India has one of the largest numbers of people with diabetes in the world, and many more have prediabetes without knowing it. Understanding your blood sugar numbers is the first step towards catching problems early. Here is a clear guide to what the common tests measure and which ranges doctors use.
The three common blood sugar tests
- Fasting blood sugar (FBS): measured after at least 8 hours without food, usually first thing in the morning.
- Post-prandial or 2-hour sugar (PPBS / OGTT): measured 2 hours after a meal or after drinking a measured glucose solution.
- HbA1c: shows your average blood sugar over roughly the last 2 to 3 months. You do not need to fast for it.
Blood sugar chart for adults
These are the widely used diagnostic ranges for non-pregnant adults (values in mg/dL):
| Test | Normal | Prediabetes | Diabetes |
|---|---|---|---|
| Fasting sugar | Below 100 | 100 to 125 | 126 or higher |
| 2 hours after glucose / meal | Below 140 | 140 to 199 | 200 or higher |
| HbA1c | Below 5.7% | 5.7% to 6.4% | 6.5% or higher |
A single high reading is not a diagnosis. Doctors usually confirm diabetes with a repeat test or a second type of test.
Does "normal" change with age?
For diagnosing diabetes, the same cut-offs are used for adults of all ages. What changes with age is the target for people who already have diabetes.
- Children and teenagers: the diagnostic ranges are broadly the same as adults. Children with type 1 diabetes are usually given an HbA1c target of around 7% or lower, set by their paediatric team.
- Adults (roughly 18 to 60) with diabetes: a common HbA1c goal is below 7%, with fasting readings often targeted between 80 and 130 mg/dL and post-meal readings below 180 mg/dL.
- Older adults: for healthy older people, targets are often similar. For those with other illnesses, memory problems or a high risk of falls, doctors may relax the HbA1c target to around 7.5% to 8% to avoid dangerous low sugar episodes.
Your own target should always be set with your doctor.
What is low blood sugar?
A reading below 70 mg/dL is considered low (hypoglycaemia). Symptoms include shaking, sweating, sudden hunger, confusion and a fast heartbeat. It mainly affects people taking insulin or certain diabetes tablets and needs prompt treatment with a quick source of sugar.
Warning signs of high blood sugar
- Frequent urination, especially at night
- Excessive thirst
- Unexplained weight loss
- Blurred vision
- Slow-healing cuts and frequent infections
- Tiredness
Who should get tested?
Consider regular screening if you are over 30 to 35, are overweight, have a family history of diabetes, have high blood pressure, had diabetes during pregnancy or have a sedentary lifestyle. South Asians tend to develop diabetes at a younger age and at a lower body weight than many other groups.
Simple habits that help
- Fill half your plate with vegetables and choose whole grains over refined rice and maida.
- Cut down on sugary drinks, sweets and packaged snacks.
- Walk for 10 to 15 minutes after meals.
- Aim for at least 150 minutes of moderate activity a week.
- Sleep well and manage stress.
The bottom line
Know your three numbers: fasting sugar, post-meal sugar and HbA1c. Prediabetes can often be reversed with lifestyle changes, so an early test is one of the best investments you can make in your health.
Disclaimer: This article is for general information only and is not medical advice. Please consult a qualified doctor for advice about your own health.
