A major new review inThe Lancet Regional Healthhas challenged the widespread reliance on the HbA1c blood test for diagnosing and monitoring diabetes, especially in South Asian populations such as Indians. The researchers highlight that conditions commonly found in India—including iron deficiency anaemia, inherited haemoglobin disorders, and glucose-6-phosphate dehydrogenase (G6PD) deficiency—can significantly skew HbA1c readings.

HbA1c estimates average blood sugar levels over several months, but its accuracy depends on normal red blood cell turnover. In people with anaemia or abnormal haemoglobin variants, HbA1c may either understate or exaggerate true glucose levels. This distortion can delay diabetes diagnosis by several years in some individuals or incorrectly label others as diabetic.

The concern is particularly relevant for India, where anaemia remains widespread and G6PD deficiency is common in several regions. Variations in laboratory quality control, especially in low-resource settings, further compound the problem.

The authors recommend moving away from exclusive dependence on HbA1c and adopting a combined diagnostic approach. Glucose-based tests such as the oral glucose tolerance test (OGTT), self-monitoring of blood glucose, or continuous glucose monitoring should be used alongside HbA1c, depending on available resources.

The review also supports newer International Diabetes Federation (IDF) guidelines that advocate a one-hour OGTT for high-risk individuals, noting its strong ability to predict future diabetes and related complications.

With India already facing a massive diabetes burden—over 10 crore people with diabetes and nearly 14 crore with prediabetes—the study underscores the need for region-specific diagnostic strategies. Experts say a resource-adapted, personalised approach to diabetes testing is essential to ensure timely diagnosis, accurate monitoring, and better long-term outcomes.