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. 2017 Aug 17;12(8):e0182192.
doi: 10.1371/journal.pone.0182192. eCollection 2017.

Discordance in the diagnosis of diabetes: Comparison between HbA1c and fasting plasma glucose

Lan T Ho-Pham  1 , Uyen D T Nguyen  2 , Truong X Tran  2 , Tuan V Nguyen  1   3   4   5
Affiliations

Discordance in the diagnosis of diabetes: Comparison between HbA1c and fasting plasma glucose

Lan T Ho-Pham et al. PLoS One. .

Abstract

Objective: HbA1c has been introduced as a complementary diagnostic test for diabetes, but its impact on disease prevalence is unknown. This study evaluated the concordance between HbA1c and fasting plasma glucose (FPG) in the diagnosis of diabetes in the general population.

Materials and methods: The study was designed as a population based investigation, with participants being sampled from the Ho Chi Minh City, Vietnam. Blood samples were collected after overnight fasting and analyzed within 4 hours after collection. HbA1c was measured with high pressure liquid chromatography (Arkray Adams, Japan). FPG was measured by the hexokinase method (Advia Autoanalyzer; Bayer Diagnostics, Germany). Diabetes was defined as HbA1c ≥ 6.5% or FPG ≥ 7.0 mmol/L. Prediabetes was classified as HbA1c between 5.7% and 6.4%.

Results: The study included 3523 individuals (2356 women) aged 30 years and above. Based on the HbA1c test, the prevalence of diabetes and prediabetes was 9.7% (95%CI, 8.7-10.7%; n = 342) and 34.6% (33.0-36.2; n = 1219), respectively. Based on the FPG test, the prevalence of diabetes and prediabetes was 6.3% (95%CI, 5.5-7.2%; n = 223) and 12.1% (11.1-13.2; n = 427). Among the 427 individuals identified by FPG as "pre-diabetes", 28.6% were classified as diabetes by HbA1c test. The weighted kappa statistic of concordance between HbA1c and FPG was 0.55, with most of the discordance being in the prediabetes group.

Conclusion: These data indicate that there is a significant discordance in the diagnosis of diabetes between FPG and HbA1c measurements, and the discordance could have significant impact on clinical practice. FPG appears to underestimate the burden of undiagnosed diabetes.

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Conflict of interest statement

Competing Interests: The authors have declared that no competing interests exist.

Figures

Fig 1
Fig 1. Relationship between fasting plasma glucose and HbA1c.
The dotted lines represent the threshold for the diagnosis of diabetes by FPG (7 mmol/L) and by HbA1c (6.5%).
Fig 2
Fig 2. Area under the receiver operating characteristic curve for model I (gender, age, body mass index and waist-to-hip ratio; blue line), and model II (age, waist-to-hip ratio, and glucose; red line).
The area under the ROC curve for model I was 0.776, and model II 0.956.
See this image and copyright information in PMC

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