Mealtime insulins are fast-acting insulins. They’re taken immediately before or after meals to help control blood sugar spikes that happen when you eat. Your doctor will most likely prescribe a mealtime insulin to take on top of a long-acting insulin.

The main job of insulin is to keep the level of glucose in the bloodstream within a normal range. The amount and type of insulin varies from person to person. This depends on diet, lifestyle, and your particular diabetes case.

Read on to learn more about mealtime insulin, including how it differs from other types of insulin and the best way to take it.

Mealtime insulin works differently than other types of insulin. The major difference between the different types of insulin is how quickly they start acting in the blood and how long they’re effective. Here’s a breakdown:

  • Rapid-acting (mealtime) insulin, sometimes called bolus insulin, is designed to quickly act on blood sugar during a meal. The effects of this type of insulin can start in as little as five minutes and peak after about an hour. It works for roughly three hours.
  • Regular (short-acting) insulin begins to work 30 minutes after injection, peaks around two hours after the injection, and works for between five and eight hours.
  • Long-acting insulin, also called basal or background insulin, works in your body throughout the day to control your blood sugar, even when you’re not eating. The effects usually start about two to four hours after injection, and last for between 18 and 42 hours, depending on the exact brand of basal insulin.
  • Intermediate-acting insulin is similar to a long-acting insulin, except it doesn’t work for quite as long. It reaches the bloodstream about two hours after injection and is effective for about 12 to 16 hours. You’ll have to take more doses of an intermediate-acting insulin throughout the day.
  • Combination or mixed insulin, also known as basal-bolus therapy, includes both a long-acting insulin and a rapid-acting insulin in the same vial. An injection more closely imitates how the body’s insulin would naturally work throughout a typical day.

The biggest benefit of taking a mealtime insulin on top of a long-acting or intermediate regimen is that it allows you to closely match how your own body would naturally release insulin if it was able to do so.

Another advantage is that it allows your mealtimes to be flexible. As long as you remember to take your mealtime insulin 15 to 20 minutes before your meal or snack, you can eat your meals whenever you’d like.

Most doctors will start you on a long-acting insulin at first. But sometimes long-acting insulin isn’t enough to keep your blood sugar at your target level throughout the day.

When you eat a meal, sugar levels in the blood can rise rapidly. This “spike” in blood sugar may be too high for long-acting insulin to control. This is when your doctor may want to add a mealtime insulin to your long-acting therapy or prescribe a combination insulin.

Your doctor will work with you to figure out if you need a mealtime insulin. They will have you take note of how much your blood sugar fluctuates throughout the day. They’ll also ask about your lifestyle and eating habits.

Your doctor will likely recommend that you add a mealtime insulin to your long-acting insulin if your glucose levels are still too high after eating a meal.

You’ll continue to take your long-acting insulin as prescribed by your doctor. But you’ll also take the mealtime insulin right before you eat your meals (such as right before breakfast, lunch, dinner, and before a large snack).

As the name suggests, mealtime insulin is taken at mealtimes, usually right before a meal.

Before you inject a mealtime insulin, you’ll have to determine what dose you need. The dose you take depends on how many carbohydrates you plan on eating in your meal.

The higher the amount of carbohydrates, the more that food will raise your blood sugar. This means you’ll need more insulin. You’ll also need to watch what you eat and avoid foods high in processed sugar and carbohydrates.

If you’re not sure how to calculate the dose based on your meal, ask your doctor. There are also several smartphone apps available to help you figure out your dose.

In addition to your diet, exercise also has an effect on how much insulin you need to inject at mealtimes. Exercise can increase sensitivity to insulin for up to 48 hours and may require a reduction to insulin doses.

Insulin shots work fastest when given in the abdomen. Each mealtime injection of insulin should be given in the same general part of the body (but not the exact same spot) for best results.

When you begin taking insulin, your doctor might check in with you often. They may have you tweak the amount you take or the time you take it based on the results of blood sugar tests. You’ll need to fine-tune your dose and schedule until you find one that works best.

Research shows that the best time to take a mealtime insulin is 15 to 20 minutes before you eat a meal. You can also take it after your meal, but this may put you at a higher risk of a hypoglycemic episode.

Don’t panic if you forget to take your insulin before your meal. Instead, take it at the end of the meal and keep an eye on your blood glucose.

If you forget to take your insulin and it’s already time for another meal, your blood glucose level will probably be higher than it normally is before a meal. If this happens, measure your blood glucose and then dose for the meal, plus a correction dose to cover the higher glucose level.

If you forget to take your mealtime insulin often, talk with your doctor and they may prescribe a different type of insulin for you.

One disadvantage of mealtime insulin is the need to inject yourself with insulin multiple times per day. You’ll need to get comfortable with injecting at work and when you’re out with friends.

Mealtime insulin also requires you to count your carbohydrates and adjust your dosage accordingly. This can take a fair amount of patience and practice. Your doctor and diabetes care team can give you guidance on how much insulin to take.

Blood glucose testing will be useful to help you learn how much insulin you need to take.

One side effect of mealtime insulin is weight gain. Weight gain while on insulin can be difficult to manage, but there are ways to keep it under control.

Mealtime insulin also comes with other risks. If you take your mealtime insulin, but are unable to eat, you could become hypoglycemic. Hypoglycemia occurs when your blood sugar levels get too low. This can be very dangerous.

To stop the effects of hypoglycemia, you’ll have to have glucose tabs or another source of carbohydrates on hand. Here are some examples:

  • 1/2 cup of fruit juice
  • 5 small candies, such as LifeSavers
  • 2 tablespoons of raisins

When used together with a long- or intermediate-acting insulin, mealtime insulin is a great way to mimic your body’s natural insulin schedule. It may take a little practice to understand how much mealtime insulin you need to inject before you eat a meal or snack, but you’ll eventually learn what is best for your body.

If you’re not sure how often to inject a mealtime insulin, how much to inject, or how to measure your blood glucose, ask your doctor or diabetes educator.