In a critical viewpoint published in The Lancet Regional Health – Southeast Asia, leading medical experts are sounding the alarm over the widespread reliance on the HbA1c test for diagnosing and monitoring diabetes in India. The researchers argue that the test—long considered the “gold standard”—frequently provides misleading results due to India’s high prevalence of anemia, genetic blood disorders, and poor laboratory standardization.

While the HbA1c test is convenient because it doesn’t require fasting, it assumes that everyone’s red blood cells live for the same amount of time and glycate (bind with sugar) at the same rate. However, for millions of Indians, this assumption is false.

“The tendency toward oversimplification by both physicians and patients can lead to misinterpretation, particularly in populations with altered erythrocyte dynamics”, said experts.

Three Major Factors Distorting Results

The report identifies several clinical and biological factors that skew HbA1c levels in the Indian population:

• Iron Deficiency Anemia (IDA): Affecting between 25% and 68% of Indian adults, IDA can falsely elevate HbA1c readings, leading to an overestimation of diabetes prevalence.
• Genetic Disorders: Conditions like Sickle Cell Disease and Beta-Thalassemia, which are common in certain regions and tribal populations, shorten the lifespan of red blood cells. This often results in falsely low HbA1c levels, potentially masking active diabetes.
• G6PD Deficiency: This under-recognized enzymatic disorder affects approximately 8.5% of the Indian population. In some carriers, it can reduce HbA1c by nearly 1 percentage point without a change in actual blood sugar, leading to a median delay in diagnosis of over four years.

Beyond biological factors, the study highlights a significant “quality gap” in Indian laboratories. A survey of 147 accredited labs found that while nearly 90% offered HbA1c testing, the methods were poorly standardized. Shockingly, only 70% of the assays used were National Glycohaemoglobin Standardization Programme (NGSP) certified, and participation in proficiency testing was limited.

Given these limitations, the experts advocate for a “multiparametric, risk-stratified approach”. Key recommendations include:

1. Return to the OGTT: The Oral Glucose Tolerance Test (OGTT) should remain the gold standard for diagnosis, especially in rural or tribal areas where blood disorders are endemic.
2. Look at the RDW: Clinicians are advised to check Red Cell Distribution Width (RDW). If it is greater than 17, the HbA1c should be considered unreliable and replaced with glucose-based testing.
3. Use Modern Tools: For monitoring, the report suggests using Continuous Glucose Monitoring (CGM) or alternative markers like Glycated Albumin, which are not affected by anemia or hemoglobin variants.

The experts warn that relying solely on HbA1c for national health data could lead to a massive misallocation of resources and misleading public health assessments. They call for national surveillance programs to ensure all laboratories adopt NGSP-certified methods and for the development of diagnostic tests specifically tailored to the unique biological profile of the Indian population.

Priyanka Dutta