Diagnostic differences in glycemic markers for detecting impaired glucose tolerance in Black African and White European men in the United Kingdom: The SOUL-DEEP cross-sectional study.

Ethnic differences in type 2 diabetes risk highlight the need for accurate detection of impaired glucose tolerance (IGT) across all ethnic groups. This study assessed the sensitivity and specificity of HbA1c, fasting plasma glucose (FPG), and 1-h plasma glucose for identifying IGT in 66 Black African (BA) and 77 White European (WE) men. Participants underwent a 75 g oral glucose tolerance test, and diagnostic performance was evaluated using ROC analyses. One-hour glucose showed the highest sensitivity (BA 77.8%, WE 94.1%) and AUC (0.78), whereas FPG 6.1-6.9 mmol/L had the poorest sensitivity (≤7.4%) and lowest AUC (0.49). HbA1c demonstrated ethnic variation: WHO criteria (6.0-6.4%) were more sensitive but less specific in BA than WE men; ADA criteria (5.7-6.4%) showed reduced specificity in BA men. Optimal cut-points differed by ethnicity for all markers. Findings suggest HbA1c and FPG may inadequately detect IGT, while 1-h glucose offers superior diagnostic performance.