Type 2 diabetes (T2D) disproportionately affects racial and ethnic minority populations in the United Kingdom (U.K.). Asian and Black populations have two to four times the T2D prevalence compared to White populations. Socioeconomic deprivation (SED) affecting lifestyle conditions, and differences in genetic ancestry (GA), are risk factors for T2D health disparities. Examples of SED include food insecurity, exposure to high levels of stress, and lack of access to health care or exercise facilities. Previous studies have found that SED can reduce the effect of GA on T2D status in Black and Hispanic populations in the United States. However, there are no studies that consider the joint impact of SED and GA on T2D disparities.
An NIMHD-supported study aimed to understand the combined effects of SED and GA on T2D disparities in the U.K. The study included 474,184 adults between 40 and 70 years of age enrolled in the U.K. Biobank between 2006 and 2010, of which 5.9% had T2D. Researchers used the Townsend deprivation index to measure SED, which incorporates unemployment, non-car ownership, non-home ownership, and household crowding. By clustering genetic principal components, researchers were able to create GA groupings—African, European, and South Asian—to capture the genetic diversity among the study cohort. Together, the data was analyzed to determine whether severity of SED (low, medium, or high) and/or GA are associated with T2D prevalence within self-reported Asian, Black, and White populations in the U.K.
The study investigators identified that the prevalence of T2D was highest among Asian individuals (17.9%) in the U.K., followed by Black (11.7%) and White (5.5%) individuals. Using White Europeans with low SED as a baseline, medium and higher SED levels were associated with increased risk of T2D across all White, African, and South Asian ancestries. However, SED and GA interacted in non-additive ways, yielding group-specific effects of SED on T2D. The effect of SED on T2D risk was greatest for individuals with South Asian and African ancestry, even those with low SED, when compared with low SED White individuals. South Asian individuals with high SED had the greatest overall risk with a reported odds ratio of 7.95 (95% CI, 7.32-8.63).
The study results may be attributed to lifestyle and environmental exposures that often occur with higher SED. For example, SED-related experiences of structural oppression may differ among different populations and increase risk of developing T2D. The findings from this study support the need for community- and population-specific interventions that recognize the importance of SED for T2D risk across different populations in the U.K. Policies that support these interventions may help decrease T2D health disparities.
We would like to acknowledge Janette Norrington, Ph.D., for contributing this Spotlight.