A Comparative Study of HbA1c and Fasting Plasma Glucose in Annual Health Check-Up Participants

Jirasak Piyapromdee; Nattakarn Suwansaksri; Manthana Mitchai

doi:10.64960/srimedj.v41i2.268381

Authors

Jirasak Piyapromdee Internal Medicine Department, Khon Kaen Hospital, Mueang Khon Kaen District, Khon Kaen Province, Thailand 40000
Nattakarn Suwansaksri Internal Medicine Department, Khon Kaen Hospital, Mueang Khon Kaen District, Khon Kaen Province, Thailand 40000
Manthana Mitchai Clinical Pathology Department, Khon Kaen Hospital, Mueang Khon Kaen District, Khon Kaen Province, Thailand 40000

DOI:

https://doi.org/10.64960/srimedj.v41i2.268381

Keywords:

FPG, HbA1c, diagnosis of diabetes, hemoglobinopathies

Abstract

Background and Objective: The number of diabetes patients is escalating worldwide. Currently criterion for diagnosing diabetes used fasting plasma glucose or HbA1c. In Thailand, especially the northeast region had high prevalence of HbE. Hemoglobinopathies affect the immunoassays used for HbA1c measurement. In this study, we evaluate the concordance between HbA1c and FPG criteria in the diagnosis of diabetes and explores the prevalence of hemoglobinopathies that may affect HbA1c interpretation.

Methods: A cross-sectional analytical study was conducted on Khon Kaen Hospital staff undergoing annual health check-ups between September and December 2018. Total 893 participants were evaluated both FPG and HbA1c. Statistical analyses were performed using Stata version 6.0 by percentages, means, standard deviations, Pearson Chi-square test, two-tailed tests, and logistic regression.

Results: A total of 893 participants, 57.7% were female, mean ages of 47.6 years, and mean BMI was 24.5 kg/m². Most participants had no underlying disease (78.5%) and were not taking medication regularly (89.5%). When using FPG criteria, the prevalence of diabetes was 4.6% and prediabetes was 13.2%. There were relatively higher prevalence using HbA1c criteria, with diabetes was 10.1% and prediabetes was 18.0%. However, the correlation between these 2 diagnostic criteria was fair by kappa coefficient of 0.38, 95%CI; 0.35 to 0.40. Prevalence of hemoglobinopathies was 37.8% with high prevalence of homozygous Hb E (3.6%) and Hb E trait (30.2%). Diabetes diagnosis did not differ significantly by hemoglobinopathy status for both FPG (OR 1.29; 95% CI 0.67–2.47, p=0.44) and HbA1c (OR 1.61; 95% CI 0.85–3.05, p=0.15) criteria.

Conclusions: HbA1c and FPG showed fair to moderate agreement for diabetes diagnosis, unaffected by hemoglobinopathy status. However, due to the high prevalence of HbE and higher costs, HbA1c is more suitable as a confirmatory test than a screening tool.

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