Alzheimer's patients often have undiagnosed diabetes
In a nationwide study of patients with mild to moderate Alzheimer's disease, Dr. R. Scott Turner, a neurologist at Georgetown University, expected to find only a handful of participants with undiagnosed glucose intolerance because all the patients were already under the care of a physician and would have been excluded from the study if they had been diagnosed with diabetes.
According to Turner, he was therefore "shocked" when he discovered just how many study participants were found to have pre-diabetes. Such a discovery is a significant one that prompts important questions.
For Turner's study, the compound resveratrol was examined to see if it might change glucose levels in patients with mild to moderate Alzheimer's disease (AD). Resveratrol is found in red grapes and red wine, and Turner says it is thought to act on proteins in the brain in a way that mimics effects of a low-calorie diet.
"We know from animal studies that caloric restriction prevents diseases of aging such as diabetes and Alzheimer's," explains Dr. Turner, who is also a Ph.D and serves as director of the Georgetown University Medical Center's Memory Disorders Program.
"On the flip side of the coin, having diabetes increases one's risk of developing AD," he added. "So perhaps by improving glucose tolerance, we will prevent or delay both diabetes and Alzheimer's."
To participate in the resveratrol study, people were first given a fasting glucose tolerance test to obtain a baseline level before being retested two hours after eating.
Blood sugar levels increase during digestion, but the pancreas produces insulin to lower it; thus, a high sugar level after two hours indicates glucose intolerance (pre-diabetes) or diabetes if the level is very high.
"The number of people with glucose intolerance (pre-diabetes) was much higher than expected," Turner said. "I was surprised by how many people didn't know they were pre-diabetic, and these are individuals who already get the best medical care."
Five of the 128 participants had impaired fasting glucose levels, while three others had levels consistent with type 2 diabetes mellitus. Among the 125 subjects who completed the two-hour test, 38 of them demonstrated glucose intolerance while 16 of them had very high blood sugar levels consistent with diabetes. Therefore, the overall prevalence of impaired glucose tolerance or diabetes at two hours was 43 percent, which is nearly half of all the individuals who participated in the study.
"How does glucose intolerance or diabetes lead to AD? Does the inflammation associated with AD trigger glucose intolerance? Or do both events create a vicious cycle of Alzheimer's and glucose intolerance?" Turner asked.
Although Turner's study wasn't designed to answer these questions, it could provide important clues.
While a glucose tolerance test is not typically ordered by neurologists, Turner says "this result suggests that perhaps we should test all our patients with early Alzheimer's. It's a simple, inexpensive study that reveals critical health information."
Turner discussed his findings at the Alzheimer's Association International Congress in Boston on July 14.
SOURCE: Georgetown University Medical Center, "Early Alzheimer's Disease Study Uncovers High Prevalence Of Undiagnosed Pre-Diabetes" (July 16, 2013)