Why does my pump display shows less insulin than the amount I put in the cartridge?
The pump estimates how much insulin is in the cartridge after you complete the cartridge load sequence. This “fill estimate" is shown on the top right of the pump screen and is less than the amount you filled the cartridge with. The pump will either display +60, +120, +180, or +240, depending on how much insulin you fill it with. After 10 units of insulin are delivered, the “+” in front of the number will go away.
If the initial fill estimate is lower than the actual cartridge insulin level, the displayed value will stay the same until the cartridge insulin level is below the fill estimate.
Each time the pump delivers insulin (such as giving a bolus), the pump updates the insulin level in the cartridge, 5 units at a time, until insulin level is estimated to be below 40 units. When fewer than 40 units remain, the insulin fill level will decrease by 1 unit at a time.
Why isn't the insulin level on my pump showing a full cartridge, even though I filled it with the maximum amount (300 units)?
The fill estimate, or insulin level shown on the pump, includes only the amount ready for delivery. When you filled the cartridge, you also filled the tubing (the amount can vary, depending on the tubing length of the infusion set). In addition, there is a small amount of insulin that is not available for delivery. You can think about this like a tube of toothpaste, there is going to be some residual leftover that cannot get squeezed out. When you are determining how much insulin to put in your cartridge, add about 45 additional units to the amount you want ready to deliver.
For example, if you think you will use about 100 units of insulin before your next cartridge fill in 2-3 days, it is a good idea to fill the syringe and cartridge with about 145 units.
Watch the video below to see how your pump displays the amount of insulin that is found in the cartridge.
Check out our support and troubleshooting pages for more helpful information.
Always refer to the User Guide for important safety information and detailed step-by-step instructions on how to load a cartridge on your t:slim X2 pump. Please consult the applicable user guide and refer to the table of contents.