Tandem T2 vs Medtronic 780G? Which one to choose?

Hello all.

I’m in the market for a new pump. Planning to upgrade from my rustic Medtronic 723 in conjunction with the Libre 2 sensor. I like the reliability of the Libre but I’d like something more automated.

My A1c is usually in the mid 8s/ TIR barely hitting 50%. Using lyumjev I was able to bump up my TIR to the high 50s. My main issues are sustained uncorrected highs (happens to me during sleep or work when I can’t or won’t bolus for it).

My concerns between the two are:

  1. not a fan of the Medtronic sensors although I’ve tried the predecessors to the G4. I imagine Dexcom has a better user experience overall but is it worth going for tandem for this alone?
  2. not a big fan of the charging but I’ll do it if I have to
  3. no customization to duration of insulin action on the Tandem. With lyumjev’s action not sure if it’ll be a good fit for the tandem.
  4. it seems the algorithm on the 780g is more aggressive and is therefor able to get you in a tighter range than tandem based on anecdotal stories. Anyone find this to be true?

I heard Gary Scheiner say that the population that is using Medtronic currently is mostly people who’ve been on the pump for many years and continue to do so out of comfort with the brand. I don’t want to stick around for that sole reason. Any insight into the matter appreciated.

I switched to Tandem X2 from Medtronic 523/723 in 2020, so current X2 soon out of warranty.

My endo provided lots of details on success other patients had with Tandem X2, so that’s what I went with, no regrets. Some are bothered by the cartridge filling, but easy once you do it a few times. And some really like tubeless Omnipod.

I use the Tandem X2 Sleep mode 24x7, since pump targets 112 BG, and works well for me.

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I went to Tandem x2 after Animas went out of business. I am now 6 months into my second Tandem (5-1/2 years). I, too, am running Sleep Mode 24/7. Tandem is awesome keeping me steady during the night. It will automatically keep you in the 6s even in regular mode. I am usually in range 80% and below 2% low. In my old age I decided to indulge occasionally in both fruit (which I love) as well as some past no-nos such as a slice of pie or a bagel. Of course, I have to dose appropriately when I do. I can’t comment on Medtronic products since I have never used them.


I was a Medtronic user for many years, but changed to Tandem in 2021 mainly due to the Dexcom connection. While Dexcom has a far superior sensor, Medtronic definitely has the better pump. Once the Medtronic Simplera is released I plan to go back. Tandem has a lot of draw backs:

  1. Built in battery is just not convenient and draws down faster with age, so requires more charging. It is much easier to replace the AAA battery in Medtronic.
  2. Filling the canula is a much longer process and more difficult than Medtronic.
  3. Insulin waste is significant. Since you cannot see the canula you must rely on the pump for information. I immediately noticed numbers not matching what I put in, so started manually emptying the cartridges when it said I was out. There was always at least 20 units of insulin so I started filling an empty bottle. In a little over three months that bottle is about 80% filled. That means users waste at least 3 bottles of insulin annually due to Tandems lack of concern.

Here are some photos I took of the insulin waste:

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I have used Medtronic Minimed pumps and CGMs exclusively for 17 years. About a year ago I upgraded to the 780G and am about to start using Guardian 4 sensors after having been on Guardian 3. I like that the Minimed pumps combine, in one device, the display and memory with the insulin-dosing system. I don’t have a smartphone at present, so can’t consider a pump that depends on one for readout and dosing.

I have used Apidra for all 17 years. As long as I continue using it, I cannot use Tandem pumps because Apidra is incompatible with the Tandem’s bladder, according to what I have seen on the Internet.

About Oct. 3, 2021, I reported on this forum https://forum.tudiabetes.org/t/dexcom-g6-cgm-trial/88437 my comparison of two samples of Dexcom G6 sensors with Minimed Guardian 3. Contrary to what many people assume, I found that one of the two Dexcom sensors was seriously inaccurate. At the beginning it read too high by about 65 mg/dL, but the Guardian 3 reading was close to my measured BG. Later, when I was feeling somewhat hypoglycemic (BG 69), the Guardian 3 sounded an alarm, but the Dexcom G6 read 82 and gave no alarm.

The second Dexcom sensor behaved better, but it was still less accurate than the Guardian 3.


I am a tandem user with Dexcom. I think the Guardian 4 is likely equal to or better than the G7 Dexcom. A great endorsement comes form Diabetic Dannica

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I’m a very happy Tandem user. I use the Tandem X2 with BIQ (which suspends basal when I am trending low). With the BIQ version, I can change the insulin duration - I gather with CIQ you can’t. I also like the temp basal function where I can for a few hours increase/decrease the basal delivery when Needed. With BIQ I can set my own bg target (mine is 80) CIQ has the target set at 110 bg. One of the benefits of Tandem is that the Dexcom info shows up on the home screen of the pump - no need to carry a separate PDA (and after so many years working where I was on call - I prefer to leave my smart phone at home as well!). Charging is easy - you can charge while using your computer, in your car if it has a USB port. And I don’t have to try to find a place to property dispose of a bagful of dead batteries.

I am hoping that when my warranty is up - I can still get a pump with BIQ. I don’t allow myself to get above 140-150 (although I do have T1D so there are rogue numbers). CIQ does an auto-infusion when the bg reaches 160 and is trending upwards. That’s of no value to me. And CIQ doesn’t have the temp basal function. I especially make use of it when my bg is high (for me) and trending upwards. I can correct and then do a 2 hour temp increase of basal since we all know the higher the bg - that changes the ISF for corrections.

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I also have a Tandem X2 with BIQ. The warranty on my pump has expired. Tandem talks about “renewing the warranty on your pump”. That does not mean what you think it does—it means purchasing a new pump. I talked with Tandem about a new pump. They no longer offer/support BIQ; so few people used it, that they have discontinued it. The new pump comes with CIQ. I like the rechargeable feature—just plug it in while I shower or while at my computer and the pump battery is quickly recharged. The new pump is compatible with both G6 and G7.

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What do you think of the higher (unchangeable) target and loss of temp basal? The higher target and loss of temp basal are enough that I will

if I have to get a new pump) use it the old-fashioned way. My Dexcom data will still show up on the pump (so I don’t have to have a receiver device nor my phone with me 24/7). So have you noticed a difference in your mgt with the higher target etc?

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I am not a fan of CIQ—I have a long-standing, horrible fear of hypos (I’ve had T1D for 66+ years). If and when I get a new pump, I’ll probably use it in manual mode. I am loath to give up my current pump because of BIQ, but now because my pump is out of warranty, my endo can’t see my uploads to T-Connect, I am comfortable using a work-around to accomplish this, so for now, it’s okay. I carry my phone 24//—my spouse and I use the DexCom Share App, so I have to have my phone with me all the time. I was hoping Tandem would allow the pump user to set their own BG maximum and minimum in CIQ–that is currently a false hope.

I don’t like that there’s no temp basal function in CIQ. I like that function! Probably the closest thing to temp basal is the sleep or exercise modes in CIQ. I see posts where people. say they use those 24/7.

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40+ years with T1D here. I like having my target at 80 - I only eat when at target. My low alerts are70 (and of course lower). If you’re fearful of hypos, I think you can set the alarms where ever you want. I also set my high alarm at 120 so I can nip it in the bud. If I have 0 IOB, and probably some FOB (food on board) I will correct, otherwise no - but I will keep an eye on things. My aversion to using the phone is while I was working I was on call - often24/7. We had smart phones before they were consumer goods. I’m quite “over it” when it comes to those phones. I have one, and I use it - but not 24/7 - too short a leash for me.

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You can have different personal profiles with higher or lower basals. The drawback is you have to remember (or set a reminder) to go back to your regular profile.
For a higher temp basal, you can give yourself an extended bolus which amounts to the same thing. The longest period is 2 hours, I think.


I’m team Tandem all the way. They’ve got the most exciting product pipeline in all of diabetes. They are constantly listening/polling their customer base and rolling out requested updates. We’re even expecting a big update to Control-IQ this year that promises more customization options. (Tandem’s social media team has said to expect version 2.0 later this year in response to comments on their new Mobi ads.) They’re willing to partner with other companies to bring the best tech and options forward. But must importantly, it’s the only one that allows me to customize how the algorithm works. The systems that throw out your own basal settings are very slow to adjust to changes in your insulin needs. There isn’t one yet that can handle rapid changes like hormonal fluctuations, sick days, travel, injuries, medication changes (like the crazy highs that follow cortisone injections), etc…

Both systems are awesome in their own right, but I think they’re better suited for different people. Tandem offers more choice, flexibility, and control, but at the expense of more personal responsibility. You control how well it does or does not work for you based on the settings you program. It does exactly what you tell it to do. So either you or your medical team need to understand what the different settings do and how to adjust them. That’s both it’s greatest advantage and weakness all in one. It just depends on what side of the line you fall on here.

This is a really great interview with Gary Scheiner of Integrated Diabetes Services and the acclaimed “Think Like A Pancreas” book. It compares the current pump offerings. It’s a really good watch!:

If you want to stay with Libre, Tandem is the only pump manufacturer that allows this with Libre 2+ integration (the 2+ is more accurate than the 2, isn’t affected by vitamin C or acetaminophen, and doesn’t require scanning when used with the pump), and Libre 3+ integration is coming real soon. There’s mixed reviews about Dexcom’s G7. There’s some growing pains during this transition period. Some people just love it, while some people think it’s not as good as the G6. Medtronic is always lagging at least 1 generation behind Dexcom and Abott with their sensors, though.

The charging itself really isn’t a big deal. You don’t have to disconnect, so you can charge basically anytime you’re sitting still. If you do disconnect to shower or whatever, you can charge it then. I really only charge it once a week. Used to be once every 10 days, but my T:slim is more than 7 years old. How long the charge lasts depends on how many alerts/vibrations you get, though, and whether or not it’s talking to your phone. That said, charging it is my biggest complaint about the pump. I hate that it’s got a micro-usb plug. That’s the one that unevenly shaped, so it has to be aligned just right. My port also sticks up just a little bit, making it even harder to get it to fit. It just shouldn’t be that big of a PITA to plug in. But if that’s my biggest complaint about the pump, I think we’re doing alright.

This isn’t as big of a deal as you think it is, either. Control-IQ uses a different insulin decay model than Medtronic. All of our rapid acting insulins actually last for roughly 5-6.5 hours in the body. But they work harder and more noticably in the first few hours. After that, they start tapering off with a long tail of minimal activity. Medtronic uses a curvilinear model that really only focuses on that first section of peak activity, and it forces you to choose how much of that remaining insulin you feel comfortable ignoring. In fact all commercial pumps use that curvilinear model, even Tandem when you turn Control-IQ off. (possibly excluding iLet, because we know nothing about what it does under the hood.) Control-IQ on the other hand uses a brand new decay model that counts ALL the insulin, including that minimal action at the end. When the pump is potentially giving extra insulin every five minutes, those ignored insulin trails start stacking up, so that 5-hour DIA increases accuracy, and prevents stacking/over-dosing. The 5-hour setting on Control-IQ lines up really well with approximately a 3.5 hour setting on a curvilinear pump.

Basically, Medtronic thinks that only the big hill of the rollercoaster is important, while Control-IQ keeps it’s eyes on you all the way to the end of the ride.

Also, Lyumjev has a very similar duration as Humalog/Novolog. It peaks a little sooner, but it plays out the same in the later hours. Lyumjev has already been through Clinical Trials with Control-IQ, but not added to the official list of supported insulins yet. I believe official support for Lyumjev is coming when they roll out the Control-IQ 2.0 update.

Have no idea where you’d get that idea from. There’s some vocabulary differences between the pumps, but both potentially give small corrective doses every 5 minutes. Tandem does it whenever you’re predicted to stray outside your selected target range (112-120 in sleep mode, 112-160 in the default mode, or 140-160). Tandem counts that insulin as basal adjustments, and doesn’t call then corrections. Proponents like to say that Tandem only corrects once every 60 minutes, and that’s really not true. It’s the same thing, just different vocabulary. Tandem also gives bigger boosts of insulin every 60 minutes, which it DOES call correction.

I’m surprised by the number of Basal-IQ comments in this thread. For the record, Basal-IQ was discontinued last December. You can’t buy a pump with that algorithm anymore, so it’s not really relevant to the conversation. (Though I can sympathize with not liking forced change!) I’ve used both and consider Control-IQ superior. Basal-IQ had one job, stop insulin delivery when you’re low, and in my experience Control-IQ does it better. Control-IQ can predict lows 30 minutes in the future and reduce insulin, often avoiding the low altogether. Whereas Basal-IQ only does a hard stop when you’re already down in the hole. You really don’t lose the temp basal feature with Control-IQ either, you just set it in a different way. You can preset basal profiles to mimic temporary basal rates. Instead of setting a temp rate of 50% if you’re going to be active, you just switch basal profiles and run the one that’s programmed to be 50%. The pump even makes setting this up easy, with a button to clone an existing profile. Then you just have to edit the basal rate to whatever you want. I have 5 profiles I switch between regularly. 0 u/hr, if I want to suspend background delivery but still get help if I go high, 50% (I call it Low IQ) for high activity, 100% (Avg IQ) is my standard profile, 150% (High IQ) for insulin resistance flare ups, sick days, PMS, and all that fun stuff, and 200% (I call this one MENSA, but I mostly only get that “smart” after cortisone injections). The various activity modes are also similar to setting a temp basal. You’re just moving the target the pump adjusts to instead of dictating a specific amount of insulin. Since Control-IQ works by adjusting basal, it doesn’t make sense to set a specific rate. That would override and cancel the algorithm. The DIY systems Control-IQ is modeled after do this, too.

That might be a lot to take in, but I think it really illustrates the difference between the 780G and T:slim. Remember, our insulin is slow, even Lyumjev. Basal changes are most effective 2 hours before the problem. It’s the difference between chasing a high and preventing it in the first place because you knew in advance your insulin needs were changing. If you do nothing, both systems will chase that high in a similar fashion. With Tandem, though, you can put in some extra effort and get a bigger payout.


I asked a similar question on this forum about a year ago. Lots of research and helpful information from forum. Have Dexcom G7 CGM (previously G6, G5) , which was way more reliable for me than Medtronics CGM. But i had Medtronics pump, which went out of warranty, and couldn’t read Dexcom. I wanted to try a closed loop system.

I was quite interested in Omnipod but insurance didn’t offer much coverage. Much better coverage with Tandem. T-slim x2 has a bit of learning curve, but so far so good. Also using the closed loop system/control - iq technology because i finally have a pump that “talks” to cgm. Too soon to comment on how my A1c will be, or time in range. Without tandem last A1c was 6.2 and i’m fine with that. But if i get better, i’m not gonna complain! :wink:

I have read about concerns with wasted insulin. With more research i found there are some hacks to get around that. Not ideal, but i want to try a closed loop system and for some reason Medtronics cgm was never accurate for me, so i didn’t think i’d trust it’s system. For some folks, i’m sure it is great.

I thought this was excellent review of Omnipod vs T-Slim. Even if you are not interested in Omnipod, this fellow gives a good overview of Tandem:

Best of luck!

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Hello everyone. Thank you all for giving me such detailed reviews and I appreciate the feedback. I’ve decided to go with the tandem after all. I hope it works out for the best.


I don’t think you could go wrong with either one. I switched from Medtronic + sensor to Tandem + Dexcom when I went from private ins. to Medicare as Medtronic sensor (at that time) was not covered under Part B (DME) while Dexcom was (and is). I compared the pumps and sensors that were in the market, and decided on the t:slim X2+IQ control. My A1C has gone down from 7’s to 5.6 +/-, so very happy with my decision. Yes, filling the Tandem cartridge is a learning process but once learned, becomes 2nd nature.


TANDEM>>> I had the 780G for a few years and there’s no comparison!

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If you were on a Dexcom G6. I would tell you to check out the NEW Tandem Mobi pump. It is the smallest pump on the market.

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