Adiposity and metabolic health in Asian populations: An epidemiological study using Dual X-Ray Absorptiometry

BackgroundDiabetes, cardiovascular disease, and related cardiometabolic disturbances are increasing rapidly in the Asia-Pacific region. We investigated the contribution of excess adiposity, a key determinant of diabetes and cardiovascular risk, to unfavourable cardiometabolic profiles amongst Asian ethnic subgroups. MethodsThe Health for Life in Singapore (HELIOS) Study is a population-based cohort comprising multi-ethnic Asian men and women living in Singapore, aged 30-84 years. We analyzed data from 9,067 participants who had assessment of body composition by Dual X-Ray Absorptiometry (DEXA) and metabolic characterization. We tested the relationship of BMI and visceral Fat Mass Index (vFMI) on cardiometabolic phenotypes (glycemic indices, lipid levels, and blood pressure), disease outcomes (diabetes, hypercholesterolemia, and hypertension), and metabolic syndrome score with multivariate regression analyses. FindingsParticipants were 59.6% female, with mean (SD) age 52.8 (11.8) years. The prevalence of diabetes, hypercholesterolemia, and hypertension was 8.3%, 29% and 18.0%, respectively. Malay and Indian participants had 3-4 folds higher odds of obesity and diabetes, and showed adverse metabolic and adiposity profiles, compared to Chinese participants. Excess adiposity contributed to all adverse cardiometabolic health indices including diabetes (P<0.001). However, while vFMI explained the differences in triglycerides and blood pressure between the Asian ethnic groups, increased vFMI did not explain higher glucose levels, reduced insulin sensitivity and risk of diabetes amongst Indian participants. InterpretationVisceral adiposity is an independent risk factor for metabolic disease in Asian populations, and accounts for a large fraction of diabetes cases in each of the ethnic groups studied. However, the variation in insulin resistance and diabetes risk between Asian subgroups is not consistently explained by adiposity, indicating an important role for additional mechanisms underlying the susceptibility to cardiometabolic disease in Asian populations. FundingNanyang Technological University--the Lee Kong Chian School of Medicine, National Healthcare Group, National Medical Research Council, Singapore. Research in context Evidence before this studyWe searched Embase and MEDLINE using MeSH terms and respective alternative terms for ["body fat distribution" OR "visceral adiposity" OR "diagnostic imaging"] and ["metabolic syndrome" OR "diabetes mellitus" OR "hypertension" OR "hyperlipidemia" OR all corresponding phenotypes] from 1946 till 7th August 2023 and identified 456 relevant studies. Overall, there have been substantial attempts to characterize the impact of adiposity quantified with imaging techniques on cardiometabolic health. However, most works focused on validating novel adiposity indices (such as body shape index) or metabolic biomarkers (such as cytokines), and rarely provided insights on the contribution of excess visceral adiposity across cardiometabolic phenotypes. Some investigations focused on delineating the effect of various fat depots in the viscera on insulin resistance. Very few studies evaluated health disparity across populations; Nazare et al. characterized the impact of visceral vs. subcutaneous fat measured using Computed Tomography on various cardiometabolic outcomes across major ethnic groups in United States. In summary, it remains unclear how visceral adiposity contributes to differences in cardiometabolic health burden across large Asian ethnic groups. Added value of this studyOur multi-ethnic population cohort (n=9,067) included standardized assessments of people of Chinese, Malay, and Indian ancestries living in shared environment, bringing relevance to a wide spectrum of global Asian diaspora. We used the whole-body DEXA-based quantification of visceral fat mass which enables separate assessments of visceral adiposity and overall body fat. We show that there are major differences in adiposity and metabolic health between the Chinese, Malay, and Indian Asian people we studied, and that adiposity makes an important contribution to metabolic health in all three of these Asian ethnic subgroups. However, we also show that excess visceral adiposity only partially explains the difference in diabetes, insulin resistance and related metabolic disturbances between major Asian ethnic subgroups, indicating the presence of additional pathophysiological processes that remain to be identified. Implications of all the available evidenceExcess visceral adiposity is an important contributor to cardiovascular and metabolic health in Asian populations. Strategies to reduce excess adiposity, in particular visceral fat, in Malay and Indian subgroups offer opportunities for major improvements in cardiometabolic health in Asian people, who account for [~]60% of the global population. The difference in diabetes, insulin resistance and related metabolic disturbances between major Asian ethnic subgroups remains unexplained, providing the motivation for further research to identify additional pathophysiological processes underlying these leading global diseases.