Hypoglycaemic, Hyperglycaemic Events Associated With Increased Dementia Risk in People With Type 1 Diabetes
June 3, 2021

For older individuals with type 1 diabetes, severe hypoglycaemic and hyperglycaemic events are associated with increased future risk of dementia, according to a study published in the journal Neurology.

Older people with type 1 diabetes who had been to the hospital at some point for both hypoglycaemic and hyperglycaemic events may be at 6 times greater risk for developing dementia years later.

“People with type 1 diabetes are living longer than before, which may place them at risk of conditions such as dementia,” said Rachel A. Whitmer, PhD, University of California Davis School of Medicine, Sacramento, California. “If we can potentially decrease their risk of dementia by controlling their blood sugar levels, that could have beneficial effects for individuals and public health overall.”

The study looked at 2,821 people with an average age of 56 years who had type 1 diabetes. Of those, 398 (14%) had a history of hypoglycaemia, 335 (12%) had a history of hyperglycaemia, and 87 (3%) had both. The researchers followed-up with the people for an average of 7 years to determine who had been diagnosed with dementia.

A total of 153 people -- about 5% -- developed dementia. After adjusting for age, sex, and ethnicity, the people with hypoglycaemic events had a 75% greater risk of developing dementia than those without one. People with hyperglycaemic events had more than twice the risk of developing dementia than those without one. However, the people who experienced both types of events had more than 6 times the risk of developing dementia than people who had neither event.

The researchers also looked at dementia incidence rates. After adjusting for age, the incidence rate of dementia in people with hypoglycaemic events was 26.5 cases for every 1,000 person-years compared with 13.2 for people without. Person-years take into account the number of people in a study as well as the amount of time spent in the study. The incidence rate of dementia in people with hyperglycaemic events was 79.6 cases for every 1,000 person-years, compared with 13.4 for people without.

For people who had both hyperglycaemic and hypoglycaemic events at various times, the incidence rate of dementia was 98.5 for every 1,000 person-years, compared to 12.8 for those who had neither.

“Our findings suggest that exposure to severe glycemic events may have long-term consequences on brain health and should be considered additional motivation for people with diabetes to avoid severe glycemic events throughout their lifetime,” said Dr. Whitmer.

A limitation of the study is that people had to be diagnosed with dementia by a healthcare provider to be counted as having dementia. Since many dementia cases go undiagnosed, this may have resulted in underreporting the number of dementia cases. Dr. Whitmer noted that the study was not designed to determine whether hyperglycaemic and hypoglycaemic events caused dementia -- it only showed an association.

Reference: https://n.neurology.org/content/early/2021/06/02/WNL.0000000000012243

SOURCE: American Academy of Neurology