Are Type 2 Diabetes and Dementia Linked?
Post by Rebecca Glisson
The takeaway
Type 2 diabetes can lead to worse cognitive health and even dementia. This study found that in a large sample of over 350,000 individuals, type 2 diabetes leads to a higher risk of Alzheimer’s disease.
What's the science?
The relationship between type 2 diabetes and brain health is not yet understood; however, some evidence suggests that diabetes symptoms are related to dementia symptoms. One common symptom of diabetes is the level of glucose (sugar) in the bloodstream 2 hours after eating, which should typically return to baseline levels in healthy individuals but stays high in diabetic individuals because they lack insulin to process glucose out of the bloodstream. This week in Diabetes, Obesity and Metabolism, Mason and colleagues studied the possible mechanisms of how diabetes is linked to dementia.
How did they do it?
The authors used a large database of survey questions and health measurements to test for correlations between diabetes and cognitive function. They used data from 357,883 participants who were between 40 and 69 years old (54.1% female). They tested cognitive functioning using MRI scans to measure volume in the hippocampus, a brain region involved in memory processing, along with total brain volume. To measure diabetes symptoms, the authors obtained blood samples from participants.
What did they find?
The authors found that individuals who had elevated levels of glucose had a 23% increased risk of dementia, and a 69% increased risk of Alzheimer’s disease. This supports the idea that individuals with type 2 diabetes are more at risk for developing cognitive disorders. However, the authors did not find any link between diabetes symptoms or brain measurements. This suggests that the increased risk for dementia from diabetes likely acts through other mechanisms. The authors suggest that future research should look into tau and amyloid plaques, which are other markers of Alzheimer’s disease and could be one cause for the link between diabetes and risk of developing dementia.
What's the impact?
This study is the first to show a clear link between diabetes symptoms and symptoms of cognitive dysfunction. However, the mechanism for this link is still unclear and needs further study. An important caveat is that only white, British participants were included in the study due to a lack of data availability for other groups, and further study should be conducted on diverse populations.