Pump Basal Terms Explained
Demystifying Basal Terminology: Standard, Alternate, Active & Temp Basals
You may have heard about a Temporary Basal rate, a Primary or Standard Basal program, an Alternate Basal profile, an Active Basal program… are you confused yet?! If you're wondering what the difference is between the various basal terms, plus when to use which one, then wonder no more. Let’s clear up the confusion with a brief overview of each basal option.
It’s important to point out that all of these options are related to basal insulin. Basal insulin is the background insulin that the pump “trickles out” every few minutes to keep blood glucose steady in the absence of food and exercise. It is differentiated from bolus insulin, which is given in a “lump sum” dose to cover carbs or to correct highs. So keeping this in mind, here are some of the options available to pumpers in terms of background insulin:
Standard (Primary) Basal Program
The Standard (or Primary) Basal program — often called simply “basal program”, “basal rates”, or “basals” — is the main set of basal insulin doses that you have programmed into the insulin pump to use on a typical day and which, if you never touched the pump again, would automatically deliver a specified amount of insulin every few minutes. Each basal rate is expressed as a discrete unit-per-hour number, such as 3.5 U/hr, or 0.125 U/hr (as just a few examples), which specifies how much basal insulin will be delivered during a given hour of the day.
For Medtronic Minimed pumps (630G/670G/770G), this standard basal profile is called Basal 1 pattern; for Omnipod/Omnipod DASH, it's called Basal 1 Program; for YposPump it's called Basal Rate Profile A. For Tandem t:slim X2 pump, the basal profile is contained within the main Personal Profile (along with individualized carb ratios, correction factors, target blood glucose, insulin duration and max bolus. With other pumps, all of these settings can be customized, but you program each on its own rather than within a broader Personal Profile.)
This main, Standard basal profile is the one that the pump will use by default if it exits Automode or Control-IQ.
Alternate Basal Profile
An Alternate Basal program is a set of basal rates with different doses of insulin than the Standard Basal program, so that you can conveniently switch over to a profile that matches a specific, other-than-usual, but regularly-occurring situation. For example, the rates may be lower than Standard for the afternoons in which your child has swimming lessons, for Saturday soccer practices, or for the mornings in which you (if you’re the PWD) take a run before work. Or the rates may be higher for couch-potato Sunday afternoons, or for the few days before your menstrual period. Just like with the Standard Basal program, the rates in an Alternate Basal program are also expressed as a discrete unit-per-hour number, such as 1.75U/hr (as just one example). To switch into, and out of, any Alternate Basal programs that you have set up, you need to manually select the desired basal program.
For Medtronic Minimed pumps (630G/670G/770G), these alternate basal profiles are called Basal 2, Basal 3, Basal 4, Basal 5, Workday, Day Off, or Sick Day; for Omnipod/Omnipod DASH, the default naming system is Basal 2, Basal 3, etc but you could instead enter a custom name of your choosing, such as Weekend, Workday, Soccer Game, Period, am Run; for YposPump you can program one other basal profile in addition to the main profile, called Basal Rate Profile B; For Tandem t:slim X2 pump, you can name each of the main and alternate Personal Profiles as you choose. For example, you could call them Workday, Weekend, Period, Illness, Hockey Practice, etc.
Active Basal Program
The Active basal program is the one you are using at the moment, whether it’s the Standard basal pattern or one of the Alternate programs. You need to manually select the basal or personal profile that you want the pump to use. The others hang around in the wings, waiting until you need them. The active basal program will stay active indefinitely, until you manually select a different basal profile.
Temp Basal Rates
While alternate basal patterns switch over to an entirely different set of basal rates, a Temporary Basal Rate, or temp basal, alters the Active basal rates by increasing or decreasing the basal rate by a certain amount relative to the programmed basal rates. The Temp Basal is often expressed as a percentage (such as 150%, or -40%, which the pump will convert into a discrete, unit-per-hour basal rate; for example, increasing a basal rate of 3.0 U/hr by 30% (which your pump may express as 130% of, or +30% of the current rate) will result in a temporary basal rate of 3.9 U/hr.) but some pump models also allow you to set a temp basal according to the insulin rate (in units per hour). Unlike an Alternate Basal program, when the temp basal expires (at the end of the time period you specified when you set it, such as 12 hours, for example) the basal rates will automatically return to the usual, pre-temp-basal rates (as set in the Active Basal program).
The above information was reviewed for content accuracy by clinical staff of the Alberta Children’s Hospital Diabetes Clinic.
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