Ancestral and environmental patterns in the association between triglycerides and other cardiometabolic risk factors

Background West Africans and African Americans with substantial (similar to 80%) West African ancestry are characterized by low levels of triglycerides (TG) compared to East Africans and Europeans. The impact of these varying TG levels on other cardiometabolic risk factors is unclear. We compared the strength of association between TG with hypertension, blood pressure, BMI, waist circumference, type 2 diabetes (T2D), and fasting glucose across West African (WA), East African (EA), and European (EU) ancestry populations residing in three vastly different environmental settings: sub-Saharan Africa, United States, and Europe. Methods We analysed data from four cross-sectional studies that included WA in sub-Saharan Africa (n = 7201), the U.S. (n = 4390), and Europe (n = 6436), EA in sub-Saharan Africa (n = 781), and EU in the U.S. (n = 8670) and Europe (n = 4541). Linear regression analyses were used to test the association between TG and cardiometabolic risk factors. Findings Higher adjusted regression coefficients were observed in EU compared with WA ancestry for TG on hypertension (EU beta [95% CI]: 0.179 [0.156, 0.203], WA beta [95% CI]: 0.102 [0.086, 0.118]), BMI (EU beta [95% CI]: 0.028 [0.027, 0.030], WA beta [95% CI]: 0.015 [0.014, 0.016]), and waist circumference (EU beta [95% CI]: 0.013 [0.013, 0.014], WA beta [95% CI]: 0.009 [0.008, 0.009) (all ancestry x trait interaction P-values <0.05), irrespective of environmental differences within ancestry groups. Less consistency was observed among EA. Associations of TG with T2D did not follow ancestry patterns, with substantial variation observed between environments. Interpretation TG may not be an equally strong associated with other established cardiometabolic risk factors in West and East Africans in contrast to European ancestry populations. The value of TG for identifying individuals at high risk for developing metabolic disorders needs to be re-evaluated for African ancestry populations.

Automated summary

West Africans and African Americans with West African ancestry have lower triglyceride levels compared to East Africans and Europeans. This study compared the association between triglycerides and cardiometabolic risk factors among different ancestry populations and found that the association was more consistent in West Africans and Europeans, while it varied in East Africans.