Diagnostic Utility of HbA1c Compared with Fasting Plasma Glucose for Early Detection of Type 2 Diabetes Mellitus

Abstract

Background: Type 2 diabetes mellitus is a major public health problem and early detection is essential to prevent long-term microvascular and macrovascular complications.

Objective: To compare the diagnostic utility of HbA1c with fasting plasma glucose for the early detection of type 2 diabetes mellitus.

Methodology: This descriptive cross-sectional study was conducted in the Department of Medicine in Collaboration with Biochemistry and Clinical Pathology, Allama Iqbal Teaching Hospital, DG Khan/ DG Khan Medical College DG Khan from October 2024 to June 2025, included 125 adult patients who presented for diabetes screening or evaluation of raised blood glucose levels. Demographic and clinical information including age, gender, body mass index, family history of diabetes, hypertension, and smoking status were recorded.

Results: The mean age of participants was 46.8 ± 11.7 years, and the mean body mass index was 28.4 ± 4.6 kg/m². There were 70 males (56.0%) and 55 females (44.0%). Based on fasting plasma glucose criteria, 39 patients (31.2%) were diabetic, 43 (34.4%) were prediabetic, and 43 (34.4%) were non-diabetic. Based on HbA1c criteria, 45 patients (36.0%) were diabetic, 47 (37.6%) were prediabetic, and 33 (26.4%) were non-diabetic. HbA1c showed a sensitivity of 89.7%, specificity of 88.4%, positive predictive value of 77.8%, negative predictive value of 95.0%, and diagnostic accuracy of 88.8%. A strong positive correlation was observed between fasting plasma glucose and HbA1c levels (r = 0.76, p < 0.001).

Conclusion: HbA1c demonstrated high diagnostic accuracy and substantial agreement with fasting plasma glucose for detecting type 2 diabetes mellitus. It identified a slightly higher proportion of diabetic and prediabetic patients and showed strong correlation with fasting plasma glucose.