Role of Fasting Plasma Glucose, 2-hour Post Load Plasma Glucose and Glycated Hemoglobin to Diagnose Diabetes Mellitus Among Bangladeshi Adults Attending a Tertiary Care Hospital: Concordance and Discordance

Abstract

Background: Diabetes mellitus (DM) and its associated complication is getting a big concern day by day around the whole world including Bangladesh. Fasting plasma glucose (FPG),2hour post load plasma glucose (2hPG) and glycated hemoglobin (HbA1C) are commonly used diagnostic tools to diagnose diabetes mellitus (DM) but there is disparity and discordance among these three diagnostic tools in detection of DM.

Objective: The aim was to address the issue of concordance and discordance among the three diagnostic tools (FPG, 2hPG,HbA1C) in detection of diabetes mellitus.

Method :This cross sectional analytical study was conducted among the individuals attending for screening of diabetes mellitus to outpatient department of endocrinology, Bangladesh Medical University (BMU), Dhaka during the period of March 2019 to February 2020.A total 1165 subjects were recruited by non-probability sampling technique. Individuals were identified as diabetic by positivity of any of the three tools (FPG,2hPG and HbA1C) and individuals were regarded as nondiabetic by negativity of all three tools simultaneously. Frequency of diabetes mellitus detected by these three tools were compared among them to determine their concordance(agreement) or discordance(disagreement) by Kappa test. Data were analyzed using SPSS.

Results: This study shows that; out of 1165 study subjects, 339(29%) were diabetic by any tool positivity and 826(71%) were non diabetic by all three tools negativity. The frequency of diabetes was found 15.9% detected by FPG, 21.2% detected by 2hPG and 23.2% detected by HbA1C. Here, 2hPG and HbA1C detected almost similar number of diabetic population but FPG underestimates the diagnosis of DM significantly. In agreement test, all three diagnostic tools showed merely good agreement with the lowest kappa value, which was not satisfactory from clinical point of view. In case of missed diagnosis; FPG alone missed 45.5%, 2hPG 27.0% and HbA1c 20.0% of diabetic patients. The rate of missed diagnosis by HbA1c found to be lowest.

Conclusions: DM detection rate was found highest by use of HbA1C and lowest by FPG; on the other hand, FPG showed highest missed diagnosis and HbA1C showed the lowest. No clinically satisfactory agreement (concordance) was found among the three diagnostic tools (FPG,2hPG and HbA1C) for diagnosis of DM.

Bangladesh Medical Res Counc Bull 2025;51(1):33-38