Burden of Diabetes and First Evidence for the Utility of HbA1c for Diagnosis and Detection of Diabetes in Urban Black South Africans: The Durban Diabetes Study

• Published in: PloS one Vol. 11; no. 8; p. e0161966
• Main Authors: Hird, Thomas R, Pirie, Fraser J, Esterhuizen, Tonya M, O'Leary, Brian, McCarthy, Mark I, Young, Elizabeth H, Sandhu, Manjinder S, Motala, Ayesha A
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 25-08-2016; Public Library of Science (PLoS)
• Subjects: Adolescent; Adult; Adults; Age; Aged; Analysis; Biology and life sciences; Black People - statistics & numerical data; Blood Glucose - analysis; Blood pressure; Cost of Illness; Cross-Sectional Studies; Diabetes; Diabetes mellitus; Diabetes Mellitus - blood; Diabetes Mellitus - diagnosis; Diabetes Mellitus - ethnology; Diagnosis; Diagnostic systems; Diagnostic tests; Endocrinology; Epidemiology; Exercise; Fasting - blood; Female; Glucose; Glucose tolerance; Glucose Tolerance Test; Glycated Hemoglobin - analysis; Glycosylated hemoglobin; Hemoglobin; Humans; Laboratories; Male; Measurement; Medical diagnosis; Medicine; Medicine and Health Sciences; Middle Aged; Obesity; Physiological aspects; Population; Population Surveillance - methods; Prevalence; Research design; ROC Curve; Sensitivity; South Africa - epidemiology; Urban Health - statistics & numerical data; Urban Population - statistics & numerical data; Young Adult; South Africa; United Kingdom
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0161966

Glycated haemoglobin (HbA1c) is recommended as an additional tool to glucose-based measures (fasting plasma glucose [FPG] and 2-hour plasma glucose [2PG] during oral glucose tolerance test [OGTT]) for the diagnosis of diabetes; however, its use in sub-Saharan African populations is not established. We assessed prevalence estimates and the diagnosis and detection of diabetes based on OGTT, FPG, and HbA1c in an urban black South African population.
We conducted a population-based cross-sectional survey using multistage cluster sampling of adults aged ≥18 years in Durban (eThekwini municipality), KwaZulu-Natal. All participants had a 75-g OGTT and HbA1c measurements. Receiver operating characteristic (ROC) analysis was used to assess the overall diagnostic accuracy of HbA1c, using OGTT as the reference, and to determine optimal HbA1c cut-offs.
Among 1190 participants (851 women, 92.6% response rate), the age-standardised prevalence of diabetes was 12.9% based on OGTT, 11.9% based on FPG, and 13.1% based on HbA1c. In participants without a previous history of diabetes (n = 1077), using OGTT as the reference, an HbA1c ≥48 mmol/mol (6.5%) detected diabetes with 70.3% sensitivity (95%CI 52.7-87.8) and 98.7% specificity (95%CI 97.9-99.4) (AUC 0.94 [95%CI 0.89-1.00]). Additional analyses suggested the optimal HbA1c cut-off for detection of diabetes in this population was 42 mmol/mol (6.0%) (sensitivity 89.2% [95%CI 78.6-99.8], specificity 92.0% [95%CI: 90.3-93.7]).
In an urban black South African population, we found a high prevalence of diabetes and provide the first evidence for the utility of HbA1c for the diagnosis and detection of diabetes in black Africans in sub-Saharan Africa.