Diabetes Aerobic and Resistance Exercise (DARE) Study
Condition: Diabetes Mellitus, Type 2; Diabetes Mellitus
MeSH terms: Diabetes Mellitus; Diabetes Mellitus, Type 2
Study type: Interventional

Summary: 
      The main purpose of this study is to assess the impact of exercise training (aerobic
      exercise, resistance exercise, combined aerobic and resistance exercise) versus a sedentary
      waiting list control on glycemic control (as reflected in reduced hemoglobin A1c [HbA1c]),
      body composition (weight, body mass index [BMI], waist circumference, total body fat,
      visceral and subcutaneous abdominal fat, mid-thigh muscle cross-sectional area), lipids
      (Apo-B, Apo-A1, Apo-B/A1 ratio, low density lipoprotein (LDL) particle diameter,
      high-sensitivity C-reactive protein) and quality of life.
    

Detailed description: 
      Background. The incidence of type 2 diabetes mellitus in the Western world is rising rapidly
      due to increases in obesity and sedentary behaviour, and diabetes is among the most potent
      common risk factors for premature disability and mortality. Landmark clinical trials such as
      the UK Prospective Diabetes Study proved that these excess risks in type 2 diabetes can be
      reduced through relatively modest improvements in glycemic control (HbA1c difference of 0.9%
      over time). The excess morbidity and mortality in diabetes is attributable both to
      hyperglycemia and to a cluster of other metabolic disturbances associated with insulin
      resistance, and exercise can have beneficial effects on all of these abnormalities. The
      standard recommendation to people with diabetes has been to perform aerobic exercise such as
      brisk walking, swimming, or jogging. There is very little research on resistance exercise
      (such as weight lifting or exercise with weight machines) in type 2 diabetes. Resistance
      exercise in non-diabetic subjects increases lean body mass, resulting in increased metabolic
      rate, decreased insulin resistance and increased glucose disposal. Furthermore, in a recent
      randomized trial the addition of resistance exercise to a cardiac rehabilitation program
      resulted in marked improvements in quality of life, to a far greater extent than seen with
      aerobic exercise alone. For these reasons, we feel that resistance exercise in type 2
      diabetes is a modality worthy of further research. A pilot study of our present proposal,
      funded by the Canadian Diabetes Association (CDA) is in progress; compliance has been
      excellent with >90% attendance.

      Primary research question: In patients with type 2 diabetes, does a 6-month resistance or
      aerobic training program result in improved glycemic control as reflected in reduced
      hemoglobin A1c (HbA1c)? Is the effect of one type of exercise additive to that of the other?

      Secondary research questions: In patients with type 2 diabetes, what are the effects of each
      exercise modality on:

        1. Body composition (assessed using gold-standard methods including CT scan and deuterium
           oxide), resting energy expenditure (using indirect calorimetry) and insulin resistance?
           To what extent do changes in these parameters mediate changes in HbA1c?

        2. Important nontraditional metabolic CHD risk factors (LDL particle diameter, plasma
           insulin, apoprotein B, c-reactive protein, free fatty acids) and traditional metabolic
           CHD risk factors (HDL-C, LDL-C, triglycerides, total/HDL cholesterol ratio, BP)?

        3. Health-related quality of life (QOL) as measured by the Well-Being questionnaire or the
           SF-36? Does modality of exercise or change in quality of life from baseline to 6 months
           predict frequency of exercise during the 6 months following the intervention?

      Study design: Randomized controlled trial. After a 4-week supervised low-intensity exercise
      run-in period to test compliance, previously inactive Type 2 diabetic subjects not currently
      engaging in regular exercise are randomized to 4 arms: aerobic exercise 3X per week,
      resistance exercise 3X per week, both combined or waiting-list control. The exercise
      intervention takes place at YMCA branches in metropolitan Ottawa. Exercise is closely
      supervised and progressive in intensity and duration. Compliance is verified through direct
      supervision, completion of detailed exercise logs, and central automated electronic tracking
      of YMCA attendance through scanning of membership cards. Primary outcomes are measured at 6
      months. At the end of 6 months subjects are given a maintenance program and reexamined 6
      months later to assess the durability of any benefits from the exercise program. During the 6
      month intervention period diet is standardized using repeated sessions with a dietitian, and
      doses of medications altering glucose, lipids and BP are held constant unless change is
      medically urgent.

      Significance: The global burden of type 2 diabetes is increasing, and complications of the
      illness occur primarily in those whose glycemic control is fair or poor. If appropriately
      selected exercise training improves glycemic control and is adopted by more patients, it is
      likely that the morbidity associated with type 2 diabetes will be decreased. This is
      particularly true if such training also improves quality of life, and more people are thus
      inclined to continue exercising in the long term.
    

Intervention name(s): Aerobic and Resistance Exercise
Intervention type(s): Behavioral
Intervention description(s): Aerobic activities are performed on a cycle ergometer or treadmill. Exercise intensity is standardized using Polar Heart rate monitors that display the subject's heart rate.
Resistance training:Exercises are performed at weight machines arranged in a circuit. Throughout the resistance training program, subjects will alternate between the exercises of group A and group B below.
Group A: abdominal crunches, seated row, seated biceps curls, supine bench press, leg press, shoulder press; leg extension Group B: abdominal crunches, lat pulldown, sitting chest press, leg press, upright row, triceps pushdown, leg curls.
Combined aerobic and resistance training group will perform both aerobic and resistance training programs, as described above.
Control: members of this group are asked to revert to their pre-study activity levels for 5 months, at which point they begin the combined aerobic and resistance exercise program.
Other intervention name(s): non applicable
Allocation: Randomized
Intervention model: Factorial Assignment
Masking: Single (Outcomes Assessor)
Primary purpose: Treatment
Keywords: Diabetes Mellitus; Type 2 Diabetes; Aerobic; Resistance; weight training; Exercise