Medtronic 770G vs Tandem/Dexcom

I have had a Medtronic pump for 25 years, but have been counting down the days until my 670G went out of warranty to I could switch to the T-slim/Tandem with Dexcom. Of course, the day I ordered the Tandem, Medtronic called to try to convince me to stay. I have been so frustrated with alarms, poor sensor, calibration errors, etc for so long I didn’t even want to talk to her, but she has got me thinking. Apparently the 770/780 will fix a lot of these problems with a new transmitter, decreased alarms, bluetooth enabled for sharing and software updates, etc. BUT, I fell for this 4 years ago and have regretted it ever since. I am thinking that this upgrade might actually be worth while, but am feeling torn because I know the Dexcom is superior. Can anyone give me reasons that I might NOT like the Tandem/T-Slim that would help convince me to give Medtronic another chance?


Rather than saying why you shouldn’t make the switch, I would rather say that one common frustration for people switching from Medtronic to Tandem is the fill process. I made the switch long ago and it no longer bothers me, but people do complain that it takes longer. I’ve solved that problem by filling several cartridges with insulin so they’re ready to go when I do a site change.
Some people are also concerned about plugging in to charge vs using batteries. I have a charger in my car and carry “charging bricks” so on the event of an exegesis power outage I’m covered. It doesn’t take long.
Tandem has a demo app you can use to get a feel what it will be like.

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that’s helpful. thank you. I have thought that the fill process looked cumbersome, so that’s an interesting work around.

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@annieoverman Hi Annie, and welcome to the JDRF TypeOneNation Forum!!

Hindsight is so beautiful and crystal clear. Like you, I used MiniMed pumps [3] for several years, was happy with them and, at least for the first few years Customer Service was easily available and very proactive. I looked very closely at the 670G, met personally with Medtronic sales and training specialists, and also spent time [at a JDRF meeting] with users and testers of the latest Medtronic gear. I came close to buying the latest Medtronic system.

I ended up getting a Tandem t-Slim x2 after holding it in my hands and “playing with it”. I found the t-Slim met all my requirements and more - especially the internet up-grade feature. [The Medtronic 780G has this feature.]

Now, especially with the Control IQ algorithm I know I made the correct choice. Overall, the t-Slim is easier to use, and the screen much better for my weak eyes, than any other insulin device I ever used.

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Thank you for your thoughts. I am positive, without a doubt that Tandem/Dexcom would be better than the 670G. I’m just wondering with all the upgrades if I will prefer the customer service, reservoir refill, sturdiness, etc of the new Medtronic. I wish I didn’t have to commit for 4 years at a time!

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My first pump was a Minimed (prior to Medtronic) a couple of decades ago. Believe it or not, when I was going to start using one I was allowed to wear it for a week or so, filed with sterile saline, so I could practice changing infusion sets, programming, delivering a bolus etc! And of course since it was my first pump I got to see what it would be like to be “tubed.” Can’t recall whether it was a loaner or the one I would be keeping - I believe the latter - but it was great to “take a test drive” before making that commitment.

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Lol! Me too :slight_smile: I also had a “trial pump” and was the first one in town to have one and always got called out for wearing a “pager” at school. Unfortunately, they still have the same look 25 years later! I also got a week stay in the hospital for training and getting regulated on it. How times have changed.

My endo had 3 patients starting on Minimed together and - another wish and a man. We had to do a hospital stay. I think it 2 nights were expected, depending on how things went. I shared a room with the other woman. I thought I was going to have to stay another night but was able to go home as planned. I stayed friends with her for several years but we lost touch a long time ago.

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In a way Annie @annieoverman, cartridge fills with tandem ay be easier than the MiniMed reservoir fills with the Medtronic unique transfer gadget; and the tandem are filled using a readily available syringe. I’ve found tandem customer and technical support to be very good, knowledgeable.

The pump is very sturdy, dropped. Ine a couple of times. I only once got it wet, forgot to remove before taking a dip.

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You know that the 3 pump companies in the US all have an option to switch early? Of course, that does involve a fee but it is much less than purchasing a pump out of pocket.
If it turns out you really don’t like the Tandem, Medtronic will let you switch back with their program.
If your anything like me, you hate to change whatever seems to be working,…even though it may be better…

I did NOT know that! Thank you for sharing that does make it seem like less of a commitment! I’m really stressing here :slight_smile:

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I too am in the same boat. The tslim has several features that interest me, but cartridge fill does seem much slower… i plan on using the prefilled several at a time advice… I can say am not real impressed with tandems customer service thus far. Seems as if I want a new pump much worse than they want me to get one from them.

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Jason @jdiesel, we are all different, and beginning any new mechanic will most always go slower. I’ve been using t-Slim cartridges for just over a year-and-a-half, and find cartridge filling to take just about the same amount of time that it took me to fill a Medtronic reservoir.

Do keep in mind, that Lilly cautions AGAINST prefilling and storing plastic cartridges. The package flyer with two Lilly Insulin packages says "… to throw out insulin that has been in a cartridge/reservoir for more than seven days".

I don’t have a current Novo-Nordisk Flyer, so I cant speak about Novolog. If I recall correctly from about 15 years ago, Lilly insulin might crystalize when stored in plastic.

Thanks for that info. I must admit I have never read that insert. I sometimes struggle with how long it takes to change cartridges and sites as I seem to find the most inopportune times to do such things.

Thanks for this info @Dennis. I’ve been doing this since I was on Minimed and asked my DNE or someone with my endos office at the time and they said it would be fine (I’ve always kept mine in the fridge as well).
I’ve never had any problems but it’s important to know and consider.

Jason @jdiesel , I listen to the three Alerts the t-Slim is programmed to supply. So I’m not caught unaware. For instance, when I see my cartridge will ned to be replaced sometime during morning, I fill a new cartridge the previous evening when not under time pressure. A filled cartridge fits neetly in the box with the insulin vial.

I also do a prefilled for travel days; although I once needed to fill a reservoir while in the air.

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@Dennis I once had to swap my entire site and cartridge midflight as well as I developed a blockage during the flight. That was one of my most uncomfortable encounters with strangers and my treatment program. They wouldn’t let me get up and the lady next to me screamed when I removed the needle from the new site. I often wondered if I was the only person who had luck like that.:grin:


I too am struggling with decision on which pump to choose or whether I will be able to continue to use a pump at all as I am severely visually impaired. The tandem rep is really urging me to order the pump but she did say that you have up to 30 days of using it and if it does not work out for you you can return it and they will credit your insurance. I have a friend who is on the tandem and her trainer told her that it is not advisable to pre-fill cartridges because they are pressurized. Apparently other people are doing that and it certainly sounds like it would help with convenience. I have used pumps since 1997 and they were always Medtronic but I am concerned about their safety for me now even though my husband is available a lot of the time for sighted assistance. With all of my scar tissue after 60 years of diabetes, multiple daily injections doesn’t sound like a real good option either. My 723 pump is just now out of warranty and I think I’m just going to continue to use it as long as it works and hope that technology for the new pumps will eventually have apps where you can control the pump directly from the app and that my screen reader on my Will read aloud buttons so I can safely select the options I want.

@Pmaddix I can tell you that the 670 now has a random button that must be pushed based on screen directions.I personally struggle with this especially when driving. I can only imagine how frustrating that would be for someone struggling with vision issues. I certainly hope that you are able to find a good solution. I did stretch out my original Deltec Cosmo pump well beyond the warranty end. The only downside was I was forced back to mdi treatment when I did finally fail, as Deltec nolonger offered new pumps and it takes a long time to process new customer paperwork with any company. I reached out to Tandem back on 9/17/20 , and I still don’t have a good estimate on when I might actually get a pump.

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Speaking of pressing buttons: when you open the screen on your Tandem pump you must press 1 2 3 (or your own passcode if you set one) in order to do anything. The pump vibrates as you push those buttons (unless you turn off the keypad vibration). Here’s the thing: I often let the screen time out so it goes to black, rather than turning it off myself. But sometimes I mistakenly press the Bolus button before it times out. There are a few steps to actually give a bolus so you can’t do it accidentally; and if I don’t go through them all, even if the screen does time out I get a “bolus not completed” alert, “0 units” which I have to cancel. It’s annoying, however I could eliminate it by turning my screen off manually.