Diabetes affects multiple organ systems and has the potential to contribute significantly to the development of a number of issues that we associate with aging. A new study has found that adults between 51 and 70 with diabetes develop age-related ailments like cognitive impairment, incontinence, falls, dizziness, vision impairment and pain at a faster rate than those without diabetes.
For adults aged 51-60 with diabetes, the odds of developing new geriatric conditions were nearly double those of their counterparts who didn’t have diabetes. By the time people with and without diabetes reach 80, the overall effects of aging and impact of other diseases start to reduce the disparities between the two groups, the researchers found.
The research was based on nationally representative data from the University of Michigan Health and Retirement Study and the results published in the March issue of the Journal of General Internal Medicine.
“The findings suggest that adults with diabetes should be monitored for the development of these conditions beginning at a younger age than we previously thought… “If we know to start looking for these conditions earlier, we can manage and treat them more effectively,” said lead author Christine Cigolle, M.D., M.P.H., an assistant professor of family medicine and internal medicine at the University of Michigan Medical System and research scientist at the VA Ann Arbor Healthcare System
These findings echo the findings of another study published in the journal Diabetes last year. Margaret Gatz and researchers from Sweden showed that getting diabetes before the age of 65 corresponds to a 125 percent increased risk for Alzheimer’s disease.
This risk of Alzheimer’s disease or other dementia was significant for mid-life diabetics — as opposed to those who develop diabetes after 65 — even when controlling for family factors. In other studies, genetic factors and childhood poverty have been shown to independently contribute to the risk of both diabetes and dementia.
Indeed, the chances of a diabetic developing Alzheimer’s disease may be even greater in real life than in the study, the researchers said. They identified several factors that might have led them to underestimate the risk of dementia and Alzheimer’s among those who develop diabetes before the age of 65.
Diabetes usually appears at a younger age than dementia does, the researchers noted. Diabetes is also associated with a higher mortality rate, which may reduce the size of the sample of older adults. In addition, approximately 30 percent of older adults with diabetes had not been diagnosed.
The results of the study implicate adult choices such as exercise, diet and smoking, as well as glycemic control in patients with diabetes, in affecting risk for Alzheimer’s disease and diabetes, according to the researchers.
In fact, researchers from Mayo Clinic’s Florida campus say that dementia in some diabetics appears to be caused often by vascular disease in the brain, and the dementia that develops in people without diabetes is more likely associated with deposition of the plaque seen in people with Alzheimer’s disease.
“This helps in understanding diabetes and dementia. It suggests that the vascular dementia seen in diabetics, which appears to be related to small blood vessel disease and strokes, can potentially be averted if development of diabetes is prevented,” says Mayo neurologist Neill Graff-Radford, M.D.
The results agree with a number of autopsy studies conducted on patients with dementia and diabetes, in which vascular abnormalities were found to be related to the dementia but the Alzheimer’s pathology of plaque and tangles was not, he says.
The findings also suggest that an experimental blood test to predict development of Alzheimer’s disease may be more accurate than some studies of people with dementia have suggested, because those studies included participants with diabetes, says Dr. Graff-Radford. “We now propose that future studies of this test should take into account diabetic status,” he says.
The test is based on discoveries made by Mayo neuroscientists, which measure the ratio of two different kinds of amyloid beta proteins in blood. Plaque found in the brains of Alzheimer’s disease patients at autopsy started when the toxic form of amyloid beta, known as Aβ42, began to be deposited.
The findings also make sense biologically, Dr. Graff-Radford says. Both the insulin hormone and amyloid beta proteins are degraded by the insulin-degrading enzyme (IDE). He adds that if the blood contains excess insulin, as is the case in diabetics, then IDE preferentially degrades insulin instead of amyloid. “That means there would be higher levels of both Aβ42 and Aβ40 in the blood of diabetics,” he says.
Indeed, patients with dementia and diabetes appear to display a different pattern of injuries in their brains than patients with dementia but without diabetes, Joshua A. Sonnen, M.D. of the University of Washington, Seattle, discovered. The association between diabetes mellitus and increased risk for dementia in the elderly is well documented. Several possible mechanisms have been proposed for this association, including the direct effects of high blood glucose and insulin, the build-up of beta-amyloid plaques in the brain and the effects of diabetes-related vascular disease on blood vessels in the brain.