None listed
Conditions
Brief summary
Insulin pumps are increasingly being used to deliver insulin for people with type 1 diabetes. The two main components of insulin pump delivery are firstly "bolus" insulin, used with meals or to correct high glucose levels, and secondly "basal" insulin which provides the background insulin requirements. The rate of basal insulin delivered is adjustable, and may vary according to the time of day, stress, illness or exercise. Basal insulin rate reductions are typically made by patients prior to exercise to account for changing insulin requirements that occur with physical activity. Information regarding the effects of exercise, and exercise-related changes in basal insulin rate, on insulin and glucose levels is essential to guide clinical decision-making. The purpose of this study is to investigate the impact of exercise, preceded by a major reduction in basal insulin delivery, on insulin levels and associated glucose levels.
Interventions
Two-stage randomised crossover study, with a 1-8 week interval between stages. Stage 1 (comparator): following an overnight fast and stable baseline subcutaneous insulin infusion rate for at least 6 hours, a 50% basal rate reduction will be instituted and the participant will be monitored at rest for 210 minutes. Venous samples will be collected for plasma insulin and glucose levels at 15 minute intervals from 60 minutes prior to the rate reduction until 210 minutes after. Stage 2 (intervention)
Two-stage randomised crossover study, with a 1-8 week interval between stages. Stage 1 (comparator): following an overnight fast and stable baseline subcutaneous insulin infusion rate for at least 6 hours, a 50% basal rate reduction will be instituted and the participant will be monitored at rest for 210 minutes. Venous samples will be collected for plasma insulin and glucose levels at 15 minute intervals from 60 minutes prior to the rate reduction until 210 minutes after. Stage 2 (intervention): protocol as per stage 1, with the addition of a 30 minute standardised moderate-intensity exercise protocol starting 60 minutes after the basal rate reduction. Exercise will be performed on a stationary bicycle, with target workload 65-70% age-predicted maximal heart rate. The baseline insulin infusion rate will be individualised, and equal to the usual overnight rate of each participant. The total dose of subcutaneous insulin infused during the 210 minute intervention period will be between 0.8 units and 2.5 units (depending on the insulin requirements of the individual). Standardised insulin pump, aspart insulin, pump consumables and line change protocol will be used for each study stage, and participants will resume their usual insulin and insulin pump at the conclusion of each stage.
Sponsors
St Vincent's Hospital Melbourne
Study design
Allocation
Randomised controlled trial
Intervention model
Crossover
Primary purpose
Treatment
Masking
Open (masking not used)
Eligibility
Sex/Gender
All
Age
18 Years to No maximum
Healthy volunteers
No
Inclusion criteria
Clinical diagnosis of type 1 diabetes, managed with insulin pump therapy for minimum of 3 months, established insulin:carbohydrate ratio, established insulin sensitivity factor, established basal insulin delivery profile including overnight basal rate between 0.50-1.40 units per hour (without significant overnight variation), able to tolerate moderate-intensity exercise.
Exclusion criteria
Symptoms of ischaemic heart disease or known cardiac condition precluding moderate-intensity exercise, ischaemic changes on electrocardiogram, episode of diabetic ketoacidosis or severe hypoglycaemia (requiring third party assistance) within the last month, pregnant or planned pregnancy within study period, renal impairment (estimated glomerular filtration rate <60 mL per minute), body mass index <18 or >32, adverse skin condition in the area of cannula or device placement, allergy to insulin aspart.
Outcome results
None listed