Understanding and Managing Fasting Blood Sugar
Maintaining fasting blood sugar levels below 5.7% is key to preventing diabetes. Learn about the role of fasting blood sugar in diabetes management, effective testing methods, and practical tips for supporting a healthy lifestyle.
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Last updated on 3rd Jul, 2025
Fasting blood sugar is measured several hours after eating to get an accurate glucose level. Ideally, it should be below 5.7%; levels between 5.7-6.4% indicate prediabetes, while 6.5% or higher signals diabetes. Elevated fasting blood sugar can point to insulin resistance or diabetes, and extremely low levels may result from diabetes medications.
Regular monitoring of blood sugar levels is crucial for managing diabetes or preventing its onset. Keep reading to learn more about fasting blood sugar levels, how to test them, and tips to maintain a healthy range.
The Physiology of Blood Sugar Regulation
Insulin and glucagon generally work together in sync to maintain balanced blood sugar levels. For example:
Glucagon increases blood sugar by converting glycogen stored in the liver into glucose, while insulin enables cells to take in glucose from the blood to produce energy.
The pancreas produces insulin to lower blood sugar levels when they are high and releases glucagon to raise them when they are low. This balance generally ensures cells get energy while preventing damage from high blood sugar.
An imbalance in this process can result in conditions such as diabetes.
Hence, prescription insulin and glucagon help to keep blood sugar within a safe range.
On the other side, when a person eats, their body breaks food into parts such as proteins, carbohydrates, vitamins, and minerals, including:
Carbohydrates turn into blood sugar; more carbs mean higher blood sugar levels.
Liquid carbs, like soda, raise blood sugar faster than solid foods, such as pizza.
Fibre, a type of carbohydrate, doesn’t turn into sugar because it isn’t digested but is still essential for health.
Protein, water, vitamins, minerals, and fat don’t affect blood sugar.
Therefore, if an individual has diabetes, managing carbohydrate intake is essential to controlling their blood sugar.
Optimal Fasting Blood Sugar Levels
The American Diabetes Association classifies HbA1c (Haemoglobin A1c) test results as:
Normal: Less than 5.7%
Prediabetes: Between 5.7% and 6.4%
Diabetes: 6.5% or higher
Prediabetes generally occurs when blood sugar levels are above normal but not high enough to be called diabetes. Taking steps to lower blood sugar can help reverse prediabetes and prevent diabetes.
These guidelines from the ADA (American Diabetes Association) provide recommendations for managing diabetes. This chart outlines target goals for different groups of people with diabetes.
| Variation Based on Age or Health | Before Meals (fasting) | After Meals (post-prandial) | Other |
| 65 or older | 80 to 180 mg/dL | — | A blood sugar range of 80 to 200 mg/dL is advised for people with limited mobility, those in assisted living, or those approaching the end of life. |
| Children with type 1 diabetes | 90 to 130 mg/dL | — | 90 to 150 mg/dL at bedtime/overnight |
| Adults with type 2 diabetes | 80 to 130 mg/dL | less than 180 mg/dL | — |
| Adults with type 1 diabetes | 80 to 130 mg/dL | less than 180 mg/dL | — |
| Pregnant women | less than 95 mg/dL | 140 mg/dL (1 hour after meal) | 120 mg/dL (2 hours after meal) |
These guidelines are a general starting point, but individual goals may differ. A person may consult a doctor to find what suits them best.
Factors Affecting Fasting Blood Sugar
High blood sugar can develop due to numerous reasons, such as:
Food choices and lack of exercise
Not drinking enough water
Certain medications like steroids
Missing or taking too little diabetes medication
Using medications incorrectly
Illness, infection, or surgery
Stress or hormonal changes, including lack of sleep and menstruation
Blood sugar testing helps identify patterns, such as spikes after meals or dips during fasting, enabling more effective management of blood sugar levels. If high blood sugar persists, it is essential to consult a healthcare provider to review and adjust the treatment plan accordingly.
Risks Associated with Abnormal Fasting Blood Sugar
Blood sugar outside the healthy range can be too high (hyperglycemia) or too low (hypoglycemia). Both conditions are dangerous, especially for people with diabetes. High blood sugar is mainly caused by diabetes but can also result from certain medications, an overactive thyroid, pancreas issues, or rare tumours.
Symptoms of high blood sugar may take time to appear and include:
Increased thirst
Blurred vision
Frequent urination
Increased hunger
Fatigue
Skin infections
Slow-healing cuts and sores
Low blood sugar can develop if a person takes insulin or medications to lower blood sugar, skip meals, exercise, etc. Symptoms of low blood sugar include:
Shaking or sweating
Feeling pale, anxious, or irritable
Hunger and tiredness
Dizziness or headache
Fast or irregular heartbeat
Without prompt treatment, both conditions can lead to unconsciousness or seizures. When blood sugar levels are low, it is necessary to eat something sugary, drink juice or soda, or take glucose tablets to raise them effectively.
Diagnosis and Monitoring of Blood Sugar Levels
People or healthcare professionals can use the following tests to check fasting blood sugar levels:
The HbA1c test measures the average blood sugar levels over the last three months. It is generally conducted in a lab or doctor’s clinic, and the results are shown as a percentage.
Home blood sugar testing is performed upon waking or before meals to measure fasting blood sugar. Diabetes patients may test multiple times daily to adjust insulin doses.
This process involves preparing a monitor, cleaning the fingertip, lancing, collecting blood on a strip, inserting it into the monitor, and recording the results.
Continuous Glucose Monitoring (CGM) devices track blood sugar levels 24/7, providing detailed data on fluctuations. While highly effective, CGM systems can be costly.
Nonfasting tests, like Random Plasma Glucose (RPG), measure sugar levels at any time, while the Oral Glucose Tolerance Test (OGTT) evaluates glucose levels over two hours after consuming a sugary drink.
Strategies to Maintain Optimal Fasting Blood Sugar Levels
Individuals can easily manage and maintain their blood sugar levels by:
Eating meals at regular times
Avoiding skipping meals, especially if low blood sugar is a concern
Including enough lean protein in their diet
Drinking plenty of water
Maintaining a healthy weight as per their age and height
Exercising or doing any physical activity for at least 150 minutes a week, if possible
Getting enough sleep every night
Treatment Options for Abnormal Fasting Blood Sugar
A combination of medical treatment and lifestyle changes is essential to effectively manage abnormal blood sugar levels and prevent its complications.
Doctors may prescribe insulin or other medications to help control blood sugar levels.
Regular blood sugar monitoring helps track changes and adjust treatment as needed.
Eating a balanced diet with lean proteins, whole grains, and healthy fats while limiting sugary foods is essential for blood sugar control.
Including physical activity or exercise in the daily routine can help maintain healthy blood sugar levels.
Reducing stress levels is important to prevent blood sugar spikes.
Regular visits to a healthcare provider ensure progress is monitored, and necessary adjustments are made.
Complications of Poor Fasting Blood Sugar Control
Conclusion
Regular monitoring of fasting blood sugar is essential, particularly for individuals at risk of diabetes. Tools like the HbA1c test and continuous glucose monitoring provide valuable insights into blood sugar trends.
By adopting these strategies and collaborating with healthcare professionals, individuals can effectively manage blood sugar levels, minimise health risks, and maintain a healthier lifestyle.
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