Relationship between diabetes risk and admixture in postmenopausal African-American and Hispanic-American women

Abstract

Aims/hypothesis Type 2 diabetes is more prevalent in African-Americans (AFAs) and Hispanic-Americans (HAs) than in European-Americans. We assessed whether continental admixture was correlated with diabetes risk in these high-risk groups. Methods We estimated the proportion of sub-Saharan African (AFR), Amerindian (AMI) and European admixture using 92 ancestry-informative marker genotypes in 16,476 AFA and HA women from the Women's Health Initiative. Cox regression models were used to examine the association between admixture and diabetes risk, with and without accounting for socioeconomic status (SES) and adiposity measurements. Results AFR admixture was significantly associated with diabetes risk in AFA women when adjusting for entry age, neighbourhood SES and BMI or waist/hip ratio (WHR) (all p<0.0001). In HA women, AMI admixture had significant associations with diabetes risk that remained significant after adjustment for SES and BMI (all p<0.0005). In both AFAs and HAs, SES showed significant negative associations while BMI or WHR had significant positive associations with diabetes risk, with and without adjustment for genetic admixture. Conclusions/interpretation In AFAs, admixture, SES and BMI/WHR each independently contribute to diabetes risk after accounting for each of the other factors; in HAs, admixture, SES and BMI each independently contribute to diabetes risk after accounting for each of the other factors, whereas admixture is not significantly associated with diabetes risk after accounting for SES and WHR. The findings emphasise the importance of considering both genetic and environmental causes in the aetiology of type 2 diabetes.

The contribution of biogeographical ancestry and socioeconomic status to racial/ethnic disparities in type 2 diabetes mellitus: results from the Boston Area Community Health Survey

“…In our unadjusted estimates of the effect of BGA we found that having 100% African ancestry versus 100% European ancestry conferred a 1.5 fold risk of T2DM. Due to the conflicting findings regarding BGA to date, the finding that socioeconomic status explains a large proportion of this association agrees with some studies [29, 30, 32] but is in contrast with others [6, 31, 32]. …”

“…While BGA and race/ethnicity are constant, the effects of socioeconomic and lifestyle/behavioral factors may be fine-tuned in a proportional hazards regression model. However, our study does provide evidence for a temporal effect between SES and diabetes incidence whereas many studies of BGA have been limited to cross-sectional [6, 30, 31] or limited measures of SES [30–32]. Finally, although the sample is geographically limited to Boston, Massachusetts, the BACH Survey sample has been compared to other large regional (Behavioral Risk Factor Surveillance System) and national (the National Health and Nutrition Examination Survey) on a number of socio-demographic and health-related variables.…”

“…To our knowledge, this is the first study to report the effects of BGA in a large cohort of Black, Hispanic, and White men and women. Most of the literature on the effects of BGA on T2DM have been restricted to one racial or ethnic group, such as African Americans [6] or Hispanics [30, 31] with the exception of the WHI [32]. Limiting the sample to one racial/ethnic group may restrict on the cultural, social, and economic factors that most directly appear to influence T2DM.…”

“…In contrast, a study of Puerto Rican participants living in the continental US showed a negative association between African ancestry and prevalent T2DM [31]. In one of the few studies to examine the associations between ancestry and diabetes risk among African and Hispanic Americans, the Women’s Health Initiative (WHI) found that ancestry was significantly associated with diabetes risk, but that socioeconomic factors attenuated the effects among Hispanic but not African American women [32]. …”

Relative Contributions of Socioeconomic, Local Environmental, Psychosocial, Lifestyle/Behavioral, Biophysiological, and Ancestral Factors to Racial/Ethnic Disparities in Type 2 Diabetes

“…Many factors have been identified as contributing to these disparities (4), including variations in lifestyles and behaviors, biophysiological, psychosocial, sociodemographic, and environmental factors and biogeographic ancestry (BGA) (5,6). Research to date, however, has largely focused on individual risk factors in isolation, and the relative contribution of these influences have not been identified (4).…”