Diabetes and Alzheimer’s – What’s the Link?

A French study reported in the journal Neurology has re-opened the discussion about the relationship between type 2 diabetes and Alzheimer’s disease.  It’s generally accepted that diabetes is associated with cognitive decline and an increased risk of developing Alzheimer’s.  But the French study has examined the effect of diabetes on the rate of cognitive decline in people with established Alzheimer’s.

The study enrolled 608 patients with a probable diagnosis of Alzheimer’s disease (Mini-Mental State Examination [MMSE] scores between 10 and 25).  They were followed for up to 52 months (averaging 26 months).  Diabetes was assessed at baseline (a history of the condition, or taking anti-diabetic medication).  Cognitive function, using the MMSE, was determined every 6 months. 

There were 63 participants (10.4%) with diabetes at baseline.  After adjustment for differences in gender, age, education, severity of dementia, use of Alzheimer medication (cholinesterase inhibitors), and vascular factors, such as high blood pressure, atrial fibrillation etc., baseline MMSE were similar in both diabetic and non-diabetic patients.  However, cognitive decline was slower in the group with diabetes; the difference between the groups was statistically significant.

This report has generated some criticism from Alzheimer experts.  A spokesman for the Alzheimer’s Association stated that previous studies along these lines have had mixed results; some show a faster decline, some show a slower decline.  An important factor is the stage of the disease in the participants.  Those in the French study were reported to have had Alzheimer’s for a shorter period of time than the non-diabetics, and it’s known that the rate of decline depends, to an extent, on the stage of the disease.  Moreover, the difference seen in the MMSE scores between the two groups was very small – statistically significant but “clinically meaningless”, according to one expert.   

Clearly, additional studies are needed.  But, as someone with diabetes, I’m happy to think that, should I get cognitive decline, it may progress slower than if I didn’t have diabetes.  And the good things I’m trying to do for my general health – exercise, good nutrition, avoiding obesity – should help stave off both diseases!