WEDNESDAY, Sept. 2, 2015 (HealthDay News) -- People with type 2 diabetes may be more prone to developing the brain "tangles" associated with Alzheimer's disease, a new study suggests.

The study found that people with type 2 diabetes had a greater accumulation of brain tangles -- even if they were free of dementia or milder problems with memory and thinking.

The findings, reported Sept. 2 in the journal Neurology, hint at one explanation for why people with type 2 diabetes have an increased risk of Alzheimer's disease.

That is, type 2 diabetes may cause brain abnormalities that pile on to other degenerative changes that ultimately lead to dementia, explained study senior researcher Dr. Velandai Srikanth, a geriatrician at Monash University in Melbourne, Australia.

However, he said, this study shows only a correlation between type 2 diabetes and brain tangles. It's not clear whether the type 2 diabetes is the cause, since there are many other factors to consider.

Obesity is one example, Srikanth said. People with type 2 diabetes are often obese, and other research has linked obesity to a greater accumulation of brain tangles.

On the other hand, diabetes might directly contribute -- by causing chronically high blood sugar levels, for instance. But more research is needed to clarify the cause, Srikanth said.

Studies have found that people with type 2 diabetes have nearly twice the risk of developing Alzheimer's or other forms of dementia as people without diabetes, background information in the study noted. That could partly be due to their higher rates of stroke and narrowing in the arteries supplying blood to the brain, according to Srikanth's team.

But it could also be related to degeneration in brain tissue. In an earlier study, the current study's researchers found that older adults with diabetes tended to show more brain "shrinkage" than those without the disease.

The new findings are based on 124 older adults with type 2 diabetes and almost 700 without the disease. Some had Alzheimer's, others had milder problems with memory and thinking, and others were mentally sharp.