Insulin pump terminology

Using an insulin pump means getting to grips with some new terminology. The five terms below – basal, temporary basal, bolus, active insulin, and insulin sensitivity factor – are commonly used terminology and there are all described on this page. 

Basal

Basal is the ‘background’ insulin that you need throughout the day and night to maintain your target blood glucose values when you are not eating. This replaces your Lantus (glargine), Abasaglar/Basalglar, Levemir, Humulin I, Degludec (Tresiba), Toujeo or Insulatard insulin. 

Your basal insulin accounts for approximately one-half of your daily insulin requirements. Your insulin pump mimics a pancreas by delivering insulin continuously over 24 hours. Your basal insulin is delivered in small increments continuously and the rate can be changed to suit your individual needs. 

Temporary basal

A temporary basal rate is a basal rate that you use in place of your scheduled basal rate for short-term situations. It can be applied for 30 minutes to 24 hours. This will speed up or slow down the background rate of insulin delivered.

Bolus

A bolus is a larger amount of insulin delivered quickly to cover carbohydrate foods (meal bolus) and/or corrective doses (correction bolus) to bring blood glucose to target. 

Active insulin  

Active insulin, also known as insulin on board, is the amount of insulin still active from a previous bolus to lower blood glucose levels. 

Insulin sensitivity factor

Your insulin sensitivity factor (ISF) determines how many mmol/L your blood glucose will drop with 1 unit of insulin. This helps the pump work out your correction doses if required.  An ISF of 1:4 is usually a good starting point,  i.e. 1 unit will drop blood glucose by 4 mmol/L.