Background and Aims / Part 1There is growing evidence linking hyperglycemia and diabetes to cognitive decline and dementia risk. Because cognitive decline is a precursor to dementia, identifying risk factors for cognitive decline can suggest avenues for prevention and individuals to target for early intervention. Our results from the Atherosclerosis Risk in Communities (ARIC) Study suggest that prevention of diabetes and maintaining glucose control in midlife may slow or prevent late-life cognitive decline. Cognitive impairment can pose challenges for diabetes management, leading to a cycle of harm whereby diabetes contributes to cognitive dysfunction and cognitive dysfunction leads to poorly controlled diabetes. There is epidemiologic evidence that episodes of sustained hypoglycemia may also contribute to cognitive impairment and dementia, although mechanisms are uncertain. The current evidence suggests a strong link between diabetes and cognitive outcomes. In older adults with diabetes, assessment of cognitive impairment is important, especially in the setting of a history of hypoglycemia.