Study Overview The primary aim of this study is to test whether the rate of cognitive decline and structural brain change in people with diabetes treated with standard care guidelines is different than in people with diabetes treated with intensive care guidelines. This comparison will be made in a sub-sample of 2800 people with diabetes participating in the already funded National Heart Lung and Blood Institute (NHLBI) randomized factorial clinical trial Action to Control Cardiovascular Risk in Diabetes (ACCORD). Background Type 2 diabetes and cognitive impairment are two of the most common chronic conditions found in persons 60 years and older. Approximately 18%-20% of older persons suffer from diabetes. And, in the general population, the prevalence of cognitive impairment, measured with the simple Mini-Mental State Exam, increases steadily from 5% at 65 years to 15% percent at 80 years of age. Many persons with cognitive impairment go on to develop dementia, which doubles in incidence and prevalence every additional 5 years of age. Studies suggest diabetes is one risk factor for cognitive impairment and dementia. Further, the brains of people with diabetes are at risk for adverse sequelae following repeated hypoglycemic events. Magnetic Resonance Imaging (MRI) provides a measure of the structural changes in the brain that form the anatomical substrate for cognitive decline and dementia. At present there are a few MRI studies showing people with diabetes have increased risk for brain atrophy and (mainly silent) lacunae. 25 year old brain 72 year old brain The images show resting blood flow to the brain in young and older adults and demonstrate a reduction in blood flow in the brains of older adults throughout most of the cerebral cortex.