ANALYSIS OF ETHNIC AND POPULATION-BASED VARIABILITY IN OPTIMAL HBA1C THRESHOLDS AMONG INDIANS AS COMPARED TO GLOBAL RECOMMENDATIONS (ADA, WHO).

Abstract

The HbA1c test provides a convenient, fasting-independent diagnostic tool for type 2 diabetes mellitus. However, ethnic and physiological variations influence glycation rates, making the globally accepted HbA1c threshold of 6.5% potentially less applicable to the Indian population.

Objective:To determine the optimal HbA1c diagnostic cut-off for Indian populations by analyzing regional and ethnic variations, and to compare its accuracy with the ADA-recommended 6.5% threshold.

Materials and Methods:This comparative analytical study included 203 adults from Tata Main Hospital, Jamshedpur, and data from major Indian studies conducted in North (Kumar et al.), South (Mohan et al.), and multicentric cohorts (Manisha Nair et al.). Fasting plasma glucose (FPG), 2-hour OGTT, and HbA1c were measured simultaneously. Diagnostic accuracy was assessed using Receiver Operating Characteristic (ROC) curves and Kappa statistics, with statistical analysis performed using SPSS version 10.

Results:Across regional datasets, the optimal HbA1c cut-off for diagnosing diabetes ranged between 5.8% and 6.3%. The present study identified 6.3% as the most accurate cut-off (sensitivity 84.6%, specificity 87.2%, AUC 0.91). Pooled ROC analysis from all Indian studies showed a combined optimal threshold of 6.0% with AUC 0.89, sensitivity 82.4%, and specificity 85.7%. The ADA cut-off of 6.5%, though more specific (89.4%), exhibited lower sensitivity (74.3%), indicating under-detection in Indian cohorts.

Conclusion:A lower HbA1c diagnostic threshold around 6.0–6.3% provides superior diagnostic balance for Indian populations compared with the ADA criterion, ensuring improved detection and earlier management of diabetes.