The purpose of this study is to determine the effect of a worksite-based intensive lifestyle therapy intervention (weight loss with exercise training) on blood sugar control in people with obesity and type 2 diabetics.

The purpose of this study is to conduct a randomized, controlled trial in people with obesity and type 2 diabetes to determine the therapeutic effects of intensive lifestyle therapy conducted at the worksite compared to standard care on: i) the major factors involved in the pathogenesis of type 2 diabetes (insulin sensitivity, β-cell function and the metabolic response to glucose ingestion), ii) body composition; iii) physical function (cardiorespiratory fitness and muscle strength); iv) and the potential cellular mechanisms that can affect insulin action in muscle and adipose tissue (fat).

Inclusion Criteria:

1. Age 25-68 yrs old
2. BMI 27.0-50.0 kg/m²
3. Diagnosis of type 2 diabetes based on HbA1C>6.5% or results of an oral glucose tolerance test or current use of anti-diabetic medications
4. HbA1C ≤9.5 %.
5. Work at Washington University in St. Louis, Barnes Jewish Hospital, St. Louis Children's Hospital, Shriners, St. Louis College of Pharmacy, Central Institute for the Deaf, Rehabilitation Institute of St. Louis, and/or any institutions affiliated with these.

Exclusion Criteria:

1. Any change in diabetes medication in previous 3 months
2. Treated with >0.5 units of insulin/kg body weight per day
3. Unstable weight (>2% change during the last 2 months before entering the study)
4. History or evidence of serious pulmonary or cardiovascular disease, including acute coronary syndrome, heart failure requiring medications, or New York Heart Association class III heart failure (patients with marked limitation of activity and who are comfortable only at rest) or IV heart failure (patients who should be at complete rest, confined to bed or chair and who have discomfort with any physical activity).
5. Evidence of serious cardiac abnormalities during exercise stress testing that increase cardiac risk of initiating an exercise program.
6. Creatinine >1.5 mg/dL
7. Microalbuminuria; spot urine albumin:creatinine ratio >50 (50 μg albumin/mg creatinine)
8. Coagulation disorders
9. Anemia (Hemoglobin <10.0 g/dL)
10. Liver enzymes (ALT and AST) ≥3 times the upper limit of normal
11. Uncontrolled proliferative diabetic retinopathy
12. Severe peripheral neuropathy diagnosed by monofilament testing
13. Severe organ dysfunction
14. Pregnant or breastfeeding
15. Participating in regular exercise (>1 h of structured exercise/week)
16. Joint replacement within the last year
17. Smokes tobacco
18. Severe lactose intolerance
19. Take any medication that might interfere with interpretation of the metabolic studies
20. Unable or unwilling to follow the study protocol or for any reason the research team believes the volunteer is not an appropriate candidate for this study, including non-compliance with screening appointments or previous medical visits.