A four-year study of elderly women has found that chronically elevated blood sugar is associated with an increased risk of developing either mild cognitive impairment (MCI) or dementia.
The study was the first to investigate the association over time between glycosylated hemoglobin a long-term measure of blood sugar and the risk of cognitive difficulties, and the first to investigate that association in people without diabetes. It appears in the Volume 10, Number 4 issue of the Journal of Nutrition, Health, and Aging.
"We already know there's a connection between diabetes and cognitive problems," says lead author Kristine Yaffe, MD, a staff physician at the San Francisco VA Medical Center and a professor of psychiatry, neurology, and epidemiology at the University of California, San Francisco. "We were interested in what this measurement would tell us about a group of women with and without diabetes who were followed for four years. Nobody has really looked at that before."
The glycosylated hemoglobin test measures the percentage of hemoglobin the oxygen-bearing protein in red blood cells that is bound to glucose. Unlike the standard diabetic blood sugar test, which measures blood sugar at the moment of testing, glycosylated hemoglobin is considered an accurate measure of blood sugar levels over the course of two to four months preceding the test. A result of seven percent or less indicates good long-term blood sugar control.
The researchers studied 1,983 post-menopausal women with a mean age of 67 years. Their baseline glycosylated hemoglobin levels were tested at the beginning of the study, and they were assessed for dementia every year for four years. At the end of the study, each one percent increase in glycosylated hemoglobin at baseline was associated with a 40 percent increased risk of developing MCI or dementia four years later.