Adults 18 to 30

Blood sugar levels for adults aged 18 to 30

The same thresholds as every other adult age band. The question that actually differs at this age is whether you should be tested at all.

Reference range — adults 18 to 30

99mg/dL or below

The normal fasting band for adults aged 18 to 30 is the band published for every non-pregnant adult: 99 mg/dL or below, with 100–125 mg/dL the prediabetes band and 126 mg/dL or above in the diabetes range. No health authority publishes a separate range for this age.

Same published cut-points at every adult age. What differs at this stage of life is set out below.

ஆதாரம்·ADA Standards of Care 2025 · WHO/IDF 2006·no age-banded range is published by either body·மறுபரிசீலனை ஜூலை 2026

This page is reference information, not medical advice.

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.

Clinical note

The thresholds on this page are the ones published for all non-pregnant adults. Nothing about them is adjusted for being in your twenties.

What is genuinely age-related is screening — who gets tested in the absence of symptoms. Western guidance has historically started routine screening in mid-life. Indian guidance generally starts earlier, because type 2 diabetes appears at younger ages and at lower body weights in South Asians than in European populations. The national survey found a substantial burden well below the ages at which Western charts suggest looking.

Being young, slim and asymptomatic is a weaker reassurance in India than the international literature implies. Whether you should be tested is a question for a doctor, and family history, waist measurement and blood pressure all feed into the answer.

How a published range becomes the line on your report

A specimen is drawn under a stated condition — fasting means at least eight hours with nothing but water; the two-hour value means two hours into a standardised 75 g glucose drink, not two hours after dinner.
The laboratory reports a concentration: mg/dL in India, mmol/L in the UK, Australia and most of Europe. The measurement is identical; only the unit differs.
That concentration is read against a published cut-point — a figure a named body wrote down in a dated document, not a figure derived from the population being tested.
Two bodies publish, and they agree everywhere except one number. This site prints both rather than picking the one that makes a tidier table.
Confirmation, then interpretation, both belong to a clinician. A value on either side of a cut-point is a reason to see a doctor, never a conclusion.

mmol/L = mg/dL ÷ 18.016
ADA fasting cut-points   99 · 100-125 · 126
WHO fasting cut-points  109 · 110-125 · 126

Full methodology →

Panel one

The published criteria — unchanged for this age band

This is the same table that appears on every page of this site, because the thresholds genuinely are the same. If a chart shows you a different range for this age, that chart is not quoting a health authority.

Test results used to identify normal glucose, prediabetes and diabetes in non-pregnant adults, as published by the American Diabetes Association and restated by the US National Institute of Diabetes and Digestive and Kidney Diseases. The mmol/L column is converted from the published mg/dL figures at 18.016 mg/dL per mmol/L.
Result	Published value	Same value in mmol/L
Fasting plasma glucose — at least 8 hours with no food
இயல்பானது	99 mg/dL or below	5.5 mmol/L or below
Prediabetes	100 to 125 mg/dL	5.6 – 6.9 mmol/L
நீரிழிவு வரம்பில்	126 mg/dL or above	7.0 mmol/L or above
2 hours into a 75 g oral glucose tolerance test
இயல்பானது	139 mg/dL or below	7.7 mmol/L or below
Prediabetes	140 to 199 mg/dL	7.8 – 11.0 mmol/L
நீரிழிவு வரம்பில்	200 mg/dL or above	11.1 mmol/L or above
HbA1c
இயல்பானது	below 5.7%	—
Prediabetes	5.7% to 6.4%	—
நீரிழிவு வரம்பில்	6.5% or above	—
Random (any time of day)
நீரிழிவு வரம்பில்	200 mg/dL or above with the classic symptoms of high blood glucose	11.1 mmol/L or above

A result in the diabetes range is not a diagnosis. Published criteria require confirmation — normally a repeat of the same test on a separate day, unless someone has unmistakable symptoms with a clearly raised glucose. Your doctor makes that call, not a chart.

ஆதாரம்·ADA, Standards of Care in Diabetes 2025·restated by NIDDK, NIH·மறுபரிசீலனை ஜூலை 2026

ஆதாரம்: American Diabetes Association, Standards of Care in Diabetes — Diagnosis and Classification of Diabetes. Diabetes Care 2025;48(Suppl. 1):S27–S49. Link
ஆதாரம்: National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), National Institutes of Health — Diabetes Tests & Diagnosis. Link

Panel two

And the WHO version

World Health Organization / International Diabetes Federation criteria (2006), with the 2011 WHO position on HbA1c. WHO publishes in mmol/L; the mg/dL column is the equivalent, as printed in the WHO report.
Category	Fasting plasma glucose	2 h after a 75 g glucose load
Diabetes	7.0 mmol/L (126 mg/dL) or above	11.1 mmol/L (200 mg/dL) or above
Impaired fasting glucose (IFG)	6.1 – 6.9 mmol/L (110–125 mg/dL)	below 7.8 mmol/L (140 mg/dL), if measured
Impaired glucose tolerance (IGT)	below 7.0 mmol/L (126 mg/dL)	7.8 – 11.0 mmol/L (140–199 mg/dL)

WHO also accepts a random plasma glucose of 11.1 mmol/L (200 mg/dL) or above, in the presence of symptoms, and — since the 2011 consultation — an HbA1c of 6.5% or above. WHO is explicit that an HbA1c below 6.5% does not rule diabetes out.

ஆதாரம்·WHO/IDF consultation, Geneva 2006·published in mmol/L·மறுபரிசீலனை ஜூலை 2026

ஆதாரம்: World Health Organization / International Diabetes Federation. Definition and diagnosis of diabetes mellitus and intermediate hyperglycaemia: report of a WHO/IDF consultation. Geneva: WHO, 2006. 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.

Other age bands

Children and teenagerssame thresholds Adults 18 to 30same thresholds Adults 30 to 45same thresholds Adults 45 to 60same thresholds Adults 60 and abovesame thresholds Pregnancydifferent thresholds

Why the age-banded charts you have seen elsewhere are not published by anyone →

Questions this report anticipates

What is a normal fasting blood sugar level?

On the American Diabetes Association criteria, 99 mg/dL (5.5 mmol/L) or below. 100 to 125 mg/dL is the prediabetes range and 126 mg/dL or above is in the diabetes range. WHO uses the same 126 mg/dL diabetes threshold but places the lower edge of impaired fasting glucose at 110 mg/dL rather than 100.

What is a normal sugar level after eating?

The published thresholds — 140 and 200 mg/dL at two hours — are written for a standardised 75 g oral glucose tolerance test, not for an ordinary meal. A post-prandial reading after home food is not the same measurement and varies with what was eaten. Doctors do use post-meal readings, interpreted alongside everything else about you.

Does the normal blood sugar range change with age?

No. The diagnostic thresholds published by WHO and the American Diabetes Association are the same for every adult age. Popular "sugar level by age" charts are not published by any health authority. Pregnancy is the one genuine exception, and its thresholds are lower, not higher.

Is one high reading enough to diagnose diabetes?

No. The published criteria require confirmation — normally a repeat of the same test on a separate day — unless someone has unmistakable symptoms alongside a clearly raised glucose. A single number is a reason to see a doctor, not a diagnosis.

What is the normal blood sugar level for adults aged 18 to 30?

The same as for any other non-pregnant adult: fasting 99 mg/dL or below, two-hour glucose tolerance test 139 mg/dL or below, and HbA1c below 5.7% on the ADA criteria. There is no separate published range for this age group.

Thresholds from the ADA Standards of Care, NIDDK and the WHO/IDF 2006 consultation. 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 தரவு & முறை page, and every publication is listed with its issuing body and its date in the source register.

ஆதாரம்·Published reference ranges + GI tables·மறுபரிசீலனை ஜூலை 2026

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