Is the diabetes test inaccurate in India?
New research suggests that the standard diabetes test may not properly measure the blood glucose levels in millions of Indians. The study was published in The Lancet Regional Health: Southeast Asia journal.
But what do we know about the study? Have millions of diabetes patients in India been misled?
Let’s take a closer look
The HbA1c test
First, let’s take a look at the standard diabetes test.
According to MedlinePlus.gov, the haemoglobin A1C (HbA1C) test is used to determine if a person has diabetes. The test measures your blood sugar levels, also known as glucose, over the past two or three months. Glucose is a type of sugar in your blood. Your cells use glucose to make energy.
The test can check your average glucose level for the past three months. This is because glucose sticks to haemoglobin via protein for the duration that the red blood cells live.
These red blood cells usually live for around three months. It does this by measuring the percentage of haemoglobin with glucose attached to your red blood cells. This is because, as your blood glucose levels increase, more and more glucose will attach itself to your haemoglobin.
The HbA1C test can be used to check:
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Type 2 diabetes: When the body does not produce enough insulin or does not use insulin effectively.
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Prediabetes: When blood glucose levels are higher than normal but not enough to be diagnosed as diabetes.
The US Centers for Disease Control (CDC) recommends A1C testing for diabetes and prediabetes if:
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You are over 45
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Are overweight or obese
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Have a parent or sibling with type 2 diabetes
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Suffer from high blood pressure or high cholesterol levels
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Have heart disease or have had a stroke
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Are physically active fewer than three times a week
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Have had gestational diabetes
Doctors may also recommend this test if you have symptoms of diabetes, including:
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Feeling very thirsty
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Urinating (peeing) a lot
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Losing weight without trying
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Feeling very hungry
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Blurred vision
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Numb or tingling hands or feet
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Fatigue
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Dry skin
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Sores that heal slowly
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Having more infections than usual
The test is conducted via a
blood sample that is drawn from your arm using a needle. This is then placed in a vial and sent for analysis.
The test diagnoses diabetes or prediabetes as follows:
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Normal: A1C below 5.7 per cent
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Prediabetes: A1C between 5.7 per cent and 6.4 per cent
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Diabetes: A1C of 6.5 per cent or higher
What we know about the study
Researchers who put together the study in T_he Lancet Regional Health: Southeast Asia_ journal have claimed that the test may not accurately measure blood sugar in vast swathes of the Indian population.
They said this is particularly of concern in areas with a high prevalence of anaemia, haemoglobinopathies, and red blood cell enzyme (G6PD) deficiency, the Lancet study has said.
Essentially, the problem is that the conditions that are prevalent in India impact red blood cells and haemoglobin — which is exactly what the HbA1c test measures.
This is true of:
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Anaemia, particularly the iron-deficient variety
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Inherited haemoglobin disorders such as sickle cell disease and other types
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G6PD deficiency, which is an issue with genetic enzymes
These conditions can affect how long red blood cells live or the amount and structure of haemoglobin, which can, in turn, distort HbA1c levels. This means that some people might wrongly show a lower or higher HbA1c than their true blood sugar level, resulting in doctors missing, delaying or wrongly classifying diabetes.
This can have real-world impacts.
For example, those with undiagnosed G6PD deficiency could see their diabetes diagnosis delayed by an average of four years if doctors use only the HbA1c test.
This can result in treatment starting late and patients suffering eye, heart and kidney problems.
“Relying exclusively on HbA1c can result in misclassification of diabetes status,” Professor Anoop Misra, author of the study and chairman of Fortis C-DOC Centre of Excellence for Diabetes, told New Indian Express. “Some individuals may be diagnosed later than appropriate, while others could be misdiagnosed, which may affect timely diagnosis and management. Similarly, monitoring of blood sugar status may be compromised,” he added.
Things could be even worse outside the big cities.
Business Today quoted the National Family Health Survey-5 (NFHS-5) as saying that over 57 per cent of women and about 25 per cent of men in India are anaemic.
Dr Shashank Joshi, co-author of the study and an endocrinologist from Joshi Clinic, Mumbai, told New Indian Express: “Even in well-resourced urban hospitals, HbA1c readings can be influenced by red blood cell variations and inherited haemoglobin disorders. In rural and tribal areas, where anaemia and red blood cell abnormalities are common, the discrepancies may be greater.”
What do the researchers suggest?
The authors of the study have offered a solution.
They recommend adding other tests to the HbA1c, including:
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Oral glucose tolerance test (OGTT)
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Self-monitoring of blood glucose
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Continuous glucose monitoring (CGM)
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Additional blood tests, including checking for anaemia or G6PD deficiency
They recommended that the standard oral glucose tolerance test — which measures blood sugar after fasting and again two hours after a glucose drink — should remain the standard for diagnosing prediabetes and diabetes.
They added that HbA1c may be used in addition to these other tests.
“We recommend combining HbA1c with glucose-based tests such as the oral glucose tolerance test, self-monitoring of blood glucose, or continuous glucose monitoring, depending on local resources,” the researchers wrote.
Why this matters
The warning comes at a time when India is facing a massive burden of diabetes cases. According to an Indian Council of Medical Research (ICMR)-led survey published in 2023, around 10 crore Indians are suffering from diabetes and 13.6 crore Indians have prediabetes.
With inputs from agencies
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