Normal Blood Sugar Levels By Age (Chart)

Blood sugar, or glucose, is the primary type of sugar in the body. It comes from carbohydrates found in foods. Glucose is essential for providing energy to cells throughout the body, including brain cells.

Your blood sugar level fluctuates throughout the day as you eat, exercise and sleep. Stress and hormones also play a role. People with diabetes should monitor blood sugar levels closely to ensure they remain within the appropriate target range—often determined by a medical provider.

A blood sugar level outside the target range can have profound health implications. “When blood sugar levels are too high or too low, it can have serious health consequences, such as nerve damage, kidney damage and heart disease,” says Brenda Peralta, registered dietitian and certified diabetes educator at FeastGood.com.

High blood sugar (hyperglycemia) can lead to conditions like diabetes, cardiovascular disease and stroke, she explains. Low blood sugar (hypoglycemia) can cause confusion, anxiety, weakness, sweating and vision problems. Extremely low levels of blood sugar can result in seizures and fainting.

Why Does Blood Sugar Matter With Diabetes?

Diabetes is a condition that makes it difficult or impossible for the body to regulate glucose levels on its own. When someone is living with diabetes, their body is either unable to produce enough insulin—or make enough insulin available for use. Insulin is a hormone that helps the body use glucose for energy. When insulin levels are too low, glucose accumulates in the bloodstream and can damage organs and other tissues.

“Diabetes occurs when a person’s body cannot adequately manage sugar that’s ingested normally in our everyday diet,” says Jennifer Meller, M.D., chief medical officer at Sweetch—a digital health care innovation company based in Tel Aviv, Israel. “Chronically elevated sugar levels can lead to changes in both large and small blood vessels.”

Over time, changes to large vessels can lead to an increased risk of heart attack and stroke, while damage to small vessels can cause nerve damage, vision loss and kidney failure, explains Dr. Meller.

For people living with diabetes, maintaining healthy blood sugar levels is essential to preventing serious health complications in the future. This requires understanding target glucose levels for different age groups and making lifestyle changes accordingly, as blood sugar can go up or or down based on what you eat and when, among other factors.

What Is an A1C Number?

An A1C test, also called glycosylated hemoglobin, is a standard diagnostic tool used to measure a person’s average blood sugar levels over the past three months (90 days). It reflects how well your blood sugar is controlled during that time period.

“It’s an essential measure of blood sugar control in diabetes because it provides a long-term view of blood sugar levels and can help predict the risk of complications from diabetes,” explains Peralta.

The test uses a small blood sample to analyze the amount of hemoglobin—a protein found in red blood cells that carries oxygen and binds to glucose molecules. The higher the glucose level in your bloodstream, the more hemoglobin will bind to it and be detected by the A1C test. This test is often done with a finger prick in the doctor’s office..

An A1C number is expressed as a percentage, with higher percentages indicating higher levels of glucose in the bloodstream. A healthy A1C reading for someone without diabetes is between 4% and 5.7%. A value between 5.7% and 6.4% is considered prediabetic, while 6.5% and higher are consistent with diabetes^[1]Hemoglobin A1C. National Library of Medicine. Accessed 1/2/2023. .

One important note to consider about one’s A1C number is that it may be affected by other medical conditions such as anemia, which could result in an inaccurate reading. This is why looking at additional numbers, such as one’s fasting glucose, in conjunction with an A1C number, is usually recommended.

Blood sugar is often tested with a glucometer, which measures the amount of glucose in a sample of blood. A small drop of blood from the fingertip or arm is placed on a test strip and inserted into the glucometer. The results display on the glucometer’s LCD screen within a few seconds.

Another way to test blood sugar is via continuous glucose monitoring (CGM), which typically involves placing a disposable, water-resistant sensor on the back of the arm or stomach. These sensors can be scanned with a reader, and can be used for three to 14 days, depending on the brand. Many CGM sensors are used along with a smartphone, allowing the individual and others (such as caregivers) the ability to see glucose trends over the last eight hours.

Those living with diabetes usually check their blood sugar levels several times a day, including before meals and snacks and two hours after eating.

In certain cases, a doctor may also order other tests, such as a fasting glucose test or an oral glucose tolerance test. These tests measure the glucose levels in the blood at specific times (fasting or after eating).

When to Test Blood Sugar

For many people living with diabetes, standard times to test blood sugar are before meals and before bed. However, a doctor may ask someone to test their blood sugar as often as two hours after eating and in the middle of the night, depending on their condition. The best way to determine how often to test your blood sugar is by consulting with your doctor, who can recommend times based on your specific health needs.

Other instances in which a person may consider testing their blood sugar include:

• When experiencing symptoms of low blood sugar, such as dizziness, sweating or confusion
• After dining at a restaurant or trying new foods
• When feeling sick
• When experiencing stress
• While consuming alcohol
• Before and after exercising
• When starting a new medication
• After taking too much insulin or diabetes medication
• After taking diabetes medication at the wrong time

It’s crucial to understand that normal blood sugar levels vary depending on age, lifestyle factors and health issues.

The chart below uses insight from studies including those conducted by the American Diabetes Association (ADA), the Centers for Disease Control and Prevention (CDC) and John Hopkins Medicine to illustrate the typically recommended blood sugar levels by age. It was reviewed by Dr. Meller.

Fasting and non-fasting blood sugar tests are used to screen individuals for diabetes and prediabetes.

Fasting blood sugar tests measure blood sugar levels after not having eaten for eight hours and are typically performed in the morning prior to breakfast. Fasting blood sugar levels may indicate that an individual is prediabetic or diabetic based on the following ranges.

• Normal: 99 mg/dL or lower
• Prediabetes: 100 mg/dL to 125 mg/dL
• Diabetes: 126 mg/dL or higher

Non-fasting blood sugar tests don’t require an individual to abstain from eating beforehand. Non-fasting blood sugar levels may indicate that an individual is prediabetic or diabetic based on the following ranges.

• Normal: 140 mg/dL or lower
• Prediabetes: 140 mg/dL to 199 mg/dL
• Diabetes: 200 mg/dL or higher

If your blood sugar levels are consistently too high or low, you may experience certain signs and symptoms. According to Peralta and Dr. Meller, the following are common signs of unbalanced blood sugar:

Symptoms of high blood sugar include:

• Increased thirst
• Frequent urination
• Fatigue
• Blurred vision
• Slow-healing sores
• Weight loss
• Frequent infections

Symptoms of low blood sugar include:

• Hunger
• Shaking
• Sweating
• Rapid heartbeat
• Headache
• Dizziness
• Confusion and difficulty concentrating

What Level of Blood Sugar Is Dangerous?

Low blood sugar—or hypoglycemia—occurs when an individual’s glucose levels fall below 70 mg/dL. Severe low blood sugar occurs when glucose levels fall below 54 mg/dL and may lead to fainting. Low blood sugar is common in individuals with type 1 diabetes and requires treatment.

High blood sugar—or hyperglycemia—occurs when an individual’s glucose levels rise to 240 mg/dL or higher. If untreated, hyperglycemia may lead to ketoacidosis, a condition commonly known as diabetic coma.

Ketones are waste products made when the body breaks down fats due to insufficient insulin. They’re intolerable in large amounts and are released via a person’s urine. If the body is unable to release large amounts of ketones through urine, they may build up in the blood causing high ketone levels. This may lead to ketoacidosis, a medical emergency in which ketones make the blood more acidic, and requires immediate medical treatment.

What to Do When Blood Sugar Is Too High or Low

For individuals experiencing hypoglycemia, treatment consists of the following options:

• Taking four glucose tablets
• Drinking 4 ounces of fruit juice, such as apple or orange juice
• Drinking 4 ounces of soda
• Eating four pieces of hard candy

Individuals should test their blood sugar levels again 15 minutes after attempting to raise their blood sugar to determine whether glucose levels have reached 70 mg/dL or higher. If glucose levels remain low, continue one of the above treatments until blood sugar has returned to normal.

Individuals experiencing hyperglycemia should use an over-the-counter test kit to measure ketone levels in their urine. If ketone levels are above 80 mg/dL, seek medical attention immediately.

If blood sugar levels are high but a urine test detects normal ketone levels, the following options may to help lower blood sugar:

• Stay hydrated: Dehydration can cause the sugar in your blood to become more concentrated, leading to higher glucose levels. Increasing your water intake can help regulate blood sugar by introducing more water into the bloodstream.
• Get more exercise: Physical activity makes your body more sensitive to insulin and lowers your blood sugar for up to 24 hours after exercise. If you have ketones, do not exercise. This may cause your blood sugar to rise even higher.
• Manage stress: Stress may lead to elevated blood sugar levels. Learning healthy ways to cope with stress through therapeutic activities (such as listening to music or going for a walk) can help combat high blood sugar.
• Get enough sleep: Research indicates that poor sleep quality negatively affects the body’s ability to control blood sugar levels. Aim to get seven to eight hours of sleep per night. Speak with your health care provider if you suspect you may have a sleep disorder.
• Count carbohydrates: Carbohydrates are broken down into glucose during the digestion process and can cause blood sugar levels to rise. Counting carbs can help manage blood sugar levels and can help some people with diabetes make sure they’re getting enough insulin.

Diabetes is a serious condition, and it’s important to talk to your doctor if you’re concerned about your blood sugar levels. Your provider can order tests to confirm a diagnosis of diabetes or prediabetes and provide treatment recommendations. They may also suggest lifestyle changes to help keep your blood sugar within the recommended target range.

Taking steps to monitor and manage your blood sugar levels is key to maintaining good health and avoiding the long-term complications of diabetes. With proper care and regular check-ups, it’s very possible to manage your blood sugar levels.