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Postprandial Blood Sugar: Norms and Signs You Should Get Tested

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a person is using a glucometer, Postprandial Blood Sugar
Melissa Mitri post Reviewer Melissa Mitri post Reviewer
Verified by Melissa Mitri
MS, Registered Dietitian, Former President of CT Academy of Nutrition & Dietetics

Table of Contents

Your blood sugar levels are good indicators of your metabolic health. Periodic blood sugar measurements can help you identify blood sugar-related metabolic malfunctions such as diabetes. Early detection of these conditions makes it easy to gain more effective control of these diseases.

If left untreated, abnormally high—as well as low—blood sugar concentrations can lead to serious health hazards that can even be life-threatening. It is therefore recommended to get your blood sugar levels checked regularly and at least annually, even if you don’t have diabetes.

There are several tests that can evaluate your body’s ability to regulate blood sugar—which is often referred to as blood glucose. The postprandial blood sugar level is one such test used to evaluate your level of blood glucose control [1]

What is Postprandial Blood Sugar?

Postprandial means ‘after eating,’ and postprandial blood sugar is a test that assesses your blood glucose levels after a meal.

In order to understand how this test works, you need to have a basic understanding of how blood sugar fluctuates after a meal:

  • Step 1. Carbohydrates in your meals get broken down in your small intestine into simple sugars such as glucose.
  • Step 2. These glucose molecules are then absorbed into the blood, thus increasing blood glucose levels. 
  • Step 3. Elevated blood glucose levels signal the pancreas to produce insulin, a hormone that transports glucose from the blood and into the cells.
  • Step 4. This glucose is used up by the cells to produce energy, and the remainder gets stored in the liver and muscles in the form of glycogen. [2]

This process clears up blood glucose, thus lowering blood sugar levels. 

In a person who doesn’t have diabetes, blood sugar levels typically peak after 1 hour of starting a meal. Then, blood sugar levels fall to pre-prandial (before meal) levels within 2-3 hours [3]. In those with diabetes, however, blood sugar levels can continue to climb and stay high longer [1]

For instance, in a person with type 2 diabetes, the insulin response is delayed and is often not strong enough to effectively control blood sugar elevations [3]. Thus, in such people, it takes a long time for the blood sugar levels to drop to normal. 

For those with type 1 diabetes, known as insulin-dependent diabetes, the duration and height of blood sugar spikes depend on the type and schedule of insulin they are taking [3].

How Is Postprandial Blood Sugar Measured?

Postprandial blood sugar is generally measured by taking your blood sugar reading after 2 hours of eating. You can do this on your own at home using a glucometer, but the results can slightly vary from those obtained in a clinical setting. 

For a more accurate result, you’re expected to fast for 12 hours before the test and then eat a meal that contains around 75g of carbohydrates. After waiting for 2 hours, your blood sugar levels will be checked. 

You are not supposed to eat or exercise during the 2-hour waiting period as it can affect the blood glucose concentration [4]

In specific conditions such as pregnancy, a 1-hour postprandial blood sugar test is sometimes recommended [3]. Many times 2-hour postprandial blood sugar readings can be a little lower than readings taken after 1 hour, as the body has more time to bring the blood sugar down.

Normal Ranges of Postprandial Blood Sugar Test

What is considered ‘normal’ for postprandial blood sugar levels differs depending on the individual. The recommendations are different if you have diabetes vs. if you don’t. They also differ based on whether you are pregnant or not. 

The following table gives you a basic idea of recommended postprandial sugar levels for different individuals [4] [5]:

Postprandial Blood Sugar Level Recommendations for Adults
Adults with diabetes< 180 mg/dL
Adults without diabetes< 140 mg/dl (after 1 hour)
Pregnant Adults< 140 mg/dl (after 1 hour)< 120 mg/dl (after 2 hours)

Factors that Influence Postprandial Blood Sugar Levels

Postprandial plasma glucose levels can change depending on several factors. Below, we are discussing the aspects that can affect your post-meal glucose readings.

The Composition Of Your Meal

What you eat will affect your postprandial blood glucose levels. If you eat a meal high in simple carbs, your blood sugar will peak immediately and then dip very low [6]. This can result in sudden fluctuations in postprandial blood sugar.

an illustration of how different carb foods elevate blood sugar levels, postprandial blood sugar

Foods made up of complex carbs, such as whole wheat bread and brown rice, take longer to digest, so they release glucose slowly. These types of foods keep your blood glucose levels steady for a long time. 

Also, eating a balanced meal containing moderate amounts of proteins can prevent frequent blood glucose fluctuations after meals. It may do this by slowing the absorption of glucose into the blood. [7]

The Quality Of Your Sleep

Research has shown that sleep deprivation can cause impaired glucose metabolism and elevate the risk of diabetes [8].  A night of good quality sleep is known to promote healthy systems, thus supporting healthy blood glucose levels [9]

Physical Activity

Lack of exercise increases the risk of glycemic disorders. Therefore, moving your body more can lower your blood sugar levels. Research has confirmed that something as simple as walking after eating can effectively lower post-meal glucose levels [10].


Although seemingly unrelated, stress is a major factor affecting blood sugar levels. Studies suggest that stress induces hormonal fluctuations that lead to high blood sugar levels. Eventually, this can lead to insulin resistance as well as diabetes [11]

Apart from these possible causes, several other reasons, such as ineffective insulin treatment, illnesses, and dehydration, can also cause changes in postprandial blood sugar levels [12].

Do You Need to Track Your Postprandial Blood Sugar?

You can get a better understanding of your body’s insulin response by keeping track of your blood sugar levels. Research indicates that postprandial glucose levels are better predictors of blood sugar metabolism than fasting glucose levels. 

This is thought to be because they are more closely related to Hemoglobin A1C levels than fasting blood sugar readings [13]. Hemoglobin A1C, or HbA1c, provides a 3-month average of your daily blood sugar levels.

If You Have Diabetes

If you have diabetes or prediabetes, you definitely need to monitor your postprandial blood sugar measurements.

Diabetes can cause post-prandial hyperglycemia (high blood glucose levels) or hypoglycemia (low blood glucose levels), depending on your hormonal fluctuations and the efficacy of your medications. 

Prolonged and frequent bouts of hyperglycemia can lead to heart disease, kidney damage, and nerve problems [14]. They can even lead to diabetic coma if not promptly treated [15]

On the other hand, too low blood glucose levels can cause vision problems, confusion, difficulty focusing, and even seizures and coma [16]. Therefore, you need to keep a close eye on your blood sugar concentrations, including your postprandial glucose levels.

If You Don’t Have Diabetes

Periodically assessing your blood sugar is important even if you don’t have diabetes. These measurements help you identify early changes in your blood sugar, thus making it easy to detect any problems or connections to certain foods or habits.  

Post-meal glucose levels are one of the important factors when it comes to blood sugar-related disorders. In fact, research suggests that in the events of glycemic malfunction, it is often revealed in high postprandial blood glucose levels before it’s indicated in fasting blood sugar levels [17]

Furthermore, it has been shown that postprandial glucose levels are a more accurate predictor of death from heart disease than fasting blood sugar [18]. This means that it can be useful to keep track of your postprandial blood sugar levels even if you don’t have diabetes.

6 Signs You Should be Tested

You should get yourself checked if you have signs of blood glucose impairments such as [19]:

  1. Frequent urge to urinate
  2. Excessive thirst
  3. Blurred vision
  4. Numb or tingling sensation in hands or feet
  5. Slow wound healing
  6. Increased incidents of infection

The test should be prescribed by your healthcare professional if you need to get it done by a testing laboratory. 

Postprandial Blood Sugar and Weight Gain

High postprandial blood sugar levels have been shown to promote weight gain via various mechanisms [20]

One such mechanism involves increased eating. Blood sugar spikes after meals are often followed by sudden dips in blood sugar, and this leads to increased appetite and, in turn, increased food intake [21]

These blood sugar fluctuations usually occur after eating high GI (glycemic index) foods that mostly contain simple sugars. Research has shown that such diets trigger weight gain, belly fat storage, and high concentrations of enzymes that promote fat accumulation [22].

Wrapping Up

Postprandial blood glucose is a key measure that can be used to assess your level of glycemic control. The reference level of postprandial sugar for people who have diabetes is a bit higher than that for those who don’t have diabetes. 

Postprandial blood sugar levels are a reliable indicator of glycemic disorders and heart disease mortality. Therefore, it’s helpful to keep track of your post-meal glucose levels regardless of whether you have diabetes or not. 

This can be done in a clinical or lab setting or by using a glucometer in your own home. Your doctor can determine the best plan for you and what your blood sugar testing frequency should be. 

Disclaimer This article is intended for general informational purposes only and does not address individual circumstances. It is not a substitute for professional advice or help and should not be relied on to make decisions of any kind. Any action you take upon the information presented in this article is strictly at your own risk and responsibility!

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