HbA1c of 6.4% is NOT 'almost normal': Why this borderline reading can be a warning sign
An HbA1c of 6.4% may not qualify as diabetes, but it is far from a reading that should be dismissed as “almost normal”. Neurologist Dr Sudhir Kumar explains why this high-end prediabetes reading can signal rising metabolic and cardiovascular risk.
- Sep 5, 2026,
- Updated Sep 5, 2026 1:05 AM IST
An HbA1c reading of 6.4% may fall just below the diabetes threshold, but calling it “almost normal” can be misleading. Neurologist Dr Sudhir Kumar says the reading is at the very upper end of the prediabetes range and should be viewed as a warning sign for future diabetes and cardiometabolic risk.
HbA1c, or glycated haemoglobin, is a blood test that measures the percentage of haemoglobin in red blood cells that has glucose attached to it. Unlike a single blood glucose test, which captures sugar levels at one point in time, HbA1c provides an estimate of average blood glucose levels over roughly the previous two to three months.
This makes the test important because it can identify sustained elevations in blood sugar that may otherwise go unnoticed. According to the thresholds cited by Dr Kumar, an HbA1c of 5.7% to 6.4% is classified as prediabetes, while 6.5% or above meets the diagnostic threshold for diabetes.
Why 6.4% is different from 5.4%
Dr Kumar points out that HbA1c should not be viewed as a simple switch that changes from “normal” to “diabetes” at 6.5%. Metabolic risk generally increases as HbA1c rises.
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“So 6.4% is very different from 5.4%,” he said, adding that cardiovascular risk can begin to rise before diabetes develops.
A large meta-analysis involving more than 10 million people found that prediabetes was associated with an approximately 16% higher risk of coronary heart disease, 14% higher risk of stroke and 15% higher risk of cardiovascular disease overall. Dr Kumar stressed that these are population-level associations and do not predict an individual's risk.
The concern is also not limited to the possibility of developing diabetes. Prediabetes has been associated with cardiovascular disease, coronary artery disease, stroke, hypertension, dyslipidaemia, visceral obesity and insulin resistance.
Higher risk of progressing to diabetes
The risk of progression also becomes more significant at higher HbA1c levels. Dr Kumar cited studies summarised by the American Diabetes Association showing that people with HbA1c between 6.0% and 6.5% had an approximately 25-50% five-year risk of progressing to diabetes.
This is why an HbA1c of 6.4% should not be dismissed simply because it remains below 6.5%.
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At the same time, prediabetes represents an opportunity to intervene before diabetes develops. Dr Kumar recommends regular exercise, including resistance training, maintaining healthy weight and waist circumference, improving diet quality, getting adequate sleep and controlling blood pressure and LDL/ApoB levels.
He also recommends looking at the broader risk profile. Someone with an HbA1c of 6.0%, high blood pressure, elevated ApoB and abdominal obesity could have substantially greater cardiovascular risk than someone with the same HbA1c but without those additional risk factors.
The key message, according to Dr Kumar, is that 6.4% is not diabetes, but it is not “nothing” either. Instead of waiting for HbA1c to cross 6.5%, monitoring and lifestyle changes during the prediabetes stage can provide an opportunity to reduce future metabolic, heart and brain health risks.
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An HbA1c reading of 6.4% may fall just below the diabetes threshold, but calling it “almost normal” can be misleading. Neurologist Dr Sudhir Kumar says the reading is at the very upper end of the prediabetes range and should be viewed as a warning sign for future diabetes and cardiometabolic risk.
HbA1c, or glycated haemoglobin, is a blood test that measures the percentage of haemoglobin in red blood cells that has glucose attached to it. Unlike a single blood glucose test, which captures sugar levels at one point in time, HbA1c provides an estimate of average blood glucose levels over roughly the previous two to three months.
This makes the test important because it can identify sustained elevations in blood sugar that may otherwise go unnoticed. According to the thresholds cited by Dr Kumar, an HbA1c of 5.7% to 6.4% is classified as prediabetes, while 6.5% or above meets the diagnostic threshold for diabetes.
Why 6.4% is different from 5.4%
Dr Kumar points out that HbA1c should not be viewed as a simple switch that changes from “normal” to “diabetes” at 6.5%. Metabolic risk generally increases as HbA1c rises.
MUST READ: Eli Lilly’s diabetes drug Mounjaro approved to reduce cardiovascular risks
“So 6.4% is very different from 5.4%,” he said, adding that cardiovascular risk can begin to rise before diabetes develops.
A large meta-analysis involving more than 10 million people found that prediabetes was associated with an approximately 16% higher risk of coronary heart disease, 14% higher risk of stroke and 15% higher risk of cardiovascular disease overall. Dr Kumar stressed that these are population-level associations and do not predict an individual's risk.
The concern is also not limited to the possibility of developing diabetes. Prediabetes has been associated with cardiovascular disease, coronary artery disease, stroke, hypertension, dyslipidaemia, visceral obesity and insulin resistance.
Higher risk of progressing to diabetes
The risk of progression also becomes more significant at higher HbA1c levels. Dr Kumar cited studies summarised by the American Diabetes Association showing that people with HbA1c between 6.0% and 6.5% had an approximately 25-50% five-year risk of progressing to diabetes.
This is why an HbA1c of 6.4% should not be dismissed simply because it remains below 6.5%.
ALSO READ: Moderna's cancer vaccine cuts melanoma recurrence risk in early trial: What we know
At the same time, prediabetes represents an opportunity to intervene before diabetes develops. Dr Kumar recommends regular exercise, including resistance training, maintaining healthy weight and waist circumference, improving diet quality, getting adequate sleep and controlling blood pressure and LDL/ApoB levels.
He also recommends looking at the broader risk profile. Someone with an HbA1c of 6.0%, high blood pressure, elevated ApoB and abdominal obesity could have substantially greater cardiovascular risk than someone with the same HbA1c but without those additional risk factors.
The key message, according to Dr Kumar, is that 6.4% is not diabetes, but it is not “nothing” either. Instead of waiting for HbA1c to cross 6.5%, monitoring and lifestyle changes during the prediabetes stage can provide an opportunity to reduce future metabolic, heart and brain health risks.
DO READ: GLP-1 market may be smaller than expected, says Lupin; plans next wave of weight-loss drugs