People with type 2 diabetes are at higher risk for dementia in general. And for one form, called vascular dementia, diabetes brings more risk to women than men, according to a new review.
The most common cause of dementia is Alzheimer's disease, which is non-vascular, said senior author Rachel R. Huxley of Curtin University in Perth, Australia.
Nonvascular means it's not related to problems with blood vessels.
"In Alzheimer's disease, nerve cells throughout the brain die off, and abnormal proteins accumulate in the brain for reasons not entirely known," Huxley said. "Vascular dementia, in contrast, is the result of impaired blood flow to the brain, usually by a series of small, imperceptible strokes."
Diabetes in women seems to confer more risk for other conditions as well, Huxley said.
"These findings add to the evidence that diabetes confers a greater vascular hazard in women compared with men," Huxley told Reuters Health by email. "Diabetes confers a greater risk of developing heart disease, stroke and now vascular dementia in women compared with men."
The authors reviewed 14 studies involving a total of more than 2 million individuals, including more than 100,000 dementia patients. They reported their findings in Diabetes Care.
Overall, people with diabetes were 60 percent more likely to develop any dementia than people without diabetes.
Women with diabetes were more than twice as likely as those without it to develop vascular dementia, compared to a smaller increase in risk for men with diabetes.
There need to be more research into how sugar in the blood interacts with the blood vessels and whether that process is different in women in men, Huxley said.
Women tend to be undertreated for vascular risks relative to men, she noted.
"We can't definitively say whether the relationship is causal or not because the studies were all observational (rather than randomized trials) and therefore there always remains the possibility that the relationship is confounded," Huxley said.
A third factor, like obesity, could have been part of the relationship between diabetes and dementia, she said.
Keeping fit, maintaining a healthy diet, quitting smoking and giving your brain as well as your body regular work-outs can help decrease the risk of dementia for people with diabetes, Huxley said.