The diagnostic accuracy of HbA<sub>1c</sub>, compared to the oral glucose tolerance test, for screening for type 2 diabetes mellitus in Africa—A systematic review and meta‐analysis
Tawanda Chivese, Jennifer Hirst, Joshua T. Matizanadzo, Michael Custodio, Andrew Farmer, Shane A. Norris, Naomi Levitt
Abstract
Abstract Objective To assess the diagnostic accuracy of glycated haemoglobin A 1c (HbA 1c ), compared to fasting plasma glucose (FPG) and the oral glucose tolerance test (OGTT), in screening for type 2 diabetes (T2D) in Africa. Methods We systematically searched databases for studies that compared the HbA 1c to either the OGTT, or the FPG for T2D diagnosis were included. The QUADAS 2 tool was used for assessing the quality of included studies. We used the split component synthesis (SCS) method for the meta‐analysis of diagnostic accuracy studies to pool the studies for meta‐analysis of sensitivity and specificity, primarily at the HbA 1c ≥48 mmol/mol (6.5%) cut‐off and at other cut‐offs. We assessed heterogeneity using the I 2 statistic and publication bias using Doi plots. Results Eleven studies, from seven African countries, with 12,925 participants, were included. Against the OGTT, HbA 1c ≥48 mmol/mol (6.5%) had a pooled sensitivity of 57.7% (95% confidence interval [CI] 43.4–70.9) and specificity of 92.3% (95% CI 83.9–96.5). Against the FPG, HbA 1c ≥48 mmol/mol (6.5%) had a pooled sensitivity of 64.5% (95% CI 50.5–76.4) and specificity of 94.3% (95% CI 87.9–97.5). The highest sensitivity for HbA 1c , against the OGTT, was at the 42 mmol/mol (6.0%) cut‐off. Conclusion In Africa, the HbA 1c ≥48 mmol/mol (6.5%) cut‐off may miss almost half of the individuals with T2D based on blood glucose measures.