HbA1c

HbA1c (glycated hemoglobin) shows your average blood sugar over the past two to three months. When glucose circulates in the blood it attaches to hemoglobin inside red blood cells; the more sugar there is, the more hemoglobin becomes "sugar-coated". Since red cells live about 120 days, HbA1c reflects long-term control rather than a single moment.

This makes it very different from a fasting or post-meal sugar test, which can swing with last night's dinner or this morning's stress. HbA1c is used to diagnose prediabetes and diabetes, and to judge how well diabetes treatment is working. Most adults with diabetes are advised to test it every three to six months, and doctors usually set an individual target, often around 7%.

The result can be unreliable in anaemia, recent blood loss or transfusion, sickle cell trait, thalassaemia, kidney disease and some haemoglobin variants, so doctors may use fasting glucose or fructosamine instead in these situations.

How to understand your HbA1c result

HbA1c is a percentage: it tells you what share of your hemoglobin has sugar attached. A result of 6.8%, for example, means roughly 6.8 of every 100 hemoglobin molecules are glycated. Because the figure reflects the last two to three months, with the most recent month counting for about half of it, a sharp improvement in diet or medicines takes weeks to show fully, and a few good days before the test cannot hide poor control.

Some labs and doctors also report the estimated average glucose (eAG), which converts the percentage into the more familiar mg/dL value. This can help you relate the number to the readings on your glucometer.

Why a single HbA1c is not the whole picture

Two people can have the same HbA1c but very different daily patterns: one may have steady moderate sugars, while another swings between lows and highs. A continuous glucose monitor or a home glucose diary shows these swings, which HbA1c averages away. That is why doctors review HbA1c together with fasting and post-meal readings, and why people on insulin or sulfonylureas should also watch for low sugars.

Factors that can make HbA1c unreliable

• Iron-deficiency anaemia can push HbA1c falsely high; hemolytic anaemia, recent blood loss or transfusion can push it falsely low.
• Thalassaemia trait and haemoglobin variants, which are not rare in India, can distort some methods, so tell your doctor if you have them.
• Chronic kidney disease, liver disease and pregnancy change red cell life span.
• High-dose vitamin C or E may interfere with some methods.

Lifestyle changes that move HbA1c

For people with prediabetes or type 2 diabetes, a 5–7% loss of body weight, about 150 minutes of brisk activity a week, reducing sugary drinks, sweets and refined flour, and eating more vegetables, pulses and whole grains can each lower HbA1c, often by a meaningful amount. Sleep, stress and medicines taken on time also matter. Do not stop or change prescribed medicines without medical advice.

HbA1c and complications

Sustained high HbA1c raises the long-term risk of damage to the eyes (retinopathy), kidneys, nerves and blood vessels. Large trials have shown that keeping HbA1c in the range your doctor advises lowers these risks. Even so, tighter is not always better: in older adults or people prone to low sugars, doctors may accept a higher target such as 7.5–8%.

Booking an HbA1c test

HbA1c is a routine, widely available test, and prices vary by lab and city. On LabDekho you can compare labs, check NABL accreditation and choose home sample collection, and results are usually available the same day or the next. Many labs include it in diabetes and full-body health packages, so compare package prices as well.