Lara Dugas
AXA Research Chair of Non-Communicable Disease Epidemiology; University of Cape Town
Lara Dugas, PhD, MPH, FTOS is the AXA Research Chair in Non-Communicable Disease Epidemiology, hosted at the University of Cape Town (2021-2026), and an Associate Professor of Epidemiology in the Department of Public Health Sciences, Parkinson School of Health Sciences and Public Health, Loyola University Chicago. She received her doctorate in Exercise Physiology from the University of Cape Town, South Africa. In 2007 she joined Loyola University Chicago, utilizing her training in the measurement of human metabolism, including whole body energy expenditure, diet and physical activity monitoring. In 2011, she completed her masters in Clinical Research Methods and Epidemiology, and in 2013 was awarded her Masters of Public Health, both from Loyola University Chicago. As the project coordinator on a large international study investigating the effects of diet and physical activity in 2,500 adults of African-origin (NIH R01-DK070853), she became interested in the role of intermediary metabolites, including metabolite profiles and short chain fatty acids derived from the gut microbiota, and chronic diseases, such as obesity and diabetes in populations of African-origin. The 5 populations span the epidemiologic transition, and include the US, South Africa, Ghana, Jamaica and Seychelles. In 2017, she was awarded her first federal funding to explore the role of the gut microbiota, short chain fatty acids and obesity in the same 5 international populations (NIH R01 DK111848), and in 2019 expanded this work to include the role of the sleep metabolism, circadian rhythm and cardiometabolic risk in populations of African-origin.
Abstract
Background: 17% of African American’s have diabetes (T2D) and are 1.5 times as likely to have T2D compared to whites. This is consistent in African-origin people living outside of the US. The IDF estimates that by 2045 there will be over 1.1 billion people living in Sub-Saharan Africa with T2D.
Methods: In this longitudinal study of African-origin adults spanning the epidemiologic transition, we collected demographic’s, anthropometry, and stool samples from 1,578 participants across 5 countries (Ghana, South Africa, Jamaica, Seychelles, and US). Gut bacterial diversity and composition were assessed by sequencing 16S rRNA gene libraries.
Results: Over 10 years, the prevalence of obesity more than doubled among the Ghanaians (9.8-22.4%), which was associated with a more than a quadrupling of T2D (1.0-11.6%). While the prevalence of obesity only increased slightly in the US (52.4-64.0%), the prevalence of T2D more than doubled (9.6-18.2%). Both Alpha (Shannon diversity index: p<0.05) and Beta diversity (Unweighted Unifrac: p<0.001) were highest among Ghanaians and lowest in the US. Random forest classification by area under the receiver operating characteristic curve (AUROC) revealed that the composition of the microbiota successfully predicted T2D status (macro-average AUROC=0.65). Amplicon sequence variants (ASVs) belonging to Prevotella, and Clostridiaceae were more relatively abundant in participants without T2D, while T2Ds had higher relative abundance of ASVs related to Megasphaera.
Conclusions: We confirm previous research reporting associations between gut microbiota and T2D but in an understudied population of African-origin adults. While, the gut microbiota was associated with T2D status, the direction of this relationship is unclear, paving the way for future studies to understand the impact of epidemiologic transition on T2D risk.