The brain affects diabetes, and diabetes affects the brain, a complex relationship that goes in both directions.
For many patients, the brain-metabolism connection means challenges and health declines. Most people that have experienced hypo- and hyperglycemia are well aware of the way that blood sugar troubles can inflict brain fog and other minor short-term malfunctions. Unfortunately, that’s just the start of it. The cognitive dysfunctions associated with diabetes can become permanent.
The first days of the recent American Diabetes Association Scientific Sessions featured several sessions on the intersections between brain health and diabetes. Some presenters sketched out the scope of the problem; others suggested potential solutions. Patients with both type 1 and type 2 have a lot to think about.
The Vicious Cycle
At the heart of the brain-diabetes relationship is a negative feedback loop that pushes people towards bad decision-making and bad health outcomes. Hyperglycemia leads to both short- and long-term cognitive impairment, which leads to increasingly poor glucose management decisions, which leads to more cognitive impairment, a vicious cycle if there ever was one.
Australia’s Dr. Fergus Cameron sketched out this dynamic:
This feedback loop helps define how and why brain issues tend to snowball as the years go by.
The Developing Brain
Diabetes can impact brain function at every age, but perhaps most important is its immense effect on the developing brain. Acute and chronic hyperglycemia during those early, critical years of development can easily cause lasting damage.
Many of the most important negative cognitive effects of type 1 diabetes seem to occur in the first days and weeks leading up to diagnosis. Just days after diagnosis, children already perform more poorly than expected on intelligence tests. “We’re seeing impacts right from the get-go,” said Dr. Ferguson.
The severity of hyperglycemia at diagnosis is also significant: children that are diagnosed during diabetic ketoacidosis (DKA) see much more cognitive impairment than children that never experience that critical state. That difference alone might mean as much as 6 points of IQ, on average.
We don’t like to dwell on immutable factors—today, you cannot change the circumstances around your diagnosis or that of a loved one. It is more important to people with diabetes to learn what they can do now to help improve their health and quality of life. The answer to that is clear: avoid chronic hyperglycemia.
Mental Issues Accumulate
The effect of chronic hyperglycemia is cumulative and comprehensive. As people with type 1 diabetes age, they perform worse on tests of executive functioning, IQ, information processing speed, and memory. The differences are bigger in high school than in elementary school, and the gap just continues to widen throughout adulthood. A 2019 study found that an incredible (and terrifying) 48% of older adults with longstanding diabetes displayed “clinically significant cognitive impairment.”
Dementia and Diabetes
Dr. Anna Marseglia, a neuropsychologist with Sweden’s Karolinska Institutet, took the baton to discuss cognitive impairment and dementia in old age. Most of her talk referred to patients with type 2 diabetes, although it’s possible that patients with other forms of diabetes could still benefit from her conclusions.
Diabetes is a major risk factor for dementia—in fact, the link between metabolic dysfunction and late age mental decline is so clear that Alzheimer’s disease has sometimes been called type 3 diabetes.
But diabetes is not destiny—the risk of dementia is significantly amplified by lifestyle.
The Power of Activity
Dr. Marseglia presented the results from her own study, a look at thousands of older Swedish adults with diabetes, to see if an active lifestyle might prevent progression to dementia. Researchers tried to track both the number of leisure activities that participants enjoyed and the strength and extent of their social connections. Would an active social life reduce the risk of dementia?
The answer was yes, and the correlation was enormous, as you can see in the graph below. “Inactive” adults with diabetes were vastly more likely to develop dementia than “active” adults, whose risk was barely higher than that of people without diabetes. Dr. Marseglia suggested that if all of the adults in the study had led “active” lives, as many as 48% of dementia cases could have been avoided.
The study suggests that while both diabetes and social inactivity are hazards in and of themselves, the real danger is when those two conditions coexist.
Accordingly, Dr. Marseglia highlighted two broad strategies to improve one’s risk of late age cognitive decline. The first is to employ strategies that reduce physical cardio-metabolic burden: improved glucose control, healthier diet, exercise, weight loss, quitting smoking, and so on. The second is to create a kind of resilience within the brain through education, challenging work, and vibrant social activities.
The protective effect of an active life is physically verifiable. Adults labeled “inactive” actually have significantly smaller brains than active adults. Activity, by preserving brain volume, somehow overrides the vascular damage associated with diabetes.
An active life to fight dementia doesn’t just start in old age—good health, mental stimulation, and social activity early in life will also protect the brain from decline decades later.
Executive Functioning in Teens
Teens have a particularly tough go of it; typically, they are the age bracket with the highest A1c.
Anxiety, depression, and diabetes burnout are distressingly common in the teenage years. Such mental health issues can easily throw diabetes decision-making out of whack. As Oregon’s Dr. Danny Duke stated, “When we’re emotionally dysregulated, it affects all of our other executive functions.”
Executive functioning, explained Oregon’s Dr. Danny Duke, is the part of the brain that’s “in charge of making sure things happen when and how they’re supposed to happen.” It’s like “the conductor of the orchestra of our thinking.”
Good executive functioning is of paramount importance to all humans, but especially to those with diabetes, who must almost continually balance short- and long-term costs and benefits. And because executive functioning usually does not fully mature until age 25, it’s no surprise that teens can have so much difficulty managing their conditions.
Some teens have better executive functioning than others, and those that struggle to make good diabetes management decisions need as much help as they can get. Otherwise, the vicious cycle will rear its ugly head once again: poor executive functioning leads to reduced glycemic control, and reduced glycemic control leads to poor executive functioning.
While Dr. Duke focused mostly on the ways that executive functioning failures could lead to dangerous blood sugar swings, he had little doubt that the converse was equally true:
I’ve worked with a lot of these kids that are hanging up there in the mid-300s [mg/dL], doing the bare minimum necessary to stay out of DKA. When we get them back down into range, they’ll often say ‘Wow, I had no idea how bad I felt and how foggy I was thinking.’
A Family Affair
For kids and teens, good diabetes decision-making is a family affair. Dr. Maartje de Wit, of Amsterdam University Medical Center, pointed to several studies assessing the role that parental executive functioning plays in diabetes management success.
Naturally, in younger children, parents will make all significant treatment decisions, but even as children age, parents continue to play a surprisingly big role in treatment success (or lack thereof). Studies show that, for example, maternal executive functioning skills have a significant influence on a child’s A1c levels, and that both the father’s and mother’s involvement played a big role in delivering better glucose control, especially when the children had executive functioning issues themselves. This did not change as children aged, even as they presumably took on more of their own management decisions.
This sounds obvious—less disciplined kids need more help—but it’s not necessarily so easy to determine who needs help, and how to help them.
Identifying and Improving Executive Function Issues
Children and teens with subpar executive function, when asked why they can’t adhere to their diabetes treatment regimen, may say things like “I forget” or “I’m lazy,” or “I don’t know why.”
Whether by nature or nurture, executive function problems are often shared between parents and children. In a presentation aimed at medical professionals, Dr. Rachel Wasserman encouraged practitioners to consider disorganized or scatterbrained parents a real warning sign of potential executive function issues in children.
If you recognize these sorts of behaviors in your child (or in yourself!), it might be worth trying to work with your child to improve his or her executive functioning skills.
Dr. Wasserman recommended activities that require repeated practice and offer progressive challenges. That could describe schoolwork and related academic pursuits; it could also describe athletics like martial arts and yoga.
Today there are also a dizzying number of scheduling apps that people with diabetes can use to help enforce good habits. More old-fashioned techniques, like alarm clocks and post-it notes, can be equally effective. Dr. Wasserman cautioned that advanced diabetes technology, such as insulin pumps and continuous glucose monitors, as helpful as they can otherwise be, do not necessarily lessen the cognitive load on the executive functioning system.
Diabetes has a significant negative effect on cognitive abilities. In type 1 diabetes, this effect can begin very early in life, with the first bouts of acute hyperglycemia leading up to diagnosis. In both type 1 and type 2 diabetes, the damage wrought by high blood sugars is cumulative, and symptoms are likely to get worse over the years.
Hyperglycemia can also set a vicious cycle in motion, whereby high blood sugars cause bad decisions, which just cause more high blood sugars.
The best way for a person with diabetes to avoid cognitive decline, probably, is to avoid chronic and acute hyperglycemia—the more time you spend with your blood sugar in a healthy range, the more likely that you will avoid accumulated damage to your brain.
It also may be possible to strengthen executive functioning skills and make the brain more resilient to age-related decline by enjoying a robust social and intellectual life. Hobbies, education, challenging work, and community involvement—in short, an active and stimulating mental life, at every age—may protect against eventual decline.