India: Rethinking Diabetes Diagnosis Beyond HbA1c, Plasma Tests Recommended

A significant review published in *The Lancet Regional Health: Southeast Asia* has brought to light serious concerns regarding the reliability of the glycated haemoglobin (HbA1c) test for diagnosing and monitoring diabetes, particularly within the South Asian population, including India. The article, highlighted by India Today, suggests that relying solely on HbA1c may lead to misclassification of diabetes status for millions of Indians, potentially delaying accurate diagnosis and appropriate care. The primary reason for the HbA1c test's reduced accuracy in India stems from the high prevalence of certain medical conditions that can significantly distort its readings. These include anaemia, various inherited blood disorders known as haemoglobinopathies, and glucose-6-phosphate dehydrogenase (G6PD) deficiency. G6PD deficiency, a genetic condition increasing the risk of anaemia, is notably prevalent across India. Such factors can result in misleading estimates of average blood glucose levels, either masking the early stages of diabetes (false negatives) or exaggerating its severity (false positives). Dr. Anoop Misra, the corresponding author of the study and Chairman of Fortis C-DOC Center of Excellence for Diabetes, stated that exclusive reliance on HbA1c can lead to individuals being diagnosed much later than appropriate or even being misdiagnosed altogether. This can compromise the effective monitoring of blood sugar control. The review also points out that variations in laboratory quality control, particularly in low-resource settings, can further compound the issues with HbA1c-based assessments. Given these limitations, the researchers strongly recommend a more comprehensive diagnostic approach. They advocate for combining HbA1c with glucose-based tests such as the Oral Glucose Tolerance Test (OGTT), self-monitoring of blood glucose (SMBG), or continuous glucose monitoring (CGM), depending on available local resources. The Oral Glucose Tolerance Test (OGTT) is specifically highlighted as being more sensitive than HbA1c. This is because OGTT directly measures the body's response to a glucose load, by taking blood samples before and after consuming a sugary drink, rather than relying on an estimation of long-term sugar exposure. This direct measurement helps reduce the chances of false-negative results, which are a concern with HbA1c in affected populations. The Indian Council of Medical Research (ICMR) guidelines for managing type 2 diabetes, published in 2018, acknowledge the limitations of HbA1c use in India and recommend OGTT as the diagnostic test of choice. Other options include fasting plasma glucose (FPG) and random plasma glucose (RPG). The American Diabetes Association (ADA) also recognizes HbA1c, FPG, and 2-h plasma glucose (2-h PG) during an OGTT as valid diagnostic criteria, but advises considering factors that may affect HbA1c accuracy, such as certain types of anaemia. The urgency of this issue is underscored by India's escalating diabetes burden. A highly cited ICMR-led survey, INDIAB, published in 2023, estimated that a staggering 10.1 crore (101 million) Indians are living with diabetes, with an additional 13.6 crore (136 million) classified as prediabetic. The International Diabetes Federation (IDF) also reported nearly 90 million adults with diabetes in India in 2024. This immense scale makes accurate and timely diagnosis paramount for effective public health interventions and individual patient management. Misrepresenting the true burden of diabetes due to flawed diagnostic methods could have significant implications for national health policies, resource allocation, and insurance assessments. The International Diabetes Federation (IDF) had updated its guidelines two years prior, recommending a newer version of the OGTT, specifically a one-hour OGTT after a 75-gram glucose load for individuals at high risk of diabetes. Experts in India are increasingly keen to adopt this recommendation, given that the one-hour glucose value has demonstrated strong predictive capabilities for progression to type 2 diabetes and associated complications. In conclusion, while the India Today headline "Move over HbA1c: The plasma glucose test that could spot diabetes better" may be slightly sensationalized, the core message about the limitations of HbA1c in the Indian context and the enhanced utility of plasma glucose tests is accurately supported by credible medical research. The shift is not about entirely replacing HbA1c but about adopting a more nuanced and combined diagnostic strategy to ensure accurate diabetes detection and management in a country facing a significant diabetes epidemic. This nuanced understanding is crucial for clinicians, policymakers, and the public alike to ensure that the diagnostic tools employed are truly reflective of an individual's glycemic status, ultimately leading to better health outcomes and more effective control of diabetes in India. The news is highly relevant to an Indian audience due to the direct impact on health, diagnostic practices, and public health policies in the country.

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