Lancet Study Questions HbA1c Accuracy for Diabetes in India

A new study published in The Lancet Regional Health has raised concerns over the widespread reliance on glycated haemoglobin (HbA1c) testing for diagnosing and monitoring type-2 diabetes in India. The findings suggest that HbA1c may not accurately reflect true blood glucose levels in large sections of the population, potentially misrepresenting the country’s actual diabetes burden.

Why HbA1c May Be Unreliable in India

HbA1c reflects the glycation of haemoglobin over the lifespan of red blood cells and is widely used for diabetes diagnosis and long-term glucose monitoring. However, the study highlights that conditions affecting haemoglobin quantity, structure or lifespan can distort HbA1c values. These include anaemia, haemoglobinopathies and red blood cell enzyme disorders such as glucose-6-phosphate dehydrogenase (G6PD) deficiency, all of which are prevalent in India.

Risk of Misdiagnosis and Delayed Treatment

According to the study, exclusive reliance on HbA1c can lead to both under-diagnosis and over-diagnosis of diabetes. Anoop Misra, corresponding author and chairman of Fortis C-DOC Centre of Excellence for Diabetes, warned that some individuals may be diagnosed much later than appropriate, while others could be incorrectly labelled as diabetic. The study notes that in men with undetected G6PD deficiency, diagnosis may be delayed by up to four years, increasing the risk of long-term complications.

Regional Disparities and Laboratory Challenges

The problem is more pronounced in rural and tribal regions, where anaemia and inherited red blood cell disorders are common. Co-author Shashank Joshi noted that even well-equipped urban hospitals are not immune to HbA1c distortions caused by red blood cell variations. The study also flagged inconsistent laboratory quality control as an additional factor compromising HbA1c accuracy across India.

Important Facts for Exams

• HbA1c reflects average blood glucose over red blood cell lifespan.
• Anaemia and haemoglobinopathies can distort HbA1c values.
• Over 50% of populations in some Indian regions have iron-deficiency anaemia.
• Exclusive HbA1c-based surveys may misrepresent India’s diabetes burden.

Alternative Diagnostic Framework Suggested

The authors propose a resource-adapted diagnostic framework for India. In low-resource settings, they recommend the oral glucose tolerance test (OGTT) using fasting and two-hour post-glucose values, combined with limited self-monitoring of blood glucose and basic haematological screening. In tertiary care centres, a combination of standardised HbA1c testing with OGTT is advised, while continuous glucose monitoring and alternative markers such as fructosamine are suggested for more accurate long-term monitoring.