Higher Education, Income Does Not Shrink Disparities for Black Americans

Higher educational attainment and income are widely assumed to lower a person's risk of type 2 diabetes (T2D) and obesity, an assumption now built into some clinical risk calculators. However, a study published in PLOS One found that this protective effect is markedly weaker, absent, or even reversed among nonHispanic Black, Hispanic, and other minoritized adults compared with nonHispanic white and Asian adults.¹

Researchers from Harvard Medical School and Massachusetts General Hospital analyzed adult participants in the National Health and Nutrition Examination Survey (NHANES) from 1999 to 2018 and the All of Us (AoU) cohort, examining whether education and income associate uniformly with T2D and obesity across racial and ethnic subgroups. The findings add to a growing body of literature on so-called "diminished returns" and carry direct implications for how pharmacists and other clinicians interpret socioeconomic status (SES)-adjusted risk tools.¹

What the Study Found

The analysis included 54,991 adults in NHANES and 404,990 adults in AoU, making it one of the larger contemporary examinations of this question. Age-adjusted rates of T2D and obesity were highest among nonHispanic Black, Mexican American, other Hispanic, and other or multiracial participants and among those with lower SES overall. However, the size of the benefit tied to more education or income varied sharply by group.¹

Each one-unit increase in continuous education—roughly 1 to 2 additional years of schooling—was associated with a 12% decrease in T2D prevalence among nonHispanic white (NHW) participants in NHANES (OR, 0.88; CI, 0.85-0.91) but only a 4% decrease among nonHispanic Black (NHB) participants (OR, 0.96; CI, 0.92-0.99). In AoU, the gap was even wider, with a 19% decrease for NHW participants compared with a 6% decrease for NHB participants. Formal interaction testing confirmed that adding race-by-SES interaction terms significantly improved model fit in both cohorts, meaning the difference was not simply statistical noise.¹

The pattern was similar, and in some cases starker, for obesity. In NHANES, higher income was tied to significantly lower obesity odds among NHW participants (OR, 0.97; CI, 0.95-0.996), but that association reversed among NHB participants, whose obesity odds rose with income (OR, 1.05; CI, 1.01-1.08). The authors also noted that Black participants with a college degree had T2D prevalence similar to or higher than white participants who had not finished high school, underscoring that racial disparities in these diseases outweigh the socioeconomic gap within any single racial group.¹

What the Study Authors Believe This Means

The study's authors describe this phenomenon as "marginalization-related diminished returns," a concept documented previously across outcomes including childhood obesity, asthma, and heart disease. They point to potential mechanisms including structural racism, residential segregation that shapes exposure to environmental toxins, chronic stress from discrimination, and cultural or employment-related differences in how education translates into food security.¹

A frequently cited example predates this study in an analysis published in the American Journal of Public Health, which found that a poor white person in a poor neighborhood had more than double the diabetes risk of an affluent white person in an affluent neighborhood, but the comparable gap for Black individuals was only a 17% increase in risk.²

The disparities in this new study track with long-documented federal data. Age-adjusted figures from the National Institute of Diabetes and Digestive and Kidney Diseases show diagnosed diabetes prevalence is highest among American Indian and Alaska Native adults (13.6%), followed by nonHispanic Black adults (12.1%) and Hispanic adults (11.7%), compared with nonHispanic Asian adults (9.1%) and nonHispanic white adults, who have the lowest rate among the groups tracked.³

Nationally, the CDC estimates 40.1 million people, or 12.0% of the US population, had diagnosed or undiagnosed diabetes in 2023, including 28.8 million adults with a diagnosis.⁴ Data from the National Center for Health Statistics further show diabetes prevalence differs by educational attainment, reinforcing that SES and race both independently track with disease burden even before accounting for how they interact.⁵

What This Means for Pharmacists

Pharmacists are often a patient's most frequent point of contact for chronic disease management, and many already work within value-based and social-determinants-of-health (SDOH) frameworks. The American Pharmacists Association has promoted tools within the Pharmacists' Patient Care Process specifically to help pharmacists recognize how SDOH affects a patient's diabetes management.⁶ Health care disparities in diabetes care are commonly classified as racial/ethnic, socioeconomic, and geographical, with certain racial and ethnic groups and lower-income individuals facing heightened risk of diabetes and its complications.⁷

The new findings suggest pharmacists should be cautious about assuming that counseling a patient toward employment, education, or income gains will uniformly translate into lower metabolic disease risk. The study's authors explicitly caution that clinical risk calculators increasingly incorporating SES measures could produce biased estimates if they don't account for this heterogeneity across racial and ethnic groups.¹

REFERENCES

1. Cromer SJ, Gervis JE, Burnett-Bowie S-AM, Patel CJ. Heterogeneous associations of socioeconomic status with metabolic disease in racial and ethnic subgroups in the United States: a cross-sectional cohort study in NHANES and All of Us. PLOS One. 2026;21(7):e0351075. doi:10.1371/journal.pone.0351075

2. Gaskin DJ, Thorpe RJ Jr, McGinty EE, et al. Disparities in diabetes: the nexus of race, poverty, and place. Am J Public Health. 2014;104(11):2147-2155. doi:10.2105/AJPH.2013.301420

3. National Institute of Diabetes and Digestive and Kidney Diseases. Diabetes Statistics. NIDDK. Accessed July 9, 2026. https://www.niddk.nih.gov/health-information/health-statistics/diabetes-statistics

4. Centers for Disease Control and Prevention. National Diabetes Statistics Report. CDC. Accessed July 9, 2026. https://www.cdc.gov/diabetes/php/data-research/index.html

5. Gwira JA, Fryar CD, Gu Q. Prevalence of Total, Diagnosed, and Undiagnosed Diabetes in Adults: United States, August 2021-August 2023. NCHS Data Brief No. 516. National Center for Health Statistics. November 2024. Accessed July 9, 2026. https://www.cdc.gov/nchs/data/databriefs/db516.pdf

6. Pauling EE, Nguyen TT, Valentino AS, Ducker Coleman M. Using the Pharmacists' Patient Care Process to address social determinants of health in patients with diabetes. J Am Pharm Assoc (2003). 2022;62(3):685-692. doi:10.1016/j.japh.2022.01.008

7. Terrie YC. Healthcare Disparities in Diabetes Care. US Pharmacist. 2023;48(5):37-42. Accessed July 9, 2026. https://www.uspharmacist.com/article/healthcare-disparities-in-diabetes-care