My blood sugar is high. What is a normal blood sugar level?

Understand Singapore’s blood sugar ranges, what a high result can mean, and why trends and follow-up testing matter.

3 July 2026 · 7 min read

For adults in Singapore, a normal fasting blood sugar is below 6.1 mmol/L. A fasting result of 6.1 to 6.9 mmol/L is in the prediabetes range, and 7.0 mmol/L or higher in the diabetes range. For HbA1c, which reflects your longer-term average, 6.0% or below is normal and 7.0% or above points to diabetes.

It's important to know that one high result does not confirm diabetes. A reading can be elevated for short-term reasons, or it can signal a longer-term change. Only your doctor can tell the two apart, and seeing your readings over time helps them do it.

If your health reports are in the Genie Health app, the Health Locker reads your blood sugar and flags whether it is within range or needs attention. Adding past reports gives your doctor a fuller view of how your readings have changed, which helps them interpret a single high result and decide on the right next step.

What is blood sugar, and what causes it to rise?

Blood sugar, or blood glucose, is the sugar your blood carries to fuel your cells. Most of it comes from carbohydrates, such as rice, noodles and bread, and from refined sugar in sweet drinks and desserts. Post-meal blood sugar spikes are normal. Your pancreas secretes insulin to transport glucose into cells, stabilising blood sugar levels within a few hours.

The problem starts when blood sugar stays high over time. This happens when the pancreas does not make enough insulin, or when the body stops responding to it well. In type 2 diabetes, the most common form, extra body fat makes cells respond poorly to insulin. The pancreas compensates by making extra insulin, often for years, before blood sugar begins to drift into the prediabetes range, and for some, into diabetes.

This slow build is why risk rises with age, and it is also why the condition can often be caught early. The main factors driving high blood sugar are ones you can change: excess body fat, little physical activity, and a diet high in refined carbohydrates and sugar. Family history matters too. If a parent or sibling has type 2 diabetes, your own risk roughly doubles. This reflects a mix of inherited traits that affect how your body uses insulin and where it stores fat, and the shared lifestyle habits within a family.

What blood sugar level means prediabetes or diabetes?

In Singapore, a fasting blood sugar of 6.1 to 6.9 mmol/L points to prediabetes, and 7.0 mmol/L or higher to diabetes.

Alongside the fasting result, doctors also look at HbA1c, which reflects your average blood sugar over the past three months.

The chart below shows the ranges used in Singapore, following MOH and ACE clinical guidelines.

The two tests measure different things, so the figures are not interchangeable. There is no standard after-meal range for people without diabetes; the 4.0 to 10.0 mmol/L figure often seen online is a target for people already managing diabetes. An HbA1c in the 6.1 to 6.9% band is followed up with a fasting test or an OGTT before any diagnosis.

The OGTT (oral glucose tolerance test) is a third test, used when a result is borderline or when a clearer picture is needed. You drink a measured glucose solution and your blood sugar is checked two hours later. A reading below 7.8 mmol/L is normal, 7.8 to 11.0 mmol/L is prediabetes, and 11.1 mmol/L or higher is diabetes.

Other countries use slightly different ranges, so you may come across different numbers online. The American Diabetes Association, for example, starts prediabetes at a fasting 5.6 mmol/L and uses HbA1c bands of below 5.7%, 5.7 to 6.4%, and 6.5% or higher.

What are the symptoms of high blood sugar?

Mildly high blood sugar usually causes no symptoms at all. Most people only find out from a blood test, which is why screening matters.

Symptoms appear once blood sugar has stayed high for a while. The kidneys start flushing out excess glucose through urine, pulling water with it, and cells run short of usable energy. The earliest and most common signs are passing urine often (especially at night), feeling unusually thirsty, and tiredness that does not go away with rest. Hunger, unexplained weight loss and blurred vision tend to follow. Slow-healing cuts, frequent infections and tingling in the hands or feet usually appear later, once blood sugar has been high for a longer stretch.

Having one or two of these on their own is not a diagnosis. Thirst and tiredness are common with many conditions. What matters is the pattern, especially if it is new, persistent, and lines up with risk factors like age, weight or family history.

Over the years, high blood sugar damages blood vessels and nerves, raising the risk of heart disease, stroke, and kidney, eye and foot problems. The damage builds quietly, which is why catching it early makes a real difference.

Does one high reading mean I have diabetes?

Usually not. A diagnosis normally needs a second confirmatory test on another day, unless the first result is very high or you have clear symptoms. Blood sugar shifts with food, sleep, illness and stress, so your doctor will consider the test type, whether you fasted, and your earlier readings before concluding anything.

Trends matter too. A fasting result of 5.4, then 5.8, then 6.0 mmol/L looks normal each time, but together the three show a steady climb. This is the kind of pattern that is easy to miss on a single visit, and part of why HbA1c is useful alongside a fasting result.

My blood sugar is high. What should I do?

See your family doctor, or your Healthier SG clinic if you are enrolled, and bring your earlier screening reports. Your doctor will usually repeat the test and may add HbA1c if you have not had one recently.

Depending on the diagnosis, your doctor may advise:

• Monitoring: screening every 3 years from age 40 if results are normal (earlier with risk factors), or at least every 6 months with prediabetes
• Diet and lifestyle changes: these do most of the work, especially for prediabetes
• Medication, if necessary

For prediabetes, weight is the biggest lever. Losing 5 to 10% of body weight can help move blood sugar back toward normal. Cutting refined carbohydrates and sugar does the next most work, because these are what drive the sharpest post-meal spikes. Activity and sleep support both. In practical terms, this might look like:

• Less sugar in your coffee or tea, and fewer sweet drinks and desserts
• Smaller rice or noodle portions, and brown rice where available
• Half the plate filled with vegetables
• Around 150 minutes of moderate activity a week, such as brisk walking
• Enough sleep, and no smoking

For people with prediabetes, these changes cut the risk of type 2 diabetes by 31 to 37% over 2 to 6 years, roughly a third. For more, read how to lower blood sugar.

High blood sugar builds over years, which means there is time to change its course. Knowing what your numbers mean, and which habits move them, is where that starts.

Note: This content is for general informational purposes only and is not medical advice, diagnosis or treatment. It does not replace consultation with a qualified healthcare professional. If you have concerns about your health, please consult a qualified physician.

Read Next: What is HbA1c, and what is a normal HbA1c level?

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