What are the ideal blood glucose levels?

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Measuring blood glucose levels is an essential step in managing diabetes. Tools for blood glucose management, also called glycemic control, include:

• the A1C test, which shows blood sugar levels over time
• continuous glucose monitoring (CGM), an ongoing measure that tracks levels throughout the day
• self-monitoring of blood glucose through fingerprick tests

Doctors measure blood sugar levels in milligrams per deciliter (mg/dl), but A1C results may also appear as a percentage. The percentage refers to the amount of hemoglobin that glucose has bound to in the blood.

The following charts outline general target levels for those with and without diabetes.

These figures serve as a guide, but each person’s individual needs vary according to age and other factors. A doctor will work with a person to establish their suitable blood sugar levels and help them stay close to their target goals.

General target levels

General blood sugar target levels are as follows:

A1C levels

An A1C test measures a person’s average blood sugar levels over 3 months. It can show if glucose management strategies are working over time.

According to the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), a person’s A1C results may be as follows:

A doctor will need to carry out two tests to diagnose diabetes unless the person shows clear signs of the condition.

Blood sugar charts for children

Ideal blood sugar levels vary at different ages. Based on data from the Nationwide Children’s Hospital, the following chart shows the ideal levels for children aged 0–10 and over.

The following chart, using information from Diabetes UK, gives a rough idea of how a child’s blood sugar levels may vary during the day. However, they do not differentiate by age. A doctor will advise on levels that are suitable to the individual.

Experts note that strict adherence to complex blood sugar targets is not always the best approach, especially for children. Parents may find that a doctor provides more straightforward guidelines for children than adults if the benefits outweigh the risks.

Blood sugar chart for teens

The following are average guideline levels for teens, but people should ask a doctor for individual recommendations.

People with gestational diabetes

Gestational diabetes can occur during pregnancy. Often, it is a temporary condition, but it can lead to pregnancy complications.

The American Diabetes Association (ADA) recommends that people with a diagnosis of gestational diabetes aim for blood sugar levels similar to those for people without diabetes, although individual targets may vary.

The ADA offers the following as a guideline:

A doctor will advise the individual on what to do if blood sugar levels are not within the target range.

A doctor may recommend higher blood sugar targets for a person with diabetes than for someone who doesn’t have diabetes.

Target levels vary throughout the day. They tend to be lower before eating and after exercise and higher an hour or so after meals.

When working out a person’s glucose targets, a doctor will consider individual factors, such as:

• age and life expectancy
• the presence of other health conditions, particularly cardiovascular disease
• how long a person has had diabetes
• problems with the smallest arteries in the body
• any known damage to the eyes, kidneys, blood vessels, brain, or heart
• personal habits and lifestyle factors
• how aware a person is of low blood sugar levels
• stress

Blood sugar charts often show recommended levels as a range, allowing for differences between individuals.

Why is diabetes more common in Black Americans? Find out here.

Some actions can help adjust glucose levels if they are slightly high or low.

Raising low blood sugar

A person with very low blood sugar, or hypoglycemia, may notice the following symptoms:

• feeling shaky or jittery
• being hungry or tired
• feeling dizzy or lightheaded
• confusion
• changes in heart rhythm
• headache
• difficulty seeing or speaking

If these symptoms occur, the NIDDK advises people to:

1. Check their glucose levels.
2. Consume something containing 15–20 grams of glucose or carbohydrates.
3. Wait 15 minutes.
4. Recheck glucose levels.
5. Repeat if levels are still low.

If levels remain low, the person should seek medical advice. If the individual loses consciousness, someone should seek emergency medical help.

Lowering high blood sugar

High blood sugar is called hyperglycemia and may lead to:

• thirst
• weakness or tiredness
• headaches
• frequent urination
• blurred vision

Exercising may help. If high levels persist, the person should speak to a doctor as they may need to adjust their treatment plan.

A person should also contact a doctor if high or low blood sugar symptoms are severe, as they may need emergency medical attention.

What is a diabetic emergency, and what action should a person take?

Monitoring blood sugar levels is an important part of diabetes management. A monitoring plan may include:

• tests in a doctor’s office
• a fingerprick test
• using a CGM device, which monitors glucose levels throughout the day

Typical times a person will check their levels include:

• before meals
• before bedtime
• on noticing symptoms

People may also do additional testing:

• before, during, and after exercise
• during the night
• when unwell
• after adjustments to their treatment plan

The frequency of testing will vary according to the type and stage of diabetes and individual factors. A doctor will advise the person on how often to test and when.

Usually, the body can manage excess blood sugar either by eliminating it or converting it into fat cells. If high blood sugar levels persist, however, problems can arise.

In time, persistent high blood sugar may result in damage to the:

• eyes
• nerves
• kidneys
• blood vessels

A wide range of complications can also result, such as slow wound healing and frequent infections. Other possible complications include:

Diabetic ketoacidosis (DKA)

If the body cannot use glucose for energy, it starts to break down fat instead. In doing so, it releases substances called ketones. At high levels, ketones are toxic.

If high levels of ketones build up in the blood, DKA can occur. Symptoms include:

• a fruity smell on the breath
• difficulty breathing
• nausea and vomiting
• a very dry mouth
• in some cases, loss of consciousness and coma

DKA is a life threatening emergency, and a person will need immediate medical attention. Research suggests it is the most common complication of type 1 diabetes.

Why does my breath smell like acetone? Find out more about DKA.

Hyperosmolar hyperglycemic syndrome (HHS)

HHS is a potentially life threatening condition that involves high blood sugar and dehydration.

Symptoms include:

• extreme thirst
• increased urination
• weakness and a feeling of being unwell
• dry skin
• changes in vision and consciousness due to reduced blood flow to the brain
• coma, in severe cases

Anyone showing signs of HHS needs immediate medical attention.

The following are answers to commonly asked questions about blood sugar.

What are the normal ranges for blood sugar?

Typical ranges for blood sugar are 72–99 mg/dl before meals and less than 140 mg/dl two hours after a meal.

What is a good blood sugar level in the morning?

A healthy blood sugar level upon waking is 72–126 mg/dl.

What is a healthy A1C level by age?

For a person without diabetes, a healthy A1C level is below 5.7%. This changes to 6.5% for someone with diabetes.

Managing blood sugar levels is an important step in preventing the complications of diabetes. If blood sugar levels stay within a moderate range, this can indicate that treatment is working.

Individual needs can differ, and a doctor will set goals at the start of treatment. They may adjust these targets as treatment progresses.

If anyone has concerns about their blood sugar levels, they should seek medical attention.

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