Associations between obesity indices and both type 2 diabetes and impaired fasting glucose among West African adults: Results from WHO STEPS surveys

Background and aim: Various obesity indices such as BMI, waist circumference (WC), waist-hip ratio, (WHR) and waist-to-height ratio (WHtR) are associated with the risk of type 2 Diabetes Mellitus (T2DM). Given few studies examining the strength of the association in this population, we aimed to identify which obesity indices are most strongly associated with T2DM and impaired fasting glucose (IFG) among adults from five West African countries. Methods and results: Data from 15,520 participants from the World Health Organisation (WHO) STEPs surveys in Burkina Faso, Benin, Mali, Liberia, and Ghana were included in analyses. Multinomial logistic regression was used to calculate the relative risk (RR) per standard deviation (SD) of each anthropometric measure, modelled as both continuous variables and as categorical variables based on established cut-points. In the analyses with continuous variables, the unadjusted RRs for T2DM per SD were 1.30 (1.23, 1.37) for body mass index (BMI); 1.56 (1.46, 1.67) for WC; 2.57 (2.15, 3.09) for WHtR and 1.16 (1.03, 1.31) for WHR. WHtR showed the strongest association with T2DM in all adjusted analyses. For models using categorical variables based on established cut-points, obesity defined using waist circumference (OB-WC) and OB-BMI showed the strongest associations with T2DM, and OB-WHR, the weakest association in all adjusted analyses. Conclusion: WHtR and WC appear to be the indices most strongly associated with T2DM and IFG respectively. Given its simplicity, WC may be the metric that most usefully conveys risk for T2DM in West African adults.