What’s A Good Blood Glucose Level?

Average Blood Sugar Levels By Time of Day, Age, + Diet

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If you have diabetes or you know someone who does, you are probably well aware of the need to monitor and manage your blood sugar levels. 

Diabetes is a health condition marked by an inability of the body to use glucose, which is blood sugar, properly.

While maintaining good blood sugar levels is critical for people with diabetes, having healthy blood sugar levels is also just as important for those who are currently metabolically healthy.

So, what is a good blood glucose level? What is a normal fasting blood glucose level?

In this health guide, we will discuss what blood sugar tests are looking at, the importance of having normal blood sugar levels, and what good blood glucose levels are.

Let’s dive in! 

A person taking a test and showing a good glucose level results of 98.

What Is Blood Sugar Level?

Before we discuss what “normal blood sugar levels“ are, let’s review how your blood sugar level impacts your body.

Blood sugar levels refer to how much glucose, which is a sugar molecule, is circulating in your bloodstream at any given time.

Glucose is a monosaccharide, which is a simple sugar molecule, that is released into the bloodstream from the small intestines after carbohydrates are consumed and broken down in the stomach and small intestines.

Carbohydrates in one of the three macromolecules, alongside proteins and fats.

There are numerous types of carbohydrates in terms of the structures of the molecules.

Simple carbohydrates are composed of monosaccharides like glucose and fructose or disaccharides, such as sucrose (table sugar).

In a healthy individual, blood sugar levels are regulated by the dynamic interplay of insulin and glucagon, which are hormones released by the pancreas.

A doctor taking a patient's blood glucose level.

After a high-carbohydrate meal is consumed, there is an influx of glucose into the bloodstream. As a result, the pancreas secretes insulin. 

In a healthy individual who is sensitive to insulin, the insulin signals the cells in your body, such as muscle cells, brain cells, liver cells, red blood cells, heart cells, etc., to take up glucose from the bloodstream for use.

Glucose serves as an energy molecule and is broken down in the cells to produce ATP, which is the “energy currency“ of the cell.

For example, muscle cells can take in glucose from the bloodstream during exercise and break down the energy-rich molecules through metabolic pathways such as glycolysis or the Krebs cycle to produce ATP. 

This ATP is then used so that the muscles can contract and sustain your physical activity.

If an individual with type one diabetes, the pancreas produces an insufficient amount of insulin.

This means that even when the individual eats carbohydrate-rich food, the glucose will circulate in the blood but the cells are not able to take in the glucose. This can lead to abnormally high blood glucose levels and even dangerously high blood sugar levels.

A doctor taking a patient's blood glucose level.

Moreover, because the cells aren’t actually getting the glucose, someone with type 1 diabetes could have very high blood sugar yet feel like they have very low blood sugar in that they have no energy, feel dizzy, and might even pass out.

You can imagine that insulin acts like a key to open all of the doors in the cells.

When the body is not producing insulin, all of the doors stay closed so the glucose just passes by without being able to get into the door to enter the cell for use.

There is a similar outcome in type 2 diabetes although the mechanism of action is different.

Whereas with type 1 diabetes, insulin is not produced by the pancreas, with type 2 diabetes, the body is no longer sensitive to insulin.

Type 1 diabetes is an autoimmune condition whereas type 2 diabetes is considered to be a lifestyle disease that develops due to a confluence of factors including habitually poor diet, genetics, obesity, and inactivity, among other health challenges that the individual might face.

With pre-diabetes and type 2 diabetes largely develop from chronically elevated blood sugar levels from frequently eating high-carb meals with simple sugars.

An app showing a blood glucose level.

As a result of all of these simple sugars constantly spiking blood sugar levels, the body has to produce large amounts of insulin so that the blood sugar gets taken up by the cells.

Over time, the body becomes less sensitive to the insulin in the bloodstream. Insulin acts like a messenger signaling the body to act quickly and take in glucose.

However, if this is always happening numerous times a day and in great magnitudes, it is somewhat like the fable of the Boy Who Cried Wolf—eventually, the cells start to ignore the signal instead of responding to it.

This ends up leaving all of the blood sugar in the bloodstream. 

With either type of diabetes, blood sugar circulating in the bloodstream that is not taken by the cells can cause damage to capillaries over time. 

This is why having very high blood glucose levels can eventually lead to peripheral neuropathy in the feet, trouble with vision, and other paresthesias throughout the body; the small capillaries have been damaged by high blood glucose levels for too long.

An app showing a blood glucose level.

What Affects a Normal Blood Glucose Result?

A “good blood glucose level“ or “normal blood glucose level” will depend on your age, time of day, and fasting status, meaning how long it has been since you have eaten.

It is important to note that you should consult with your healthcare provider about what is a healthy blood sugar level for you; this article is not intended to be not medical advice but rather an informative resource about blood glucose and blood sugar management.

There are several factors that can impact what might be considered a “good blood glucose level“ for an individual. 

Certain factors impact what might be considered a normal blood sugar level between two different individuals while other factors will impact your blood sugar level at any given time of the day. 

That is to say that even within the same individual, blood glucose levels can and should fluctuate throughout the day.

Here are the main factors that affect your blood glucose levels:

  • Age
  • Hydration Status
  • When You Last Ate and What You Ate
  • Physical Activity
  • Medications
  • Hormones
  • Caffeine and Certain Herbs and Supplements 
  • Stress Levels
  • Health Conditions 
A person measuring their blood glucose level.

What’s A Good Blood Glucose Level? Average Blood Glucose Levels By Time of Day, Age, and Diet

Your blood glucose levels are typically measured as a fasting glucose test. This requires a minimum of 8 hours of fasting from all foods before the lab test.

Normal blood sugar levels after eating are elevated relative to fasting blood glucose levels because the glucose is still being released into the bloodstream and insulin is still responding to take in glucose.

According to Mount Sinai, fasting blood glucose tests usually begin at age 35 in those without risk factors for diabetes and then should be retested at least every 3 years if you have no signs of diabetes.1Blood sugar test – blood Information | Mount Sinai – New York. (n.d.). Mount Sinai Health System. https://www.mountsinai.org/health-library/tests/blood-sugar-test-blood

Some common signs of diabetes can include:

  • Urinary frequency
  • Excessive thirst
  • Recently gained a lot of weight
  • Sweating
  • Fruity breath
  • Tingling or numbness 
  • Blurred vision
  • Confusion 
  • Shakiness
  • Fainting spells
A person measuring their blood glucose level.

Normal Blood Glucose Levels for Children and Teens

As per the Nationwide Children’s Hospital2Monitoring Blood Glucose. (n.d.). Www.nationwidechildrens.org. https://www.nationwidechildrens.org/family-resources-education/health-wellness-and-safety-resources/resources-for-parents-and-kids/managing-your-diabetes/chapter-three-monitoring-blood-glucose and the Mayo Clinic,3Diabetes – Diagnosis and treatment – Mayo Clinic. (n.d.). Www.mayoclinic.org. https://www.mayoclinic.org/diseases-conditions/diabetes/diagnosis-treatment/drc-20371451#:~:text=Oral%20glucose%20tolerance%20test.&text=A%20blood%20sugar%20level%20less here are the normal blood sugar levels for kids and teens:

 Children Age 6-12 YearsTeens and Young Adults
Blood Glucose Level By Time of Day  
Before Breakfast (Fasting at Least 8 Hours)70-120 mg/dL70-90 mg/dL
1-2 Hours After MealsLess than 140 mg/dLUp to 140 mg/dL
Before Meals and Before Bed70-120 mg/dL 
Normal Glucose Throughout the Day80-120 mg/dL70-140 mg/dL
A person measuring their blood glucose level.

Normal Blood Glucose Levels for Adults

According to the World Health Organization (WHO), here are the normal blood sugar levels for adults:4Riley, L. (2023). Mean fasting blood glucose. World Health Organization. https://www.who.int/data/gho/indicator-metadata-registry/imr-details/2380#:~:text=The%20expected%20values%20for%20normal

 Fasting Blood Sugar (at least 8 hours after eating)Blood Glucose 2 Hours After Eating
Normal Blood Glucose70-90 mg/dLless than 140 mg/dL
Pre-Diabetes100-120 mg/dL140-180 mg/dL
Diabetes126 mg/dL and abovemore than 200 mg/dL

To learn more about the worst foods that can spike blood sugar levels, check out our guide here.


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Amber Sayer is a Fitness, Nutrition, and Wellness Writer and Editor, as well as a NASM-Certified Nutrition Coach and UESCA-certified running, endurance nutrition, and triathlon coach. She holds two Masters Degrees—one in Exercise Science and one in Prosthetics and Orthotics. As a Certified Personal Trainer and running coach for 12 years, Amber enjoys staying active and helping others do so as well. In her free time, she likes running, cycling, cooking, and tackling any type of puzzle.

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