Understanding Meal Time Insulin and Post Prandial Glucose Control

Dr. Jean-Francois Yale, MD, CSPQ, FRCPC, Endocrinologist, discusses how to control post prandial glucose levels with fast acting meal time insulin.

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Dr. Jean-Francois Yale, MD, CSPQ, FRCPC, Endocrinologist, discusses how to control post prandial glucose levels with fast acting meal time insulin.
Video transcript

Featuring Dr. Jean-Francois Yale, MD, CSPQ, FRCPC, Endocrinologist

Duration: 4 minutes, 12 seconds

Postprandial means after a meal. So postprandial glucose is really the elevation of glucose after we’ve eaten. When we eat we digest the food, it goes in the blood, and the first thing we have to do is to store it in our cells and that’s done because insulin goes with the food to tell the cells “store the food.”

So normally after we eat the glucose goes up for an hour or two and then slowly comes back to where it’s normal because of the action of insulin. In some cases, when people have diabetes, and it’s not very well controlled, the glucose rises after the meal but can stay higher for a longer period of time, and we call that postprandial hyperglycemia, where the insulin action was not sufficient, and we ended up with high glucose levels eating.

The A1C levels represent the average glucose level of someone over a period of about two to four months – that’s what we use to assess if the diabetes is well controlled or not, and we’re usually aiming for levels under seven percent.

The A1C is affected by the glucose levels throughout the day, so it includes the effects of fasting glucose, but also the glucose levels after eating, the postprandial glucose levels. So if either or both of these are high, that makes the A1C be higher, and when the A1C is higher that increases the risk of complications of diabetes, whether it be complication in the eyes, the kidneys, the feet, the heart etc. We really aim to control the A1C to normal levels to prevent long-term complications of diabetes.

When we eat the glucose rises, and therefore the insulin levels have to rise with the meal, in order to tell the body to store the food, so it’s important to coordinate the insulin rise with the food that’s entering the system.

In people that are treated with insulin, that is done by giving rapid-acting insulin, which tries to reproduce this action of our normal insulin that’s usually secreted by ourselves. So this rise in insulin that occurs after a meal, if it’s a rapid-acting insulin, helps to control the glucose levels.

If the insulin is slower, because there are some older insulins that are slower, then of course they’re not able to reproduce this and we end up having high glucose levels after meals. So more and more we’re developing some insulins for the mealtime that are faster and faster. So they reproduce better and better the normal response of the body, so that if the insulin rises in time with the food, then there’s no postprandial hyperglycemia.

The best timing for mealtime insulin depends on the kind of insulin that’s being used. With the slightly older insulins that are used a little bit less often now, it was very important to give it up to 30 minutes before the meal, because it took some time to get to the blood, so in order to reproduce the normal response of the body, it had to be taken sometime before, which complicates things because then people don’t always know 30 minutes before what they’ll end up eating.

So the newer insulins tend to be faster acting, so they can be given closer to the meal. They can be given within 15 minutes and even right at the beginning of the meal, in order to still be able to better control glucose levels.

And finally the most recent ones, the ones that just came out, can even be given after the meal, right after the meal, and it will still be able to control postprandial glucose, because they go in the blood so rapidly. So the best timing depends on which kind of insulin is being used, and it’s important to respect that, because if you don’t take it at the right time, you can end up having very high glucose levels.

So in summary, postprandial hyperglycemia, or glucose levels that are too high after meals, is a contributor to high A1Cs, and therefore can lead to complications in the long term. So it’s important to take the appropriate action to control postprandial hyperglycemia.

If you need more information or are interested in this topic, you can consult your family physician, your diabetes educator or your endocrinologist, who will be able to give you some strategies to help you better control postprandial hyperglycemia.

Presenter: Dr. Jean-François Yale, Endocrinologist, Montreal, QC

Local Practitioners: Endocrinologist

Post Prandial Glucose Control in Diabetes ( 109 participated.)

Rapid Acting Insulin


When a healthy individual has a meal the body releases insulin that keeps blood sugar levels under control.


In patients that have diabetes, the body either does not produce insulin or cannot produce enough insulin to control blood sugars adequately.


Post prandial glucose refers to the sugars that are released into the blood after eating a meal.


Patients with diabetes who take insulin only need one type of insulin to manage their diabetes effectively.


Fast acting, or rapid acting insulins are taken before a meal anywhere from 30 to 5 minutes prior to a meal.


If a rapid acting insulin is not taken on time, there can be a gap of time where sugars are elevated after a meal.


Post prandial glucose or meal time sugars don't typically effect overall glycemic control, such as a persons A1C level.

This content is for informational purposes only, and is not intended to be a substitute for professional medical advice, diagnosis or treatment. Always seek the advice of your physician or other qualified healthcare professional with any questions you may have regarding a medical condition.