrinologist/Exercise Physiologist) so that they are able to complete the full HIIT exercise session by week 3. Measurement of exercise intensity: A polar heart rate monitor (heart rate sensor soft chest strap + watch) will be used for all exercise sessions to achieve the required target exercise intensity. Control group: Participants will continue their usual daily activities and diet. Study Period 2: “Partial Cross Over” (Weeks 15-26): Intervention group: Participants will continue 3 sessions/week of HIIT exercise (33minutes/session) unsupervised at home for 12 weeks. Control group: Participants will undertake 3 sessions/week of high-intensity interval training (HIIT) exercise for 12 weeks: consisting of 2 sessions/week on a cycle ergometer or treadmill in the Royal Prince Alfred Charles Perkins Centre gym supervised by a study investigator (Endocrinologist and/or Accredited Exercise Physiologist), and 1 session/week unsupervised walking/jogging at home, as described for the week 1-12 exercise program in the original intervention group. Insulin dose adjustment: All participants in the intervention and control groups will have once-weekly review of their home blood glucose monitoring results by the study Endocrinologist (in person, on phone, or via email as per participant preference) for advice on individualised insulin dose adjustment during Study Period 1 and Study Period 2. Adherence: For the participants participating in the HIIT exercise intervention, attendance will be recorded in an attendance record logbook at the gym, and reported as a percentage of total gym exercise sessions performed. At the weekly review, participants will be asked about their performance of home HIIT exercise, and this will be reported as a percentage of home exercise sessions performed.
Sponsors
Sydney Local Health District
Study design
Allocation
Randomised controlled trial
Intervention model
Other
Primary purpose
Treatment
Masking
Open (masking not used)
Eligibility
Sex/Gender
All
Age
18 Years to 70 Years
Healthy volunteers
No
Inclusion criteria
Inclusion criteria: a. Age 18-70 years, b. Type 1 diabetes greater than or equal to 1 year duration, c. HbA1c 7.5-10.5%, d. BMI greater than or equal to 25 kg/m^2, e. Self-manage diabetes with multiple-daily insulin injections or subcutaneous insulin pump, with flexible dosing according to carbohydrate counting and self-monitored blood glucose testing, f. Exercising less than 150minutes/week moderate-intensity exercise for the past 6 months.
Exclusion criteria
Exclusion criteria: a. Conditions which prevent exercise participation (such as arthritis, unstable cardiac condition, active foot ulcer, untreated severe retinopathy), b. Unable to have an MRI scan due to immovable implanted metal in the body (eg. Cardiac pacemaker/defibrillator, eye or ear implants, shrapnel), or severe claustrophobia. c. Pregnancy or breastfeeding.
Outcome results
None listed