Relying on HbA1c alone may be giving India an incomplete—and potentially misleading—picture of its diabetes burden.

 

This inference can be drawn from a new evidence-based Viewpoint published online in The Lancet Regional Health: Southeast Asia that is raising serious questions about the reliability of HbA1c, one of India’s most widely used diabetes tests. 

 

The review warns that glycated hemoglobin (HbA1c), a cornerstone of diabetes diagnosis and monitoring, may not accurately reflect blood glucose levels for millions of Indians.

 

Led by Professor Anoop Misra and a team of leading clinicians, the paper highlights how conditions common across India—including anemia, inherited hemoglobin disorders, and glucose-6-phosphate dehydrogenase (G6PD) deficiency—can significantly distort HbA1c readings. 

 

These disorders alter the quantity, structure, or lifespan of red blood cells, directly affecting how hemoglobin becomes glycated and potentially masking true glucose levels.

 

“Relying exclusively on HbA1c can result in misclassification of diabetes status,” said Professor Anoop Misra, corresponding author and Chairman of Fortis C-DOC Center of Excellence for Diabetes. 

 

“Some individuals may be diagnosed later than appropriate, while others could be misdiagnosed, which may affect timely diagnosis and management. Similarly, monitoring of blood sugar status may be compromised.”

 

The authors caution that the implications extend well beyond individual patients. In regions where anemia is widespread—affecting more than half the population in some parts of India—HbA1c may either underestimate or overestimate blood glucose, leading to delayed diagnosis, inappropriate treatment, and flawed public health data.

 

Shashank Joshi, co-author from Joshi Clinic, Mumbai, underscored that the problem is not limited to underserved areas. “Even in well-resourced urban hospitals, HbA1c readings can be influenced by red blood cell variations and inherited hemoglobin disorders. In rural and tribal areas, where anemia and red cell abnormalities are common, the discrepancies may be greater.”

 

The review also points to evidence suggesting that exclusive reliance on HbA1c could delay diabetes diagnosis by up to four years in men with undetected G6PD deficiency—potentially increasing the risk of long-term complications. Variations in laboratory quality control across India further compound the problem, making HbA1c interpretation inconsistent.

 

Dr Shambho Samrat Samajdar, co-author from Kolkata, called for a broader diagnostic lens. “Combining oral glucose tolerance test, self-monitoring of blood glucose, and hematologic assessments provides a more accurate picture of diabetes risk. This approach can help refine public health estimates and guide resource allocation.”

 

To address these gaps, the authors propose a resource-adapted framework for India. In low-resource settings, they recommend oral glucose tolerance testing for diagnosis, alongside regular self-monitoring of blood glucose and basic blood tests to detect anemia and red cell disorders. 

 

In tertiary care centers, HbA1c should be combined with oral glucose tolerance testing, while advanced monitoring tools such as continuous glucose monitoring and alternative biomarkers like fructosamine may offer more reliable insights. When clinically indicated, detailed iron studies, hemoglobin electrophoresis, and quantitative G6PD testing are advised.

 

The authors stress that no single test fits all populations. Instead, diabetes diagnosis and monitoring must be tailored to regional disease patterns, healthcare resources, and individual risk factors—especially in countries like India, where anemia and inherited blood disorders are common.