All the lingo of a pump can be overwhelming. Temporary basal, extended bolus, combo bolus, insulin on board, max basal and bolus. So here is a pump-dictionary, to help you sort through the jargon.
Basal insulin is small amounts of insulin given by the pump over a 24-hour period in order to suppress glucose coming from the liver. The basal rate keeps your glucose level in control between meals, overnight, or whenever you are in a fasting state. The rate may change over the 24 hours to correspond to your body’s need for more or less insulin at different times.
Basal insulin is supplied by Lantus, Levemir or NPH when given by injection. In a pump, rapid acting insulin (Apidra, Novolog and Humalog) is used for both the basal and bolus coverage.
So what’s a temporary basal? You program the pump to set your varying basal amounts for a 24-hour period. Temporary basal rates are used for changes in activity level that aren’t consistent day to day.
For example, you may take aerobics class twice a week, but some weeks it is on Monday and Thursday and others on Tuesday and Friday. On the days of your aerobics class you could set a temporary bolus for a percentage of your usual basal to run for 1.5 hours- the time of your class plus a bit more. This would help prevent you from going low during the class without having to eat extra carbohydrates
You may need less basal for:
Planned or unplanned exercise
Long-distance driving expedition- to avoid low blood glucose
During an extended fast such as Yom Kippur or Ramadan
When you drink alcohol close to bedtime and want to avoid low blood glucose during the night.
And more basal for
When ketones are present
Max bolus and max basal- are safety features built into the pump. They prevent you from giving a bolus or programming a basal rate that is so large that it is likely to cause significant hypoglycemia.
Usually the max bolus is set in the range of 30 percent higher than your usual high meal bolus and the max basal at double your starting basal. For example if you start with a basal rate of 1.0 then 2.0 might be your max basal.
Extended and combo boluses are used to handle the extra time needed to metabolize high fat or leisurely-eaten meals.
Rapid acting insulin works for approximately 4 hours, but high fat meals can take considerably longer to be digested and metabolized. This can lead to a situation where you may become low an hour after giving your insulin and very high at three hours post infusion. This is where the extended and combo bolus features come in handy. (Note: each pump has its own proprietary way of identifying these features)
Extended boluses work well for high fat meals that are low in carb: think large steak and fried vegetables. They also can be used in situations where you know you are going to be eating over a long period of time, like a cocktail party. In an extended bolus the insulin is given in small drops over a set period.
Combo boluses are used to “cover” meals that are high both in carb and fat. The classic examples are pizza and Chinese food. Some insulin is given upfront in a bolus to cover the glucose spike from the carbohydrate and then a second bolus is spread over a number of hours.
Insulin on board is another safety feature of the pump. Although calculated in different ways by different manufacturers, it basic premise is to let you know how much insulin is still working in your body if you decide to give another bolus.
Using a variety of equations, the pump will factor in your current blood glucose, how much insulin you gave at the last bolus, how long it has been since that bolus, and how long your insulin is scheduled to last to tell you how much additional insulin it is safe to take.
There is much more to pumping, but learning the lingo is as good a place as any to start.