Home-Based Walking Study in Older Adults With Type 2 Diabetes

Not Applicable

Completed

Brief Summary: Older persons with diabetes have a harder time maintaining blood pressure when standing up. When blood pressure drops when standing up, fainting may occur. This study will see how regular exercise can improve the ability of the body to keep blood pressure up when standing. We want to see how this improvement varies with a home-based walking program.

Detailed Description: Detailed Summary

1. PURPOSE: Older adults with diabetes faint frequently, due to an impairment in the cardiovascular control mechanisms (arterial baroreceptor function, autonomic nervous system function and cerebral autoregulation) that prevent syncope. The purpose of this study is to examine the ability of a home based walking program to reverse these impairments.

2. HYPOTHESES: a) A home-based walking program will improve the compensatory cardiovascular responses that prevent syncope in older adults with Type 2 diabetes. A moderate, regular exercise program will:

* increase arterial baroreflex sensitivity

* increase heart rate variability (marker of autonomic nervous system function)

* decrease cerebrovascular resistance

* improve cerebral autoregulation during upright tilt. b) There will be relationship between the improvement in compensatory cardiovascular responses and regular exercise.

c) Design of more practicable training prescriptions than that used in a research setting.

Recruitment & Eligibility

Inclusion Criteria

Type 2 diabetes for at least 5 years treated with diet alone or oral agents
Nonsmoker for at least 5 years
Subjects must be sedentary (as defined by no strength training and less than 30 minutes brisk walking/moderate exercise per week and no vigorous exercise in the preceding 6 months)
All subjects will have a fasting glucose of <12 mM and a hemoglobin A1c < 8.5%
Orthostatic hypotension defined as a decrease in systolic blood pressure of at least 20 mm Hg or diastolic blood pressure of at least 10 mm Hg within 3 minutes of assuming an upright posture on the initial screening visit as per current American Academy of Neurology guidelines.

Exclusion Criteria

Abnormalities on complete blood count, electrolytes or creatinine, on resting ECG, treadmill exercise stress test
Significant pulmonary, exercise-limiting orthopedic or neurological impairment
Evidence of valvular disease, exercise-induced syncope, angina, arrhythmias or peripheral vascular disease
Poor blood pressure control as defined as systolic blood pressure greater than or equal to 160 mm Hg or diastolic blood pressure greater than or equal to 90 mm Hg
Total cholesterol/HDL cholesterol greater than or equal to 5.0 or LDL cholesterol greater than or equal to 4.21 mmol/L
Peripheral neuropathy severe enough to cause discomfort (for safety reasons)
Overt diabetic nephropathy excluding subjects with a urine albumin to creatinine ratio of greater than 2.0 in men or 2.8 in women
Diabetic retinopathy

Arm && Interventions

Group	Intervention	Description
Control Phase; Exercise Phase	Control Phase; Exercise Phase	Participants act as their own control. Control Phase: Participants will not change their activity during the 3 month control phase (defined as no strength training and less than 30 minutes brisk walking/moderate exercise per week, no vigorous exercise) Baseline measures will be obtained. Exercise Phase: This phase will consist of a Titration phase followed by an Intervention Phase. During the Titration phase, under the guidance of a trainer, subjects will increase their number of steps by 20% per week until they have reached 10,000 steps or 3 months have passed. During the Intervention Phase subjects will continue to walk 10,000 steps (or the number of steps they reached in the Titration phase).

Primary Outcome Measures

Name	Time	Method
Pulse wave velocity (central and peripheral)	Measured at Baseline, 3 months after control phase and after 3 months of Intervention phase
Drop in middle cerebral artery velocity with upright tilting	Measured at Baseline, 3 months after control phase and after 3 months of Intervention phase
Drop in blood pressure with upright tilt	Measured at Baseline, 3 months after control phase and after 3 months of Intervention phase
Arterial baroreflex sensitivity	Measured at Baseline, 3 months after control phase and after 3 months of Intervention phase

Secondary Outcome Measures

Name	Time	Method
VO2max	Measured at Baseline, 3 month after control phase and after 3 months of Intervention phase.
Fasting blood glucose, HgbA1C	Measured at Baseline, 3 month after control phase and after 3 months of Intervention phase.
Dynamometry measures of muscle strength	Measured at Baseline, 3 month after control phase and after 3 months of Intervention phase.
Resting and maximal heart rate	Measured at Baseline, 3 month after control phase and after 3 months of Intervention phase.
Waist to hip ratio, BMI	Measured at Baseline, 3 month after control phase and after 3 months of Intervention phase.
Lean body mass/% fat	Measured at Baseline, 3 month after control phase and after 3 months of Intervention phase.
Catecholamines	Measured at Baseline, 3 month after control phase and after 3 months of Intervention phase.
Increase in Gosling's pulsatility index	Measured at Baseline, 3 month after control phase and after 3 months of Intervention phase.

Locations (2): Dr. Scott Lear's Lab, Simon Fraser University, Harbour
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Vancouver, British Columbia, Canada
VITALiTY Research Centre - VGH Research Pavilion
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Vancouver, British Columbia, Canada