Key takeaways

A blood glucose test measures the amount of glucose in the blood to test for health conditions like diabetes.
Diet, physical activity, medications, medical conditions, age, stress, dehydration, and illness influence blood sugar levels. Tests like A1C, fasting blood glucose test, glucose screening test, and glucose tolerance test help monitor blood glucose.
Normal blood sugar levels differ by age and diabetes status, and charts detailing fasting, before-meal, after-meal, and bedtime glucose levels are provided for children, adolescents, adults, and pregnant women.
High or low blood sugar levels require medical attention, with low being under 70 mg/dL and high above 130 mg/dL before meals or 180 mg/dL after meals. Management includes lifestyle changes, monitoring, and possibly medication.

A blood glucose test measures the amount of glucose, or sugar, that someone has in their blood at any given time. Having high or low blood sugar levels could indicate an underlying health condition, like diabetes, that may require medical attention. Blood glucose levels fluctuate during the day, and what’s considered a normal range differs between people with and without diabetes. If you’ve recently had your blood sugar tested, use the charts below to understand what your results mean.

Types of blood sugar tests for diabetes

Your healthcare provider may order tests regularly based on your age and risk factors. Or, if you are experiencing certain symptoms, your doctor may order one or more of the following tests to check your blood sugar. Blood glucose is measured in milligrams (mg) per deciliter (dL).

A1C test

What to expect: A hemoglobin A1C test, known as “A1C,” is a measure of blood sugar control over three months. This test can be done in the lab; however, many endocrinologists can perform this test with a finger stick in the office. Your provider will tell you what your A1C goals should be.

Test results: In general, normal A1C in people without diabetes is 5.6% or less, a level of 5.7% to 6.4% is in the prediabetes range (and the higher the number in this range, the greater the risk is for developing Type 2 diabetes), and a level of 6.5% or more indicates diabetes.

RELATED: More about A1C levels

Fasting blood glucose test

What to expect: This glucose blood test can be done in the lab or the healthcare provider’s office with a simple finger stick—or your doctor may prescribe a meter and have you test regularly at home. Some people have a continuous glucose monitor (CGM) where they can see their blood sugar levels in real-time.

Test results: Fasting blood sugar levels indicate what your blood sugar is when you haven’t eaten for at least eight hours. Normal blood sugar levels for adults without diabetes are less than 100 mg/dL after fasting. A fasting glucose level of 100-125 mg/dL indicates prediabetes, and 126 mg/dL or higher indicates diabetes.

Glucose screening test

What to expect: The test for gestational diabetes is called a glucose screening test. During the test, you will drink a sugary beverage. Then, your blood sugar will be checked one hour later.

Test results: A normal result is 140 mg/dL or less. If the level is higher than 140, your provider will order a glucose tolerance test.

Glucose tolerance test

What to expect: A glucose tolerance test (also known as an oral glucose tolerance test) will measure your blood glucose levels before and after you drink a sugary liquid. You will first have a fasting blood sugar level taken. Then you’ll drink the sugary liquid, and have your blood sugar tested one hour later, two hours later, and possibly three hours later.

Test results: At the two-hour mark, normal blood glucose levels are 140 mg/dL or lower, while 140-199 mg/dL indicates prediabetes and 200 mg/dL or higher indicates diabetes.

RELATED: Types of diabetes

Factors that affect blood glucose levels

Glucose is a simple sugar that’s always present in the bloodstream. You’ll get different results depending on when you test your sugar. Many factors affect the variation of blood sugar levels throughout the day:

Type of food consumed, how much, and when
Physical activity
Medications
Medical conditions
Age
Stress
Dehydration
Illness
Menstrual periods
Alcohol

Risk factors for diabetes include genetic and environmental factors, such as having a family member with diabetes, having prediabetes, being overweight or obese, having certain genes, and being of a certain race or ethnicity. High-risk individuals can prevent some forms of diabetes by consulting a diabetes educator, maintaining a healthy body weight, and improving their overall health.

What are healthy blood sugar levels for a nondiabetic person?

Normal glucose levels in adults without diabetes, who haven’t eaten for at least eight hours (fasting) are less than 100 mg/dL. Blood sugar levels after eating will rise and hit their peak in about one hour. Blood sugar levels in healthy people without diabetes will usually stay under 140 mg/dL, and return to normal levels within two or three hours.

Normal blood sugar levels by age for people without diabetes
Age	Time of day	Blood sugar in mg/dL
Children < 6 years old	Fasting	Less than 100 mg/dL
	1-2 hours after eating	Less than 120 to 140 mg/dL
	Bedtime	Less than 100 mg/dL
Children 6-12 years old	Fasting	Less than 100 mg/dL
	1-2 hours after eating	Less than 120 to 140 mg/dL
	Bedtime	Less than 100 mg/dL
Adolescents 13-19 years old	Fasting	Less than 100 mg/dL
	1-2 hours after eating	Less than 120 to 140 mg/dL
	Bedtime	Less than 100 mg/dL
Adults 20+ years old	Fasting	Less than 100 mg/dL
	1-2 hours after eating	Less than 120 to 140 mg/dL
	Bedtime	Less than 100 mg/dL
Pregnant women	Fasting	Less than 100 mg/dL

Normal blood sugar levels for people with diabetes

Normal sugar levels for those with diabetes will also vary depending on someone’s age and the time of day. For example, when fasting, blood sugar levels are often in the target goal range. The type of food eaten will impact blood sugar levels in different ways. A meal with a lot of carbohydrates (cereal, cookies, waffles) will raise blood sugar quicker than a meal that contains carbohydrates, protein, and fat (a hamburger and french fries). Blood sugar will rise after a meal but will start to return to normal levels in several hours.

Let’s look at what blood sugar levels should be in those with diabetes based on their age.

Target blood sugar levels by age for people with diabetes
Age	Time of day	Blood sugar in mg/dL
Children < 6 years old	Fasting	80-180
	Before meal	100-180
	1-2 hours after eating	~180
	Bedtime	110-200
Children 6-12 years old	Fasting	80-180
	Before meal	90-180
	1-2 hours after eating	Up to 140
	Bedtime	100-180
Adolescents 13-19 years old	Fasting	70-150
	Before meal	90-130
	1-2 hours after eating	Up to 140
	Bedtime	90-150
Adults 20+ years old	Fasting	Less than 100
	Before meal	70-130
	1-2 hours after eating	Less than 180
	Bedtime	100-140
Pregnant women	Fasting	<95
	Before meal	95 or less
	1-2 hours after eating	1 hour: 140 or less 2 hours: 120 or less

Target blood glucose levels in children with diabetes

Children younger than 6 years of age should have a target range of 80 to 200 mg/dL each day. The amount of glucose in a child’s body will fluctuate from the time they wake up to after they’ve eaten meals and again before bedtime. For this reason, kids with diabetes or hypoglycemic episodes may have to have their blood sugar levels tested in the middle of the night by their parents. Many children (and adults) with Type 1 diabetes use continuous glucose monitoring, which mostly eliminates the need for finger sticks.

Target blood glucose levels for young adults with diabetes

Teenagers should have average blood sugar levels that range between 70 to 150 mg/dL over the course of their day. Teenage years can often be the most difficult for adolescents with diabetes to manage, not only because of the hormonal component but also because managing diabetes requires a lot of responsibility.

Target blood glucose levels for adults with diabetes

When you wake up in the morning, your fasting blood sugar is generally at its lowest because you haven’t consumed food for about eight hours. However, many people experience an increase in blood sugar levels in the early morning hours. If you’re an adult and struggling with glucose control, your healthcare provider can help you develop a treatment plan to manage your blood sugar better. Blood glucose levels outside the ranges listed in the blood sugar levels chart by age above are categorized as either high or low blood sugar.

Target blood glucose levels for adults with gestational diabetes

The American Diabetes Association’s targets for pregnant women are 95 mg/dL before a meal, 140 mg/dL or less one hour after a meal, and 120 mg/dL or less two hours after a meal.

Gestational diabetes is a type of diabetes that develops in pregnancy—in women that were not already diagnosed with diabetes. Gestational diabetes usually develops around 24 weeks of pregnancy, so your healthcare provider will order a test around 24 to 28 weeks of pregnancy—or earlier if you are at higher risk.

Managing gestational diabetes consists of dietary changes, exercise, checking blood sugar, and monitoring the baby. Diabetes medication or insulin may be required. It is important to manage gestational diabetes because the condition can increase the mom’s risk of high blood pressure as well as having a larger baby (9 pounds or more) that will need a C-section delivery. Gestational diabetes also increases the baby’s risk of being born early, having low blood sugar, and developing Type 2 diabetes later in life. Although blood sugar levels will likely return to normal after childbirth, about 50% of women with gestational diabetes will eventually develop Type 2 diabetes. Your care team will continue to monitor you after childbirth.

What level of blood sugar is dangerous?

Low blood sugar in adults is generally considered to be less than 70 mg/dL. Dangerously low blood glucose levels are below 54 mg/dL.

Blood sugar levels are considered high if they’re above 130 mg/dL before a meal or 180 mg/dL within one to two hours after a meal. However, many people won’t start to experience symptoms of high blood sugar until their levels are at 250 mg/dL or higher.

Different people will have different blood glucose targets set by their healthcare provider, based on various factors such as age and other medical conditions. Your healthcare provider will give you more information about what actions to take for your particular high or low blood sugar ranges.

Low blood sugar levels

Hypoglycemia happens when blood glucose levels drop too low. People who take insulin may have low blood sugar if they take too much insulin or mistime the insulin dose in relation to food, or if they exercise more than usual when there is fast-acting insulin in the body.

Low blood sugar can also be caused by many things including certain medications or combinations of medications, alcohol, endocrine disorders, eating disorders, and disorders of the liver, kidneys, or heart.

RELATED: Low blood sugar symptoms

The only way to know for sure if your blood sugar is low is to test it with a glucose meter (a glucose monitoring device) or monitor it with a continuous glucose monitor such as the Dexcom G6.

How to raise blood sugar

If your blood sugar is low (or if you don’t have access to these tools and start to feel the symptoms of low blood sugar), the general guidelines from the American Diabetes Association (ADA) are to consume 15 grams of fast-acting carbs (such as Smarties, fruit juice, or glucose tablets) to raise your blood sugar levels and avoid further symptoms. Your healthcare provider will give you a plan for what to do in case of low blood sugar that is specifically designed for you.

You should also have glucagon on hand that you take everywhere with you, such as Baqsimi nasal spray, in case of a low blood sugar emergency. After learning how to use it, teach your family, friends, and caregivers how to administer it to you in case of an emergency where you are unconscious and cannot eat or drink. Also, always wear a medical alert identification to let first responders know that you have diabetes in case of an emergency.

High blood sugar levels

Hyperglycemia is the medical term for having too much sugar in your blood. Hyperglycemia happens when the body doesn’t have enough insulin or when it can’t use insulin correctly. Many things can cause high blood sugar levels like Type 1 diabetes, Type 2 diabetes, stress, illness, or the dawn phenomenon.

RELATED: High blood sugar symptoms

Untreated hyperglycemia can lead to a condition called diabetic ketoacidosis. Ketoacidosis is where the body creates waste products called ketones that can build up in the blood and become life-threatening. A blood or urine test can check for the presence of ketones.

Symptoms of ketoacidosis include abdominal pain, fast or deep breathing, nausea, vomiting, exhaustion, fruity-smelling breath, and vision loss (in rare cases).

“When patients experience any of these accompanied by elevated blood sugar levels, diabetic patients are advised to go directly to the ER to avoid diabetes-induced coma,” says Vikram Tarugu, MD, a gastroenterologist and the CEO of Detox of South Florida. “Patients who have elevated blood sugar may also present with frothy, ketone-like smelling breath.”

How to lower blood sugar

Here are some healthy lifestyle changes and medical treatments that can help treat hyperglycemia:

Eat a healthy diet with whole, low-sugar foods that are minimally processed to keep the amount of glucose in the body at a lower level.
Only exercise if there are no ketones present in the bloodstream. You can check if you have ketones with a urine test or blood glucose meter.
Drink lots of water to help your body get rid of sugar in your urine.
Use your insulin to correct high glucose levels. Your healthcare provider can help you determine the correct insulin dosages to help reduce elevated blood sugar levels.
Take medications as per your healthcare provider’s recommendations. Some of the most commonly prescribed oral medications for high blood sugar are metformin HCl, glipizide, and glyburide.

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When to see a healthcare provider

Getting professional medical advice from a healthcare provider like your primary care doctor or an endocrinologist is the best way to learn more about whether your blood sugar levels are where they should be.

Not getting proper treatment for low or high blood sugar levels can lead to long-term, serious health problems. Diabetes complications include diabetic ketoacidosis, nerve damage, severe infections, kidney disease, high blood pressure, damaged blood vessels, heart disease, heart attack, or stroke. Regular checkups with your diabetes care team can help prevent these complications.

If you see a healthcare provider about your blood sugar levels, be prepared to answer questions about risk factors like what you eat, how much you exercise, and your family history. Some healthcare providers may want to take a blood sample to test your blood sugar levels and A1C. You may have to fast eight hours beforehand to get accurate test results, so it’s always a good idea to check before your appointment. Your healthcare team can create a diabetes treatment plan if you’re prediabetic or if you have diabetes.

Be sure your treatment plan includes instructions on when you would need to seek emergency medical care. Emergency rooms are equipped to handle high blood sugar levels and can administer treatments like insulin therapy and fluid or electrolyte replacement.