The diagnostic accuracy of HbA1c , compared to the oral glucose tolerance test, for screening for type 2 diabetes mellitus in Africa-a systematic review and meta-analysis.

OBJECTIVE: To assess the diagnostic accuracy of HbA1c , 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 HbA1C 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 HbA1C ≥48mmol/mol (6.5%) cut-off and at other cut-offs. We assessed heterogeneity using the I2 statistic and publication bias using Doi plots. RESULTS: Eleven studies, from seven African countries, with 12925 participants, were included. Against the OGTT, HbA1C ≥48mmol/mol (6.5%) had a pooled sensitivity of 57.7% (95%CI 43.4-70.9) and specificity of 92.3% (95%CI 83.9 - 96.5). Against the FPG, HbA1C ≥48mmol/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 HbA1C , against the OGTT, was at the 42mmol/mol (6.0%) cut off. CONCLUSION: In Africa, the HbA1C ≥48mmol/mol (6.5%) cut-off may miss almost half of the individuals with T2D based on blood glucose measures.