Risk factors associated with cognitive decline in older people with type 1 diabetes

Researchers identified risk factors that contribute to cognitive decline in people with type 1 diabetes as they age—findings that could inform strategies to preserve cognitive function over the lifespan. Because multiple avenues of research have demonstrated the importance of controlling blood glucose (sugar) levels and led to the development of improved diabetes management technologies, people with type 1 diabetes are living healthier and longer lives. In further research to help people maintain good health as they age, scientists sought to determine whether type 1 diabetes affected the cognitive decline that is seen as people age, as well as to identify risk factors associated with cognitive decline. Understanding any loss of cognitive function is important to ensuring that high quality of life and diabetes self-management can be maintained as people with type 1 diabetes age.

The NIDDK’s Epidemiology of Diabetes Interventions and Complications (EDIC) study has followed over 1,000 participants from the landmark Diabetes Control and Complications Trial (DCCT) for over 30 years from a median age of 27. As part of the follow up, participants completed cognitive assessments at the start of the DCCT and 2, 5, 18, and 32 years later (median age of 59), as well as other assessments. Overall, the researchers found that, as the group aged, they performed less well on assessments of memory and psychomotor and mental efficiency. These cognitive declines were associated with higher hemoglobin A1c (HbA1c) levels (a measure of blood glucose levels over time), more episodes of severe hypoglycemia (dangerously low blood glucose levels), and elevated systolic blood pressure levels. When combined, the presence of these three risk factors was associated with a cognitive decline equivalent to an additional 9 years of age, suggesting premature aging.

Participants who maintained better control of these risk factors, however, showed fewer changes in cognition. Lower average HbA1c, fewer episodes of severe hypoglycemia, and lower blood pressure were each associated with better performance on the cognitive assessments, suggesting that blood glucose control and blood pressure management could help to preserve cognitive function in people with type 1 diabetes as they age. These results add to the wealth of information that has come from the DCCT/EDIC demonstrating the long-term health benefits of maintaining blood glucose levels as close to those of a person without diabetes as safely possible.