Abstract

A COMPARISON BETWEEN HbA1c AND FASTING PLASMA GLUCOSE IN THE DIAGNOSIS OF TYPE 2 DIABETES IN TRINIDAD A HIGH PREVALENCE SETTING

ABSTRACT

Objective: To compare the performance of fasting plasma glucose with HbA1c in the diagnosis of type 2 diabetes in Trinidad. Methods: The study was a community based prospective study of patients referred to a large teaching hospital for the laboratory confirmation of type 2 diabetes. Patients with no prior confirmation of type 2 diabetes mellitus were eligible for entry into the study. On entry into the study venous blood samples were taken for both fasting plasma glucose and HbA1c. Results: Of the 308 patients entered into the study using a FPG>128mg/dl, 102 (33.1%) patients were classified as having type 2 diabetes mellitus. 64 (20.8%) patients were classified as having IFG (110-125mg/dl) and the remaining 142 (46.1%) patients were classified as euglycaemic (plasma glucose 6.5% and were classified as having type 2 diabetes mellitus. In other words more participants (50, 16%) were classified with diabetes using HbA1c. Conclusion: Against an HbA1c >= 6.5% a single fasting glucose >=126 mg/dl, the sensitivity and specificity for detection of diabetes was 57% and 90%, respectively (AUC 0.79). HbA1c has a strong correlation (r=0.72) with fasting blood glucose above 126mg/dl. HbA1c classified more people as diabetic (49.4%) compared to FPG (33.1%).

Keywords: Type 2 diabetes, HbA1c, fasting plasma glucose.