There have been some studies of the relationship between Diabetes and Alzheimer's disease. The latest study, coming out of Kyushu University, Japan, found that diabetics were 3.1 times more likely to develop Alzeimer's disease than non-diabetics.
This number far exceeds the proportion found in studies in the US. One US study of more than 2,500 people found the ratio to be 1.8 times. A study in the Netherlands of more than 6,000 people found that diabetics were 1.9 times more likely to develop Alzheimer's.
Hiroshi Kiyohara, who leads the Kyushu University team, said, "Prevention of diabetes and proper control of blood-sugar levels will become an important issue for society as it continues to age."
These findings are scary for me, because there is a history of Alzheimer's in my family. As far as I know, I am the only one with type 1 diabetes. My uncle, who is not related to me by blood, had diabetes for years before he was diagnosed recently with Alzheimer's. My grandfather was type 2 diabetes when he developed a form of dementia at age 80. We don't really know whether this this was Alzheimer's. It was 1966.