Alzheimer's, Dementia & Mental Health
Severe Hypoglycemia Linked to Increased Risk of
Dementia for Senior Citizens with Type 2 Diabetes
No studies have evaluated whether or to what extent
hypoglycemic episodes are a risk factor for the development of dementia
in older patients
April 14, 2009 - Having hypoglycemic (low blood
sugar level) episodes that are severe enough to require hospitalization
are associated with a greater risk of dementia for older adults with
type 2 diabetes, according to a study in the April 15 issue of the
Journal of the American Medical Association (JAMA), a theme issue on
diabetes.
Hypoglycemic episodes may include dizziness,
disorientation, fainting or seizures. While most hypoglycemia is mild
and self-managed, more severe hypoglycemia can require hospitalization.
Although some studies have reported an association
between history of hypoglycemia and impaired cognitive functioning in
children and young adults with type 1 diabetes, no studies have
evaluated whether or to what extent hypoglycemic episodes are a risk
factor for the development of dementia in populations of older patients,
who are more likely to have type 2 diabetes than type 1.
"With the increasing prevalence of type 2 diabetes
worldwide, and potentially of hypoglycemia and dementia among patients
with diabetes, the relationship between these conditions should be
evaluated," the authors write.
Rachel A. Whitmer, Ph.D., of Kaiser Permanente,
Oakland, Calif., presented the findings of the study at a JAMA media
briefing at the National Press Club in Washington, D.C.
Dr. Whitmer and colleagues conducted a study to
determine whether prior episodes of hypoglycemia that required
hospitalization or emergency department (ED) visits are associated with
an increased risk of dementia. The study, that included 22 years
(1980-2002) of follow-up for hypoglycemic episodes and more than 4 years
(starting in 2003) of follow-up for diagnosis of dementia, included
16,667 patients with type 2 diabetes (average age, 65 years).
The researchers found that a total of 1,822
patients (11 percent) had a diagnosis of dementia and 1,465 patients
(8.8 percent) had at least 1 episode of hypoglycemia; 250 patients had
both dementia and at least 1 episode of hypoglycemia (16.95 percent).
Age-adjusted incidence rates of dementia by
frequency of hypoglycemic episodes were significantly elevated for
patients with at least one episode compared with patients with no
episodes.
"Specifically, we observed a 2.39 percent increase
in absolute risk of dementia per year of follow-up for patients with
history of hypoglycemia, compared with patients without a history.
Although this 1-year absolute risk difference is modest, the cumulative
effects would be sizeable," the authors write.
Compared with patients with no hypoglycemia,
patients with single or multiple episodes had a graded increase in risk
of dementia. Patients with 1 hypoglycemic episode had a 26 percent
increased risk; 2 episodes, an 80 percent increased risk; and 3 or more
hypoglycemic episodes were associated with nearly double the risk for
dementia.
"Our results suggest that hypoglycemic episodes
severe enough to require hospitalization or an ED visit are associated
with increased risk of dementia, particularly for patients who have a
history of multiple episodes," the researchers write.
"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.
Pharmacologically induced severe hypoglycemia may be associated with
neurological consequences in an older population already susceptible to
dementia. More scientific studies examining hypoglycemia and cognitive
performance and brain-imaging sequelae in populations of older patients
with type 2 diabetes are needed."
