Study illuminates ethnic disparities in diabetes and cognitive impairment

A new study finds that decreasing the disparities in rates of type 2 diabetes among Whites, Blacks and Hispanics could eliminate some racial and ethnic disparities in the development of cognitive impairment or dementia. Prior research has shown that type 2 diabetes is a risk factor for all forms of major cognitive impairment, including Alzheimer’s disease.

José Luchsinger, M.D., MPH, study author and associate professor of medicine at Columbia University Medical Center, said that the research team was attempting to show how disparities with regard to one major public health problem, type 2 diabetes, might be leading to disparities in another major public health problem for our aging society, cognitive impairment and dementia (CID). The study appears in the journal Ethnicity & Disease.

A much higher proportion of people who belong to ethnic minorities have type 2 diabetes as compared to White people, he said. Growing evidence also indicates that ethnic minorities are more likely to develop CID.

“Diabetes is a potentially modifiable risk factor for cognitive impairment and dementia. Considering the impact of diminishing this and other modifiable risk factors may be important since you cannot modify some of the other known risk factors: things like your genes, age or, to some extent, your education, ” said first author James M. Noble, M.D., M.S., assistant professor of clinical neurology at Columbia University Medical Center.

The researchers collected data from 941 participants in a longitudinal study who were ages 65 or older and free of CID at the start of the study. Participants disclosed their ethnicity and whether they had diabetes. Overall, 448 patients developed CID over approximately 7 years of follow-up: 31 percent of Whites, 49 percent of Blacks and 56 percent of Hispanics.

In their analysis, the researchers found that type 2 diabetes could be a risk factor for CID, and eliminating ethnic disparities in type 2 diabetes could reduce the relative difference in CID by approximately 17 percent.

“This research is important because it investigates the role of the most common form of diabetes, type 2 diabetes, in the differential development of cognitive impairment among urban older adults of various racial and ethnic groups. Reducing these sorts of health disparities is an important component of the Affordable Care Act,” said Darcy Phelan, DrPH, MHS, an assistant scientist at the Johns Hopkins Bloomberg School of Public Health. She added that the study’s findings require careful interpretation since the researchers relied upon participants’ own reports regarding whether they had diabetes and because a causal link between diabetes and CID is not yet established.