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Memory, Brain Health & Diabetes

The links between blood sugar management and cognitive function

Think of the human brain, which is the most complex organ in the body, as the control center of a vast network for bodily functions and abilities. For people living with diabetes, some research suggests that type 2 diabetes (and possibly type 1) may have serious long-term consequences for the brain. These include higher risks of memory loss, depression and difficulty with decision-making, as well as other forms of cognitive impairment and premature brain aging. Having diabetes in one’s 50s or 60s has also been associated with significantly more cognitive problems 20 years later. In other words, what a person does today may impact their future, which is both good and bad news.

Little is certain about why, exactly, this diabetes-related cognitive impairment occurs, but two current theories may provide clues as to how it may be prevented.

First, long-standing diabetes has been shown to affect the physical structure of the brain. According to Vera Novak, MD, PhD, a neurophysiologist at Beth Israel Deaconess Medical Center, this may be related to the fact that chronic high blood sugar levels cause inflammation and damage to small blood vessels. As a result, tiny blood vessels in the brain constrict and blood flow to these areas decreases. Such insufficient blood flow damages and destroys brain tissue. According to Novak’s work, this reduction in blood flow appears to be particularly harmful to parts of the brain that are responsible for important cognitive tasks such as decision-making and language. While the exact connection between glucose control and brain damage is not yet clear, avoiding chronic high blood sugars appears to be important for the brain. (Read more about hyperglycemia or high blood sugar, including signs and symptoms.)

Second, insulin resistance itself may affect the brain. Insulin resistance is a condition, common both in prediabetes and T2, in which the body doesn’t use insulin as effectively as it should. For most tissues in the body, insulin’s primary role is to enable them to absorb glucose, which is why therapeutic insulin might be prescribed to reduce blood glucose levels. (Learn more about insulin’s role in the body.)

But the brain is different than most tissues in the body, and it uses insulin to regulate a number of other important functions, including how different parts of the brain communicate with each other (for example, those that control memory). This means that being insulin resistant – even if one doesn’t have a type 2 diabetes diagnosis – may itself put a person at an increased risk for cognitive decline.

With that said, according to Elizabeth Seaquist, 2014 president of medicine and science for the American Diabetes Association, most questions about how insulin resistance and diabetes might affect the brain remain unanswered. Researchers don’t yet know the details, for example, of whether type 1 and type 2 diabetes may affect the brain differently, whether intensive glucose management makes a difference or what the long-term effects of frequent low blood sugars and wide fluctuations in glucose levels might be.

According to Seaquist, one may want to take measures that may help avoid insulin resistance and type 2 diabetes by reducing risk factors, keeping blood glucose levels in range and by staying more lean and active – both of which may help prevent insulin resistance. That may mean monitoring cholesterol, triglyceride and blood pressure levels (all of which may be associated with a risk of developing insulin resistance), exercising regularly – even walking can be quite effective – and maintaining a more healthful weight. Certain medications, including metformin, may also help.

When it comes to preventing type 2 diabetes-related cognitive decline, Novak believes that it’s the long-game that may matter most. “The damage isn’t going to happen over a month,” Novak explains. “It’s small changes that occur over prolonged period of time.” In other words, any investment someone makes in managing their diabetes today may impact their brain health in the future.

Catherine Price is a freelance journalist and type 1 diabetic who has written for The New York Times, Slate, Popular Science and O Magazine, among others. Her newest book, Vitamania: Our Obsessive Quest for Nutritional Perfection, is available from Penguin Press. She blogs about diabetes at ASweetLife.org and you can follow her on Twitter @Catherine_Price. Price is a paid contributor for The DX. All opinions contained in this article reflect those of the contributor and interviewee, and not of Sanofi US, its employees, agencies, or affiliates.

© 2015 The DX: The Diabetes Experience

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