The investigators will use exercise training and weight loss to discover localized lipid species related to diabetes risk in people.

Inclusion Criteria:

• Obese men and women with pre-diabetes; (BMI 30-40 kg/m2)

• Ages ranging from 30-60 years old;

• Individuals with:

  • impaired fasting glucose (IFG), (between 100-125mg/dl, with post-prandial glucose (<140 mg/dl 2 hrs after 75g OGTT)
  • impaired glucose tolerance (IGT), (normal fasting glucose <100mg/dl, with post-prandial glucose (>140 mg/dl 2 hrs after 75g OGTT)
  • a combination of the two (IFG/IGT) (both impaired fasting glucose (100-125mg/dl), and impaired glucose tolerance (>140 mg/dl 2 hrs after 75g OGTT), will be verified using oral glucose tolerance testing at initial screening, and

• Sedentary (<2 hours/week of planned physical activity).

To increase generalizability, and because each subject serves as their own control, women will be enrolled regardless of menopausal status, use of hormone replacement therapy and oral contraceptives.

Exclusion Criteria:

• Regular exercise more than 2 hours/week,
• medications that could affect glucose,
• lipid metabolism,
• thyroid disease,
• history of lung disease,
• pregnancy,
• active cigarette smoking or exposure to second hand smoke, and
• Severe plasma lipid disorders.