Blood sugar numbers, with the source attached
Reference ranges as WHO and the American Diabetes Association actually publish them, an HbA1c converter that shows its equation, and glycemic index values only for foods somebody has genuinely measured. Not a diagnosis, and never a substitute for a doctor.
Illustrative shape only — no numbers are attached to this curve, because the height and timing of the rise differ between people and between meals.
Nothing here can diagnose you, and nothing here is a treatment plan. Blood glucose results are interpreted by a doctor alongside your history, your symptoms and a repeat test — a single number on a screen is not a diagnosis. If any reading concerns you, or if you feel unwell, see a doctor rather than a website.
The pages
Each one carries a full static table, so it works with JavaScript switched off and on a slow connection.
Normal blood sugar levels
Fasting, post-prandial and random ranges, from both the WHO and ADA published criteria — including where the two disagree.
Open →HbA1c converter
HbA1c to estimated average glucose using the ADAG regression, in mg/dL, mmol/L and mmol/mol.
Open →HbA1c chart
Every value from 4.0% to 14.0% converted, with the ADA band beside it.
Open →Glycemic index of Indian foods
Measured values only. Where nobody has measured a food, this site says so instead of inventing a number.
Open →mg/dL ↔ mmol/L
Convert between the Indian and the international unit, with the full table both ways.
Open →Prediabetes
What the range actually is, why WHO and the ADA draw its lower edge in different places, and what it does and does not mean.
Open →Why this site is smaller than the ones above it in search
The most-searched question in this subject is some version of "normal sugar level by age". The charts that answer it — a slightly higher range for each decade of life — are not published by any health authority. They appear to have been assembled from population averages and from treatment targets for people who already have diabetes, then copied from site to site until the original was forgotten.
The published diagnostic thresholds are the same at 25 and at 75. Saying so is less satisfying than a colour-coded chart. It is also true, and it is the reason the levels page answers the question and then explains why the question is built on a false premise.
The same discipline applies to food. Glycemic index cannot be calculated from a composition table — it is produced by feeding a food to volunteers and sampling their blood — so it exists only where a study exists. This site publishes 15 of them. Sites listing a GI for three hundred Indian dishes are publishing arithmetic they cannot have done.
The scale of it
Source: Anjana RM, Unnikrishnan R, Deepa M, et al. Metabolic non-communicable disease health report of India: the ICMR-INDIAB national cross-sectional study (ICMR-INDIAB-17). Lancet Diabetes Endocrinol 2023;11(7):474–489. Link
PeakForm is a training and accountability programme. It is not a treatment for diabetes or prediabetes, it is not a substitute for your doctor's advice, and nothing on this site should be acted on before speaking to one.
Guides
The "sugar level by age chart" is not a real thing
Popular charts list a different normal blood sugar range for every age group. The published diagnostic criteria do not work that way — here is what actually changes with age and what does not.
Open →How to read an Indian blood sugar lab report
FBS, PPBS, RBS, OGTT and HbA1c — what each line on a pathology report actually measured, what the units mean, and why the lab's own reference range may not match the guideline.
Open →What HbA1c actually measures — and when it misleads
HbA1c reflects average glucose over roughly three months. It is convenient and standardised, and there are well-documented situations in which it is the wrong test. Both halves matter.
Open →Glycemic index vs glycemic load, with the arithmetic
GI ranks a food against glucose at a fixed 50 g of carbohydrate. Glycemic load scales that to the amount you actually eat. One line of arithmetic separates them.
Open →Rice does not have a glycemic index
Published GI values for rice run from the high 30s to the 90s depending on variety, parboiling and cooking time. That range is the finding — and it is why this site refuses to print one number.
Open →Diabetes in India: what the national survey found
The ICMR-INDIAB study measured glucose across every state and union territory. Its headline estimates — 101 million with diabetes and 136 million with prediabetes — reset what the scale of this actually is.
Open →General information only — NOT medical advice, and never a diagnosis. Only a doctor can interpret your results and diagnose or treat diabetes. If a reading concerns you, see a doctor rather than a website. Every threshold, equation and glycemic index value used on this site is listed with its publication on the data & method page.