Friday, 30 March 2012

Bolus Options

One of the neat things about an insulin pump is how you can choose how and when the insulin is delivered based on what you are eating, what you are doing, and if you are in a situation where you don't know what is going to happen with your meals.

On syringe therapy you will notice that even if you are counting carbs and you eat exactly the same number of carbs for days in a row at a certain meal, your blood sugars are never the same for a few hours after the meal.  Without getting into the specifics of it all, it generally has to do with something called the glycemic index, protein levels, as well as fat content in different foods. 

First, a couple definitions to start with.  An insulin pump will deliver insulin to you 24 hours a day (generally at 5, 10, or 15 min. intervals), and this is called a "basal" amount of insulin.  This acts as the more traditional "long acting" insulin in syringe therapy.  Then for meals (or times when you find yourself with a high blood sugar) you will give yourself a "bolus", or a spike of insulin to counteract the increase in sugar levels in your blood.  There are times that you will change your basal rate of insulin delivery, but that is for another blog post.  Today, I am looking at what you can do with your bolus.

Your diabetes educator will go over with you how to establish how much insulin to give yourself for the number of carbohydrates you are eating, or how to counteract a high blood sugar.  What I will look at here is what options your pump will have to use the insulin bolus.

Your insulin pump will generally give you three options for doing your bolus:
1. Normal/standard bolus: This type of bolus is the one that will be used most by beginner insulin pumpers. This is equivalent to giving yourself an injection of fast acting insulin.  The entire amount of insulin will get to your blood stream in the fastest possible time. Honestly, I default to this most of the time, myself, because it is easiest.  However, for people who are better in control and more fully understand the nutrition associated with various foods, this bolus will only be used for meals that are both low in proteins and low in fat.

2. Square-wave/extended bolus: This type of bolus will take the amount of insulin you wish to give yourself and evenly distribute the bolus over a certain time frame (again, something you control, and can be anywhere from 30 min. to a few hours).  This bolus setting is more used by advanced users, again.  You would use this setting if you were eating a high protein and high fat meal (like a steak or turkey and gravy).  Given that this type of meal would give a slow but steady increase of blood sugar levels, this square-wave bolus tries to match the insulin delivery with the sugar delivery to the blood stream.  The timing of how long to set the bolus for is best discussed with your diabetes educator and nutritionist.  This is also ideal if you are at a party and know that you are going to be eating a little bit all the time, but not really settling down for a full and proper meal.

3. Dual-wave/combination bolus: This type of bolus is exactly what it seems, a combination of the first two types discussed.  Again, this is used by an more advanced user of their insulin pump.  It is used in a couple different scenarios.  If you have a high blood sugar before doing the bolus, your pump will not allow you to simply do a "square-wave".  It will tell you that you must do some sort of insulin delivery immediately (to bring your blood sugar back in line with normal), and then will follow with the remainder of the square wave. It is also used if you are eating a high carb high fat meal (like pizza, chocolate cake, or pasta with a heavy cream sauce).  You can choose how much insulin will be split between the instant delivery and the remainder goes towards the square-wave for the time period you choose.

These different patterns may seem overwhelming at first, but it just take some practice and work with a nutritionist to understand what foods will have what effect.

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