Can someone summarize current pump/Dexcom advice?

I mentioned elsewhere that my family has used their deductible for the year for the first time ever. I have an appointment with an endo in a month (my last endo retired and I’ve been going without for the last few years). My previous endo was my primary care also, and really wasn’t involved in my diabetes management, other than writing prescriptions. (He never looked at my meter results for example). A nice guy, but whatever I learned about diabetes I learned on my own or from books (and more recently from the internet, thank you!)

This time I’ll be going to Joslin, with a newly minted endo, so I suspect he will have much more advice for management, and will probably promote a CGM and or pump. I’ve had T1 for 43 years and have considered a pump/CGM many times in the past, but decided to wait until there was a decent Open-loop APS before pulling the trigger. I like the freedom and simplicity of injections and BG tests without requiring attached technology. But it sounds like the Tandem/Dexcom or OpenAPS/Dexcom solutions may be worth pulling the trigger for. From what I’ve read the Dexcom and Tandem are a good match with current technology. In the future I may decide to go with OpenAPS using an old Minimed pump. I will be paying 10% of whatever I get this year, so doing it now makes sense if it can be done.

I apologize in advance for asking here what I could probably find by reading a bunch of posts. But because the tech is always changing, and new versions coming out, I hope its OK if I ask here for the latest summary.

First question - would the cannula, etc. from a Tandem be usable with an old Minimed pump?

Second - has anyone compared the Tandem/Dexcom to OpenAPS and have any advice? I write software for a living and got OpenAPS running on a Pi as an experiment a couple years ago, and think it is even easier now, so I am not intimidated by the technology.

Third - I think I read that the Tandem/Dexcom combination requires the G6? I’ve seen some complaints about the G6 - is there any reason to consider getting a G5 instead?

Fourth - is either the Tandem/Dexcom or OpenAPS usable without being constantly connected to Xdrip or whatever? I don’t like the idea of being wifi connected all the time.

Fifth - is it even realistic to think I could get all this in place before the end of the year? I would plan to contact the pump and CGM companies to start the ball rolling so the paperwork would be ready when I see the endo, assuming that is feasible.

Anything I’ve completely missed?


@Thomas probably has the latest on this one. Tandem made recent (about 1 year?) changes. I think they might have gone to proprietary tech only?

As of today, Tandem is only implementing predictive suspend, which, to me, is already a pretty big deal. On the other hand, both OpenAPS and Loop have both ends of the business (hypo/hyperglycemia) covered. However, Tandem is announcing an aggressive deployment schedule for their closed loop plans: I think @bkh published their last quarterly briefing with an updated schedule. They have held their development and deployment timelines lately, so there is a fair chance they will hold to schedule—although their deployment schedule is FDA dependent…

Their latest solution does. I figure that G6 supply issues will be ironed out in a couple of months.

Neither of them requires to be wifi connected for BG control. But, to be able to access and manipulate the data, that is another thing.

It probably depends upon your endo clinic, your pump/CGHM reps, and your insurance. I think it is quite aggressive, but not impossible if you are lucky in all 4 dimensions. But if you hit a glitch anywhere you won’t make it.

One thing you might need to look into: your endo clinic may require that you take pump and CGM classes before signing off on your prescription. These classes can take quite a while to schedule. For us, they took a whole summer.


The current infusion sets from Tandem have a proprietary connector at the end of the tube.

But if you happen to have a supply of minimed/paradigm tubes that mate with the tandem infusion set, you could throw away the tandem tube and use your own minimed tube. The tube can be reused multiple times, but the infusion set must be moved every 3rd day or so to minimize the risk of developing “scar tissue” that will impair future absorption of insulin. (Actually, the 3-day interval is just one that is “generally safe”. I’ve read that some folks start to have set failures within the first 24 hours, whereas others can go 7 days on a site without issues, but if you ruin your interstitial tissue by not changing the site frequently enough, there’s no way back to healthy sub-q tissue.)

My general impression from reading the internet (so it must be true) is that overall the G6 is well received and considered an improvement over the G5. Highlights are better first day accuracy and easier insertion. There have been some adhesion issues with the G6; at the recent Dexcom quarterly conference they stated that they are testing a better adhesive and expect to be shipping the improved version relatively soon. I think the G6 sensor may be a bit more difficult to restart, but it can be done if you think it will last more than 10 days for you.

Tandem/Dexcom does not require an internet connection to work. It is local bluetooth radio between pump and transmitter. The same is true of LOOP on an iPhone with a dexcom sensor and compatible medtronic pump. Likely this is also true for openAPS.

It’s plausible. The companies are motivated to complete sales during this year. I suggest you call Tandem and say you want the t:slim X2 / G6 with Basal-IQ but only if they can complete it under this year’s insurance. Explain the date that you will first see the new endo — but first you may wish to consider whether you have an internist/GP/family doctor who would write a prescription and statement of medical necessity now, so that you don’t have to wait for the new endo. If you show up to the new endo already wearing a pump and CGM they won’t turn you away.


Thank you both, very helpful information.

My current doctor (not an endo) won’t even write me a prescription for a different basal insulin (I wanted to try Tresiba) and wants to defer a pump to an Endo as well. I think he thinks I’m doing well enough with what I’m doing and he doesn’t know enough about diabetes to want to be responsible for any changes.

I had a kind of bizarre call with Dexcom yesterday. I called to see if I could talk to a sales rep about starting the ball roll before my endo appt (on Dec 7). And was told no, that I had to instead fill out a form on their website and wait for a call from a sales rep. I did that, but so far no call back. I guess that must mean that they are very busy fielding new business? Really strange to me that they didn’t just patch me through to someone.

I think I decided that I won’t push on getting a pump this year. I bought an OpenAPS-compatible Minimed pump (722) a couple years ago when I first read about OpenAPS. So if I am happy with the CGM and want to try a pump with it I can buy supplies on ebay for it. I was disappointed to hear that the Tandem is still not a full solution, so I think it makes sense for me to wait until it is, especially given the time frame.

Jag, I am sorry I didn’t see your post earlier. You may want to at least give some consideration to the Tandem/G6 combo. It works really really well for us. Plus when they complete their next clinical trial they will make their upgrade available to include their full loop functionality.

Yes, the system uses a proprietary connector, the official reason is that it is better designed, but to me at least it is clear that they were losing money not getting all of the site business and so they changed so you have to use their connector and they have a better chance of staying in business.

The loop/Open APS system will undoubtedly have more control available than the Tandem system, but the Basal-IQ works better than I had ever hoped. This allows us to get really aggressive with my son’s insulin therapy and the system helps ensure the landing is smooth.

We aren’t having any issues with the G6, but it is clear that the company is under stress with growth?? because a few years ago the Rep almost jumped over backwards for us. If you have any other questions let them fly.

On the timing issue, this came up for us when we had to switch insurances suddenly due to a job loss. Our endo group got us all of the technology within 2 weeks of request.


In the last quarterly conference call, they attributed about a quarter of their business revenue to the sales of infusion sets. Tandem Diabetes Care, Inc. (TNDM) CEO Kim Blickenstaff on Q3 2018 Results - Earnings Call Transcript | Seeking Alpha

Pump sales continue to be the most significant driver of our growth at 67% of total sale, followed by infusion sets at 23%, and cartridges at 10%. This brings us on a year-to-date basis to $108 million in sales, an incredible 60% growth year-over-year considering that the prior year also included a $5 million benefit from the Technology Upgrade Program in place at that time.

I have no doubt that they introduced a proprietary connector to capture those revenues that mostly were going to other companies before.


Way better than expected.


My daughter was diagnosed with T1D one month ago. We got her on a CGM within 10 days. My insurance covers CGM as a pharmacy benefit. And the pediatric diabetes clinic at University of Michigan Mott’s Children’s Hospital was fantastic and faxed in a prescription for Dexcom G6 with no hesitation.

I got the Dexcom G6 from Costco Pharmacy. So easy! So much better than durable medical equipment company. My insurance required a pre-authorization, which the clinic called in instantly also and it was approved in less than a day.

Going through Dexcom itself would have taken far longer than going through Costco Pharmacy. I called Dexcom to get the free overpatches, and it took 5 days for the sales rep to call me back to setup an account.

Another word of advice: your insurance may cover a CGM as pharmacy benefits and their agents might not even know it. I talked to one (at United Health Care) that said yes, and another arrogant agent that said no. The easiest way to know for sure is to have Costco attempt to run the prescription through your insurance and see what the outcome is. The computer system will tell them instantly.


100% Agree.

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Keep in mind that unfortunately, the Costco rebate expired, so no more cheap Dexcom parts. I too have Express Scripts and yes, most don’t even know that they are covered. Doc has to send over a script to their mail order or have Costco try to run it would work. They also cover my Omnipod and insulin.

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