Postprandial Blood Sugar: How Long After Eating Does it Take for Blood Sugar to Return to Normal?

In the process of managing diabetes, you’ve likely read and heard all sorts of new terms. Even with that in mind, “postprandial blood sugar” may be a new one. 

While this phrase may sound confusing, it refers to a simple concept. Keeping your postprandial blood sugar under control is an essential part of living with diabetes. Here, you’ll find US MED’s in-depth explanation of postprandial blood sugar, along with tips on how to control it. 

What is postprandial blood sugar? 

Simply put, postprandial blood sugar is your blood sugar after you eat a meal. It’s the opposite of preprandial blood sugar, which – as you might expect – is your blood glucose level right before you eat. 

Why does your blood sugar rise every time you eat? 

Postprandial blood sugar isn’t exclusive to people with diabetes. Everyone sees some increase in blood glucose after eating, especially when they have consumed foods packed with carbs. But people who have diabetes handle these increases differently than people who don’t have this disease. 

For most of the population, rising blood sugar levels after meals aren’t a cause for alarm. That’s because the insulin in their body can remove glucose from the bloodstream by helping it enter individual cells. On the other hand, people with diabetes either can’t make their own insulin or have problems related to insulin resistance.  

As a person with diabetes, why is it important to test your blood sugar after you eat? 

People with diabetes are at risk of adverse consequences from untreated blood sugar spikes. On top of that, postprandial blood sugar can impact your overall HbA1c. That means it’s crucial to pay close attention to your changing blood glucose levels throughout the day – especially after meals. 

Regular glucose level checks are the best way to track your blood sugar. For many people with diabetes, this process involves measuring a blood sample with a traditional glucose meter. Alternatively, you may wish to use a continuous glucose monitor (CGM) system for fingerstick-free* glucose results. Either way, you won’t be able to understand how meals affect your blood sugar without these tests.  

Post-meal blood sugar peaks: what causes them? 

Immediately after you eat foods containing carbs, the sugars and starches in these foods get broken down into simple sugars and enter your blood. Typically, that’s when the pancreas releases insulin – unless you have diabetes, in which case these sugars will linger in the bloodstream instead. 

Several factors can determine the severity of blood sugar spikes after a meal. Along with your pre-existing steps to control your blood glucose, you should double-check: 

• The foods you eat. You’ll have an opportunity to learn more about this in a bit, but different foods affect your body differently. Even when it comes to carbohydrates, some foods will increase your blood sugar more than others. 
• Carb-counting accuracy. Keeping an inaccurate tally of the carbs you consume throughout the day could wreak havoc on your diabetes treatment efforts. 
• Your insulin-to-carb ratio. Be sure the amount of insulin you inject is appropriate for your carb consumption. 
• Your injection-meal interval. That refers to the time between a pre-meal bolus and when you eat. Everyone’s ideal IMI is different, so take time to decide whether or not your interval is working for you. 

How long after eating does it take for blood sugar to return to normal? 

The timing of blood sugar spikes can vary, but they should peak about 90 minutes after eating a meal. In people without diabetes and people who are successfully treating diabetes, blood sugar should start going down again a few hours later. However, blood sugar levels in people with untreated diabetes can stay high even two hours after eating. 

How long should you have to wait after eating to check blood sugar? 

Many people with diabetes should check their blood sugar about 90 minutes after a meal. That’s because rapid-acting analog insulin reaches its maximum effectiveness at this point. Regular insulin works on a different schedule, so make sure you know how long to wait after eating to check blood sugar based on the type of insulin you use. 

What are normal blood sugar levels? 

Low blood sugar levels 

According to guidance from the American Diabetes Association, people with diabetes should aim for blood sugar levels of at least 70 mg/dL before eating and less than 180 mg/dL after eating. 

High blood sugar levels  

The ADA’s guidance also encourages people with diabetes to keep their blood sugar under 130 mg/dL before meals. Talk to your healthcare team to confirm that this advice fits your situation. 

What foods do not raise blood sugar levels? 

Understanding the glycemic index (GI) is crucial when trying to control your blood sugar. This scale ranks carbohydrates between zero and 100 – high-scoring foods are associated with larger blood sugar spikes. Many types of fresh produce and plant-based proteins are on the low end of the GI scale. However, this is true when you consume these foods by themselves. The minute you mix different foods and add proteins and fats to a meal, the GI changes. 

What foods raise blood sugar levels? 

On the other hand, several sources of simple carbohydrates come with high GI rankings. The same is true for many protein-packed foods, snacks, and processed foods. 

What are the effects of eating proteins and fats on blood sugar levels? 

Proteins and fats don’t usually have quite as much of an effect on blood glucose as foods high in carbs. Proteins and fats typically can slow down the digestion of other carbs. That said, this category does have the second-largest impact on your blood sugar. Still, this doesn’t mean you can avoid high-GI foods entirely – an unbalanced diet can ultimately lead to overconsumption of proteins and fats. 

Of course, proteins and fats aren’t the only foods that can alter your blood glucose. It’s also wise to understand the effects of: 

Grains 

As a significant source of carbs, grains can cause major blood sugar spikes if you aren’t careful. However, the type of grains you eat matters. While white bread and English muffins have GI scores in the 70s, barley measures in at 22 – and boiled soybeans are even lower, with a score of 15. 

Dairy 

Many dairy products have relatively low GI values; for example, skimmed milk has a GI score of 32. Still, it’s important to be wary of sweetened dairy products. Condensed milk has a much higher score, coming in at 61. 

Fruit 

Fruits generally have more sugar than vegetables, but they’re still an indispensable part of a balanced diet. Especially healthy options include plums (24 GI), grapefruits (25 GI), and peaches (28 GI).Also if you combine your serving of fruit with either a protein source or healthy fat, such as nuts, this will slow down its absorption. 

Vegetables  

There are lots of vegetables with low GI scores. To name just one, boiled carrots have a score of 33. However, some veggies are packed with carbs and have the GI scores to prove it. For example, mashed potatoes have a shockingly high score of 83 – higher than many types of bread. On the other hand, if you consume a small baked potato with skin, add some olive oil and grilled chicken, the postprandial glucose levels might be much different.  

Beans 

As a rule of thumb, beans are a great way to get protein and nutrients without high GI scores. Peas, kidney beans, and chickpeas are all between 20 and 35 on this scale. 

Nuts 

Nuts are a similarly nutritious plant-based protein source for people with diabetes. While they do contain some fats, the fats they deliver are unsaturated, which means they can help protect the heart and other organs. 

Processed foods 

Not all processed foods have high GI scores – lasagna has a score of just 28. But like any other type of food, eating in moderation and doing research beforehand is crucial. That’s doubly true regarding “junk food” like chips and sweets. 

How can you check your blood sugar levels? 

Today, standard glucose meters are still the most popular way to check blood sugar. Despite this, CGM systems have seen a steady rise in popularity. Either way, be sure to order these products (and related accessories) from a reliable source like US MED! We offer free priority shipping, automatic reorder reminders, and countless other benefits. 

*Fingersticks may still be required for diabetes treatment decisions, or if your readings do not match symptoms or alarms.