Doctors flag risks of relying on HbA1c for diabetes diagnosis in India

Doctors warn that heavy reliance on HbA1c for diabetes diagnosis in India may lead to under- or over-diagnosis due to high anaemia and kidney disease burden, urging multiparametric testing

India’s heavy reliance on HbA1c as the primary tool for diagnosing and monitoring diabetes may be leading to misclassification of patients, given the country’s high burden of anaemia, haemoglobin disorders and kidney disease, leading clinicians and diagnostics experts have warned.

 

While HbA1c remains one of the most widely used and internationally accepted markers of long-term glycaemic control, doctors say its limitations are particularly pronounced in the Indian and South Asian context, raising concerns about under- or over-diagnosis when the test is used in isolation.

 

“HbA1c is among the most standardised and extensively studied markers, especially for predicting long-term microvascular and macrovascular complications. However, it is not a perfect test,” said Dr Sanjay Agarwal, head of department – diabetes, obesity and metabolic diseases at Sahyadri Super Speciality Hospital, Pune.

 

 

Dr Agarwal pointed to evidence highlighted in a recent Lancet study by Dr Anup Mishra, Dr Shashank Joshi and others, which outlines how iron-deficiency anaemia, haemoglobinopathies, chronic kidney disease and lack of uniform test standardisation can significantly influence HbA1c values. He added that HbA1c also fails to capture short-term glucose fluctuations, making it insufficient as a standalone diagnostic marker.

 

“There is no single test that can fully capture an individual’s glycaemic status. In clinical practice, HbA1c, glucose monitoring and, where required, oral glucose tolerance tests (OGTT) are used together to arrive at a more accurate assessment,” he said.

 

Call for India-specific thresholds

 

Senior diabetologist Dr Anil Bhoraskar, honorary diabetologist at S L Raheja Hospital, Mumbai, said India needs its own HbA1c reference standards rather than continuing to rely on Western cut-offs.

 

“We need independent HbA1c values derived from large-scale Indian studies involving 20,000–25,000 patients with different haemoglobin profiles,” Dr Bhoraskar said. “HbA1c values are influenced by test kits, anaemia and iron disturbances, which makes interpretation difficult.”

 

Dr Bhoraskar said he avoids relying on HbA1c in many patients except in specific situations such as pregnancy or select clinical conditions. He also cautioned against its use in patients with glucose-6-phosphate dehydrogenase (G6PD) deficiency, which is prevalent in certain populations and can distort HbA1c readings.

 

“For patients who regularly monitor blood glucose using glucometers, averaging daily readings over several weeks can provide information equivalent to HbA1c,” he said.

 

Towards a multiparametric model

 

Clinicians stressed that diabetes is a systemic disease rather than a condition defined solely by blood sugar levels. Dr Bhoraskar said comprehensive evaluation should include renal function tests, lipid profiles, blood pressure assessment, obesity metrics, screening for obstructive sleep apnoea, cardiovascular evaluation and neurological assessments.

 

“Diabetes affects almost every organ from the heart and kidneys to the nerves and brain. A multiparametric assessment is essential,” he said, adding that strict HbA1c targets are still necessary in specific situations such as complex eye surgeries.

 

From a diagnostics perspective, Dr Sujay S Prasad, chief medical officer at Neuberg Diagnostics, said clinical practice has traditionally centred on a single HbA1c value to initiate diabetes management, but this approach is gradually changing.

 

“Lifestyle and dietary interventions have shown that hyperglycaemia can be reversed or controlled before it progresses to overt diabetes. Monitoring blood glucose levels across different times of the day and over longer periods often provides a more reliable picture,” he said.

 

Dr Prasad acknowledged that while awareness exists about falsely low or high HbA1c values due to iron deficiency or G6PD deficiency, such factors may not always be accounted for in routine practice, potentially leading to under-diagnosis or suboptimal management.

 

With India estimated to have more than 140–150 million people with diabetes or undiagnosed hyperglycaemia, experts say national guidelines may need to evolve towards a more comprehensive, multiparametric framework.

 

“HbA1c remains an important tool, but it should be interpreted in conjunction with clinical findings and other investigations,” Dr Agarwal said. “Relying on a single number does not reflect the complexity of diabetes in the Indian population.”