Type 1 Diabetes Linked to Drop in This Important Mental Function

June 21, 2018

Joslin Diabetes Center researchers reveal startling study results linking decades of having type 1 diabetes and mental abilities.

Patients who have had type 1 diabetes for a long period of time show signs of mild decreases in cognitive abilities, primarily in memory, compared to those who don’t have the disease, according to a new study.

For the study, published in Diabetes Care, Joslin Diabetes Center researchers compared 82 Joslin 50-year Medalists, who have lived successfully with type 1 diabetes for at least that long, with other people of similar age with type 2 diabetes or without diabetes.

The work is the first to evaluate whether cognitive function is changing in an aging group of people who have successfully managed their type 1 diabetes.

All patients were tested on a battery of cognitive tests including IQ assessment. The tests assessed memory, executive function, psychomotor speed, and working memory. In addition, clinical variables were collected such as blood pressure, HbA1c, weight, cholesterol etc.

“Type 1 patients have been tested extensively at a number of visits across many years and we had excellent records of whether or not they suffered from diabetic complications, and if so, which ones,” says lead study author Gail Musen, PhD, an assistant investigator in Joslin’s Research Division. “There have been no other studies examining patients with type 1 diabetes for over 50 years. This group is particularly well characterized and can also help answer questions about how diabetes complications influence cognition,”.

The study found that patients with either type 1 or type 2 diabetes performed worse than controls on measures of memory and trended toward significance for measures of executive function, working memory, and psychomotor speed. Executive function refers to ability to plan, organize, and decision-make while good working memory skills require one to be able to manipulate and rehearse information for immediate use. 

“Further, when considering just those with type 1 patients, those with cardiovascular disease (CVD) performed worse on executive function compared to type 1 patients without CVD and those with proliferative retinopathy performed worse on a psychomotor speed test than those without retinopathy,” Musen says. 

The study also found that type 1 and type 2 patients showed a similar pattern of results. Previous research on younger patients with type 1 showed their deficits were more in areas of attention and executive function but this seems to change as they age.

According to Musen, healthcare executives should see that at least a simple cognitive test such as the Montreal Cognitive Assessment (MoCA) is administered in diabetic patients over age 60 or 65 years.

“They should also make sure physicians emphasize the importance of self-care behaviors to reduce complications as that can help minimize cognitive decline,” Musen says.

Based on the study, Musen offers four takeaways for healthcare executives:

  • Cognition declines in elderly patients with both type 1 and type 2 diabetes.
  • Decline is mild but may be avoidable with better self-care to reduce developing CVD or proliferative retinopathy.
  • Exercise may be helpful as it is known to reduce CVD.
  • Quick cognitive tests (e.g., MoCA) should be administered by a primary care physician or endocrinologist in older diabetic patients.