Blood Sugar & HbA1c
Glucose tells you the sugar at one moment; HbA1c tells you the average of the last two to three months, because sugar sticks to haemoglobin in proportion to how much of it there has been. Diabetes is diagnosed from either, and the diagnosis normally needs two abnormal results.
This is an educational reading aid, not a diagnosis and not medical advice. Reference ranges differ between laboratories — always read the range printed on your own report. Nothing here can see you, your history or your medicines. Do not start, stop or change any treatment on the strength of this page: take your report to a qualified doctor.
Reference ranges reviewed by Dr. Mohan Gayenlast reviewed
Your values
Fill in only the ones on your report. Anything you leave blank is simply skipped.
The average blood sugar of the last two to three months.
Blood sugar after at least 8 hours with no food or drink except water.
Blood sugar two hours into a standard glucose tolerance test.
Blood sugar at any time, regardless of meals.
Enter one or more values and your reading will appear here.
How diabetes is diagnosed
Any one of these meets the threshold. Except where symptoms are unmistakable, a diagnosis needs two abnormal results — either two different tests, or the same test repeated.
| Test | Normal | Prediabetes | Diabetes |
|---|---|---|---|
| Fasting plasma glucose | below 100 mg/dL | 100 – 125 mg/dL | 126 mg/dL or above |
| 2-hour glucose in a 75 g OGTT | below 140 mg/dL | 140 – 199 mg/dL | 200 mg/dL or above |
| HbA1c | below 5.7 % | 5.7 – 6.4 % | 6.5 % or above |
| Random glucose with classic symptoms | — | — | 200 mg/dL or above |
HbA1c and what average glucose it corresponds to
The estimated average glucose (eAG) matching each HbA1c, from the ADA relationship eAG (mg/dL) = 28.7 × HbA1c − 46.7.
| HbA1c (%) | HbA1c (mmol/mol) | Estimated average glucose |
|---|---|---|
| 5.0 | 31 | 97 mg/dL |
| 6.0 | 42 | 126 mg/dL |
| 6.5 | 48 | 140 mg/dL |
| 7.0 | 53 | 154 mg/dL |
| 8.0 | 64 | 183 mg/dL |
| 9.0 | 75 | 212 mg/dL |
| 10.0 | 86 | 240 mg/dL |
| 12.0 | 108 | 298 mg/dL |
What this panel is easy to get wrong
- A DIAGNOSIS NEEDS TWO ABNORMAL RESULTS on separate occasions, unless someone has unmistakable symptoms with a very high glucose. One reading above a threshold is not diabetes.
- HbA1c IS UNRELIABLE in anaemia, after recent blood loss or transfusion, in haemoglobin variants (including the thalassaemia and sickle traits common in India), in pregnancy, and in significant kidney or liver disease. In those situations glucose testing is used instead.
- Home glucose meters are not accurate enough to diagnose diabetes. Diagnosis uses a laboratory venous sample.
- These bands describe DIAGNOSIS. If you already have diabetes, your own HbA1c target is set by your doctor and is individual — often below 7%, but higher for some older people and lower for some younger ones.
Where these ranges come from: Diagnostic thresholds follow the American Diabetes Association Standards of Care, which are also those used by the WHO for fasting and 2-hour values.
Where this is written from: This site is written from Indian clinical practice. Drug availability and brand names, vaccination schedules, national health programmes and some reference cut-offs differ between countries — a schedule or a threshold that is standard here may not be standard where you are. If you are reading outside India, check anything on this page against your own country’s guidance before you act on it.
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Fasting and post-meal glucose, and the three-month average.