Low Calorie Diet and Diabetes

This is a prospective study on the impact of low calorie diet followed by a weight maintenance program on 12 and 24 month glucose control in a cohort of patients with obesity and diabetes mellitus. The study will consist of 3 phases: 1. Screening period (up to 12 weeks). 2. Low calorie diet weeks 1-9. Seven weeks of low-calorie diet including 800 kcal/day followed by 2 weeks of gradual introduction of normal diet of eventually 1500-2000 kcal/day, i.e. 600 kcal/day deficit, based on present body weight and sex. At entry of the LCD-period, all medication for diabetes mellitus, with the exception of metformin and insulin, will be removed. During the LCD-period, insulin treatment will gradually be reduced and, if possible, withdrawn. Patients will perform daily self-monitoring of fasting and post-prandial plasma glucose. At each visit, which will take place once a week, the patients will see a physician, a nurse and a dietician. The patients will be given specific advice to increase their physical activity. Patients will remain on medication for dyslipidemia. Blood pressure will be measured at each visit and in case of blood pressure \< 110/70 mmHg and/or in case of symptoms associated with hypotension including dizziness, medication for hypertension will be reduced or removed. 3. Weight-maintenance program weeks 10-52. 4. Follow up visits at months 15, 18, 21 and 24.