High-Intensity Exercise and Endothelial Function in Type 1 Diabetes(HIIT-T1D)

Effect of High-Intensity Interval Exercise Training Compared With Moderate-intensity Continuous Training on Endothelial Function and Cardiorespiratory Fitness of Type 1 Diabetes Patients

To study the effect of 8 week high-intensity interval training (HIIT) compared with moderate intensity (MCT) interval training and sedentary patients(CON) with type 1 diabetes. Adult T1DM patients without known complications are randomised in blocks into these 3 groups according to their baseline flow mediated dilation (FMD). After 8 week exercise training, the main outcome, FMD, is re-evaluated. Additional variables such as VO2 peak for cardiovascular fitness, oxidative stress and endothelial independent vasodilation to study vascular rigidity are also evaluated.

In a randomized controlled open trial, 36 adult type 1 diabetes mellitus (T1DM) patients without known complications were randomized into 3 groups: HIIT n=12; MCT n=12 and a sedentary control group (CON) n=12. Total sample size was calculated to a power of 80% alha 0.05 and a difference in mean FMD of 2%. Before randomisation, flow mediated dilation (FMD) and maximal exercise capacity (VO2 peak)is determined. Block Randomisation based on FMD rank values are done to equalize baseline FMD. Exercise sessions are performed in cycle ergometers during 40 minutes, 3 times a week, along 8 weeks. HIIT protocol, intensity vary from 50 to 85% of the maximum heart rate (HRmax), while in MCT, HR remained stable at 50% HRmax. Endothelial function was measured by flow mediated dilation (FMD) for endothelium-dependent vasodilation (EDVD) and smooth-muscle function was measured by nitroglycerine mediated dilation (endothelium independent vascular dilation) - (EIVD). Peak oxygen consumption (VO2peak) and oxidative stress markers were determined before and after the training period. ED was defined as an increase of less than 8% in vascular diameter after cuff release.

Inclusion Criteria:

T1DM

• Physically inactive or not involved in exercise training programs in the previous 6 months
• Interested in starting an exercise training program.

Exclusion Criteria:

• Smokers,
• Pregnancy
• Co-morbidities not related to diabetes
• Drugs other than insulin
• Loss of renal function (serum creatinine above 1.5 mg/dl),
• Moderate to severe retinopathy or blindness,
• Suspected or confirmed coronary artery disease,
• Severe peripheral neuropathy
• Foot ulcers or history of previous foot ulcer
• Suspected or confirmed clinical autonomic neuropathy.