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Blood Sugar Levels Guide:

Normal Blood Sugar Range & Diabetes Indicators

 

11-min read

Updated on 2026-7-30

Author: AIA Content Editorial Team

Healthcare professional checking a patient's blood sugar level using a finger-prick test for diabetes screening.
According to the 2020–2022 Population Health Survey conducted by the Department of Health in Hong Kong, 8.5% of people aged 15 to 84 had diabetes or raised blood glucose levels1. Diabetes often has no obvious symptoms in its early stages, and many patients may have the condition for years without knowing it1. Therefore, the Department of Health recommends that members of the public should start diabetes screening from the age of 451. What is the normal blood sugar range? What are the differences between fasting blood glucose, post-meal blood sugar levels and glycated haemoglobin (HbA1c)? This article explains the standard values of key diabetes indicators, the common causes of high blood sugar and the latest testing methods, helping you better understand your health condition and plan ahead for future medical protection.

What Are Blood Sugar Levels? Understanding the Health Signals in Your Blood

The Relationship Between Glucose, Insulin and Body Function

Glucose is the main source of energy for human cells. After we eat, carbohydrates in food are digested and converted into glucose, which then enters the bloodstream. At this point, the concentration of sugar in the blood is what we commonly refer to as "blood sugar levels". To maintain stable blood sugar levels, the pancreas secretes a hormone called insulin, which helps glucose in the blood enter the cells and be converted into energy2.
 
If insulin production is insufficient, or if the body's cells become resistant to insulin, also known as insulin resistance, glucose cannot be used effectively. As a result, glucose may accumulate in the blood and may develop into diabetes over time. Paying attention to and managing blood sugar levels early can help reduce the risk of developing various chronic vascular diseases in the future2.

Normal Blood Sugar Range: A Reference Guide from Fasting to 2-Hour Post-Meal Readings

Indicators for Normal Blood Sugar, Prediabetes and Diabetes

Clinically, fasting plasma glucose (FPG), 2-hour post-meal blood glucose and glycated haemoglobin (HbA1c) are commonly used to define normal and abnormal blood sugar levels. The reference values for these diabetes indicators are as follows2:
Test Item Normal Level Prediabetes Diabetes / High Risk
Fasting Plasma Glucose (FPG) after fasting for 8 hours                 < 5.6 mmol/L                       ​​≥ 5.6 to < 7 mmol/L​  ​​≥ 7.0 mmol/L   ​            
2-Hour Post-Meal Blood Glucose   < 7.8 mmol/L ​​≥ 7.8 to < 11.1 mmol/L​ ​​≥ 11.1 mmol/L   ​                     

Potential Risks of Blood Sugar Fluctuations: The Impact of High and Low Blood Sugar

Long-Term Health Concerns Caused by High Blood Sugar

Long-term high blood sugar may have lasting effects on the body's microvascular and macrovascular systems. Common long-term complications include retinopathy, commonly known as "diabetic eye disease", chronic kidney failure, peripheral neuropathy, and a significantly increased risk of cardiovascular diseases such as heart disease and stroke3.
 
These complications may not only seriously affect quality of life, but may also lead to heavy and long-term medical expenses.

Immediate Risks of Ignoring Low Blood Sugar Symptoms

In addition to high blood sugar, the health risks of low blood sugar, usually referring to blood sugar levels below 3.9 mmol/L, should also be noted. Acute symptoms of low blood sugar include dizziness, hunger, cold sweats, trembling hands and blurred vision3. If electrolytes or sugar are not replenished in time, the patient may experience blurred vision, confusion or even fall into a coma. Therefore, if symptoms of hypoglycaemia persist or worsen, emergency rescue services should be called immediately and the patient should be sent to hospital for treatment4.

How to Monitor Blood Sugar Scientifically? Common Testing Methods

From Traditional Blood Tests to Continuous Glucose Monitoring (CGM)

With advances in medical technology, blood sugar testing methods have developed from traditional fingertip blood sampling to modern continuous glucose monitoring (CGM). By wearing a small sensor, users can track blood sugar trends throughout the day5. For generally healthy individuals, regular health checks are key to detecting prediabetes early. Diabetes Hongkong recommends that low-risk individuals undergo HbA1c testing once a year to keep track of their health condition in a timely manner6.

Fasting Plasma Glucose Test (FPG)6

This is the most basic testing method. The person being tested needs to fast for about 8 hours before having a blood sample taken. This test is mainly used to assess the body's baseline blood sugar levels. To ensure accurate test results, the person should try to remain calm before the blood test, avoid strenuous exercise and avoid drinking any beverages that contain calories.

Oral Glucose Tolerance Test (OGTT)

The person being tested first needs to undergo a fasting blood test. They then drink a solution containing 75 grams of glucose, followed by another blood test 2 hours later. This method is commonly used by doctors to diagnose prediabetes, diabetes or other potential blood glucose regulation problems.

Glycated Haemoglobin (HbA1c) Test

HbA1c reflects the average blood sugar level over the past 2 to 3 months. Since fasting is not required before the test, a blood sample can be taken at any time. It is currently a very common and highly valuable long-term diabetes monitoring indicator in clinical practice.

From Health Management to Long-Term Planning

If abnormal blood sugar levels are not properly managed, they may develop into a chronic disease that requires long-term medication and follow-up consultations. They may even lead to various serious complications. Facing potentially large medical expenses and long-term pressure, many people may begin to consider whether daily savings alone are enough to cope with different situations. Setting aside flexibility for possible future health risks may also become part of some people's overall financial planning.
 
Depending on your personal health condition, life stage and budget, you may consider medical protection or critical illness protection plans with comprehensive coverage according to your needs. Understanding AIA's protection solutions early can help you better prepare for unexpected health challenges. It may also help reduce the financial burden in the unfortunate event of illness, allowing you and your family to focus on receiving appropriate treatment and enjoy greater peace of mind in the future.

Blood Sugar Levels FAQs

A fasting blood glucose level between 5.6 and 6.9 mmol/L is defined as prediabetes. This is an important health warning sign, indicating that the body's ability to regulate blood sugar has started to decline2. However, prediabetes may be reversible. By improving lifestyle habits, such as maintaining a balanced diet, exercising regularly and managing body weight, together with regular blood sugar monitoring, it may help reduce or delay the risk of developing true type 2 diabetes1.

Yes. Although blood sugar levels gradually return to normal after delivery for most women with gestational diabetes, research from The Chinese University of Hong Kong shows that they have a higher risk of developing diabetes later in life compared with the general population7. Therefore, CUHK recommends maintaining the habit of regular blood sugar testing after delivery. At the same time, you may also consider planning suitable health protection early to prepare for a potentially higher future health risk.

Some external factors may temporarily affect test results. For example, taking certain medications such as steroids8, or being under extreme mental stress9, may cause a temporary rise in blood sugar levels and lead to a false positive result. Therefore, if you have doubts about a single test result, you may repeat the test on a different date. You may also combine the result with long-term diabetes indicators such as HbA1c to ensure diagnostic accuracy.

Even if there are no symptoms of diabetes, healthy individuals aged 45 or above are generally advised to undergo blood sugar screening at least once every 3 years10. Maintaining good health records not only helps you understand your physical condition, but may also give you greater flexibility when choosing protection solutions in the future.
*This information is owned by AIA, and may not be copied or reproduced without AIA's written consent. You may not copy or store this content on any other website or content platform.
 
This information contains general information only and is intended for distribution in Hong Kong only. It does not constitute any sales advice and/or product recommendation. Before applying for any insurance product, customers must complete a Financial Needs Analysis and apply based on their actual protection needs and affordability. The product information in this document does not contain the full terms of the policy. For details on product features, terms and conditions, exclusions, and key product risks, please refer to the relevant product brochure and policy contract. This promotion is not applicable to cases involving plan changes from other insurance products to the promoted insurance products (basic plans or riders, if applicable). If you wish to review a sample policy contract before applying, you may request one from AIA. Life insurance policies are long-term contracts. If you surrender the policy in the early years, the amount you receive may be significantly less than the total premiums paid.
 
This information is general information and for reference only, and should not be considered as a medical, diagnosis or professional recommendation, and cannot replace any medical, diagnosis or professional recommendation from doctors. Independent professional advice should be sought from an appropriate qualified medical professional (such as doctors) before making any decision on the topics mentioned above. Treatment may vary according to individual circumstances. If in doubt, you may ask your doctor. If necessary, you may seek other medical advice as soon as possible and do not ignore or delay seeking medical advice / treatment. AlA assumed no liability for any loss or damage arising directly or indirectly from the use, misuse, understanding or application of any of the above information.

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1. Centre for Health Protection. Non-Communicable Diseases Watch November 2024 - Preventing Type 2 Diabetes by Lifestyle Changes. 2024.
3. K.K.Leung Diabetes Centre. 營。型。翼翼糖尿病完全飲食手冊​. https://www8.ha.org.hk/qmh/department/prc/file/latestnews/07/leaflet.pdf
4. Hong Kong Adventist Hospital – Tsuen Wan. The Myths and Facts About Hypoglycemia. https://www.twah.org.hk/en/conditions-and-treatments/the-myths-and-facts-about-hypoglycemia-chinese-only 
5. Jockey Club Support Project for Young People with Diabetes. Continuous Glucose Monitoring - CGM. https://jcsupportdm.hk/cgm/
6. Diabetes Hongkong. ​診斷糖尿病的指標​. https://diabetes-hk.org/diagnosis/
7. Faculty of Medicine, The Chinese University of Hong Kong. CUHK's nearly 20-year studies highlight long-term risks of gestational diabetes and elevated glucose during pregnancy. 2025. https://www.med.cuhk.edu.hk/press-releases/cuhk-s-nearly-20-year-studies-highlight-long-term-risks-of-gestational-diabetes-and-elevated-glucose-during-pregnancy 
8. The Society of Hospital Pharmacists of Hong Kong. 藥問101: 降糖藥效能​. 2017. https://www.derc.org.hk/en/news-detail.php?id=243
9. Asia Diabetes Foundation. Emotional well-being. https://www.diabetesrisk.hk/emotional_wellbeing
10. Health Bureau. Diabetes and Hypertension Care For Adults in Primary Care Settings. 2022. https://www.healthbureau.gov.hk/phcc/files/primary_care_settings_eng.pdf

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