I take X units of basal insulin daily. Tresiba lasts longer than 1 day. Should I take less each day or take it every other day?
NO! You should do neither! Tresiba is a once-daily basal insulin that can be taken at any time of day, but must be taken every single day. For users already on insulin therapy and switching to Tresiba, they should start with the same number of units of Tresiba as their previous total daily basal dose.
Many users, myself included, were concerned about the potential stack effect and ultimately over-dosing of an insulin like Tresiba that lasts longer than 1 day, if taken every day. Fortunately though, this is not an accurate understanding of how a long duration insulin, taken daily, actually works.
In an ultra-long acting insulin like Tresiba, the dose dissipates over the entire approximately 42-hour duration. Conceptually, during the first 24 hour day, only 24/42nds of the dose have been metabolized. And on the 2nd day, the remaining 18/42nds of the dose, plus a new 24/42nds from that day’s new injection will add up to equal the full metabolic dose. Essentially, after a few days to allow the dose to stabilize, the user is injecting X number of units every single day, and X number of units are wearing off each day— they’re just not all entirely the units from the previous day.
The following image can be helpful to understand how the daily layering of an ultra-long acting basal like Tresiba results in a steady coverage with minimal peaks and troughs
This is a very easy topic to overthink. The good news is that the reality is the most simple one possible-- that Tresiba is dosed 1x daily with the patient’s full basal dose each day and its ultra-long action results in a very smooth basal coverage.
- Tresiba package insert
- Haahr, H., & Heise, T. (2014). A Review of the Pharmacological Properties of Insulin Degludec and Their Clinical Relevance. Clinical Pharmacokinetics, 53(9), 787–800. http://doi.org/10.1007/s40262-014-0165-y: https://www.researchgate.net/publication/265254952_A_Review_of_the_Pharmacological_Properties_of_Insulin_Degludec_and_Their_Clinical_Relevance
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