Energy & metabolic
Also known as Glycated haemoglobin, A1c. Measured in %.
HbA1c measures the proportion of haemoglobin in your red blood cells that has sugar attached to it. Because red cells live around three months, the result reflects average blood glucose across roughly that period rather than the single moment the blood was drawn. This makes it far more stable than a fasting glucose reading, which moves with the previous evening's meal, a poor night's sleep or an early-morning stress response. HbA1c is the test used to diagnose diabetes and prediabetes worldwide, and to judge whether treatment is working. Its main limitation is that it is an average: it cannot distinguish steady moderate glucose from a pattern of sharp post-meal spikes and low troughs, and it is distorted by any condition that changes red cell lifespan, including iron deficiency and haemoglobin variants.
HbA1c reflects average glucose over roughly three months and requires no fasting.
Iron deficiency can raise HbA1c by a few tenths of a percent with no change in glucose — enough to cross a diagnostic threshold.
A normal HbA1c alongside post-meal exhaustion often means insulin resistance that a glucose-based test cannot see.
A rising HbA1c indicates higher average glucose over the preceding months. Values in the prediabetes band mark a stage that is frequently reversible; values in the diabetes range require medical management. A high HbA1c alongside normal fasting glucose usually points to post-meal spikes that a fasting test cannot see.
A low HbA1c is usually favourable, but it can also be an artefact. Anything that shortens red cell survival — recent blood loss, haemolysis, some anaemias — lowers HbA1c independently of glucose. In iron deficiency the opposite distortion occurs and HbA1c can read falsely high, which is why it is read alongside a haemogram and ferritin.
| Band | Value |
|---|---|
| Normal | < 5.7% |
| Prediabetes | 5.7 – 6.4% |
| Diabetes | ≥ 6.5%Diagnosis requires confirmation on a repeat sample |
Laboratory intervals vary. Interpret with a physician.
ICMR-INDIAB reported 11.4% of Indian adults with diabetes and 15.3% with prediabetes — a waiting room larger than the diagnosis. Only about 7% of Indians already diagnosed with diabetes are meeting their glucose, blood-pressure and lipid targets simultaneously, which is the gap between being diagnosed and being cared for.
Fasting insulin measures how much insulin the pancreas is releasing to hold blood glucose steady after an overnight fast.
HOMA-IR is a calculated index that combines fasting glucose and fasting insulin into a single number describing how resistant the body has become to its own insulin.
Ferritin is the protein the body uses to store iron, and the amount circulating in blood is proportional to how much iron is held in reserve.
An HbA1c of 6.5% or above needs a physician and a confirmatory test. Values in the prediabetes band warrant a conversation about diet, activity and follow-up, not alarm. Excessive thirst, frequent urination, unexplained weight loss or blurred vision should be assessed promptly whatever the number.
No. HbA1c reflects a three-month average and is unaffected by the previous meal, which is one of its practical advantages. Fasting is still required for the glucose, insulin and triglyceride markers usually drawn in the same panel.
Yes, and it is a common source of confusion in India, where iron deficiency is widespread. Iron deficiency prolongs red cell survival and can raise HbA1c by a few tenths of a percent without any change in glucose, which is enough to move someone across a diagnostic threshold. This is why ferritin and a haemogram are read alongside it.
A normal HbA1c does not exclude insulin resistance, because the body maintains normal average glucose for years by producing more insulin. Fasting insulin and HOMA-IR are the markers that show this phase, and they are the ones worth adding.
The programme
Peak Brain draws a full blood and urine panel at your home, has a licensed physician read every marker together rather than one at a time, and turns what they find into a ranked 90-day protocol with a retest at the end.
Authorship & review
Written by the Peak Brain clinical team. Assigned clinical reviewer: Dr. Alfia Kaki, MD, PGC — review pending; this page has not yet been signed off.
Published . Last updated .
This page is general health information, not medical advice, diagnosis or treatment. Reference ranges vary between laboratories. Never delay or disregard advice from a qualified health professional because of something you read here. If you think you may have a medical emergency, call your local emergency number.