Diabetes appears to increase the risk of dementia, which affects cognition and memory, according to Australian researchers who reviewed the results of 14 studies involving more than two million people.
The analysis also included data on 100,000 dementia patients.
People with Type II diabetes were found to be 60 percent more likely than people without diabetes to develop any form of dementia.
In particular, they were at increased risk of vascular dementia, which affects blood flow to the brain. Experts say vascular dementia is usually the result of a series of small brain strokes.
The investigators found that diabetic women were two times more likely than non-diabetics to be diagnosed with vascular dementia. The rate for women also was higher than for men with diabetes.
The most common cause of dementia is Alzheimer's disease, which is marked by an accumulation of protein debris in the brain.
Vascular dementia is caused by impaired blood vessels to the brain, and is more common in diabetics.
The authors of the study suggest that women may be more at risk of vascular dementia because they are not treated as often as men for conditions such as high blood pressure. Elevated blood pressure contributes to heart disease.
More research is needed to understand how excess blood sugar affects blood vessels, particularly in women, according to the scientists.
They emphasized that keeping fit through exercise and diet, and not smoking, can help decrease the risk of vascular dementia in diabetics.
The findings were published in the journal Diabetes Care.