Insulin is a hormone in blood that helps glucose (sugar) to enter cells and be used for energy-also known as glucose uptake. Insulin resistance, a condition in which the body has reduced glucose uptake, may lead to diabetes. It may also increase risk of Alzheimer's disease, according to a University of Washington, Seattle, study (Baker et al., 2011).
The researchers used FDG-PET scanning to measure glucose uptake in the brains of 2- cognitively normal older adults (average age, 74) with prediabetes or early diabetes. They found that greater insulin resistance was associated with an Alzheimer's-like pattern of reduced glucose uptake in brain regions important for learning and memory. Compared to healthy individuals, those with prediabetes and early diabetes showed smaller increases in brain glucose uptake during a memory task and also performed more poorly on the task. This study suggests that insulin resistance is a marker of Alzheimer's risk in cognitively normal individuals and is associated with subtle cognitive impairments at the earliest stages of the disorder, even before the onset of MCI.