Even with all the advances in insulin development in the last several years, one often overlooked truth about the way insulin works in your body has never gone away: Insulin takes time to begin to work when first injected under your skin, and if you can give it several minutes before your child eats, it is likely to be better for your child.
What is a pre-bolus?
A child with diabetes often takes a bolus dose of insulin at meal times to control glucose levels after the meal. Pre-bolusing is when a child takes this dose of insulin prior to eating.
"A pre-bolus is just what the name sounds like," explains Soumya Adhikari, M.D., Pediatric Endocrinologist at Children's Health℠ and Associate Professor at UT Southwestern. "It means that the dose of rapid-acting insulin that a child receives when it is time to eat is given at least several minutes before the child starts to eat. This can be 5-10 minutes or longer depending on the circumstances."
Why is pre-bolusing important?
Even the most modern "ultra-rapid acting" insulins take time to be absorbed and be available in the blood to lower glucose levels. The more commonly used insulins can take 10-20 minutes to begin to work, and often much longer to measurably lower glucose levels. (See an overview of the time-action profiles of many of the insulins currently on the market in the column labeled "Onset.")
The Endocrinology team at Children's Health doesn't take this challenge lightly. "Managing glucose levels at meal times can be difficult for all people with type 1 diabetes, but especially for parents of young children, who often have unpredictable eating behaviors," says Kim Jernigan, a certified diabetes educator at Children's Health. "However, there's no denying the evidence that pre-bolusing can help."
The largest study of its kind to look at pre-bolusing had many interesting findings, including:
- People who pre-bolus are achieving A1C levels about a half percentage point lower than those who are not pre-bolusing.
- People who pre-bolus are much less likely to forget to bolus for a meal altogether.
- Most people don't pre-bolus.
The reasons for not pre-bolusing are many and are magnified in children. "Fear of causing your child to go low after the dose is given and before they eat keeps many parents from wanting to take this step," says Dr. Adhikari.
Pre-bolusing can also be easier for pump users. For example, if you're able to plan with confidence that a child will eat at least 20g of carbohydrates for a meal, you can pre-bolus for that. If the child eats more, you can "catch up" to the rest of their dosing needs with a second bolus for all the carbs above 20g. This strategy is easier when a child is on a pump and a second dose means pushing a few buttons as opposed to a second shot.
Pre-bolusing is not an all-or-none commitment
It's important to acknowledge that pre-bolusing need not, and in fact should not be an "always or never" step.
"When first starting out, pre-bolus when your schedule and routine permits, and when you can pay attention to your child's glucose trends closely – with a continuous glucose meter, if available – after the pre-bolus dose, so you can see the effects it has on your child," advises Jernigan. "You should also not pre-bolus if your child's glucose levels are low heading into a meal."
How far ahead of a meal should a bolus be given?
The question of how far ahead of a meal to pre-bolus has a different answer for different children. "Even for the same child, different food choices and activity levels and glucose readings might all affect the ideal pre-bolus timing for any given meal," Dr. Adhikari explains.
If you are looking for ways to improve your child's glucose control, and are not currently pre-bolusing, talk to your doctor about this at your child's next office visit. Learn more tips for pre-bolusing to prevent high blood sugar. For a more scientific explanation on how to get pre-bolusing timing right, view this article.
The Pediatric Diabetes Program at Children's Health offers around-the-clock care for children with type 1 and type 2 diabetes. Our award-winning program gives you and your child the tools you need to live the lives you want, even with diabetes. Learn more about our program and services.