Older diabetics whose blood sugar drops to dangerously low levels have a higher risk of developing dementia, new research suggests.
The study found that aggressively trying to control blood sugar to the point that it requires a trip to the hospital may increase dementia risks in older adults with type 2 diabetes.
Several studies have found that diabetics have a higher risk of developing Alzheimer's disease, the most common form of dementia. Yet others have shown that diabetics who properly control their disease have a lower Alzheimer's risk.
This study suggests there is a key window of glycemic control that keep dementia risk low, says study author Rachel A. Whitmer, of Kaiser Permanente in Oakland, Calif.
"Episodes of hypoglycemia may be associated with neurological consequences in patients already at risk for dementia. This study seems to suggest that hypoglycemia is one of the reasons people with type 2 diabetes are at a higher risk for dementia. It also adds to the evidence base that balance of glycemic control is a critical issue, and particularly for the elderly," she said during a Tuesday teleconference.
Whitmer and colleagues looked at more that two decades of data in 16,667 patients with type 2 diabetes whose average age was 65.
The team checked to see if episodes of low blood sugar that were severe enough to require a trip to the hospital were associated with a higher risk of dementia.
They found that compared with patients who had no severe bouts of low blood sugar, diabetics with single or multiple episodes of hypoglycemia requiring hospitalization had higher dementia risks. The risk levels appeared to rise depending on the number of severe episodes.
In patients with a history of one episode of severe hypoglycemia that required hospitalization, they had a 26 per cent greater risk of dementia compared to patients who had never had a severe episode.
Patients who had experienced two episodes faced an increased risk of 80 per cent, while those who had experienced three episodes or more had a 94 per cent increase in risk, or almost double the odds of developing dementia.
The results are published in JAMA, the Journal of the American Medical Association.
The study adds to the body of evidence about the health dangers of aggressive measures to control blood sugar, at least in the elderly population. Three recent studies found tight glycemic control could cause heart disease and death in some elderly diabetics.
"A large body of evidence suggests that individuals with diabetes are at an increased risk of dementia, yet exact mechanisms are not known; our study suggests a potentially modifiable mechanism."
It's not yet clear whether less severe episodes of low blood sugar, which are more common, are also linked with an increased dementia risk.
