Hypoglycemia raises dementia risk in older diabetics

Physicians should consider screening elderly patients with diabetes for dementia now that a study shows a connection between the two diseases, said Kristine Yaffe, MD, a San Francisco-based behavioral and mental health expert.

If such patients have cognitive impairment, doctors should try to simplify their diabetes regimen and include a family member or another caregiver in the treatment, Dr. Yaffe said. She was principal author of a study published online June 10 in JAMA Internal Medicine, formerly Archives of Internal Medicine.

Simplifying diabetes treatment could include reducing the number of medications a patient takes and being satisfied with decent control of blood glucose levels rather than tight control, Dr. Yaffe said.

She also encourages doctors to be aware that certain diabetes medications have an increased risk of causing hypoglycemia, such as insulin secretagogues and some sulfonylureas. She recommends that doctors consider avoiding those drugs when treating elderly diabetic patients with dementia.

“Older patients with diabetes may be especially vulnerable to a vicious cycle in which poor diabetes management may lead to cognitive decline and then to even worse diabetes management,” said Dr. Yaffe, a professor of psychiatry, neurology and epidemiology at the University of California, San Francisco.

Among elderly people with diabetes, those who are hospitalized for hypoglycemia have a twofold increased risk of developing dementia compared with elderly people who don’t experience a hypoglycemic event, the study said.

One potential reason for the link between the two diseases is that recurrent severe hypoglycemia can cause brain damage, the study authors said.

Elderly people with diabetes who also develop dementia are more likely to be hospitalized for hypoglycemia than are older adults without cognitive impairment, data show.

It’s possible that patients with dementia have trouble following the steps recommended by their physician to manage their diabetes, Dr. Yaffe said.

More research is needed to determine exactly how diabetes and dementia are connected, said Heather M. Snyder, PhD, director of medical and scientific operations at the Alzheimer’s Assn. She said the study findings are particularly important considering the expected surge in Alzheimer’s disease due largely to the nation’s growing elderly population.

The Alzheimer’s Assn. estimates that 5.4 million Americans have Alzheimer’s disease. By 2050, the association predicts that as many as 13.2 million people could have the condition, which is the leading cause of dementia.

“Without additional research to understand the disease process, who is at risk … [and how] to slow the progression of the disease, we will not be able to stem the tide of this growing public health crisis,” Snyder said.

Study computes damage

Researchers for the JAMA Internal Medicine study examined data on 783 older adults with diabetes who participated in the Health, Aging and Body Composition study that began in 1997. Patients were from 70 to 79 years old at the start of the study.

Adults were excluded if they had possible cognitive impairment and if they experienced difficulty performing daily activities, walking a quarter of a mile or climbing 10 steps without resting.

Cognitive impairment was defined as a score of less than 80 on the Modified Mini-Mental State Examination, a screening test for dementia.

Diabetes was identified by patients’ self-report, the patient’s use of hypoglycemia medication, a fasting glucose level of at least 126 mg/dL or a two-hour glucose tolerance test that exceeded 200 mg/dL.

During 12 years of follow-up, researchers found that 61 participants (7.8%) had a reported hypoglycemic event and 148 people (18.9%) developed dementia.

Thirty-four percent of participants who were hospitalized for hypoglycemia developed dementia compared with 17.6% of adults who didn’t have an episode of low blood sugar but still developed dementia, the study said.

Participants with dementia were more likely to experience a severe hypoglycemic event (14.2%) compared with individuals who were cognitively healthy (6.3%) and hospitalized for hypoglycemia, data show.

Similar results were found when researchers adjusted for stroke, hypertension, myocardial infarction and change in cognitive scores during the follow-up period, the study said.

The authors call for further research to identify risk factors and effective management strategies to reduce incidence of hypoglycemia among older adults with dementia and mild forms of cognitive impairment.