Is Type 2 Diabetes Linked to Dementia Risk?

Some experts who study Alzheimer disease have suggested that it is closely linked to the metabolic problems of diabetes. That’s because the brains of these patients do not seem to use glucose efficiently. Alternatively, they have proposed that diabetes-related dementia may differ from classic Alzheimer disease in some important respects (Advances in Experimental Medicine and Biology, 2019). Previous research suggested that drugs to treat type 2 diabetes, especially metformin, may delay the development of dementia. Could type 2 diabetes be linked to an increased dementia risk? How does dementia affect the treatment of diabetes?

People with Diabetes and Dementia May Do Better with CGM:

Research published in JAMA Network Open utilized Medicare data to compare outcomes of people with dementia and diabetes treated with insulin (JAMA Network Open, Dec. 2, 2025). It was not clear whether they had been diagnosed with type 1 or type 2 diabetes, but since type 2 is far more common, that is probably what most of them had. You can imagine that maintaining good blood sugar control and adjusting insulin doses as necessary could be challenging for someone experiencing cognitive impairment.

As the authors state in their introduction,

“Factors such as poor nutrition, insulin dosing, and difficulty recognizing and responding to symptoms of hypoglycemia and hyperglycemia increase the risk of poor glycemic control in this population.”

After analyzing the records, there were 2,022 people in the matched cohort, with equal numbers in each group. One group was testing their own blood sugar periodically with a finger stick. (The researchers term this self-monitoring of blood glucose, or SMBG.) The other group was using continuous glucose monitors,  aka CGM.

The records show that those on continuous glucose monitors were significantly less likely to be hospitalized and less likely to die during the study period. The researchers urge clinical trials to further assess the value of continuous glucose monitors for this especially vulnerable group of patients.

They wrap up their report with this:

“In conclusion, our findings suggest that CGM use was associated with better long-term outcomes in older adults with diabetes and ADRD compared with SMBG use.”

Dementia Risk Rises With Earlier Diagnosis of Type 2 Diabetes:

A new study of British civil servants (Whitehall II) confirms that people with type 2 diabetes are at higher risk of developing dementia (JAMA, April 27, 2021). The research began in 1985 and included more than 10,000 volunteers. Doctors examined these individuals approximately every four years until 2019.

During that time, 1700 people got a diagnosis of type 2 diabetes. In addition, there were 639 cases of dementia. Analysis of these data shows that the risk of developing dementia rises as people get diabetes at younger ages. For instance, at age 70, people without diabetes had a dementia rate of 8.9 per 1,000. However, those who were diagnosed with diabetes before they turned 60 had a rate of dementia of 18.3 per 1,000.

The investigators conclude:

“younger age at onset of diabetes was significantly associated with higher risk of subsequent dementia.”

Learn More:

You may wish to listen to our interviews with Dr. Dale Bredesen to learn more about risk factors for Alzheimer disease and how they can be avoided. One is Show 1092: How Can You Overcome Alzheimer Disease?   Show 1132: Are Infections to Blame for Alzheimer Disease? may also interest you.  Our most recent interview with Dr. Bredesen is Show 1214: How to Defend Your Brain During the Pandemic and Beyond.

We focus on type 2 diabetes in our eGuide to Preventing and Treating Diabetes. It has several ideas on reducing your risk for diabetes, which in turn should lower your chance of developing demential.