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Written by Jordan R. Wagner BSN, RN, CDCES
I’m sure that many of you who are using an insulin pump have come across the terms extended bolus or dual/square wave bolus at some point. You might have an idea of what they are and may even use them, but it is safe to say that this advanced feature is most likely being under utilized by the vast majority of pumpers. So what exactly are these features and why are there 3 different names for essentially the same concept? Let’s take a look.
Of the 3 major insulin pumps on the market these days, all of them have a feature like this. Omnipod and Tandem use the term extended bolus whereas Medtronic uses the terms dual wave and square wave bolus.
An extended bolus on Tandem's T-Slim X2, lets the pumper give his or her insulin over an extended amount of time, typically 0.5 hours to 8 hours. If you are using a Tandem T-Slim X2 pump with Control IQ you can give a 2 hour extended bolus while in Control IQ mode, however, for longer time frames you will have to exit Control IQ temporarily. If you need to give more insulin while the extended bolus is delivering, you can certainly do that, just be careful of insulin stacking.
Omnipod's extended bolus is from 0.5 hours to 8 hours. Be sure that you don’t forget to bring your PDM (personal diabetes manager) with you. If you forget to bring the PDM, you are seriously out of luck because you won’t be able to give any bolus insulin (meal time or correction insulin). If you have ADD like myself or are prone to forgetting things, placing an Amazon Tile on the back of your PDM can be helpful so that you can track it or “ring” it if it is misplaced. An example of an extended bolus would be like this: Give 60% of the insulin dose now followed by the remaining 40% over the next 4 hours. It can also be programmed to deliver 0% initially followed by a slow insulin infusion over the next 0.5 hours to 8 hours.
Medtronic changed things up a bit and made their own terms, the dual wave and square wave bolus. Both are similar, but have some differences. The dual wave bolus allows the pumper to deliver a rapid bolus initially followed by a slow infusion of insulin over the next 0.5 hours to 8 hours (2 waves of insulin delivery, hence the term dual wave). The square wave allows the pumper to give an extended amount of insulin over 0.5 hours to 8 hours. If you are using the 670G or 770G, you will have to exit Auto Mode before you can use these features. As you can see dual wave/square wave boluses are basically the same as an extended bolus just with different names.
Now that we know what these features do, the question arises, “when would I use a feature like this?” To fully understand this it’s important to understand how proteins and fats impact blood sugars. This is talked about in more detail in my “Top 5 Strategies to Achieve Blood Sugar Control” guide that you can get access to by signing up for my email list. To make a long story short, if you are eating a meal with high carbohydrates, proteins, and fats you would benefit from an extended bolus. Take for example pizza… The high carbohydrate, protein, and fat content can wreak havoc on blood sugars, but with an extended/dual wave bolus, the insulin infusion can keep up with the digestion of the proteins and fats. The most challenging part with this is getting your dose right. This can take trial and error and it is best done under the guidance of an endocrinologist, but a general rule of thumb for high carbohydrate, protein, and fat meals is an extended bolus or dual wave/square wave bolus of a minimum of at least 2 hours. Likely it will need to be longer than this, but that is something to discuss with your provider.
Now I can’t write a blog article about this and fail to mention MDI (multiple daily injections). Obviously using an insulin pump in scenarios like this can be a bit easier, but a person can definitely achieve similar results using injections, it may just take multiple injections to do so. Split dosing is a technique of delivering your mealtime insulin dose in multiple shots. Example: if you needed 10 units for the meal, you could take 6 units now and wait 2 hours to take the last 4 units. This is the best way to mimic an extended/dual wave bolus from a pump while on shots. Again for the people with difficulties remembering, you may want to set an alarm to take the second dose of insulin, otherwise you’ll be riding the high sugar train all night long. Smart insulin pens can be helpful with this because they can tell you when you last took your insulin and the approximate active insulin/insulin on board in your body. If interested take a look at the Medtronic InPen.
As you can see an extended/dual or square wave bolus opens up the possibility of being able to eat foods that traditionally were quite challenging for people with insulin dependent diabetes. Remember, these are considered advanced dosing methods. If you are not comfortable using them, then don’t use them. Misusing any type of insulin dosing method can lead to serious harm. If you learned something new in this blog article that has intrigued you, I’d recommend that you bring it to your provider to talk about in more detail to see if it is right for you. If you have questions, feel free to reach out and take a look at my Facebook group, The Diabetes Group or if you are new to insulin pumps and or need a refresher, check out my Road Map to Insulin Pumps guide!