Type 2 diabetes: 2 studies unlock clues about dementia risk and brain health

• To help our audience catch up on the latest medical research developments and insights from health experts, we highlight key findings and takeaways from recent research studies that Medical News Today has covered in depth in previous news reporting.
• Two recently published studies focused on type 2 diabetes and cognitive health complications related to the condition that hundreds of millions of people are living with worldwide.
• One study indicates that maintaining stable hemoglobin A1c (HbA1c) over time can help mitigate dementia risk, while another found that a healthy lifestyle can offset brain aging accelerated by diabetes.

In the United States, nearly 15% of all adults 18 years or older had diabetes in 2021, and more than 90% of them had type 2 diabetes . Worldwide, it is estimated that the prevalence of diabetes will drastically increase over the next 20 years, according to projections by the International Diabetes Federation .

Type 2 diabetes occurs when a person’s body can’t properly respond to insulin or develops insulin resistance . As the disease progresses, the pancreas produces less and less insulin.

Medical News Today regularly reports on peer-reviewed studies related to type 2 diabetes. In this article, we highlight key findings from two recent studies on the link between type 2 diabetes and brain health as well as experts’ perspectives on the significance of the findings and insights into type 2 diabetes prevention and management.

How do A1C levels affect dementia risk?

In a nutshell:

A study published August 2 in the journal JAMA Network Open suggests that an individual’s hemoglobin A1c (HbA1c) levels over time may be a key indicator in predicting dementia risk. The findings concluded that maintaining stable A1C levels in optimal ranges is linked to a decreased risk of developing Alzheimer’s disease and related dementias in older adults.

Key takeaways:

• The study authors used a measure called HbA1c time in range (TIR) to examine blood sugar levels over time. Compared to A1C levels, which measure average blood sugar levels over a three-month period, HbA1c TIR offers better insights into how stable or “controlled” one’s blood sugar levels are over time.
• Higher HbA1c TIR indicates more stable blood sugar levels, and lower HbA1c TIR suggests more instability in blood sugar levels.
• The study recruited a large sample of 374,021 veterans with diabetes . The average age of the participants was 73.2 years, and 99% were male. Over a follow-up period of up to 10 years, 11% (41,424) of them developed Alzheimer’s Disease and Related Dementias (ADRD).
• Corresponding author, Paul R. Conlin, MD , medical service chief for the VA Boston Healthcare System and professor of medicine at Harvard Medical School, offered the following insights on the study’s key findings: “We found that patients who maintained a higher percentage time (at least 60% or greater) with A1c levels in their target range had lower risk of Alzheimer’s disease and related dementias. Dementia risks were particularly increased when A1c levels were mostly below the target range.”

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Stable A1C levels may be linked to lower dementia risk

Can a healthy lifestyle slow brain aging caused by diabetes?

In a nutshell:

Existing evidence suggests that both prediabetes and type 2 diabetes can increase the risk for certain brain-related health issues. A new study published on August 28 in the journal Diabetes Care reports that while people with type 2 diabetes and prediabetes may be at risk for accelerated brain aging, making healthy lifestyle choices such as not smoking may help them improve their brain health.

Key takeaways:

• For the study, researchers analyzed MRI brain scans of more than 31,000 people between the ages of 40 and 70 from the UK Biobank . At baseline, about 43% of study participants had prediabetes, and almost 4% had diabetes.
• The team reported that prediabetes was associated with a brain age 0.5 years older than a person’s chronological age, while diabetes was associated with a brain age 2.3 years older.
• The findings also suggest that there was slight increase in the gap between brain age and chronological age over time in those with diabetes. However, these associations were reduced in participants who participated in high physical activity , did not smoke, and abstained from heavy alcohol drinking . It is important to point out that while this study showed associations, causality has not been established.
• Medical News Today interviewed Scott Kaiser, MD , a board certified geriatrician and Director of Geriatric Cognitive Health for the Pacific Neuroscience Institute in Santa Monica, CA, who reviewed this study. Kaiser said while this study does not establish causality, it reinforces existing evidence on how a healthy lifestyle can help effectively manage diabetes and improve brain health.
• “This study provides really great targets for lifestyle interventions to promote brain health and that’s really important, again, when you think about this not just (at) an individual level, but at a population level,” Kaiser noted.
• The study’s lead author, Abigail Dove, is a PhD student in the Aging Research Centre (ARC) at the Department of Neurobiology, Care Sciences and Society at the Karolinska Institutet in Sweden. Dove told Medical News Today : “Diabetes is a well-established risk factor for dementia, but the role of diabetes — and its preclinical manifestation, prediabetes — in the early stages of brain aging is unclear. These are important questions from a public health perspective because we need to understand how to protect the brain health of people with diabetes as they grow older.”

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Healthy lifestyle may offset brain aging accelerated by diabetes