A Review of Tandem's t:slim (Continued)
The third biggest difference between the t:slim and other pumps is setting up the pump's insulin profiles and bolus calculator settings. Traditionally, a pumper sets up basal rates by time of day in one menu, an insulin to carb ratio by time of day in another menu, a correction factor by time of day in a third menu, and a target blood glucose or range by time of day in a fourth menu. The separate menus do not interact, meaning that a change in one parameter (e.g., the time a basal rate changes) is not reflected in the other menus. On past pumps, at least for me, this process has sometimes resulted in a disjointed insulin profile, with parameters that do not match up. Tandem has improved and streamlined this process, which is good news in our view because we worry a lot about optimizing glycemic management. In a recent dQ&A survey, fewer than 60% of patients and 50% of educators thought that their insulin pumps were configured optimally — very disappointing from a patient perspective!
In the t:slim's personal profile menu, all four parameters — basal rate, correction factor, insulin to carb ratio, and target glucose — are set for a particular time of day. These appear in a single menu and are saved together. The entire day's worth of settings is then saved within a particular profile, which you give a custom name and can easily and quickly duplicate. I have one profile called "Home" that is based on my level of activity at home and my normal diet and wake up time. But I also have a "Travel" profile with different settings, as well as a "Sleeping in" profile for going to bed later and waking up later. It's very easy to toggle between these profiles, and it's all located in one centralized menu. You can have up to six different personal profiles and up to 16 time segments within each.
A New Delivery Mechanism
Instead of a conventional piston driven delivery, where a mechanical screw drives a syringe built into a reservoir (the way a Medtronic, Animas, Roche, or Insulet pump works), the t:slim uses a micro-delivery technology. This means that very small amounts of insulin are shuttled from the reservoir to the infusion set, and the full insulin supply is never directly exposed to the user's body (as it is with other pumps). Notably, the pump can deliver in increments of as little as 0.001 units, compared to 0.025 for the Animas OneTouch Ping and Medtronic Paradigm and 0.05 units per hour for the Insulet OmniPod. While I cannot say that I noticed a difference from these novel accuracy and safety features in my blood glucose numbers over the last week, I can say it was comforting to know that the pump has these innovations. Perhaps Tandem will eventually conduct studies to examine whether these are indeed beneficial for glycemic control, fewer pump-related accidents, etc.
Changing an Infusion Set and Cartridge
The one area where the t:slim was different from other pumps — but in a way that created more hassle — was when it came time to change a reservoir and pump set (the t:slim works with any luer lock infusion set). The process took me an average of around nine minutes with the t:slim, more than double the average of four minutes it took me on the Medtronic Paradigm and Animas OneTouch Ping. The process is slow for a few reasons: 1) the pump takes a bit of time to automatically clear air out of the new cartridge (I appreciated this, since air bubbles can cause some unexplained and frustrating highs); 2) because of the micro-delivery technology, it takes the pump a couple minutes to prime and fill the tubing with insulin; and 3) you are guided via step-by-step on-screen pictures and prompts, which take extra time to clear relative to the Animas and Medtronic pumps. As we understand it, the cartridge change process is a leading cause of calls into manufacturers' support lines and one of the reasons Tandem included this extra guidance. In the future, I think Tandem could improve the process by prefilling the cartridges with insulin (similar to the Asante Pearl) or perhaps speeding the priming process by allowing users to turn off the pictures once they have the process down. On the plus side, the cartridge does hold 300 units of insulin, a notable feat considering the t:slim is about 25% slimmer than the Animas OneTouch Ping and Medtronic Paradigm insulin pumps. As a reminder, only the Medtronic Paradigm 723 holds 300 units.
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Saturday was the JDRF Type One Nation Texas conference in Austin, Texas. Ross and I made the drive there to participate and soak up any new information possible. We sat through five sessions covering everything from the artificial pancreas to pregnancy with type 1 diabetes. It was interesting, but unfortunately, nothing astounding as most of the topics had no significant updates from the last time I participated in 2012. The first two sessions were from Dr. Insel with JDRF with...