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A new evidence-based viewpoint published online in Lancet Regional Health: Southeast Asia highlights that the widely used glycated haemoglobin (HbA1c) test, as available in India, may not accurately reflect blood glucose levels for millions of Indians, particularly in regions with high prevalence of anaemia, haemoglobinopathies, and red blood cell enzyme (G6PD) deficiency.
Authors of the study are Anoop Misra, MD – chairman, Fortis C-DOC Center of Excellence for Diabetes, Metabolic Diseases and Endocrinology, New Delhi, Shashank R Joshi, MD DM (Endocrinology) – Department of Endocrinology, Joshi Clinic, Mumbai, Shambo Samrat Samajdar, MD DM (Clinical Pharmacology) – Department of Out-Patient Clinic, Diabetes and Allergy-Asthma Therapeutics Specialty Clinic, Kolkata, Dr. Naval K Vikram, MD, Professor of Medicine, All India Institute of Medical Sciences, New Delhi.
Led by Professor Anoop Misra and collaborators, the review questions reliance on HbA1c as a sole diagnostic or monitoring tool for type 2 diabetes in South Asia. HbA1c measurements primarily reflect the glycation of haemoglobin. Any condition that affects the quantity, structure, or lifespan of haemoglobin—such as anaemia, haemoglobinopathies, or other red blood cell disorders—can distort HbA1c values and lead to misleading estimates of average blood glucose.
“Relying exclusively on HbA1c can result in misclassification of diabetes status. 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,” said Professor Anoop Misra, corresponding author and chairman of Fortis C-DOC Center of Excellence for Diabetes.
Shashank Joshi, co-author from Joshi Clinic, Mumbai, added, “Even in well-resourced urban hospitals, HbA1c readings can be influenced by red blood cell variations and inherited haemoglobin disorders. In rural and tribal areas, where anaemia and red cell abnormalities are common, the discrepancies may be greater.”
Dr. Shambho Samrat Samajdar, co-author from Kolkata, emphasized a comprehensive approach, stating, “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.”
Key findings from the review include:
HbA1c may under- or overestimate blood glucose in populations with high rates of low blood counts (anaemia), inherited blood disorders (abnormal haemoglobin), or enzyme problems like G6PD deficiency anaemia, haemoglobinopathies.
In some regions of India (more than 50% population in some regions, data from 2025), people are nutritionally challenged with widespread have iron deficiency anaemia, which can distort HbA1c readings.
This would affect both diagnosis and monitoring thus misleading clinicians.
Reliance on HbA1c alone could delay diagnosis by up to 4 years in men with undetected G6PD deficiency, potentially increasing risk of complications.
In addition, inconsistent quality control across laboratories can further affect HbA1c accuracy, making interpretation challenging.
Public health surveys based solely on HbA1c may misrepresent India’s diabetes burden.
As per recommended approach to glycaemic monitoring, the authors outline a resource-adapted framework for India: in low-resource settings, oral glucose tolerance test (2 glucose values, one fasting and another 2 hours after ingesting 75 gm glucose) for diagnosis, and for monitoring self-monitoring of blood glucose (SMBG, using glucose meters) 2 to 3 times weekly combined with basic hematologic screening (haemoglobin, blood smear) is recommended.
In tertiary care settings, combination of HbA1C (done with standard equipment) with OGTT for diagnosis and for monitoring, continuous glucose monitoring (CGM) with alternative markers like fructosamine.
When needed, comprehensive iron studies, haemoglobin electrophoresis, and quantitative G6PD testing are advised.
The framework emphasizes that monitoring intensity and biomarker selection should be tailored to healthcare resources and patient risk factors, with particular attention to populations where anaemia, haemoglobinopathies, and G6PD deficiency are prevalent.
“In regions where anaemia from various causes is endemic (such as India), glycosylated haemoglobin (HbA1c), being derived from haemoglobin and widely regarded as the gold standard for monitoring diabetes, may yield spurious values; therefore, in many cases, it should be combined with other tests for the diagnosis and monitoring of diabetes,” the study concluded.
Fortis C-DOC Hospital is a 23-bed facility spread over an area of 20,000 square feet at Delhi’s Chirag Enclave. The hospital has been in operation since January 2012 and has emerged as one its kind hospital in North India providing comprehensive treatment, care and management for diabetes, metabolic diseases and endocrine disorders.
The National Diabetes Obesity and Cholesterol Foundation (NDOC), under the leadership of Dr. Anoop Misra at Fortis Hospital New Delhi, has established itself as a pioneering organization in metabolic disease prevention and management. The foundation's work has particularly focused on underprivileged communities, women, and children, conducting groundbreaking research that highlighted high diabetes prevalence and cardiovascular risk in urban slum dwellers.
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