Thank you!
The problems are as follows:
1. When i bolus I know it takes 30mims-1hr for the insulin to start working. The algorithm thinks it works immediately so stops the basal. That means I go high later.
2. There is often insulin on board and it tries to predict when I'm going low and stops basal. Basal tends to have an effect 2 hrs later so that does nothing except i have a hypo to deal with and an extra high later or when the sensor is off just a high 2 hrs later
3. When I've been high it increases the basal and when it doesn't respond as fast as it predicts it increases the basal so I go low later.
4. The activity session is useless as it just cuts the basal when I get to 8.3. I exercise reasonably and at different rates eg cardio vs pilates are different temp basals but this does nothing because of the speed the insulin works.
5. It particularly seems to struggle with meal bonuses. Neutral stays in the system for about 6 hours but doesn't work at a flat rate. It often has a tail hit about the 5hr point. I then get a low whereas before I adjusted basal to manage some of this
I've spent a long time figuring out my basal and how it changes over the day. The algorithm has given me days when I can't seem to get it to a normal level and am eating continually to get levels up and others which are the opposite.
Hi Tigger,
I have quite a lot of experience with insulin pumps and supposed ‘closed loop’ systems. Before the more modern ‘hybrid’ systems (see below) became available I’ve previously hacked one of my old pumps and CGM and used Xdrip, etc, to generate auto-bolusing, etc, but now utilise a Tandem X2 with control IQ, Dexcom G7 CGMs and Novorpaid insulin.
The first thing I’d like to do is respectfully correct something that perhaps you already know so apologies in advance if you do… you are not using a ‘closed loop system’. A ‘closed loop system’ is a fully automated insulin pump that reacts and self corrects your blood sugar with no (or very limited) input from the user. You are using a ‘hybrid’ closed-loop, which is marketing jargon for a relatively limited and dumb algorithm that reacts in very specific circumstances, often based on limited averages (e.g. most pumps cannot set time-in-range (TIR) or insulin durations, and give only max 60% of required dose bolusing, etc) to help you avoid hypos and control hypers. Sorry if you already knew this, but I think it’s important to start with this understanding as it moderates what can be expected with your pump… expectation management of what these hybrid pumps can do and achieve, I’ve learned through experience, is very important. These pumps are blood sugar ‘assistants’ at best not in any way 'closed loop'…
Anyhow, as you’re discovering, like I did, ‘hybrid’ pumps aren’t closed loop systems and have considerable limitations which I believe are likely causing some of the issues you mention above.
First, as mentioned in other comments, the Omnipod is not designed to be used with porcine insulin due to potential flow issues (crystallisation), and most importantly, the time it takes to impact BGL, meaning the pump algorithm, though adaptive to a limited degree within limited parameters, struggles to adjust your levels. Others go into more detail so I won’t. However, I think this could explain your points 1, 2, 3 and 5.
Regarding your point 4, it is my experience that the ‘Activity’ or ‘Sport’ modes in most of the ‘hybrid’ pumps have considerable problems. They just don’t work… they take up to 1.5 hours to bring the pump user to the unchangeable level of about 8.3 – 8.6 (why this number?) and then they under/over react… for a tightly controlled Type 1 this results in often crashing blood sugars. Also, not all activity can be planned 1.5 hours ahead… are you going to get up at 0500am to change your pump to Activity mode for a 0630am run? Google ‘Activity mode problem with Omnipod or Tandem X2 pump’ and you’ll find a rash of pump users experiencing similar issues to yours. I know I have.
Of course, this all depends on the type of activity, your fitness levels, your general blood sugar control, etc. However, add in your delayed porcine insulin impact and I suspect the Omnipod activity mode probably won’t work for you. I regularly climb mountains as a Mountain Leader and I’ve stopped using the Tandem X2 CIQ Activity mode. I just change to a carefully created, through observation and practice, sport profile of 0.1u basal per hour and CIQ turned off (so no auto-bolusing or pump auto-basal adjustments). 'Activity' mode drove me nuts causing unexpected hypos and awful long hypers. I think you need to observe and learn how your body reacts with your new hybrid pump and insulin and with medical advice consider creating a sport/activity profile... what did you do with your dumb pump?
Finally, as others mention, I think the solution is using an approved for your pump faster acting insulin. I know I’d prefer to use porcine insulin with its useful junk cells rather than the purer analogs… anecdotally I feel you can physically see the difference between porcine users (pink, healthier looking) and human analog genetically modified yeast produced insulin users (greyer, pale)… no hate mail please guys its just an opinion
… but I’m not sure the current pump technology is there yet, i.e. adaptable enough to the longer impact and varying duration times. I’m sure someone has been successful with porcine insulin in hybrid closed loop systems, but again it’ll all depend on their health, effort and many other different factors. Once a fully, adaptable real closed loop system comes into play I think I will more than happily move to porcine insulin if I can.
I hope this helped. Obviously, I’m not a medical doctor so all advice given above is under the caveat of ‘at your own risk’ and ABSOLUTELY checking with your diabetes team! All respect to my team but I find they don’t know as much as me as they can’t keep up with the regularly changing and sometimes hidden complexities of this new tech. I am still discovering issues and problems with my Tandem X2… still it’s a great improvement on earlier pumps but it comes with complexities due to the nascent technology that have made it far more work than expected and marketed. Best wishes and good luck!!!
P.S. One final thought which I think might help… there is an American podcast called ‘Juicebox episode #662 Control IQ Ninja’ an engineer Dad who has a son on a hybrid closed loop is interviewed. He discusses his journey learning the pros and cons of these systems. Summarising he says that the two most important lessons when using these pumps is to understand they are not 'AI' or 'smart', but actually very useful but limited blood sugar assistants, often highly constrained, and completely unaware of anything other than the data from your CGM. They don’t know you’re stressed, sick, going for a run, etc, so the system makes mistakes... imagine a monkey in a box who can't see outside the box. Consequently, it is also highly important to make sure the data going into the pump is as accurate as possible so it’s important to be aware of how your CGM works, i.e., the common inaccuracy during the first 24 hours and in the last. He coins the phrase ‘Garbage in, means Garbage out’… in other words Garbage (data = CGM, inaccurate carb counting, junk food) in, means Garbage (blood glucose results) out’. So regularly check blood sugars with finger pricking and calibrating the CGM so it is accurate as possible is very important. The best results from these hybrid pumps comes therefore after a period of effort, learning and observing how you and they interact with as exact data as possible, understanding the pump limitations, values you can’t change (TIR, duration, etc), and how you individually react (low carb, right insulin, profile adjustment). They don’t magically give users 95-100% TIR unless they are very lucky or have very stable BGLs anyway. It is worth the effort though!
Link to the episode:
https://www.juiceboxpodcast.com/episodes/jbp662
