CDC Study: Income-Related Inequalities Widening in Diabetes

Diabetes was more prevalent among lower-income populations from 2001-2018, particularly for females and people ages 45-64, according to a CDC study.

Assessing income-related inequalities using the Concentration Index indicated that diabetes was concentrated among low-income groups across the 18-year study period, reported Yu Chen, PhD, of the National Center for Chronic Disease Prevention and Health Promotion and the Division of Diabetes Translation in Atlanta.

The Concentration Index ranges from -1 to 1, with negative values demonstrating concentration among lower-income groups. For the overall population of diabetes patients, values hovered between -0.1 and -0.2 throughout the study period, according to the findings presented at the American Diabetes Association (ADA) virtual meeting.

Females manifested a lower index score than males for every year, they reported, while people ages 45-64 consistently showed the lowest score among age cohorts, while scores for the cohort ages 18-44 varied.

The researchers drew from the National Health Interview Survey, limiting the study population to adults diagnosed with diabetes by healthcare professionals outside of pregnancy. Trends were assessed using Joinpoint regression software.

“This research suggests addressing factors early and developing and scaling effective type 2 diabetes prevention interventions among lower-income populations can help reduce diabetes inequalities,” Chen said in an ADA press release.

Chen’s group also found that income, obesity, physical activity levels, and race/ethnicity were key contributing factors to diabetes prevalence inequality “at almost all time points.”

Previous research has shown income “is always one key factor that will affect health,” Chen told MedPage Today. Other work has shown that low-income populations are more likely to be obese, and obesity is often correlated with low levels of physical activity.

Over the full study time span, changes in income, age, and obesity were the “main factors explaining the changes in diabetes inequalities,” Chen reported, citing the combined analyses of data spanning 2001-2011 and 2012-2018.

The researchers also found that while income-related inequalities decreased by a mean 2.5% annually from 2001-2011 (P=0.01) overall, they widened from 2011-2018 by 4.7% annually (P=0.004).

Among females, these inequalities decreased by 2.5% annually from 2001-2012 (P=0.02), but then increased by 4.7% from 2013-2018 (P=0.1). The same trend among males was not statistically significant for either time span, they reported. Also, inequalities increased among each age group studied from 2001-2018 (P<0.05), they stated.

The researchers called for future studies to examine factors leading to inequalities in diabetes prevalence, according to the ADA release. Chen told MedPage Today that her group does not have such studies in development, but suggested that age and income effects should be evaluated more closely as many studies have been done on the effects of physical activity and obesity on diabetes prevalence.

The ADA release noted that U.S. diabetes prevalence has increased over the past 2 decades, disproportionately impacting low-income populations. For example, between 2011 and 2014, the relative increase in diabetes prevalence was 40.0%, 74.1%, and 100.4% for those classified as middle income, near-poor, and poor, respectively, versus those with high income.