Customizing Basal Rates

Get the Most Out of Your Insulin Pump: Individualize Your Pump Basal Rates

One of the most valuable benefits of an insulin pump (compared to injections) is that you can program varied basal, or background, insulin rates across the day, giving more or less insulin at different times to match your body's varied needs within a day. But how many basal periods do you need? And when is more insulin needed for children vs. adolescents vs. adults? Here we tell you how and why to customize your basal insulin rates using an insulin pump.

Background info on how insulin works in your pump:

Remember that an insulin pump delivers a single type of rapid-acting insulin in two ways:

  • a basal dose that is pumped continuously at an adjustable basal rate to deliver insulin needed between meals and at night.
  • a bolus dose that is pumped as a lump-sum dose to cover food eaten or to correct high blood glucose.

In our article on how a Basal-Bolus Approach applies to the use of insulin pumps, we defined “basal” insulin as the background insulin which keeps blood glucose steady in the absence of food and exercise. We also pointed out that an insulin pump provides basal insulin by infusing rapid-acting insulin (such as Humalog®, Novorapid®, or Apidra®) in small doses every few minutes.

Your child’s insulin pump delivers basal insulin according to the current Basal Rate profile that you have programmed into the pump. The Basal Rate is presented as an hourly rate; that is, it represents the total amount of insulin that will be delivered in a given hour. For example, your child’s 2 pm basal rate could be 0.100 units of insulin/hour (U/hr), which means that in that hour from 2 to 2:59pm, a total of one-tenth of a unit of insulin will be delivered by the insulin pump. Or the 2pm rate could be 4.5 U/hr, which means that in that hour, four and a half units of insulin will be delivered (split into several micro-doses given every few minutes).

As we said, the insulin pump provides basal insulin in small doses every few minutes. So within that hour, if basal insulin is delivered every 3 minutes, then the total basal rate will be split into 20 equal doses within that hour. In the first example of a basal rate of 0.100 U/hr, 0.005 units will be delivered every 3 minutes; in the second example of a basal rate of 4.5 U/hr, 0.225 units will be delivered in each of those frequent, smaller doses.

Individualizing Basal Rates Across the Day

You can individualize your child’s standard basal rate profile by programming in different basal rates for different times of the day.

Remember that:

  • Basal insulin needs vary from person to person, across the day, across different days, and across the lifespan.
  • Adults typically need more basal insulin in the early morning hours to deal with the “Dawn Phenomenon”: the liver secretes more glucose as we wake up (creating a need for more insulin).
  • Children often need more basal insulin in the late evening hours to deal with the release of growth hormones a few hours after they fall asleep.
  • Adolescents typically need more basal insulin in the late evening hours to deal with the release of growth hormone as well as more insulin in the early morning hours to counteract the Dawn Phenomenon.

The insulin pump models currently available in Canada allow for multiple time periods in a day (16-48 basal segments, depending on the pump model). Each of these could have a different basal rate (though it would be unlikely to need more than 10 of these; 3-8 different basal rates across the day would cover most needs). Basal Rates can range from as little as 0.025 for some pump models (that’s 25-thousandths of a unit in an hour, or just over 1-one-thousandth of a unit every 3 minutes! Amazing!) to as much as 35.0U/hr. Many people find that dividing the day into 4-8 time periods, each with a different basal rate, is the most effective approach.  If you have too few basal periods, you may be missing the opportunity to individualize insulin doses as needed across the day which would minimize predictable daily highs and lows; if you have too many basal periods, the excessive complication may make it harder to identify what’s working and what’s not.

The best number of basal periods, and the best basal rate to program into your child’s pump for each basal period, are the ones that best fit your child’s typical needs at different times of the day. To illustrate (but not to be interpreted as appropriate for anyone but him), here is an outline of my 5-year-old son’s current basal rates:

Time U/h
00:00 0.175
01:00 0.175
02:00 0.200
06:00 0.225
07:00 0.175
09:00 0.150
15:00 0.100
19:00 0.200
20:00 0.325
22:00 0.275

This chart, as well as the image below, shows that a basal rate program is typically divided into several time periods throughout the day, with basal rates changing across those time periods; as a whole, the rates usually do not jump around erratically, but follow a curve (darker blue line, below). Usually the graph of basal rates has 1 or 2 peaks, plus 1 or 2 corresponding valleys within that curve.

basal rate graph (example)

To assess how well your current basal rates are working for you, they can be approximated based on log sheet data, or can be empirically tested as needed. If you find that blood glucose rises each day at 4pm, for example, your child may need more insulin at that time of day. Conversely, if you find that your child's BG drops most nights at 2am, then the basal rate at that time may be too strong; bumping that rate down may help avoid these predictable overnight lows.

For guidance on assessing and adjusting basal rates, we suggest that you talk to your child’s diabetes health care team, plus check out Waltzing the Dragon’s articles on Managing Blood Glucose.

More on assessing and adjusting basal rate settings:

Testing and Tweaking Insulin Pump Basal Rates

The above information was reviewed for content accuracy by clinical staff of the Alberta Children’s Hospital Diabetes Clinic.