2 days ago
New Study Finds That A Blood Test For Diabetes Might Actually Predict Alzheimer's Progression
A new study suggests a simple blood test could tell who is at higher risk for rapid cognitive decline with Alzheimer's.
The study found that people with higher insulin resistance were up to four times more likely to have rapid cognitive decline.
Here's what to know about the test and how to get one.
Historically, it has been quite difficult for doctors to predict how fast patients will experience cognitive decline with Alzheimer's disease, especially since the neurodegenerative disease impacts people differently based on a slew of factors. But new research has discovered that a specific blood test may help doctors get more answers, which could, in theory, help them respond more quickly with appropriate treatment and providing patients with more information. (But of course, experts first need to gather more data and perform further studies on the test.)
The test measures insulin resistance, a condition where the body's cells don't respond properly to insulin, a hormone that helps escort blood sugar into cells for energy. The latest study finds a link between insulin resistance and Alzheimer's disease progression, helping doctors and patients glean more information about what may be in store. Here's what the study found, plus what neurologists want you to know.
Meet the experts: Clifford Segil, DO, is a neurologist at Providence Saint John's Health Center in Santa Monica, CA; Amit Sachdev, MD, MS, is the medical director in the Department of Neurology at Michigan State University.
The study, which was presented at the European Academy of Neurology Congress 2025, analyzed health records of 315 people without diabetes who had cognitive deficits. Of those, 200 had confirmed cases of Alzheimer's disease.
All of the patients had their insulin resistance checked using something called the Triglyceride-Glucose (TyG) index, a way to check insulin resistance, based on fasting triglyceride (a type of fat in the blood) and blood sugar levels, at the start of the study and three years later. The researchers discovered that patients in the mild cognitive impairment group with higher TyG levels had their cognitive health deteriorate a lot faster than those who were lower on the TyG index. Ultimately, the researchers found that people with higher TyG levels were up to four times more likely to have rapid cognitive decline compared to those who were lower on the scale.
For starters, this type of blood test isn't actually new. We're just discovering new ways it can be used. The TyG index is already used to look for insulin resistance in people, so technically, you could get this test now if your doctor thought that it was medically appropriate. Just know that it's usually used in the context of diabetes or when your doctor suspects you might have diabetes.
The test appears to be pretty accurate in predicting rapid mental decline. The researchers found that people with high TyG ended up losing more than 2.5 points on the Mini Mental State Examination per year, which is a standardized test used to look at cognitive function in older adults.
In Alzheimer's disease, insulin resistance is thought to interfere with how the brain uses glucose (blood sugar). It's also believed to promote the build-up of amyloid, or proteins deposits in the brain that are linked with Alzheimer's disease. Additionally, insulin resistance can disrupt the blood-brain barrier and fuel inflammation in the brain. All of these are linked with neurodegenerative diseases like Alzheimer's disease.
'Insulin resistance often reflects features of overall health," says Amit Sachdev, MD, MS, medical director in the Department of Neurology at Michigan State University, pointing out that a major contributor to insulin resistance is higher bodyweight. 'If the overall health of the body is not optimal, then the brain will not be well supported and can be less resilient.'
But the link between insulin resistance and Alzheimer's disease is still being explored, says Clifford Segil, DO, a neurologist at Providence Saint John's Health Center in Santa Monica, CA. So, while it's clear that it seems to play some role, it's hard to tell what it's specifically doing as it relates to brain health.
Your doctor can order one of these tests for you. However, neurologists say there are better options right now if you're concerned about Alzheimer's disease development and are looking for answers.
'Some tests that are more specific for Alzheimer's are serum amyloid and tau levels,' Dr. Sachdev sys. 'Tests that help predict risk for the anti-amyloid therapies used in Alzheimer's is the APO-E genotype. These studies are useful today in understand risk of dementia, type of dementia, and risk of treatment.'
Dr. Segil says that doctors are 'extremely cautious' about using blood tests like TyG to determine if someone is at risk for developing dementia in the first place. 'There remains an extremely high number of false positive results in patients receiving various blood tests being marketed to determine if you are at risk for getting dementia,' he says. However, this specific study is exploring the test to see how quickly someone who already has cognitive decline will progress—and that usage is still being explored.
All of this doesn't mean you can't or shouldn't get a TyG test. Just know that your doctor is more likely to use it while checking you for early signs of diabetes versus Alzheimer's disease right now.
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