The study declined that more than 4000 participants in the Coronary Artery Risk Development in Young Adults (CARDIA) study in their mid-20s who were followed into middle age. This study was published in the Journal of the American Medical Association. Michael P Bancks said, "Findings from the present study support this hypothesis as individual-level and neighbourhood-level social determinants did contribute significantly to disparities in diabetes."

According to the researchers, previous study suggest that living in a disadvantaged neighbourhood, inadequate access to healthcare, and having a low education level can lead to poor health-related behaviors and contribute to worsening biological factors.

Racial Differences in Risk Factors for Diabetes

"The diabetes risk factors that were selected were modifiable, available in the study, known to vary by race in the literature, and categorized into the following groups: biological, neighbourhood, psychosocial, socioeconomic, and behavioral," the researchers explain. They identified 4251 participants in CARDIA who were 18 to 30 years old when they entered the study in four American cities in 1985 to 1986 and had complete data through 2015 to 2016.

At baseline, participants were a mean age of 25 years, half (49%) were black, and 54% were women. On average, blacks had worse socioeconomic status; they were less likely to have completed high school, work, be married, or have parents who completed high school. In addition, blacks were more likely to report that their household had difficulty paying for essentials and were more likely than whites to live in a poor neighbourhood.

They were also more likely to have certain poor health behaviors; they were more likely to be current smokers (32% vs 26%), and black women were less likely to be at least moderately physically active. Racial differences in biological variables included a higher mean body mass index and mean systolic blood pressure in blacks compared with whites. During a mean follow-up of 25 years, 315 blacks and 189 whites developed type 2 diabetes.

After adjusting for age and study location, black women were nearly three-times more likely to develop diabetes than white women (hazard ratio [HR], 2.86; 95% CI, 2.19 – 3.72). Similarly, black men were more likely to develop diabetes than white men (HR, 1.67; 95% CI, 1.28 – 2.17). However, in models that successively adjusted for age and location, then biological, neighbourhood, psychosocial, socioeconomic, and behavioral factors, there were no significant racial differences in the incidence of diabetes. Specifically, in the model adjusted for all variables, black women were not significantly more likely to develop diabetes than white women (HR, 0.79; 95% CI, 0.55 – 1.14).

Similarly, black men were not more likely to develop diabetes than white men (HR, 0.92; 95% CI, 0.62 – 1.38). Authors concludes that differences in traditional variable diabetes risk factors between black and white individuals may contribute to the racial disparity in diabetes occurrence in middle age.