Initial insulin doses

Calculating your basal rate

As we mentioned before, 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. 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 hourly and the rate (how much insulin is given) can be pre-programmed with different rates (speeds of delivery) at different times of the day to suit your individual needs.

First, let’s look at calculating your basal rate. You are likely to need approximately 25–30% less insulin on a pump than your previous requirements when injecting, because of the way the insulin is delivered. Follow the steps below to calculate your hourly basal rate (this calculation is also available in a printable worksheet here):

Firstly, calculate your average pre-pump total daily dose – which is how many units of insulin injected over 24 hours. (You can do this by combining your total bolus insulin injections and your basal insulin injections over a 24 hour period.)

Reduce your daily pre-pump dose by 25% for your total daily pump dose (You can do this on a calculator by multiplying your daily pre-pump dose by 0.75) =

Divide your total daily pump dose by 2 for your total basal rate in 24 hours = ________

Divide your total basal rate in 24 hours by 24 to get your hourly basal rate =  ________

For example:

Firstly, calculate your average total units of injected insulin over 24 hours. (You can do this by combining your total bolus insulin injections and your basal insulin injections over a 24 hour period.)

Reduce your daily pre-pump dose by 25% for your total daily pump dose (You can do this on a calculator by multiplying your daily pre-pump dose by 0.75) =

In this example, the hourly basal rate is 0.7 units/hour.

This can seem complicate, but your diabetes team will support you in the calculation and may suggest slight modifications based on your experience with diabetes.

It is usual to start with a flat basal rate, but you and your diabetes team may decide differently. The pump has the ability to deliver different basal rates during the 24-hour period. These will be determined according to your individual needs over the next few weeks. Most people will eventually have between 1–6 different basal rates over 24 hours.