[Diabetes mellitus and dementia]

Diabetes mellitus, particularly type 2 diabetes, is a risk factor for dementia and this holds true for incident vascular dementia and Alzheimer's disease. Cerebrovascular complications of diabetes and chronic mild inflammation in insulin resistant states partly account for this increased risk. In addition, cellular resistance to the trophic effects of insulin on neurons and glial cells favor the accumulation of toxic metabolic products, such as amyloid and hyperphosphorylated tau protein (pTau). Weight loss frequently precedes overt cognitive symptoms of Alzheimer's disease. This results in an increased risk of hypoglycemic episodes in stable diabetic patients who are on suitably adjusted doses of oral insulin or insulinotropic antidiabetic drugs. In turn, hypoglycemic episodes may induce further damage in the vulnerable brains of type 2 diabetes patients. Patients with unexplained weight loss, hypoglycemic episodes and subjective memory complaints must be screened for dementia. Once dementia has been diagnosed the goals of diabetes management must be reevaluated as prevention of hypoglycemia becomes more important than tight metabolic control. As weight loss accelerates the rate of cognitive decline, nutritional goals must aim at stabilizing body weight. There is no available evidence on whether drug treatment of diabetes in middle-aged persons can help to prevent dementia; however, physical exercise, mental activity and higher education have preventive effects on the risk of dementia in later life. In addition, nutritional recommendations that are effective in preventing cardiovascular events have also been shown to reduce the risk of dementia.