Comparison of fasting plasma glucose and haemoglobin A1c point-of-care tests in screening for diabetes and abnormal glucose regulation in a rural low income setting

Abstract

Aims: Glycated haemoglobin (HbA1C) has been suggested to replace glucose tests in identifying diabetes and pre-diabetes. We assessed agreement between fasting plasma glucose (FPG) and HbA1C rapid tests in classifying abnormal glucose regulation (AGR), and their utility for preventive screening in rural Africa.

Methods: A population-based survey of 795 people aged 35-60 years was conducted in a mainly rural district in Uganda. FPG was measured using On-Call® Plus glucometers, and classified using World Health Organization (WHO) and American Diabetes Association (ADA) criteria. HbA1C was measured using A1cNow® kits and classified using ADA criteria. Body mass index and blood pressure were measured. Percentage agreement between the two tests was computed.

Results: Using HbA1C, 11.3% of participants had diabetes compared with 4.8% for FPG. Prevalence of HbA1C-defined pre-diabetes (26.4%) was 1.2 times and 2.5 times higher than FPG-defined pre-diabetes using ADA (21.8%) and WHO (10.1%) criteria, respectively. With FPG as the reference, agreement between FPG and HbA1C in classifying diabetes status was moderate (Kappa=22.9; Area Under the Curve (AUC)=75%), while that for AGR was low (Kappa=11.0; AUC=59%). However, agreement was high (over 90%) among negative tests and among participants with risk factors for type 2 diabetes (obesity, overweight or hypertension). HbA1C had more procedural challenges than FPG.

Conclusions: Although low in the general sample, agreement between HbA1C and FPG is excellent among persons who test negative with either test. A single test can therefore identify the majority at lower risk for type 2 diabetes. Nurses if trained can conduct these tests.

Keywords: Abnormal glucose regulation; Diabetes; Early detection; Fasting plasma glucose; Haemoglobin A(1C); Percentage agreement.