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What are normal blood glucose levels?

Normal blood glucose levels for adults, without diabetes, is 90 to 110 mg/dL. Learn the symptoms of high and low blood sugar here.

Blood glucose levels are the amount of glucose that someone has in their blood at any given time. Having high or low blood sugar levels could indicate an underlying health condition that may require medical attention. Use this overview of normal blood glucose levels to understand what your blood sugar levels mean. 

What are normal blood glucose levels in healthy individuals?  

Blood sugar levels can either be normal, high, or low, depending on how much glucose someone has in their bloodstream. Glucose is a simple sugar that’s present in the bloodstream at all times. Normal blood glucose levels can be measured when someone fasts, eats, or after they’ve eaten. A normal blood glucose level for adults, without diabetes, who haven’t eaten for at least eight hours (fasting) is less than 100 mg/dL. A normal blood glucose level for adults, without diabetes, two hours after eating is 90 to 110 mg/dL.   

Many factors affect 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 

An ideal blood sugar level for anyone without diabetes or prediabetes, regardless of age, in the morning should be less than 100 mg/dL. Remember, blood sugar levels can fluctuate throughout the day as a result of the factors previously mentioned.   

Blood sugar level charts for those with diabetes

Normal blood sugar levels, for those with diabetes, will vary depending on someone’s age and the time of day. Let’s take a look at what blood sugar levels should be, in those with diabetes, based on their age.  

Normal blood sugar levels in children

Younger than 6 years old mg/dL
Fasting 80-180
Before meal 100-180
1-2 hours after eating ~180
Bedtime  110-200

Children under 6 years of age should have blood glucose levels that range from about 80 to 200 mg/dL each day. This range is considered healthy, and 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. 

Normal blood sugar levels for adolescents

Age 6-12 mg/dL
Fasting 80-180
Before meal 90-180
1-2 hours after eating Up to 140
Bedtime  100-180

Kids aged 6 to 12 should have blood sugar levels that range between 80 to 180 mg/dL over the course of a day. Blood sugar levels go up after eating a meal because the body breaks down carbohydrates into glucose, which is then distributed throughout the bloodstream. To keep a child’s blood sugar from rising too much before bedtime, especially if they have diabetes, try limiting snacks before they go to sleep. 

RELATED: Sleepover tips for children with diabetes

Normal blood sugar levels for teens

Age 13-19 mg/dL
Fasting 70-150
Before meal 90-130
1-2 hours after eating Up to 140
Bedtime  90-150

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 because managing diabetes requires responsibility and behavior control that’s not typical for most teenagers. Teenagers should aim to keep their blood sugar levels between 70 to 150 mg/dL throughout the day by watching what they eat, exercising, and taking their diabetes medications if they have any.    

Normal blood sugar levels for adults

20+ years of age mg/dL
Fasting Less than 100
Before meal 70-130
1-2 hours after eating Less than 180
Bedtime  100-140

Adults who are 20 years or older will have blood sugar levels that range between less than 100-180 mg/dL over the course of a day. When you wake up in the morning, your fasting blood sugar should be at its lowest because you haven’t consumed food for about eight 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 above are categorized as either high or low blood sugar. Blood sugar levels are considered high if they’re over 130 mg/dL before a meal or 180 mg/dL within one to two hours after a meal. Many people won’t start to experience symptoms from high blood sugar until their levels are at 250 mg/dL or higher. The highest blood sugar level that’s considered safe will depend on the person and whether they have diabetes, but will typically be between 160 to 240 mg/dL. 

Low blood sugar symptoms

Hypoglycemia happens when blood glucose levels drop too low. Low blood sugar can be caused by many things including the two different types of diabetes, certain medications, alcohol, endocrine disorders, eating disorders, pregnancy (gestational diabetes), and disorders of the liver, kidneys, or heart.

Here are some of the most common symptoms that someone with low blood sugar might experience:  

  • Lightheadedness
  • Dizziness
  • Confusion
  • Irritability
  • Shakiness
  • Nervousness
  • Anxiety
  • Chills
  • Sweating
  • Clamminess
  • Having a fast heart rate
  • Pale skin
  • Hunger
  • Sleepiness
  • Fainting
  • Tingling lips  

If your blood sugar is low you might start to feel some of the first signs of hypoglycemia like dizziness, lightheadedness, or sweating. The only way to know for sure if your blood sugar is low is to test it with a glucose meter or other glucose monitoring device

If you don’t have access to these tools and start to feel the symptoms of low blood sugar, consume 15 grams of carbs or take a quick dissolve glucose tablet to raise your blood sugar levels and avoid further symptoms, according to the American Diabetes Association (ADA). Once your blood sugar is back in its target range, you can have a snack or meal to make sure it doesn’t drop again.    

Here are some other lifestyle and medicinal treatments that can help treat hypoglycemia:

  • Eat a healthy diet full of whole foods that are minimally processed. 
  • Take prediabetes or diabetes medications as recommended by your healthcare provider.  
  • Use a glucagon kit in emergencies. Glucagon is a hormone that raises blood sugar levels quickly.  

High blood sugar symptoms

Hyperglycemia is the medical term for high blood sugar. Hyperglycemia happens when the body doesn’t have enough insulin or when it can’t use insulin correctly. Many things can cause high blood glucose levels like Type 1 diabetes, Type 2 diabetes, stress, illness, or the dawn phenomenon. If you have hyperglycemia or suspect you may have it, talking with a healthcare provider is always a good idea. A doctor can help you determine what’s causing your high blood sugar levels and lower it to a healthy range.    

Here are some of the most common symptoms that may indicate hyperglycemia: 

  • Fatigue
  • Frequent urination
  • Headaches
  • Blurred vision
  • Difficulty concentrating
  • Increased thirst
  • Weight loss  

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. Symptoms of ketoacidosis include: 

  • Abdominal pain
  • Presence of ketones
  • Vomiting 
  • Exhaustion 
  • Vision loss (in rare cases)  

You should seek immediate medical attention if your blood sugar reaches 400 mg/dL or higher.     

“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.”

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

  • Eat 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.  
  • Adjust your insulin. Your healthcare provider can help you determine the correct insulin dosages when your blood sugar goes up or down.  
  • Take medications as per your healthcare provider’s recommendations. Some of the most commonly prescribed medications for high blood sugar are Metformin HCl, Glipizide, and Glyburide.

When to see a healthcare provider

Getting professional medical advice from a healthcare provider like 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 be serious and lead to health complications, especially for those with diabetes. Diabetes complications include nerve damage, kidney disease, heart disease, or heart attacks.  

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 about your family history. Some healthcare providers may want to take a blood sample to test your blood sugar levels. They may also order an A1C test, which is a blood test that measures blood sugar levels over several months. 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.        

If your blood sugar level goes above 250 mg/dL, you should go to the ER for immediate medical attention, says Dr. Tarugu. Emergency rooms are equipped to handle high blood sugar levels and can administer treatments like insulin therapy and fluid or electrolyte replacement.