Diabetes and pre-diabetes are associated with a seventy-five percent increased risk of Alzheimer's disease. Research has already shown that insulin resistance, with its accompanying high levels of circulating insulin, increases brain and spinal cord inflammation markers and neurotoxic peptides (molecules that cause brain and nervous system damage), just like early Alzheimer's.

Now there's more evidence linking insulin resistance to Alzheimer's. According to research by Dr. Suzanne Craft of the University of Washington School of Medicine, brain scans of insulin-resistant adults reveal reduced glucose metabolism in certain brain regions; the pattern is identical to that seen in people who get Alzheimer's years down the road.

The findings imply that reducing insulin resistance should improve memory and reduce the risk of future Alzheimer's. In a study to test that theory, Dr. Craft gave 24 insulin-resistant subjects an insulin sensitizer (which lowers insulin resistance); she gave 23 an insulin secretagogue (which causes more insulin to be secreted by the beta cells), and 24 more a placebo.

Four months later, the subjects who showed improvements in insulin sensitivity also experienced improved memory; if insulin resistance did not improve, then neither did memory.

Source: 67th Scientific Sessions of the ADA