MONDAY, March 18, 2024 (HealthDay News) -- In people with type 1 diabetes, fluctuations in blood sugar levels can affect thinking skills in various ways, new research shows.

Researchers looked specifically at what's known as cognitive processing speed (how fast people process incoming information) and attention.

“Our results demonstrate that people can differ a lot from one another in how their brains are impacted by glucose,” said study co-senior author Laura Germine.

“We found that minimizing glucose fluctuations in daily life is important for optimizing processing speed, and this is especially true for people who are older or have other diabetes-related health conditions," Germine said.

She directs McLean Hospital's Laboratory for Brain and Cognitive Health Technology, in Boston.

According to the researchers, it's long been known that big dips or spikes in blood sugar levels can impair thinking in people with type 1 diabetes. But to what extent does this happen, and does it differ between people?

To find out, they used wearable digital glucose sensors and smartphone-based cognitive tests to collect data on 200 people with type 1 diabetes as they went through their day.

Over the course of 15 days, data on each person's blood sugar levels was collected via the sensors every five minutes. Participants completed the cognitive tests three times per day.

As expected, cognitive skills declined when blood sugar levels were either very low or very high, the Boston team found. However, declines were only observed when it came to processing speed, not attention.

They theorized that processing speeds may react to quick, moment-to-moment changes in blood sugar levels, whereas attention might only be impacted by longer term highs or lows.

The team also found that certain types of type 1 diabetes patients -- older adults or folks with certain health issues, for example -- were much more vulnerable than others to the effects of glucose levels on brain function.

The findings were published March 18 in the journal npj Digital Medicine.

“In trying to understand how diabetes impacts the brain, our research shows that it is important to consider not only how people are similar, but also how they differ,” study lead author Zoë Hawks said in a McLean Hospital news release. She's a research investigator at McLean.   

There was one surprise finding: People with type 1 diabetes tended to be at peak intellectual performance when their blood sugar levels were slightly higher than the normal range.

“This was an important finding, because people with diabetes often report feeling better at a glucose level that is higher than what is considered healthy,” said co-senior study author Naomi Chaytor, a professor of medicine at Washington State University.

“It could be that your brain habituates to a glucose level that it is used to," she added. "So, a next step in this research is to see whether the glucose level associated with peak performance shifts down into the normal range when the amount of time spent above range is reduced.”

More information

The American Diabetes Association has more on type 1 diabetes.

SOURCE: McLean Hospital/Mass General Brigham, news release, March 18, 2024