Medtronic 670g sensor insertion failures

My husband has been diabetic for about 50 years. He has been using the 670g for just over two years. At first, it was relatively uneventful, aside from the constant alarms, testing, calibrating, etc. He put up and shut up, but I think he’s at the end of his rope. He has inserted a new sensor literally for three days straight this week. By the time the warmup period is done, he gets the “sensor failure” message. Yesterday there was blood underneath which tainted it, but he never noticed it until I pointed it out. Medtronic HAS replaced all of the failed sensors. He is thin (6’, 165 lbs), and has been using a pump for nearly 20 years, so he probably has some scar tissue from all the insulin port insertions (but he never has issues/failures with those). There is no rhyme or reason to the new sensor insertion failures and he maybe had three go bad in his first two years. Now he is lucky to get 1 out of 5 in a month! So, unbeknownst to him, I am seeking out info on switching to a Dexcom CGM. He has a smartphone. He would keep his 670g since the pump works fine in manual mode. The biggest issue he has is frequent lows, especially at night. He NEEDS an alarm! I NEED an alarm! Otherwise, I am getting tired of seizures and visits from paramedics in the middle of the night! Next year he plans to retire, and when working outdoors, he goes low quite often. What sort of information can anyone offer to someone who really needs a CGM, and luckily is not technologically impaired. Also, what are the approximate costs and length of time the sensor can be worn? Can you really go without blood glucose tests? Medtronic’s sensors are like gold and their cost is outrageous. We both are ready to try something different. Can anyone help??

Hello @Stephanie_Y welcome to TypeOneNation. So given that your husband gets low to the point of needing medical help, in my opinion your best bet is to use a pump system that shuts off insulin when you get low.

The CGM simply do not work reliably in some people. If he’s never had a CGM before, it might be he’s a lucky guy and the DEX won’t work either. Trying the Dexcom is a good alternate because at least the receiver will send alarms but again, only if it works for him. A stand alone CGM isn’t all that expensive in my insurance plan but you’ll want to have Dexcom check your coverage for you.

At the very least, a plan to manually reduce basal insulin when working outside is a good plan. I hope you find some relief somehow. Please check back in and tell us how your husband made out. Cheers good luck :four_leaf_clover:

I’ve used Dexcom for many years and am quite happy with it. I recently upgraded from the G5 to the G6. As I understand it the G5 is being phased out, and while current users can still get sensors for the G5 I don’t know if new users will automatically get the G6. The G6 does not require fingersticks while the G5 does (I did 4 fingerstick calibrations a day with the G5 - now just do one occasionally if my reading does not match the way I feel. G6 sensors last 10 days, the G5s last 7. Dexcom allows you to share your readings to someone else’s smartphone so if you’re out while he’s working in the garden you’ll know how his numbers are.
Cost will really depend on your insurance, and since you currently use Medtronic it is possible if not likely that his doctor will need to provide documentation for why he needs to switch. As @joe stated, CGMS do not always work reliably for some people. It’s also possible that one brand may in fact work better than the other so it’s certainly worth a shot. But I’ve been very happy with my Dexcom and the alarms and alerts I get are reasonable and go with the circumstances, not random ones out of the blue.
At the risk of being dubbed “Captain Obvious,” has your husband looked into changing his nighttime basal rate/s? If he has had multiple occasions requiring medical attention I would think that’s something he and his doctor would have discussed. Getting reliable alerts is essential; preventing the need for them - as much as possible - is even better.

@Stephanie_Y Hi Stephanie, and welcome to the TypeOneNation Forum! It is too bad that your husband’s glucose monitor fail and doesn’t work well for him.

To answer your direct question, the Dexcom G5 and now G6 sensors / monitors have worked very well for me; I usually get full and complete accurate response from my sensors - only two have failed to give 100%. My G6 is paired with my Tandem t-Slim x2 pump and has automatic suspend of insulin flow as well as reduced insulin flow when my system anticipates that my body glucose level will drop below where I want it to be 30 minutes hence. The AIDs [Automated Insulin Delivery system] is called Control IQ [CIQ]. The CIQ algorithm also increases basal insulin flow when my BGL reached as high as 160 mg/dl, and if BGL exceeds 180, the system will automatically deliver supplemental bolus insulin. The CIQ system has maintained my time-in-range to higher than 90% of the time.

I suspect that your husband marvels at how the “tools” for diabetes management have changed during his 50 years - I’ve been in this diabetes game for 63 years; but unfortunately, all the tools and devices do not work well for all of us. I have acquaintances using the 670G system who fine it works perfectly for them, and I’ve spoken with others who have had the same experience as your husband. He will need to find what works for him, and as @joe wrote, your husband should really look at a pump system that will work for him and suspend all insulin flow when his glucose level drops.

More fundamentally, I believe that your husband should find out WHY he is having so many “lows” - treat the cause rather than the symptoms. Does he need to make changes in his basal rates? Should he be using a pump Pattern that delivers less insulin on active days - especially as he moves into retirement?

Thanks, @joe–To clarify a bit, my hubby has used a Medtronic Guardian 3 CGM for over two years with his 670g pump, but just in the last three months has had sensor failures with almost every change. He spoke to his diabetes educator yesterday and she said perhaps scar tissue has built up in his normal abdomen sites, and to try the “love handle” area. He did that this morning (3rd sensor in 3 days). I haven’t received a text from him saying it has failed, so fingers are crossed for now. He could try the upper arm, but he has no fat there to speak of, and putting on the tape by himself one-handed would not be possible. I can’t help him in the morning due to my much earlier work hours. The only reason I asked about the Dexcom was the fact that it could be applied without additional tape and could be used in multiple locations. He DOES like the fact that the 670g and CGM is a closed loop system, as he tends to go low when working outside or in the middle of the night. But at least the Dexcom does have an audible alarm feature. And I do like that the info can be shared with multiple people.

@wadawabbit…thanks for the great info on the G6 Dexcom system. My hubby at first was skeptical about no fingerprick tests, but he did say if the numbers seemed to match up accurately, then he would be willing to phase them out a bit. He usually tests 6-10 times per day–some for calibrations–some because of wacky readings. LOL…Captain Obvious! Yes, he has tweaked his basal rates extensively over the last 15-20 years of using a pump. His biorhythms are somewhat predictable, not always controllable. For instance, he ALWAYS goes high in the late morning. It makes NO DIFFERENCE what basal he uses. It’s just the way his body rolls. And nights are hard because he sleeps like a rock (how I wish I shared that ability!). He doesn’t even really hear the alarms unless they go into overdrive and make a racket. I’m the one nudging him all the time to get up and eat something. He has a long-awaited appointment with his endocrinologist next month. We are gathering information now so he can give her the facts and difficulties. At this point in time, I’m willing to try just about anything–insurance or not. The 670g works just fine–it’s the sensors and his body type that are probably the issue. I’ve seen people at the beach wearing Dexcoms…very few wearing a 670g and Guardian 3 sensor. I’m just curious as to why!

@Dennis–I’m not sure why I haven’t heard of your Tandem t-Slim x2 pump before. I didn’t know they also made a closed-loop system that automatically adjusts insulin delivery like his 670g does. He does have a basal rate for work days versus weekend days. But I’m sure you know how difficult it is to fully assess the carbs in a certain meal. My dearly departed best friend was a dietitian and helped him immensely with carbs and fiber adjustments. We don’t eat out much and I cook healthy meals. Still, some meals spike his BG and others are neutral. Since he technically would be up for a new pump in 1-1/2 years, this is all good information to make an informed decision when that time comes. I like the size and display of this Tandem pump and since it works with a Dexcom G6 sensor, all the better. Maybe it’s time to switch? He had to call Medtronic AGAIN last night after his third sensor in a row failed. This time they are asking him to return the failed device so they can inspect it. We have been blacklisted from getting replacements online since he has had 8 failures in less than 3 months. However, if he calls in, they will replace it. It’s humiliating and embarrassing, to say the least. We are honest people and are not hawking sensors on the street corner. Thanks for the encouragement and valuable information!

Hi again from your new friend “Captain Obvious😊.” I saw in another response that you’re going to look into Tandem’s TSLIM pump. One reason you may see more TSLIMs than Medtronics at the beach could be its size. I switched to TSLIM before anyone had CGMS, frankly because I thought it looked sleeker and more modern. Just one of those personal taste things with other factors being pretty much equal at the time. I’ll let you do your own research - both on company websites and on this forum - for details and personal experiences about accuracy, pluses and minuses, but for me the sleek size and more modern appearance were big factors. And having it connect with my Dexcom CGM is the icing on the cake, if you will forgive the analogy.
Going back to your husband’s blood sugar issues, I don’t know about Medtronic’s CGM but with Dexcom’s G5 you are not supposed to use acetaminophen pain relievers (they are allowed with the G6). Perhaps a medication of some type that he takes, is interfering with his sensors? I’ve only had to call tech support a handful of times over a few years due to a Dexcom sensor issue, and one of the first questions they ask me is, Have you taken anything containing acetaminophin?
In addition to straight up pain relief I’ve found it present on the list of ingredients in cold and allergy meds among other things. Even if it’s not that particular ingredient, maybe something else is causing problems with his readings. Just a thought.
BTW, if he’s tired of pricking his fingers your husband might want to check out the Freestyle Libre “CGM.” Sadly it does not have alarms (hence my “air quotes,” but you can see numbers quickly by swiping the have receiver over the transmitter. It can be worn for 10 days.
“CO” signing off (for now :wink:)

Hi @Stephanie_Y, the Tandem t-Slim when paired with a DexCom G6 is the only AIDs [Automated Insulin Delivery system] with the particular FDA approval designation - the approval was issued December 13, 2019.

Coming soon, there will probably be more such systems - just in the last few days, the Abbott Freestyle Libre 2, was approved for use very similar to the DexCom G6, and the Libre 2 is now capable of delivering alarms to the receiver and to mobile devices.

Great news about the Libre 2 alarms!!!

@wadawabbit, @Dennis: Yes, the sleek look and size of the TSLIM is intriguing. I have downloaded some information for review before my hubby’s next appointment. Regarding acetaminophen…he rarely uses pain relievers except Aleve if he has overdone himself doing yardwork! So far, two days on the present sensor, which was inserted into his “love handle.” I’m thinking it’s scar tissue on his front abdomen that may be causing the premature sensor failures (bleeding, bending of the probe, not sticking properly, etc.). I have seen a few people with Freestyle Libre but discounted them as useless because of the lack of alarms. Now Dennis has provided some important info that could be a game-changer. I’m hoping that with some stiff competition, Medtronic may even lower their durable goods prices (yeah, right). Even if my hubby doesn’t switch at present, when his 670g pump’s warranty runs out in 18 months, he will have the ability/knowledge to maybe make the switch. We have quite a backlog of infusion set supplies and Contour test strips so there’s no sense not using them. He doesn’t have many extra sensors, however. Thank you, “CO” and Dennis all for the seriously great information! :slight_smile:

I saw the great news about the Libre - exciting and definitely worth checking out.

You may want to investigate Looping. Look it up on the internet. It involves a modest amount of technical skill, but relies on open source software with a very nice user interface on your phone. Your phone acts as the controller and it syncs with a Dexcom CGM. It has algorithms to anticipate changes in BG and make minor adjustments. My BG readings have decreased 40% and apparently it is a lot better than the Medtronic system.

Hi @dbunzel. I’ve had diabetes for several decades and am still a bit fuzzy about the looping I believe you are referring to. I believe Medtronic pumps worked with their CGM to make adjustments automatically. I myself have Dexcom’s CGM and am using Basal IQ technology to adjust for lows, and will be stepping up to Control IQ to help manage highs as well. I still must count my carbs and enter my own boluses (I let my pump do the calcs). That in a nutshell describes Tandem’s closed loop system - albeit very simply - and is the closest thing to looping that I can come up with. I imagine looping as a bluetooth that connects a pump to a CGM, similar to what Medtronic, and Tandem/Dexcom, have to make adjustments - a benefit being that the price point is lower, and perhaps you can connect devices that are not yet designed to work together.
Please enlighten me - I use the term seriously, not in jest, and really do want to understand. I did a quick search but was directed to Tandem - but since you didn’t refer to it I gather you are talking about something else.
I understand there are some on this forum who use a device that does it - the brand escapes me. Important to note, that one is not FDA approved and I don’t believe any others are either. They may work well, but people use them at their own risk - which is true of any diabetes devices, but approved ones have been thoroughly tested and come with known and proven safeguards, as well as some recourse in the event of failure.
I don’t know if you use one yourself - if you do and it works then wonderful. But someone new to diabetes would be better off in my opinion with a known device.

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Dorie, You are correct. It involves a Medtronic pump, an iPhone, A Dexcom CGM, and a small communication device called a Riley Link. Bluetooth is the technology that allows the devices to communicate to each other. It is not just any Medtronic pump, rather an older one, which has a system version 2.4 or earlier. So essentially you need to rely on an old pump you have that meets this criteria or source one. There is an active market in Loop-compatible Medtronic pumps. There is a “recipe” LoopDocs to create a looping system online on Github. Here is an article that talks about it DIY Looping - Taking Control Of Your Diabetes®. Seems like Tandem bought the keywords on Google search to come up first. Loop is an open source community, so it doesn’t have the marketing budgets, but it seems that passionate people with an interest in diabetes are involved. They clearly have the T1 in mind, whereas Medtronic seems to have relied more on the engineers than their customers to design the user experience.

Control IQ looks similar, but it is not clear if the controller is a separate device or your pump. My iPhone controls the Loop system. I do not use the Dexcom controller. This function is built into the Loop software. When set up you have a screen that looks like this:

Like Control IQ, it has algorithms built in to anticipate BG highs and lows. The “dashboard” at top shows with icons the following: if the device is communicating with the other devices, your BG reading (from the Dexcom device), active insulin, how much insulin remains in your pump reservoir, and how much battery life remains in your pump battery. Also graphs to show BG, Active Insulin, insulin delivery, and active carbs. You still need to count and input carbs when you eat/drink something. The interface allows you to add the carbs and gives three options (icons with candy, taco, and pizza to represent fast, normal and slow acting carbs) and suggests an amount of insulin to deliver. You can modify too. It relies on the thumbprint biometric on the iPhone in order to deliver securely. While not as slick of a device as the Control IQ, the interface is solid and I have been Looping with great success for the last six months.

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Riley Link - that’s the name that slipped my mind. Thank you for the info - I read it quickly and will look at it in more detail later.

Check out the following web page My daughter’s childhood doctor helped Medtronic roll out the closed loop system as CMO. She has since moved on to the above company. The technology is amazing and the way of the future IMO. An FDA approved implantable CGM, placed during a simple out patient visit and changed only 4 times per year! I’m pretty excited about it. So far it does not pair with a pump and operate as a closed loop system but it may give you the sensor break you need, alarms and you can still use your current pump.

I also have problems with my Tandem insertion. I’m going to try a telfon needle when supplies run out. I’ve been using Dexcom 6 for 9 months. Coming from Meditronic, Tandem is awesome. My wife loves getting alerts. Regardless, you still should be checking your BG after an insertion. When I see mine trending past 220 two hours after an insertion, I know the needle was bent and need to replace. I do go days without testing BG, but when I do Dexcom is right on. Never been 25 points difference. LOVE Tandem/Dexcom!

Dear Stephanie,

I am also a T1D for 50 years and have been on the 670G for 2 years and I AM HAVING ALL THE SAME PROBLEMS AS YOUR HUSBAND !!! Constant failures with the sensors. I CAN’T STAND IT ANYMORE. I just came from my 6 month visit with my endo and he agreed - it’s time forme to try the Dexcom. I am going to research in depth tomorrow. I prefer to use the manual mode on my medtronic pump and my endo assures me I can work the Dexcom (plus cell phone) with my current pump. I will try to get back to you with more info after my research. I do know many people on this chat use the Dexcom - I, too, am looking forward to their comments.

@TJC: Fascinating! Same history, same results, same failures! I’m biting my nails because tomorrow is “sensor day.” If he gets another “change sensor” alert after a few hours, he will lose it. I would love to know how you make out with the Dexcom. Again, the hubby has a small stockpile of sensors, but could conceivably use them up before switching. He doesn’t dislike his 670g, nor has he had any issues with the reservoirs or cannulas. Never an issue “installing” them. It’s just those dang sensors! What I am most curious about is the cost difference. Could you let me know? He is retiring next year and will be on Medicare. Would love to know what $$ we will need to plan for (before any discounts). We currently have a high deductible plan, so typically pay full price until our yearly max out-of-pocket is reached.