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Normal blood sugar is the range of blood glucose seen in people who do not have diabetes, and it is usually described by three published figures: a fasting plasma glucose below 100 mg/dL, a value below 140 mg/dL two hours after a measured glucose drink, and an HbA1c below 5.7% (American Diabetes Association criteria, as published by the US National Institute of Diabetes and Digestive and Kidney Diseases). Those figures are cut-offs clinicians use to decide what to do next. They are not a verdict on any one person, and they are not identical in every guideline or every laboratory.
What blood sugar is
Blood sugar, or blood glucose, is the amount of glucose in your blood at the moment the sample is taken. Glucose comes mainly from the carbohydrate in food and drink, and it is the fuel your brain, muscles and organs run on.
The body keeps this level inside a fairly narrow band. Insulin, made by the pancreas, moves glucose out of the blood and into cells. Other hormones push the level back up when you have gone a long time without eating. Because that balancing act never stops, blood glucose is a moving number. It rises after a meal, settles over the next few hours, and is usually lowest after a long gap without food.
So a result only means something when you also know when the sample was taken and what the person had eaten. A number with no context cannot be read.
The common blood sugar tests
- Fasting blood sugar. A sample taken after a gap without food. The NIDDK states that for the most reliable results the test is done in the morning after you have fasted for at least 8 hours. Explained in detail on our page on normal fasting blood sugar.
- Blood sugar after eating. Measured two hours after a standardised glucose drink in an oral glucose tolerance test. MedlinePlus describes the drink as usually containing 75 grams of glucose. See blood sugar after eating.
- Random blood sugar. A sample taken at any time, without fasting. The NIDDK explains that doctors sometimes use it to diagnose diabetes when a person has symptoms and there is no reason to wait for an 8 hour fast.
A fourth test, HbA1c, is different in kind. Instead of a snapshot it reflects an average over a longer period, which is why it is often used alongside the glucose tests rather than instead of them.
The published reference figures
These are the figures published by the American Diabetes Association (ADA) and reproduced by the NIDDK. They are stated in mg/dL, the unit most Indian laboratory reports use for glucose.
- Fasting plasma glucose. Normal: less than 100 mg/dL. Prediabetes: 100 to 125 mg/dL. Diabetes: 126 mg/dL or above.
- Two hours after a glucose drink. Normal: less than 140 mg/dL. Prediabetes, also called impaired glucose tolerance: 140 to 199 mg/dL. Diabetes: 200 mg/dL or above.
- Random plasma glucose. The NIDDK gives 200 mg/dL or above as the value used to diagnose diabetes in a person who has symptoms of diabetes.
- HbA1c. Normal: below 5.7%. Prediabetes: 5.7% to 6.4%. Diabetes: 6.5% or higher. WHO gives the same diabetes cut-off, written as 6.5% (48 mmol/mol).
These bands are decision rules written for clinicians. They are not a description of you, and they carry no information about how well or unwell any individual is. Only the doctor who knows your history, your medicines and your symptoms can say what your own result means.
Where the major guidelines disagree
Reference figures are not universal, and it is more useful to show the disagreement than to hide it.
- The diabetes cut-off: agreement. WHO gives a fasting value of 7.0 mmol/L (126 mg/dl) or above; the ADA gives 126 mg/dL or above. The same line.
- The in-between zone: disagreement. The ADA calls a fasting value of 100 to 125 mg/dL prediabetes. WHO and the International Diabetes Federation define impaired fasting glucose as 6.1 to 6.9 mmol/l, that is 110 to 125 mg/dl, with a two-hour value, if measured, below 7.8 mmol/l (140 mg/dl). The lower boundary is not the same.
- A third line. NICE in the UK treats a fasting value of 5.5 to 6.9 mmol/l as high risk of type 2 diabetes and below 5.5 mmol/l as moderate risk, with 7.0 mmol/l or above indicating possible diabetes that needs a second test.
The practical effect is that the same fasting number can be labelled differently depending on which guideline the doctor or laboratory follows. The label matters less than the conversation you have about it.
Why one reading is not a diagnosis
The NIDDK is direct: usually, a doctor will use a second test to confirm diabetes. One value outside a band is a reason to test again, not a conclusion. Several things can move a single reading:
- How long ago you ate, and what you ate
- Illness, infection, injury or severe stress
- Physical activity and sleep before the sample
- Other medicines you take, and pregnancy, which is assessed with its own tests and thresholds
- Whether the sample was venous blood analysed in a laboratory or a finger-prick reading on a home meter. The WHO criteria are defined on venous plasma glucose
Reference ranges also vary. They differ between laboratories and between testing methods, and they differ with age, sex, pregnancy and the clinical situation. MedlinePlus states plainly that normal value ranges may vary slightly among different labs. The range that applies to you is the one printed beside your result on your own report. If it differs from the figures above, the printed range is the one your doctor works from.
This guide explains what the tests measure. It does not interpret results and it does not replace a consultation. Your treating doctor interprets your results and symptoms together.
Urgent signs, and testing at home
Call 108 or go to the nearest hospital straight away if someone is unresponsive or cannot be woken, is having a seizure, is confused and cannot swallow safely, or is vomiting repeatedly and breathing rapidly. Do not delay to take a meter reading first.
Blood sugar can also fall too low, which can become serious quickly, and this can affect people taking glucose-lowering medicines. It has its own page: low blood sugar (hypoglycaemia).
If reaching a laboratory is difficult, a sample can be collected at home and processed by a laboratory. Varolyn offers blood sugar testing at home in Bangalore and ongoing diabetes care at home in Bangalore. A testing service collects the sample and shares the report. It does not diagnose, and it does not replace the doctor treating you.
Frequently asked questions
What is a normal blood sugar level?
The commonly published reference figures come from the American Diabetes Association: a fasting plasma glucose below 100 mg/dL, a value below 140 mg/dL two hours after a 75 gram glucose drink, and an HbA1c below 5.7%. Your own laboratory report prints the range that applies to your sample, and your doctor interprets it.
Is a normal blood sugar chart the same for everyone?
No. Published charts are decision rules for clinicians, not personal targets. Reference ranges vary by laboratory and testing method, and with age, sex, pregnancy and the clinical situation. MedlinePlus notes that normal value ranges may vary slightly among different labs. Read the range printed beside your own result and discuss it with your doctor.
Do the ADA and WHO use the same cut-offs?
Not entirely. Both set the fasting diabetes cut-off at the same place: 126 mg/dL, which WHO writes as 7.0 mmol/L. They differ on the band below it. The ADA calls 100 to 125 mg/dL prediabetes, while WHO and the IDF define impaired fasting glucose as 6.1 to 6.9 mmol/l, that is 110 to 125 mg/dl.
Can a single high reading mean diabetes?
A single reading is not a diagnosis. The NIDDK states that a doctor will usually use a second test to confirm diabetes. Recent food, illness, stress, activity, other medicines and how the sample was taken can all move one result. Take the report to a doctor, who decides whether and when to retest.
When is blood sugar an emergency?
Call 108 or go to the nearest hospital if someone is unresponsive, cannot be woken, has a seizure, is confused and cannot swallow safely, or is vomiting with rapid breathing. Do not stop to take a meter reading first. These situations need emergency assessment, which no health guide can provide.
Sources
NIDDK, NIH - Diabetes Tests and Diagnosis · American Diabetes Association - Diabetes Diagnosis and Tests · WHO - Classification of diabetes mellitus (2019) · WHO and IDF - Definition and diagnosis of diabetes mellitus and intermediate hyperglycaemia (2006) · NICE - Type 2 diabetes: prevention in people at high risk (PH38) · MedlinePlus, NIH - Glucose tolerance test (non-pregnant) · MedlinePlus, NIH - Hemoglobin A1C (HbA1c) Test
Last checked 2 September 2026. How we write and check these pages: editorial policy.
Blood sugar testing at home in Bangalore
If travelling to a laboratory is difficult, Varolyn can collect a sample at home in Bangalore and share the laboratory report with you and your doctor. Diagnosis and interpretation stay with your treating doctor.