HbA1c: Are you misinterpreting the reading?

HbA1c

isn’t just a number to glance at, compare to standard levels, and decide if someone is diabetic. While that’s often what we do when reviewing a blood sugar profile, the story behind this value runs much deeper.
HbA1c plays a pivotal role in understanding long-term

blood sugar control

and gauging the risk of diabetes-related complications. For those with diabetes, it serves as a guide to tailor treatment plans and maintain glucose within target ranges. For non-diabetics, it can identify prediabetes early, enabling timely lifestyle adjustments or interventions to delay or prevent diabetes.
But is interpreting HbA1c as straightforward as it seems? Or could you be overlooking critical nuances in what this test reveals about your health?

“HbA1c is not a direct assessment of a person’s glucose control”

According to Dr. Paras Aggarwal, Clinical Director & Head Diabetes Obesity & Metabolic Disorders, Marengo Asia Hospital Gurugram, “Hba1c (

glycosylated hemoglobin

) is a metabolic memory test, that gives a mean average indication of up to last 90 days of glucose control. It is not a direct assessment of a person’s glucose control, just tells how it would have been in last up to 12 weeks (due to lifespan of our red blood cells that harbor hemoglobin inside them) because of the linking mechanism of hemoglobin to glucose in the blood.”

Is there a standard for reading and understanding the HbA1c report?

“Many people do not know that HbA1c, or glycated hemoglobin, means much more than a number. HbA1c is different than that daily blood glucose measurement in the following way: HbA1c measures the average amount of sugar in the blood for 2-3 months, giving a much broader view of the level of blood sugar control. It is influenced by more than diet alone; stress, illness, and some medications can raise HbA1c levels. Anemia or even kidney diseases can cause results to be falsely high, and as such must be interpreted with caution by doctors. Although the normal HbA1c level is below 5.7%, patients with diabetes usually target around 7%, though the target varies based on the individual’s health factors,” explains

Dr. Tushar Tayal, Lead Consultant- Internal Medicine, CK Birla Hospital Gurugram.

What are certain unknown facts about HbA1c many people do not know?

While misinformation is a big block on the road to create awareness on diabetes, non-availability of the right information is also a problem.

Dr. Aishwarya Krishnamurthy, Senior Consultant – Endocrinology, Max Super Speciality Hospital, Vaishali explains the lesser known facts about HbA1c.

1. It cannot be used to diagnose diabetes in patients with hemoglobin variants in which the hemoglobin molecule differs from the normal hemoglobin found in most people. e.g. sickle cell anaemia, thalassemia etc
2. In patients with iron deficiency anaemia which is quite common in India, the hba1c levels can be falsely elevated making a false diagnosis of diabetes mellitus.
3. HBA1C values may be unreliable in cases of blood loss, surgery, and pregnancy.
4. Using HBA1C as the sole diagnostic criterion would result in a delayed diagnosis of diabetes in 60% of cases.

Cases where patients have misunderstood the HbA1c reading

“Doctors have faced some unusual misconceptions about HbA1c. Patients mistakenly thought that HbA1c represented the blood sugar of only one day before, and hence argued they had a great day so their result had to go down immediately or they would say, If the result is 8%, then patients have an 8% chance of having the disease. In addition, there have been cases where patients wrongly believe HbA1c is a score, as if trying to achieve a perfect 10 rather than the goal for diabetics of getting the value under 7%. These misconceptions need proper education on how HbA1c depicts long-term blood glucose levels rather than day-to-day fluctuation,” says Dr Tushar.

Dr Paras talks about a case where the patient’s blood sugar level was suppressed by another medication and the patient was not aware of it. “I had a patient, referred to me for Diabetes, who was also undergoing treatment with a dermatologist for her skin condition. Her HbA1c had come very low: 4.3 % which was unusual, as past history indicated suboptimal control so far with past treatments. On careful history and evaluation, it was noted she was on a medication Dapsone for her skin condition. Her glucose charting at home was rather at slightly high levels, clearly not correlating with her HBA1c value. The patient was worried about having low sugars, hoping to get her medicines stopped, as she had very low HbA1c levels from the lab. In fact, when I explained to her that your sugars are rather sub-optimally controlled with diabetes medicines that need minor adjustments (which was done) for good control and better skin treatment outcomes. She was rather relieved of confusion and understood the situation well. This is because her HbA1c is coming falsely low because of the medicine dapsone!,” he said.

“Doctors face odd misinterpretations from HbA1c results. A patient may once think that an HbA1c of 6.5% means that his blood is only 6.5% sugar, which brings frustration in relating this impact to one’s lifestyle. Another patient believed that lowering HbA1c was just a matter of keeping away from sugar for the day before testing. On the other hand, one of the strangest cases took place when a patient assumed that the HbA1c had referred to a genetic marker rather than a measure of glucose, and they fought lifestyle recommendations over it. In fact, some patients have even compared it to school grades, thinking that in the case of HbA1c, a higher percentage is better. Incidents like these emphasize the need to explain HbA1c as a measure of average blood sugar over months,” says Dr. Aishwarya Krishnamurthy.