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

Journal article

Objective

To assess the diagnostic accuracy of glycated haemoglobin A1c (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 ≥48 mmol/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 12,925 participants, were included. Against the OGTT, HbA1c ≥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, HbA1c ≥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 HbA1c, against the OGTT, was at the 42 mmol/mol (6.0%) cut-off.

Conclusion

In Africa, the HbA1c ≥48 mmol/mol (6.5%) cut-off may miss almost half of the individuals with T2D based on blood glucose measures.

Authors: Chivese, T; Hirst, J; Matizanadzo, JT; Custodio, M; Farmer, A

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: Wiley
• Journal: Diabetic Medicine
• Volume: 39
• Issue: 4
• Article number: e14754
• Place of publication: England
• Publication date: 2021-12-08
• Acceptance date: 2021-11-29
• DOI: 10.1111/dme.14754
• EISSN: 1464-5491
• ISSN: 0742-3071
• Pmid: 34854127
• Language: English
• Keywords: diagnostic accuracy; specificity; sensitivity; type 2 diabetes mellitus; glycated haemoglobin A1C; Africa; FFR