Type 2 Diabetes Linked to Difficulties With Mental Tasks
Jan. 26, 2000 (Boston) -- Older women with type 2 diabetes are more likely
to have problems with memory, concentration, and general mental tasks than
nondiabetic women, according to CDC researchers.
Men were not included in the study, which was part of a larger overall study
of the consequences of fractures in women with osteoporosis, but the findings
would likely apply to them as well, the researchers tell WebMD.
In a six-year study of more than 9,500 women aged 65 and over, women with
type 2 diabetes scored lower on three cognitive (mental-function) tests and had
a greater rate of decline in mental function over 3-6 years than did women
The study also showed that women who had diabetes for 15 years or longer
were most likely to have experienced a decline in abilities such as attention,
language, and eye-hand coordination, write Edward W. Gregg, PhD, and
colleagues. The results of the study appear in the Jan. 24 issue of the
Archives of Internal Medicine.
"Our finding of an increased risk of cognitive decline associated with
diabetes has important clinical, public health, and social ramifications.
Cognitive impairment may be considered a potential long-term outcome of
diabetes that clinicians should be aware of while taking care of older adults
with diabetes," they write.
Earlier studies have led the researchers to expect some differences in
mental function between diabetic and nondiabetic women. "What did come as
something of a surprise, though, was that there's a 70% increased risk of a
major decline on average, and that people who are taking insulin had a higher
risk of cognitive decline. We don't think it was the insulin itself, but rather
that insulin use was a marker of severity of disease," says Gregg, a
researcher with the CDC's division of diabetes translation.
Gregg tells WebMD that although it is still unclear exactly how diabetes
might affect mental processes, the best course of action for patients with type
2 diabetes may be to follow their doctors' advice and carefully control their
blood sugar levels through the right combination of diet, exercise, medication,
and, if necessary, insulin.
Although the study was not designed to determine how diabetes might affect
the brain, the researchers were able to rule out some other factors that are
often associated with aging or with diabetes, such as blood vessel narrowing
that could lead to decreased blood flow to the brain or stroke, high blood
pressure, or depression.
"From a research point of view, it makes us think about what is the link
between diabetes and cognitive function," David A. Bennett, MD, tells
Bennett, who wrote an editorial accompanying the study, is with the Rush
Alzheimer's Disease Center and department of neurological sciences at
Rush-Presbyterian-St. Luke's Medical Center in Chicago. "Why do people with
diabetes lose cognitive abilities? The easiest explanation is that diabetes is
associated with strokes, but on the other hand, that may not be true. It may
actually be related to insulin metabolism and the way the brain deals with
insulin and diabetes," he says.
Bennett says that because type 2 diabetes is caused by the body's increasing
inability to use insulin to process glucose, the major form of sugar in the
blood, the disease may somehow alter the ability of individual nerve cells in
the brain to store and use glucose. Some brain researchers think that problems
with glucose metabolism may cause or contribute to Alzheimer's disease or other
forms of dementia.
The study was supported in part by grants from the Public Health Service of
the National Institutes of Health.