Exercise Dose-Response Effects in Prediabetes

Exercise Dose-Response Effects in Prediabetes: Responses and Mechanisms

The purpose of the study is to evaluate the effects of different amounts and intensities of aerobic exercise training programs, with and without weight loss, in people who are at risk for diabetes. An additional purpose of the study is to evaluate the factors in the blood and in exercising muscles that contribute to the improvement in those risk factors. This information will be used to improve exercise training guidelines for improving cardiovascular and metabolic health in people with abnormal fasting glucose, also known as prediabetes.

729 subjects were consented, 288 participants were randomized.

Inclusion Criteria:

• Age: 45-75 years

• Moderately Overweight determined by Body Mass Index: 25.0 - 35.4

• Fasting plasma glucose: > 95 - < 126 mg/dL until 2/15/2012 when lower limit was adjusted to > 100 mg/dL

  o Readings from two separate days, both being > 95 (> 100 after 2/15/2012)and one of the two being < 126

• Low density (LDL) cholesterol: < 190 mg/dL

• Triglycerides: < 600 mg/dL

• Resting blood pressure: < 160/90 mmHg

• Inactive: Exercise < one day/week; Peak oxygen consumption: > 18.0 - < 40.0 ml/kg/min until 2/15/2012 when lower limit was adjusted to 12.0 ml/kg/min

• Medications: Stable use of all medications for > three months

Exclusion Criteria:

• Smoker: Tobacco use within the last 12 months
• Dieting or intending to diet
• Use of potential confounding medications, e.g. Niacin containing drugs
• History of diabetes, heart disease or taking medication for those conditions
• History of hypertension (high blood pressure) not controlled with medication
• Pregnant or intending to become pregnant
• Unwillingness to undergo a three month control/run-in period, be randomized to any one of four intervention groups, submit to thigh muscle biopsies and all other study testing or continuously participate in a randomly assigned exercise training or lifestyle intervention program for six months
• Orthopedic limitations, musculoskeletal disease and/or injury
• Allergic to xylocaine (anesthetic or numbing medicine)
• Inability to give blood continuously through a catheter (please notify the study nurse of any difficulty you have experienced in the past when having your blood drawn; the study nurse will determine whether you are excluded for this reason)
• Unwillingness to exercise at least twice per week at the Duke Center for Living Health and Fitness Center during research study staff supervised times