Non-Fasting Glucose Levels Explained: Normal Ranges & When to Worry

Non-fasting glucose levels differ from fasting glucose levels (first thing in the morning, before eating or drinking anything), in that they are either post-prandial - following a meal, or random - taken at a random time of the day. 

Monitoring blood sugar levels following meals is essential in the effective management of diabetes.

If you do not know what your post meal blood sugar is, you will not be able to effectively assess the impact of the various foods you consume or make informed decisions regarding adjusting your diabetes management plan. 

Testing your post prandial blood sugar will help you identify hyperglycemic trends.

If consistently tracked, you will be able to experiment and for example, may be able to figure out what may enable you to consume certain foods if in combination with others, and or which foods you may need to try to avoid, or decrease.  

Random glucose levels are helpful in identifying insulin resistance. In setting up at health fairs over the years and doing random glucose checks, I have witnessed many people who had no idea they had any blood sugar issues, discover with a simple check that their random glucose was elevated. 

Their next step is to contact their doctor to further investigate and request an A1C test be done. The sooner a person is diagnosed, the sooner they can learn what needs to be done and get a management plan in place to try to avoid the potential complications of unmanaged glucose levels. 

Do you know if your non-fasting glucose levels within a healthy range?

What Are Non-Fasting Glucose Levels

Non-fasting glucose levels are blood sugar levels taken at any time of the day. They differ from fasting, as fasting glucose levels are taken first thing in the morning, before eating or drinking anything. Below is a chart showing standard non-fasting glucose ranges:

• Normal: Below 140 mg/dL

• Prediabetes: 140 - 199 mg/dL

• Diabetes: 200 mg/dL

It is important to note that people without diabetes may experience a spike in glucose levels if, for example, they were to drink a sugary beverage.

But, their pancreas would produce insulin to effectively bring their glucose levels back down to around 100 mg/dL or less, within two hours. 

This is important to know because if a person without diabetes were to check a glucose level 20 minutes after consuming a large glass of juice, it is very likely their values would be higher than what is considered a “normal” non-fasting blood sugar level.

Post-prandial glucose checks are structured tests, measured at a specific time to assess how well the body is handling the consumed food and how the insulin is responding.

They are specifically done two hours after the start of the meal with a normal (non-diabetic) post-prandial glucose range being less than 140 mg/dL.

If at 2 hours post meal, the glucose value is greater than 140 mg/dL, further testing should be done, as this may indicate prediabetes or impaired glucose tolerance. 

Why Are Non-Fasting Glucose Levels Important?

Non-fasting glucose levels are important because they can help with diagnosing diabetes and prediabetes and if testing post-meal glucose levels and they are elevated, it can indicate insulin resistance.

In addition to diagnostic benefits, non-fasting glucose levels are very helpful in monitoring the efficacy of a diabetes management plan. 

Case Study - Importance of Knowing Your Non - Fasting Glucose

I have a client who came to me baffled that his A1C was so elevated, but that “every-time” he checked his blood sugar, it was “never higher than 140 mg/dL”.

He was unwilling to test his non-fasting blood sugar levels and therefore was only getting a very small picture of what his overall glucose values were, how he was responding to certain foods, and how effective his medication regimen was, because he was ONLY checking his fasting blood sugar levels. 

I convinced him to get on a continuous glucose monitor (CGM) that he did not have to scan or monitor himself and after two weeks, we reviewed his data together.

He was shocked to discover that his blood sugar level was only somewhat stable in the morning, though even that was higher than our target.

Here are the things we learned together by checking his non-fasting glucose levels in addition to his daily fasting glucose check:

• His breakfast was causing him to spike for several hours every day.

• His dinner was also doing the same.

• He was taking his morning insulin incorrectly and was bottoming out every day on his way to the breakfast joint he was eating at. This was putting him, and others on the road, at great risk for a car accident following a hypoglycemic episode.

• He was forgetting his lunch time medication.

• He was remembering his long acting insulin at bedtime, which was the one thing that was helping lower his glucose levels so that they appeared close to “normal” by the time he was checking his fasting glucose.

Him checking his fasting glucose levels only, was actually impeding his knowledge of what was going on throughout the rest of the day. He had a false sense of well managed glucose levels, because he was not checking his non-fasting glucose values as well. 

Having the knowledge of his non-fasting glucose levels helped him make informed decisions and changes that were not only beneficial for his health, but needed for his safety. 

Factors That Influence Non-Fasting Glucose Levels

A normal post-meal blood sugar for a person without prediabetes or diabetes would be less than 140 mg/dL. This is also true for a random glucose - a normal level for a person without diabetes would be less than 140 mg/dL. 

For people living with diabetes, the target post-meal and random (considered “normal”) glucose level is less than 180 mg/dL. 

Keep in mind, some people with diabetes may have tighter targets they have discussed with their doctors. But less than 180 mg/dL is the gold standard per se when it comes to post-prandial and random blood sugar targets. 

Some of the factors that influence non-fasting glucose levels include:

• Nutritional intake - Meals and snacks that are high in carbs and are not balanced with protein and or healthy fats may cause a steeper spike in glucose. Meals that are high in carbs and high in fats, for example - Chinese food or pizza, will also likely cause a sustained elevated glucose. 

• Exercise - Have you ever been told to take a walk after the largest meal of the day? This is because exercise and activity actually helps your muscles be more receptive to glucose uptake, therefore actively decreasing your blood sugar levels.

• Stress - Unfortunately stress can truly throw a damper on your blood sugar levels. This happens because during times you are under a lot of stress, your body often responds by releasing hormones like cortisol. Cortisol then triggers the “fight or flight response” which causes your liver to push glucose into your bloodstream to provide energy for the potential threat. 

• Medication - Medication like steroids can cause glucose to rise because they tend to make your body less sensitive to insulin. On the other hand, synthetic insulin, many diabetics use, can cause your blood sugar to bottom out. Knowing your non-fasting, post-prandial glucose levels can help with adjustments to your insulin regimen if, for example, your insulin dose is too strong. 

Having the ongoing knowledge of your non-fasting glucose levels is extremely important because persistent high glucose levels can lead to detrimental long term complications such as heart disease and nerve damage. 

Conversely, consistently bottoming out (as in the case study above) and being at major risk of injury to self and others, has the potential of very serious short and long term complications and risk factors as well. 

Practical Tips on How to Improve Non-Fasting Glucose Levels

• For nutritional intake, ensuring you are consuming a well balanced diet of whole foods and decreasing the amount of processed and refined carbs and sugars will help improve non-fasting glucose levels immensely. Also ensuring you add fiber and protein with some healthy fat, in addition to your carbs will help stabilize glucose levels by slowing the absorption of the carbs.

• As mentioned above, going for a 15 to 30 min walk following a meal will help lower your glucose levels. Also adding strength training 2 - 4 times per week can be very helpful because it can increase insulin sensitivity. 

• Monitoring non-fasting glucose levels can aid in improvement because it will help you and your healthcare team become aware of when your glucose levels are spiking, if they are falling, and what needs to be adjusted to improve the glucose levels. 

When to Be Concerned and Seek Medical Advice

It is not only important to know your non-fasting glucose levels for optimal glucose management purposes, but also so that you can be aware if your glucose levels rise to dangerous levels. 

Some warning signs of dangerously high blood sugar levels include: fatigue, excessive thirst, frequent urination, and blurry vision. If your blood sugar is consistently above 200 mg/dL despite following your treatment plan and or you are experiencing any of the above symptoms, it is imperative you seek medical advice. 

If you make lifestyle changes and follow the glucose management plan you and your doctor have agreed on and your glucose levels still remain consistently elevated, make an appointment to discuss adjustments to the plan. 

Maintaining healthy non-fasting and fasting glucose levels is key to minimizing the risk of long term diabetes complications and living a healthy and happy life. 

If you or someone you know needs help with understanding your glucose levels, what they should be, and how to effectively manage them, book a call with me today. 

Meet the Author

Hi! I’m Beth, a Registered Nurse and Certified Diabetes Educator. I provide diabetes coaching for newly diagnosed people with diabetes and also work with people who have been living with diabetes for some time.

With 1:1 coaching, you will feel empowered and supported to confidently manage your diabetes effectively - without it controlling your life! I can help you make sure that you feel good, stay in optimal health and take care of your well-being at all times.

First call is on me! Let’s talk.