Waist Circumference, Relative Fat Mass Index, and BMI as Classifiers of Diabetes Status: A Comparative, Cross-sectional Analysis in 82 Low- and Middle-Income Countries

OBJECTIVE Waist circumference–based measures can improve diabetes risk assessment beyond BMI. Yet, evidence to guide their integration into screening guidelines in low- and middle-income countries (LMICs) is limited, particularly to assess risk among individuals at intermediate BMI ranges. We evaluated the associations of waist circumference (WC), relative fat mass (RFM), and BMI with diabetes across 82 LMICs. RESEARCH DESIGN AND METHODS Individual-level data were analyzed from nationally representative surveys across 82 LMICs, comprising 598,883 adults aged ≥25 years with a BMI of 18.5–29.9 kg/m2. Associations of anthropometric measures with diabetes were estimated as risk ratios using Poisson regression and area under the curve (AUC), stratified by sex and geographic region. RESULTS Pooled diabetes prevalence was 9.1% (95% CI 8.51–9.68). Overall, risk of diabetes was greatest for WC and RFM at the highest quintile, compared with BMI. The AUC for WC and RFM as a classifier of diabetes status was higher than the AUC for BMI in men (AUC: WC 0.69, RFM 0.69, BMI 0.64) and women (AUC: WC 0.69, RFM 0.69, BMI 0.63). Generally, the AUC for RFM was higher than the AUC for BMI and either higher than or equal to WC across regions and sex. CONCLUSIONS WC and RFM outperformed BMI as classifiers of diabetes status among adults with a BMI of 18.5–29.9 kg/m2 across 82 LMICs. Inclusion of WC-based measures in diabetes screening guidelines could improve timely diabetes detection and resource allocation in LMICs among individuals at intermediate BMI ranges.