Thursday, May 31, 2012

Choosing Your Next Pump

For the past few weeks, I've been doing research on purchasing my next Insulin Pump. My only experience is having diabetes for 30+ years, but I'll write all of this as if it's gospel without the standard disclaimers (most of the time).

I've blogged several stories about my Insulin Pump sagas. If you are interested you can do a search for insulin pump in the upper left hand corner of this page. It should show you all the stories where I mention my insulin pump. You can, of course, search for anything you want. All of my wonderful postings have been carefully indexed for ease of searching.

For those of you still reading and completely unaware, I'll give you a short lesson on insulin pumps.

Insulin is a hormone secreted by the islets of Langerhans. Insulin's primary goal is to convert sugar into energy. You can do more research on your own, but basically, Type I diabetes is thought to be caused when your immune system attacks these islets. With Type I diabetes you are producing no insulin so you must somehow inject it. Type II diabetes is a little more complicated. It can be caused by your body's inability to use the insulin efficiently. It can be caused by the islets simply not producing the proper amount. I don't think anyone knows exactly, but suffice it to say with Type II diabetes, you're not getting enough insulin for one reason or another. Type II can sometimes be managed by diet and exercise. I have Type I.

I've tried insulin pumps in the past and I didn't like them. About 5 years ago I tried one that stuck (heheh literally). It was an Animas pump. I liked it because of the "color display" (which is riding a fine line of false advertisement -- there might be 2 colors) and because it was "waterproof" (which is also riding a fine line of false advertisement -- I've had 2 of them quit working after leaking occurred). It stuck because of the support team. I had three different nurses all calling me on a regular basis to set up what they call "the basal plan". It tries to mimic the body's natural secretion of insulin when you are not eating.

The Basal Plan
Some of this is based on fact. Some of it is based on me. A subject for another blog, but I'll summarize here for this post. I discovered the other day that I make intuitive leaps which become fact (in my mind). Over the years, I don't remember if I actually read this somewhere or it's just an "intuitive leap".

Even when you are not eating, you need energy. Your body has various ways of putting sugar into your bloodstream. Therefore, your body is always producing insulin. When getting a pump, your first goal should be establishing your fasting basal rate. If you could survive without food, how much insulin would you need?

It gets a bit complicated because your basal rate on the pump is measured in units of insulin per hour, but it can change throughout the day. Did you know your liver dumps sugar in the morning to help you wake up? My basal rate in the morning is 0.6 units per hour. During the day it is 0.375 units per hour. At night it is 0.275 units per hour.

I obtained these numbers by fasting for 8 hours at a time and checking my blood sugar levels every 2 hours. If my sugar levels stayed normal, the basal rate was good. If my sugar levels were too high my basal rate was adjusted up for that time period. If my sugar levels were too low, my basal rate was lowered for that time period. It's a bit of a guessing game and you don't want to do anything drastic, but like I said, I always had an expert going over the numbers with me.

Once you feel confident that you can wake up in the morning with a blood sugar level of 100 and it'll be very close to 100 when you go to bed, then you can move on to Boluses. From researching various pumps, it seems that the Basal rate setup is about the same on all of them. It doesn't seem to be a big selling point. Boluses, on the other hand, are entertaining because their various implementations commit one of my pet peeves: unnecessary complications.

Every time you eat anything with carbohydrates that aren't fiber, you need insulin to do something with that sugar. Boluses allow you to add additional insulin when eating. They also allow you to correct for times when your blood sugar gets too high.

Two important numbers come from this: the insulin to carb ratio and the insulin to blood sugar ratio. How many carbs will one unit of insulin cover (ICR is Insulin to Carb Ratio) and how many points will one unit of insulin lower your blood sugar (ISR is Insulin to blood sugar ratio). For me those numbers are 13 and 60 respectively. Except for some reason in the mornings I have to lower that first number to 10. Theories abound.

Not all insulin pumps support the above two numbers. My new pump has to. I like the feature. When programming my pump I almost never tell it to give me X units of insulin. 99% of the time I tell it that I just ate X carbohydrates and my blood sugar level was Y so how much insulin do you recommend? It does calculations based on my ICR and ISR and my IOB. IOB is Insulin On Board. I have mine set at 1.5 hours, but it's adjustable. Literature says humalog insulin (the kind most pumps use) is normally absorbed and gone in about 2 hours (give or take). IOB is a calculation of how many units of insulin are still working in your body when you get ready to perform another bolus.

Two basic types of boluses exist. Based on your entries for the amount of carbs and blood sugar level, your pump may recommend 5 units of insulin. You can choose to take it all now (which I never do) or you can tell it to give you some now and the rest over a specified duration. For example, I can say, give me 1 unit now and the remaining 4 units over the next hour. If it gives me a dose every three minutes, it'll do 1 now and then every three minutes do 0.2 for the next hour.

Every pump I've ever seen defaults to the "dumb" bolus. You scroll to the bolus option, click it and the first choice is Normal Bolus. Just enter how much you want and hit go. This irritates me to no end. They need to make these things customizable for gods sake.

Even if you get past the "Normal Bolus" and get into the "Wizard" that lets you compute the bolus, it still comes back to the dumb screen after the wizard is done. It'll, for example, say, "The wizard recommends 5 units, hit go do deliver. But, if you prefer, change this option over here to combo or expert or square or dual or whatever this particular pump manufacturer calls it, hold your head slightly to the left and carefully caress the go button".

Finally, you arrive at the "expert" delivery screen and here it gets ugly again. The Minimed pump says you can do a Square Wave bolus (give the entire 5 units over a duration) or a Dual Wave bolus (give part of the 5 now and the remainder over a duration). This is the ultimate in overcomplication.

My Animas pump specifies a percentage now (which can be 0% and a duration). It accomplishes the same thing as the Minimed but with a simpler nomenclature. 0% now is a "Square Wave", anything greater than 0% and less than 100% is a "Dual Wave".

However, let's simplify further. Let's not have normal, combo, dual wave, expert or anything. All boluses are an amount, a percentage and a duration. All of this naming and additional screens is completely unnecessary. A "Normal Bolus" is 100% now (duration would be ignored). The idea of having two bolus screens (one for the experts and one for the normal) is overcomplicated.

If they'd just make all of these devices use a well defined Bluetooth protocol I could write my own bolus app on my mobile phone.

Tandem t:slim
I had high hopes for this little guy (the t:slim). However, last week they released a video of someone giving themselves a bolus and my dreams were crushed. It's odd being excited and then horribly disappointed by an insulin pump (medical device), but I was. I am still in line to get one because it does seem to be a little ahead of the curve. At least it looks more like a smartphone than a pager.

Ah, the video. Basically, it shows someone doing a bolus. The t:slim came up in the "Normal Bolus" mode and you have to touch a little slider button to switch to "Combo". And I reiterate: Normal and Combo are exactly the same things! Don't make me hit a slider button and then adjust the percentage when adjusting the percentage is the only thing that is necessary. It's utterly stupid. Some other people who actually were given a chance to play with the pump have commented on its customizations. You can probably change the colors. If they'd let me unnecessarily make all Boluses default to Combo that would be something.

None of the pumps allow you to have two "Combo Boluses" active at the same time. You have to cancel the previous to do a new one. This should be customizable. I can understand the safety risk of over medicating yourself, but for those of us who know what we're doing, it's just a pain. Pizza, for example, can take an hour or more to digest. If I eat a slice of pizza at 20 carbs and do a combo bolus for an hour, then, thirty minutes later, I decide I want another piece I'm screwed. I'd have to do some kind of miraculous calculation about how much of the previous insulin was given and how much of the previous pizza was digested so that I could cancel the previous bolus and do another one. It should just allow me to do another bolus over time (BOT is my new acronym)!

Maybe I should get into the Pump Programming business.

T:slim advertises less buttons to accomplish the same task which is obvious because there are no buttons. It's a touch screen. I think there might be some marketing folks who need to be shot. It's also "rechargeable". I'm kind of curious if I'm going to have to sit next to an electrical outlet for an hour while it charges... That would be fun.


  1. Dude, you need to move to San Diego....

  2. Indeed. Or quit shopping for insulin pumps while I'm still sane. Oh wait, never mind. Guess I should move.