Monday, November 15, 2010

All About Insulin Pumps!

Okay, I realized I promised this post two days ago, but I had to designate a special post just for World Diabetes Day (which was yesterday). But, since it’s still National Diabetes Month, I’m still blogging about diabetes, so here is a post ALL ABOUT INSULIN PUMPS!

I looked around for a good definition or explanation of what exactly an insulin pump is, but I couldn’t find the perfect one, so I combined a bunch and created my own. An insulin pump is a portable insulin delivery device that delivers insulin to the person wearing it continuously and subcutaneously (basically, into the fat just underneath the skin). So, basically, an insulin pump infuses a small amount of rapid acting insulin into the wearer continuously throughout the entire day as opposed to shots which deliver more rapid acting or longer acting insulin in one big fell swoop several times during the day.


Many people think that insulin pumps basically govern themselves and that if you pump, you don’t have to check your blood sugar or do anything to manage your diabetes any more. THIS IS UNTRUE. Pumps aren’t smart. They’re not even as smart as your “smart phones” and definitely not as smart as Google and it’s ability to anticipate what I want to search for. Right now pumps can’t anticipate what I’m about to do, or what I’m about to eat and adjust my insulin dosage accordingly. You have to program the pump to do what you want to do, and the programming functions are pretty basic.

There are two basic things you have to program your pump to do. First, you have to figure out your basal (or base-line) insulin needs. This means, how much insulin you need during a given period to handle your body’s basic metabolic functions, without taking into consideration eating. Then, you can program your pump to deliver a certain amount of insulin, over a certain amount of time for that given period. You can vary that a lot, which is nice. So, for example, I can program a pump to give me 1.5 units of insulin every hour between the hours of 12am-6am, then 1.0 units every hour between the hours of 6am to 1230pm, then I can say, between the hours of 1230pm -600pm give me 1.5 units every hour, etc. These are called the pumps’ basal rates. You can make these pretty variable, and you can have as many different basal rates as you need, at whatever rate and time you need them, but you still have to program it to do it. And you have to somehow figure out how much you need at what hours of the day (which, believe me, is not easy to do, as your body’s basal insulin needs change often and that’s a whole other blog post in itself!).

The second basic thing you program a pump to do is to give you a bolus. This is insulin delivery that is given to cover food you have eaten or to correct a high blood glucose. You have to figure out how much insulin you need based on the amount of food you eat and also how much insulin you need to lower a high blood sugar to your target range. This takes a lot of trial and error, and a lot of blood sugar testing. But you end up with an “insulin to carbohydrate” ratio, and a “correction ratio” which you then use to program your pump to deliver a bolus when you need it. The pump won’t just be able to tell when you are eating or when you are high and say “Oh! Erin needs insulin! Here you go!” Like I said, they’re not that smart yet. There are lots of different kinds of boluses that basically differ on the rate at which the insulin is delivered. But, in general, a bolus is insulin delivery given to cover your body’s insulin needs over and above that needed for basic metabolic function.

Other than those two basic things your insulin pump does, you can also program it to adjust your basal or bolus rates when you exercise, when you’re going to take it off for a bit, or for any other activity that might change your insulin requirements. For example, I know that when I get anxious, my blood sugar sky rockets. So, if I’m about to do something like speak in front of a big group of people, I’d probably give my self a little bit of a higher temporary basal rate to help me keep my blood sugar down.

If you have any more questions about that, or if I didn’t do a very good job at explaining how they work, this wikipedia article actually does a decent job at explaining it.


There are many advantages to using an insulin pump over regular Multiple Daily Injection (MDI) therapy (taking shots). Pumps more closely mimic the natural human pancreas, by delivering a little bit of insulin all day long to your body, rather than insulin in short bursts like MDI. Because you are only taking rapid acting insulin, you can make finer adjustments for unexpected life events, because you don’t have to wait on the long acting insulin you took 12 hours ago to get out of your system. When I was on a pump, I felt like I had a lot more freedom to eat and exercise when I wanted without a lot of planning ahead. It is easier to achieve better glucose control on a pump (although arguably just as much, if not more, work) than on MDI.


In my opinion, the number one disadvantage to pumping is the price! It is still VERY costly, and virtually impossible to have one if you don’t have good insurance coverage for it. And, like everything, many insurance companies will fight you tooth and nail to let you have one. Another big disadvantage of pumping is constantly being attached to something. It can be difficult to find clothes to wear that cover your pump, especially if you’re a woman. Also, not all pumps are water resistant, so it is hard to just hop in the pool or shower. Also, if you’re not careful with rotating your insertion sites, you can develop scar tissue (but that’s also possible with MDI).


There are many different kinds of insulin pumps, but basically they all consist of the pump itself, a reservoir that holds the insulin, a cannula (the part that sits under your skin that the insulin comes out of) and some kind of tubing that connects the insulin reservoir to the cannula. There are some “tubeless” pumps out there now, too. Most people wear a pump on their belt or in their pocket and then the tube stretches to wherever their insertion site is. Those that have the tubeless pumps basically just wear the pump right at the insertion site.

(Image borrowed from

These days, insulin pumps are about the size of a beeper or a cell phone. When insulin pumps were first being developed, though, they were HUGE and basically had to be worn like a back pack! NOT very practical! I’m hoping that pump manufacturers will start to take their cues from places like Apple, Inc. and develop smaller, sleeker pumps, soon. Here are links to some of the major pump manufacturers, at least in the U.S., so you can get an idea of what they look like. (I am not endorsing any of these manufacturers, by the way).

Next Up: What is it like to be married to a PWD?!—A guest post from my husband!

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