Insulin Resistance and Mild Cognitive Impairment (IRMCI) Study

Dementia (Alzheimer's Disease) is sometimes called "Type 3 Diabetes" because of the strong connection between Type 2 diabetes (a function of insulin resistance) with Dementia. The investigators therefore hypothesize that Reducing Insulin Resistance using Intensive Lifestyle Intervention (Exercise and Weight loss) + Metformin Treatment in Prediabetic \& diet-control-only Diabetic overweight and mildly cognitively impaired individuals 55 years or older would lead to better Cognitive Function (compared to standard care) after 2 years. Subjects will be monitored and assessed using a battery of Cognitive and psychological tests and PET scans to demonstrate glucose utilization in the relevant areas of the brain. This 3-year open-label study aims to recruit 360 subjects with 50% (180 subjects) randomized to receiving Intensive lifestyle intervention with Metformin (if diabetic) vs the other 50% who would receive only the usual standard level of care in the primary care setting.