PROTOCOL. 1) The first visit at entry (visit 1) for both intervention and control groups: an interview about physical activity at work and leisure time, smoking, alcohol use, education, occupation, diet, history of medication; clinical measurements: blood pressure, body weight, height, bioimpedance; laboratory measurements including an oral glucose tolerance test, fasting measurements (HbA1c, total cholesterol, HDL cholesterol, total triglycerides, ALT, GAD antibodies); 2) Group sessions (about 15 participants in each) 1-7 described below for the intervention group but not for the control group, 3) A 6 month and 24 month visits (identical to visit 1) for the intervention group but not for the control group; 4) A 3-year visit for both intervention and control groups (identical to visit 1).