Overall Inequalities in Diabetes Incidence Improves for Race, Ethnicity in Recent Years, Though Still Persisting

In a large nationally, representative study, investigators at the CDC aimed to examine trends between racial, ethnic, and socioeconomical status inequalities for individuals diagnosed with diabetes, both incidence and prevalence, in the United States from 2008 until 2021. They were able to monitor inequalities over time and account for changes in population size over time.

“We found that the overall inequalities of diabetes incidence improved for race, ethnicity, and education, but they still persisted,” Ryan Saelee, MPH, PhD, an epidemiologist at the CDC, said in a session at the American Diabetes Association 83rd Scientific Session on June 23, 2023. “An important factor, which may explain this, could be the faster rate of decline in diabetes incidence in disproportionately affected groups.”

Saelee added the prevalence of undiagnosed diabetes in earlier years in racial and ethnic minorities and lower education groups could lead to a decline in incidence over time. Additionally, Saelee said that the decline could also be due to the Affordable Care Act of 2010, which increased access to patient in more recent years.

However, investigators also found that income-related inequalities increased in prevalence over time.

Investigators of the study gathered data from the 2008 to 2019 National Health Interview Survey, including individuals who were aged 18 years and older. All data were self-reported, according to Saelee.

Saelee added that individuals who were Hispanic, non-Hispanic Asian, non-Hispanic Black, and non-Hispanic White were included in the study, adding that other ethnic and racial groups were not included due to too small of a sample size.

For socioeconomical status, investigators also included education and family poverty-to-income ratio.

To measure inequality, Saelee said that they used the between group variance, which is the variance that would exist if individuals had the same probability of diabetes according to their ethnic and racial group. A larger between group variance is representative of greater inequality, with 0 indicating no inequality.

Investigators also used the slope index of inequality, representing the difference of prevalence or incidence between those in high and low socioeconomic status subgroups. A negative slope index of inequality indicated a higher concentration of diabetes in the lowest subgroup, with 0 representing no inequality.

Both the between group variance and the slope index of inequality were calculated by year. The average annual percent change in prevalence and incidence, between group variance, and slope index of inequality were also calculated for each subgroup to determine treads overtime.

In an age-adjusted analysis of the prevalence and incidence of diagnosed diabetes, there were no significant trends in prevalence from 2008 to 2021 in the United States, while there was a significant decrease in the number of incidences in the same time period, according to Saelee.

However, in the age-adjusted analysis by race and ethnicity, there was a significant increase in prevalence for non-Hispanic Asian adults. The largest decreases in incidence were seen among Hispanic adults, followed by non-Hispanic Black adults, and non-Hispanic White adults.

For education, there was a significant increase in prevalence for those who had less than high school education and some college education or an associate degree. For incidence by education, there was a significant decline for all education levels.

Investigators also found that for family poverty-to-income ratio there was a significant increase for those with less than 1 in prevalence, but a significant decrease in incidence for all groups except for those with a family poverty-to-income ratio between 1.0 and 2.9.

Data for the between group variance indicated no significant change for prevalence, but a significant decrease by racial and ethnic group for incidence of inequality. The slope index of inequality was not significant for the prevalence due to education while there was a significant decrease in inequality over time for incidence.

The slope index of inequality for poverty to income ratio significantly increased for prevalence, which indicates the prevalence of inequality over time, and was not significant for incidence.

Saelee added that to continue these trends of reductions, expanding access to lifestyle change interventions that focus on racial and ethnic groups could be important due to low participation of these groups.

“Future research could focus on identifying factors driving these trends, including the contribution of morbidity and mortality,” Saelee said in the presentation.

Reference

Saelee, R. Trends in Racial, Ethnic, and Socioeconomic Inequalities in Diagnosed Diabetes Prevalence and Incidence among U.S. Adults, 2008–2021. American Diabetes Association Scientific Session. June 23, 2023. Accessed June 28, 2023.