Effects of Walking and Heating on Vascular Function in Diabetic Patients

The purpose of the present study is to determine the effects of increased walking and lower body heating on leg vascular function in patients with type 2 diabetes (T2D).

The notion that habitual aerobic exercise increases insulin-induced vasodilation is largely founded on rodent studies, hence the urgent need for human studies, especially in patients with type 2 diabetes (T2D). For example, it remains unknown if increased walking, the most common form of physical activity, enhances skeletal muscle vasodilator actions of insulin in T2D. In addition, the molecular mechanisms by which exercise improves vasoreactivity to insulin have not been examined in humans. The investigators propose that in T2D patients who are sedentary (i.e., the vast majority), increased leg blood flow with walking or local heating signifies a vital strategy to correct vascular insulin resistance. This study will establish whether increased physical activity and associated hemodynamic forces (e.g., shear stress) are a direct form of vascular medicine in humans.

The walking program will consist of 45 minutes of walking (at a moderate pace) 5 days per week for 8 weeks.

This intervention consists of 60 minutes of lower body heating (40-42 degree C) 7 days per week for 7 days.

The walking program will consist of 45 minutes of walking (at a moderate pace) 5 days per week for 8 weeks.

This intervention consists of 60 minutes of lower body heating (40-42 degree C) 7 days per week for 7 days.

Change from baseline flow-mediated dilation at 7 days (heating intervention) or 8 weeks (exercise intervention)

Change from baseline insulin-stimulated leg blood flow at 7 days (heating intervention) or 8 weeks (exercise intervention)

Change from baseline blood glucose at 7 days (heating intervention) or 8 weeks (exercise intervention)

Change from baseline plasma insulin at 7 days (heating intervention) or 8 weeks (exercise intervention)

Inclusion Criteria: Patients with type 2 diabetes who are overweight and obese (BMI 25-50 kg/m2), 35 to 65 years of age, and sedentary (<60 minutes structured exercise/week). Healthy volunteers without type 2 diabetes: 35 to 65 years of age. Exclusion Criteria: Cardiovascular disease including myocardial infraction, heart failure, coronary artery disease, stroke; renal or hepatic diseases; active cancer; autoimmune diseases; immunosuppressant therapy; excessive alcohol consumption (>14 drinks/week for men; >7 drinks/week for women); current tobacco use; pregnancy; mobility limitations; foot ulcers; diabetic neuropathy uncontrolled hypertension (>=180 systolic / 100 diastolic mmHg)