Maybe you've heard of glucose levels before. This technical expression is used to describe the amount of glucose, or sugar, in your blood as a result of the carbs you eat. Your pancreas secretes insulin to utilize glucose, absorbing it from your blood when it's needed for energy. Though blood glucose levels will change throughout the day, science has helped us establish normal glucose levels thanks to decades of painstaking research.

So, what are normal blood glucose levels, and what do these levels say about your body? How will your habits change glucose levels, and what happens if your levels are abnormal? Let's dive into this topic to gain a better understanding of our bodies and the role blood sugar plays in our daily life.

What Are Normal Blood Sugar Levels?

It's not uncommon for your healthcare provider to test your blood sugar levels during your yearly check-up with a routine blood test. Even if you don't suffer from diabetes, annual blood sugar testing can shed light on how your body is functioning. But to better understand the day-to-day trends of your glucose levels, you can use a finger-prick test or a continuous glucose monitor (CGM) from home. Whether in the doctor’s office or at home, the results of these tests are measured in milligrams of sugar per deciliter of blood, or mg/dL.

Anyone can test their blood sugar levels at any time, but it's best to do so after fasting for eight hours or two hours after a meal. That's because fasting blood sugar, or fasting plasma glucose, delivers a clear picture that can detect the presence of diabetes. An individual with diabetes will have significantly higher blood sugar levels, even after fasting, than someone who doesn’t have diabetes. Blood sugar levels will fall within a normal range in those with an active, healthy insulin response, but remain elevated in those who do not. If you decide to test levels post-meal, wait two hours to let your levels equalize.

So, what are normal blood sugar levels, and what's considered abnormal? To be considered "normal," your fasting blood glucose must be between 70 and 100 mg/dL. Hyperglycemia, or high blood sugar, is a result of levels above 100 mg/dL. And the opposite, hypoglycemia, occurs when levels are too low, under 70 mg/dL. Criteria put forward by the American Diabetes Association (ADA) suggest an individual with a reading above 100 mg/dL may suffer from either prediabetes or diabetes. 

When it comes to normal post-meal blood sugar levels, those without diabetes should measure less than 140 mg/dL within two hours after eating.

What If Your Blood Sugar Is High?

High blood sugar levels can lead to various short- and long-term problems if left untreated. Short-term complications include increased urination, blurred vision, nausea, and tiredness. Long-term complications include nerve damage, damage to blood vessels, sudden weight loss or gain, and heart disease that increases the risk of heart attacks. Keep in mind that high blood sugar is not directly associated with diabetes, but a precursor to diabetes if left untreated. For this reason, it's important to use an at-home glucose meter to gain a better understanding of your normal levels.

There are times when high blood sugar is classified as diabetes, of which there are two types. Type 1 diabetes occurs when the pancreas can't produce insulin naturally, and an insulin pump is needed to ensure your body has the insulin it needs throughout the day. Type 2 diabetes occurs when the body builds up a resistance to insulin so that the hormone can't do its job by regulating blood glucose levels. Most individuals that suffer from diabetes have Type 2 diabetes.

If testing reveals that you don't fall within normal blood sugar levels, a treatment plan will help you manage your blood sugar by promoting a series of lifestyle changes. These include more physical activity, dietary changes, and diabetes medications, if necessary, to help manage the side effects of high blood sugar over time.

Diabetic Ketoacidosis

If an individual has Type 1 diabetes and the hyperglycemia is left untreated, toxic acids, or ketones, can build up in the blood. This serious condition, called diabetic ketoacidosis, can lead to a coma or death, which makes it all the more important to pay close attention to abnormal blood sugar levels. Those with Type 2 diabetes can also develop diabetic ketoacidosis, but it is less common and less severe.

What If Your Blood Sugar Is Low?

Low blood sugar is also uncommon, but most of us will begin to feel the effects of low blood sugar when levels fall below 70 mg/dL. Symptoms may include nausea, dizziness, trembling, sweating, hunger, and weakness. In severe cases, low blood sugar may lead to seizures or loss of consciousness if left untreated.

If you suspect your blood sugar is low, consider using a CGM or an at-home glucose monitor to establish a baseline reading. If testing reveals it is low, consume quick-absorbing carbs that are high in sugar, such as bananas, apples, or oranges, as these will elevate blood sugar levels more quickly over the short term. Raisins and fruit juice can also boost blood sugar levels in a pinch. If your blood sugar remains consistently low over time, speak with your doctor to determine the cause and create a treatment plan.

How Can a Continuous Glucose Monitor Help You Sustain Normal Levels?

Don't be alarmed if your glucose levels increase after a meal. As we've discussed, the carbohydrates in your food enter your blood quickly, and it takes time for your body to move that glucose into your cells for energy. 

That said, research suggests constant blood sugar spikes contribute to inflammation, blood vessel damage, and weight gain. Therefore, it's important to mitigate spikes whenever possible, ensuring minimal variability between meals, even in non-diabetics.

Maintaining healthy blood sugar levels means more than eating healthy foods — it also includes minimizing risk factors. Research suggests that two people eating the same food will experience different changes in glucose levels, and foods can have opposite effects on different people. For instance, eating berries may increase your blood sugar levels, but have the opposite effect on your friend’s body.

You can ensure your body maintains normal blood glucose levels by using a continuous glucose monitor that allows you to see your blood glucose levels in real time. This data is then stored for future reference, and becomes useful when establishing average blood sugar levels. Over time, this information allows you to optimize your diet and lifestyle habits. 

Studies show that continuous glucose monitoring can illustrate an individual’s glucose response to specific foods, thus helping predict responses to other foods. You can use this technology to create personalized meal plans that suit your needs and improve glucose control over time.

Don't be alarmed if your CGM suggests your blood sugar levels are abnormal. Consider reviewing the many tips to lower your blood sugar levels, and speak with your doctor if more intervention is required. There are so many lifestyle habits you can change to ensure your blood sugar falls within a normal range, and a CGM can help you maximize them.

Continuous Glucose Monitoring and Nondiabetic Individuals

The latest research that employs a CGM can provide us with insights into the health and well-being of nondiabetic individuals beyond what we consider “healthy” and “unhealthy” glucose ranges. Even though we’ve determined normal glucose levels, it’s more beneficial for us to identify what’s optimal for our personal health.

For instance, one study from 2009 examined the glucose levels of 434 nondiabetic individuals using a CGM and found the following:

• Daily levels stayed between 70-140 mg/dL for 93% of the day. 
• Mean 24-hour glucose levels averaged around 104 mg/dL.
• One-hour post-meal glucose values averaged 121-123 mg/dl for breakfast, lunch, and dinner.
• The highest post-meal values appeared to be around 60 minutes after eating.
• Mean fasting glucose was 86 ± 7 mg/dl.
• Mean daytime glucose was 106 ± 11 mg/dl.
• Mean nighttime glucose was 99 ± 11 mg/dl
  

A separate study of 74 nondiabetic individuals from 2010 found similar results that included the following: 

• Glucose levels stayed between 71-120 mg/dL for 91% of the day.
• Mean glucose over a 24-hour period was 98 ± 10 mg/dL.
• Mean fasting glucose was 86 ± 8 mg/dl.
  

A third study from 2008 analzyed 32 individuals wearing a CGM with normal glucose tolerance for nearly 30 days. Findings included the following results:

• 24-hour glucose average ranged from 94 mg/dl to 117 mg/dl among all participants.
• Overall mean glucose level was 102 +/- 7 mg/dl.
• Mean daytime glucose was 105 ± 8 mg/dl.
• Mean nighttime glucose was 97 ± 6 mg/dl.
• Some participants spent as little as four minutes per 24 hours at values greater than 140 mg/dl.
• Some individuals spent approximately 2.8 hours per 24 hours at glucose values greater than 70 mg/dl and an hour at values less than 60 mg/dl.
  

A fourth and final study from 2019 examined 153 healthy, nondiabetic children and adults ages 7 to 80 who wore a CGM for up to 10 days. This study found:

• Mean glucose levels were 99 ± 7 mg/dl.
• None of the participants had glucose readings greater than 180 mg/dL.
• 96% of glucose sensor values fell between 70-140 mg/dl.
• 89% of glucose sensor values fell between 70-120 mg/dl.
• 1.3% of glucose sensor values were greater than 70 mg/dl.
• 2.1% of glucose sensor values were greater than 140 mg/dl.
  

These findings, among others, illustrate that nondiabetic individuals maintain a glucose range that changes throughout the day but remains optimal for one’s health. We already know based on ADA guidelines that a person’s glucose values are “normal” if they have fasting glucose of <100 mg/dL and a post-meal glucose level of <140 mg/dL. But research tells us that “normal” is different for everyone as each individual body strives to maintain its own version of optimal health.

Finding Your Normal Glucose Levels

So what does all this information really mean? Well, it means that while we've established “normal” glucose ranges before and after we eat, there's more to this simple measurement than meets the eye. 

Glucose levels differ from one individual to the next over a 24-hour period, and these levels don't specify what's optimal on a personal level. A normal range for one person will differ from the next.

Even those with healthy levels may be at risk due to glucose spikes and dips. That's why it's important to wear a glucose monitor that provides you with real-time information about your body. If levels remain abnormal over time, you can use this information to enact personal changes or work with a healthcare provider.

If you find yourself looking to better understand your version of normal glucose levels, improve your health, or increase your longevity, sign up today with Vital. With Vital, you'll learn to understand your body like never before and receive personalized recommendations about exercise, food, and daily habits that will benefit your health over time.