Programming Your Pump

Basal insulin rates

You pre-program your insulin pump to deliver a tiny amount of insulin every few minutes in a cycle of 24 hours. This is known as a basal rate pattern.

The basal rate replaces the insulin that your body is not producing or producing enough of naturally.  The basal rate Provides a low, continuous level of insulin that controls glucose overnight and in between meals.  The rate is programmed as unit(s) per hour. You can program different patterns to meet different needs. Some examples that might prompt additional programming are: weekend or shift work, exercise, hormonal fluctuations, or travel.  In a basic pump the basal infusion occurs automatically; it just keeps delivering insulin in the pre-programmed pattern until you decide to change the rate.   In systems integrated with continuous glucose monitors (CGMs), the basal rate may be adjusted automatically by the pump according to the glucose trends.

Bolus insulin

You can also pre-program your insulin pump with the bolus settings, including the insulin to carbohydrate ratios, bolus infusion profiles, and insulin sensitivity factor, or correction factor.

Insulin-to-carbohydrate ratio is programmed as 1 unit of insulin per number of carbohydrate grams. This means that 1 unit of insulin will dispose of so many grams of carbohydrate. Multiple insulin-to-carbohydrate ratios may be set for different meals – breakfast, lunch, dinner, snacks, etc. For example, if 1 unit of insulin disposes of 10 grams of carbohydrates, it is expressed as the ratio 1:10 grams of carbohydrate.

The settings also can be pre-set to deliver different bolus infusion profiles, such as an extended (square wave) or dual (combination) bolus. An extended/square wave delivers the bolus insulin over a specified number of minutes, and a dual/combination bolus delivers a certain portion of the insulin immediately and the rest as an extended/square wave. The proportion of the immediate versus prolonged delivery, the overall time duration of the delivery, and the insulin to carbohydrate ratio can be varied.

Insulin sensitivity factor, or ISF, refers to how much or how many points (mg/dl) the blood sugar will drop in response to one unit of insulin. It is also known as a high blood sugar correction, and is set as one unit of insulin to lower a specific amount of glucose (in mg/dl). Different ISFs can be pre-programmed for different times of the day. A common example would be 1:50. This means that 1 unit of insulin will drop blood sugars 50 points.

Unlike the basal insulin infusion, bolus infusions are NOT necessarily automatic.  In all pumps, you need to announce carbohydrates when eating.  In a closed loop system, correction boluses may be automated as well as deliverable by the pump user.

Insulin Regimen with an Insulin Pump (CSII)

The insulin pump or continuous subcutaneous insulin infusion device (CSII)  continuously administers rapid acting insulin into the fatty tissue beneath the skin. The insulin pump is especially suited to covering different patterns of insulin resistance or sensitivity throughout the day. The pump may also have multiple methods to deliver a bolus such as: standard, dual wave, and extended boluses.  This is dependent upon the make and version of the insulin pump, check for features specific to your make and version pump.

Target blood glucose

You can program your pump with your individual target or desired blood glucose level.

Examples of target glucose, insulin-to-carbohydrate ratio and insulin sensitivity factor (ISF):

Pre-programmed:

  • Target glucose: 110 mg/dl
  • Insulin-to-carbohydrate ratio: 1:10 (1 unit insulin for every 10 grams of carbohydrate)
  • ISF: 1 per 50 (1 unit of insulin to lower glucose 50 points [mg/dl])

Example 1 | ISF

  • Current glucose: 160 mg/dl (entered by user)
  • Target glucose: 110 mg/dl
  • ISF: 1 per 50
  • Calculation: 160 minus 110 = 50 points higher than target
  • Recommendation: 1 unit of insulin to correct high glucose

Example 2 | Insulin-to-carbohydrate ratio

  • Carbohydrate grams: 50 grams (entered by user)
  • Insulin-to-carbohydrate ratio: 1:10 (1 unit insulin for every 10 grams of carbohydrate)
  • Calculation: 50 divided by 10
  • Recommendation: 5 units of insulin for 50 grams of carbohydrates

Example 3 | Insulin-to-carbohydrate ratio and ISF

  • Current glucose: 160 mg/dl (entered by user)
  • Carbohydrate grams: 50 grams (entered by user)
  • Target glucose: 110 mg/dl
  • ISF: 1 per 50
  • Insulin-to-carbohydrate ratio: 1:10
  • Calculation: 160 minus 110 = 50 points higher than target
  • Recommendation
    •  1 unit insulin to correct high glucose
    • And 5 units insulin for 50 grams of carbohydate
    • Total insulin recommended: 6 units