Why Insulin Pumps Work Well With Gastroparesis

In a Facebook group for people with gastroparesis, a member with that and Type 1 Diabetes said that he'd been hospitalized a couple of times and that his doctor recommended that he should start using an insulin pump.

Gastroparesis is a complication of Diabetes where the stomach does not digest food properly. Most usually it means that the stomach does not move food along the digestive system as rapidly as a healthy stomach. Rather, for unknown reasons the food often just "sits there." One of the symptoms is excessive fullness (picture Thanksgiving afternoon but you only had a cup of yogurt). Others include pain, cramping, nausea and vomiting. The culprit is believed to be having had high blood glucose levels for an extended period of time, though other causes are being investigated.

On top of the nasty symptoms, gastroparesis makes controlling Diabetes challenging, if not impossible. I pointedly asked my Gastroenterologist what I needed to do to minimize the symptoms of gastroparesis. She said, "Get your A1C down and it will get better and possibly become unnoticeable." I passed that along to my Endocrinologist to get her advice on how to do that. She said that gastroparesis made it difficult, if not even dangerous to try and lower my A1C. Lovely.

For the uninitiated, here is how a person with diabetes normally uses insulin to control blood glucose. Before they consume a meal, they will measure their blood glucose. If it is above their target, they have to figure out how much insulin to inject to get it back to the desire range. Then, they count how many grams of carbohydrates are in the meal. Once it is eaten, those carbs convert to glucose and enter the bloodstream. To counteract that rise in glucose, an individualized formula is used to determine how much insulin will be necessary. They will add those two doses and inject the insulin about the time the meal is served.  Once injected, the insulin "peaks" at around one hour, then the amount in the person's system falls off gradually, disappearing completely after a few hours. This "rate of action" is designed to mimic how a person's blood glucose will rise shortly after a meal and then tail off. If the stomach is functioning properly and the person gets the calculations right, things often work out nicely.

Not so with Gastroparesis. Delayed or impaired stomach emptying screws up this delicate balancing act. Say a person is about to have a meal. They measure their BG, calculate the insulin correction. They count the carbohydrates in their meal, determine how much insulin to take for the meal, then add the two doses. They do the injection and have their meal. But since the food could sit for hours in their stomach, the insulin will take effect when their isn't an increase in the BG. As a result, their BG could drop to dangerously low levels. The person then would have to take some glucose to get it back to a safe level. But after wrestling with that, the food finally starts to digest and the carbs in the meal are converted to glucose and enter the bloodstream. Now the BG rises (in my case as many as 5 or 6 hours after a meal) but there isn't any of the insulin that was injected before the meal left to push the BG back down. Now the BG is too high, and the patient has to decide whether to ride it out or to inject some extra insulin to get the BG to where it ought to be.

That is how it works when using traditional shots. You could divide up the meal bolus and give yourself a couple of small shots over time, but that is unwieldy, somewhat complicated and impractical.

I use a Medtronic 530g Insulin Pump. It has  there are several features that allow me to tailor how much insulin is delivered and when. One option is to use a "square wave bolus." This delivers the insulin at a constant rate over a user selected time period. If I was eating a meal over a long duration (say a working dinner in a restaurant) and didn't need a correction, I'd use this. If a correction was needed, I would use a "dual wave bolus." With this, you get a user selected amount of insulin immediately and the remainder is delivered over time just like the "square wave bolus." You can also add some insulin to come on the front end on top of the correction bolus and the remainder later. After much trial and error, this is what I do. Most of the time it works fairly well, but not always. If a meal is particularly heavy, I might stretch out the length of the bolus from my typical one hour to an hour and a half or even two hours. If it is light and easily digested (like a can of Ensure) then I might decrease the time period, or shift more of the insulin to the beginning of the bolus.

To answer the gentleman's question of whether an insulin pump is the way to go for managing Type 1 Diabetes with gastroparesis, I'd unhesitatingly say that for many people it is. While more costly than shots, and somewhat more complicated, those drawbacks are more than offset by the flexibility it offers in dealing with a challenging and complex set of circumstances. If available to him, I'd enthusiastically encourage him to give it a try. It has made a real difference for me and given the current state of technology in diabetes management, this is the only way to go.