Men who develop diabetes in mid-life appear to have a greater risk of developing Alzheimer's disease.

A long-term study in Sweden followed 2,269 men who were tested at age 50 for diabetes.

At an average follow-up of 32 years, 102 men were diagnosed with Alzheimer's disease, 57 showed vascular dementia and 235 demonstrated other types of dementia or cognitive impairment.

Men with low insulin secretion capacity were found to have a 1.5 times greater risk of developing Alzheimer's disease than people with normal insulin production, with this risk remaining regardless of blood pressure, cholesterol, body mass index and education.

The association between diabetes and risk of Alzheimer's disease was found to be strongest in people who did not have the APOE4 gene - known to be connected to an increased risk of the neurodegenerative condition.

Researchers noted that insulin problems are an important risk factor for Alzheimer's disease upon the absence of this high risk gene.

"Our results suggest a link between insulin problems and the origins of Alzheimer's disease and emphasise the importance of insulin in normal brain function," study author Elina Ronnemaa said.

She admitted that more studies were required to establish the exact mechanisms that could cause low insulin secretion to dementia.

Findings are reported in the online issue of Neurology, the medical journal of the American Academy of Neurology.

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