Comparison between Medtronic 770 or 780 and Tandem Slim

I’m eligible for a new pump at the end of this month. Currently, I use the Medtronic MiniMed 630. I also use G6 Dexcom sensors, which attach to my phone. I had basically decided to go with the Tandem, since I love the idea of smart IQ and that it would work with my Dexcom. I tried Medtronic Enlight sensors years ago and hated them. When I could get them on, they never read me accurately. I know the Guardians are supposed to be better, and I’ve been told by Medtronic reps that they’ll have approval for the 780 in Canada within the next couple of months, as well as the Guardian 5 (is it?) sensors, which should be like Dexcom-- no calibrations, etc. If I get the 770 before Dec. 31, I can get a software update to the 780 when it’s available in Canada. I know I won’t like charging the Tandem everyday, or the reservoir, so I’d rather stay with Medtronic if I could. What are people’s experiences/opinions with the 770, 780 and the most up to date Medtronic sensors?

Heres a good summary from Gary Scheiner’s website.

I chose to switch to Tandem last year, after using Medtronic pumps with Dexcom for previous 15 years. Used Medtronic cgm before that, and last pump model was the 523 Paradigm. So no experience with newer Medtronic models.

It took some time to get used to Tandem cartridge filling, and menus, but otherwise like the Tandem pump, and priority was to stay with Dexcom cgms.

i really like the 770g, but i cannot compare it to the 780g.

The link @MM1 shared has some good information, but you also need to take it with a grain of salt. Some of the information is outdated or partial enough to be misleading, such as they overlook the fact that BOTH systems are capable of remote updates now and they champion Medtronic for research whereas every diabetic company in the game is putting out interesting/credible research. And other things are just blatantly false…

It includes the note " *Limited unintended insulin movement with changes in pump position" as a con for the T:slim, when it should actually fall under Medtronic. It’s a problem called “siphoning” that exists with all the traditional syringe-style pump mechanisms, where actual insulin delivery can vary from what you ordered. Basically, if the pump is above your infusion site, insulin flows easily/leaks from reservoir to infusion site, but the pump struggles to push the same amount of insulin uphill if the pump is below the infusion site. Medtronic is the only one still using this mechanism in the US, but there are other manufacturers still designing pumps with this mechanism elsewhere. The very feature that makes Medtronic pumps so quick to fill the tubing is what leaves them susceptible to this siphoning. Both Tandem and Omnipod have delivery mechanisms which prevent this siphoning, by physically separating the insulin supply from the infusion line. In fact, Tandem’s micro-delivery feature was it’s major selling point (besides the small size and modern format) before the pump automation wars began, because of it’s unparalleled safety.

Personally, I’m thoroughly unimpressed by Medtronic’s offerings… But despite that opinion, I do think there’s a place and a need for them. The systems are just so very different that they serve different people.

Tandem is very modern, and they really embrace modern technology interface. They’re targeting the cell-phone generation, which lives and dies with at least one mobile device on them at all times. They mimic the smooth, sleek, bright touchscreen, and rechargeable battery this demographic is very familiar with. They’re awaiting approval any day now for the first mobile bolusing interface direct from the phone, and they’re moving towards full pump control from the phone. Their next gen pump, T:sport, won’t even have a screen but be entirely controlled by the phone.

But that doesn’t appeal to everyone. Conversely, Medtronic has cornered the old-faithful market. It’s great for the people who really like the familiar and comfortable, disposable batteries, mechanical buttons to press, etc…

And then there’s the automation… When you get down to it, both systems yield similar results, clinically speaking. They were both designed to bring the “average” diabetic up to meet the 70% TIR goal. The overwhelming majority of diabetics, 1 and 2 alike, also aren’t able to meet the sub-7 hA1c target either. At the time these systems were designed, Dexcom was reporting that their users averaged 56% TIR. (At the time the 670G w/ Auto Mode and Control-IQ were developed, I mean. There’s little difference between the 670 and the 770/780, clinical outcome speaking and how auto-mode functions. The improvements were to the user interface and to keep auto-mode active more. And Tandem’s next gen Control-IQ updates are still stuck in the regulatory boondocks. ) And both of these systems are able to drastically improve TIR to that point. It’s a little hard to compare apples to apples, though, because only Tandem’s system has different nighttime targets, and thus they reported daytime TIR separately from nighttime TIR. Tandem’s daytime averages are very similar to Medtronic’s all-day averages, but Tandem’s users did better at night with the sleep mode. Both systems showed similar improvements in A1c, too, with a slight advantage to Tandem… Presumably due to the better overnight numbers.

How they get you there are very different, though. Tandem’s system let’s you control more variables. It’s excellent for those who have a good understanding of how to manage pump settings and modify them, or who have a wonderfully supportive medical team to help them with that. I think there’s more options to bend the system to your will, for those of us who demand more from the pump’s automation. But the downside to this, is the system doesn’t work well at all if your settings are incorrect. It only does what you program it to. There’s no machine learning. Medtronic is easier from the medical professional perspective, because there’s so little to adjust. The pump tries to learn you and how to manipulate your insulin to fit you into that acceptable box the professionals dreamt up. For most people, it does that well enough. (Honestly, I could say the same about Control-IQ’s default mode… Perfectly acceptable, but too little, too late to be outstanding.). But what if it doesn’t perform as well as you’d like? There’s little you can do influence the system.

It comes down to whether you want to control the variables or give up control.

And for what it’s worth, the T:slim X2 doesn’t need charged every day. I charge about once a week, and at that point it’s down to 30%. And my pump is nearly five years old. (I’m hopefully holding out for the T:sport, but Covid had screwed up everything.). They recommend you charge it for a few minutes every day so that it’s always fully charged, then you’ve got plenty of battery life to get you through unforeseeable events. But if you’ve got other emergency power backups (battery packs, emergency solar or hand crank chargers, uninterpretable poor supply, generator, car battery, etc …), which everyone should have anyway, then it’s not important. The more you let it vibrate, the faster the battery will drain. If you set audible alerts and/or clear alerts quickly, the battery will last a really long time.

And there is absolutely nothing difficult about filling the cartridge. It’s just different. I’ve never understood the complaints. It’s nearly identical to doing MDI with a syringe and vial, but less painful because you’re injecting the cartridge instead of yourself. The pump screen walks you through the other steps.


I switched to tandem about a year ago. The Medtronic sensors never worked for me.

My a1c dropped a lot from average hi 6s to mid 5s.

The whole thing took some time to get used to. After 2 months it was really no different in filling it etc

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I second the tandem charging: it’s a total non issue for me. I plug the cable in a couple of times a week when at my computer and within half an hour or so it’s in a good place. Does NOT need to be charged every day like a cellphone.

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Thank you for the chart. I have been looking at a lot of comparison charts myself, but I hadn’t seen this one.

I appreciate your detailed analysis. Thank you. I can see why the comparison chart is misleading. You’ve eased some of my concerns about Tandem, especially about recharging. The Ontario government will pay for a new pump every 5 years, if something doesn’t work correctly, or is broken on the old pump. The manufacturers’ warranties are only for four years, so ideally, I’d hope for whatever pump I have to last for 5 years. I was worried about the Tandem battery losing its “charge-ability” after 4 years, or so. It’s good to know your Tandem holds a charge after 5 years. For me, a system that works with Dexcom, is reliable and more customizable are huge factors in my decision-making.

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That’s great. It’s always best when you like your pump. I was on Animas originally until they folded and I did like it better than my Medtronic. Another issue is that I’ve had 5 Medtronic pumps since I had to switch. The first got a cracked back, the second ate batteries and after a few months, completely failed, the third and fourth replacements worked well, but the plastic clips that went over the reservoir broke during use. Medtronic was wonderful about replacing all of the failed pumps, so that was amazing. I wonder if Tandem is as accommodating if things break or fail on their pumps.

Wow, that’s huge! I can’t break 7.2 on my Medtronic and I am always adjusting basal and bolus rates to do better. That makes Tandem more tempting for sure.

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Good to know.

@PYBM I’m approaching 4.5 years on my Tandem pump, I charge it once weekly {usually} and let it do its thing. I no longer micromanage my diabetes and am happy enough with a regular mid 6 A1c.

I think the only thing that would be better for me at least, would be to Loop


I switched to tandem in 2018 and it’s the best pump decision I ever made. The things that held me back (same as you) are not a problem. Things that are better on tandem far outweigh everything. The size, the interface, C-IQ are superior. I ran in the sixes with Metronic, I run in the fives with Tandem.


I just switched from the whole 630G system guardian sensors and all to the tandem T slim with the Dexcom and I love it! If you enjoy the dexcom sensors then I think you’ll really enjoy having it integrated with the tandem pump which is one thing I appreciated about the guardian sensors and Medtronic system. One thing I really have loved is I don’t get alerts and alarms based on calibration and pump settings. I’m getting alarms for what my blood sugar is actually doing which I’m sure you’ve experienced having the Dexcom. The one thing that I do not like about T slim is the cartridge loading process. Hands-down Medtronic has them beat as far as refill/change infusion site goes. But to me that is a small price to pay for much better control. Especially overnight. I’m actually waking up in range. Even adjusting all the settings for all the years with the Medtronic. I just was always waking up high. The Control-IQ does it all! I really love it. Good luck!


Good to know, thank you. I’ve decided to go with the Tandem pump. I can’t give up the Dexcom, since they work so well for me and I do like just about everything about the Tandem.

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