Tandem pump and dexcom sensor placement

Hi all,
Do you have to have the tandem t slim pump and dexcom sensor placed on same side of body? Where does infusion set get placed in relation to dexcom sensor? Thanks.


I find it helpful to have them both on our near the same side - I don’t know what it is about denim when I wear it and have my pump in the opposite side pocket from my sensor, it can lose connection. I think the guideline is at least 4" space between them but you should confirm that. So I might have one on my right side of my abdomen, the other closer to center.
Check with your doctor about wearing your sensor on your arm or thigh - I use both successfully but I think you need doctor’s approval in case you have any issues and need a replacement - at one point Dexcom told me they would replace ones from those sites only if my doctor was okay with it. That may have changed by now.
I hope that’s clear.

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Dianne @DFBB, the only restriction" for placement of the Tandem infusion point and the Dexcom sensor is that they should not be placed together. The reasoning for the “too close” is infusion of insulin might somehow, I haven’t figured out how, lower the body fluid glucose level surrounding the glucose sensor. Of interest, there have been trials for devices using a combined sensor and infusion so that both would be inserted with one poke and after expiration of both be replaced.

Other than that, the Tandem pump infusion set, even when pump is serving as principal data receiver, has no relation to the Dexcom sensor, and BLE signals are effective for 30 feet. Just don’t place the pump with its face pressed against your body.

Thank you both for the info. There’s so much to learn that I do often feel overwhelmed but grateful for this forum.


I place them on either side. Seems to make no difference for me. I am fairly slim. Not much to hide the signal.

I have had them on opposite sides many times as i replace infusion sets every 3 days and sensors every 10 so they get out of whack pretty often. I do find more lost comms errors when i wear the pump on the opposite side of sensor. I also find that most resolve by just temporarily moving pump closer ro sensor to reconnect and going back to business after it reconnected. It does seem to be slightly worse with a transmitter that is coming to the end of battery life.

I am very slim, and if I do not put the pump (not the infusion set) on the same side of my body as the sensor, the sugar readings often fail. I do not get why. I end up having to put the pump in a different pocket closer to the sensor.

I keep the sensor in my abdomen. It doesn’t get bumped or moved around as much there, and with a 10 day insertion time, there’s plenty of time for the previous site to heal before I need to use it again. I put the pump cannula in my limbs.

It makes sense to me. Insulin is pumped into the interstitial fluid surrounding the cannula, to be absorbed into the blood stream and distributed around the body.

The sensor is inserted into the interstitial fluid to detect glucose levels locally at that site. The idea is that the glucose level there is probably more or less the same as it is across the rest of the body. (At least, the central part of the body. Circulation to the hands and especially the feet can be less, particularly in diabetics.)

Insulin levels close to the cannula will be higher than the rest of the body, particularly after a bolus. It takes a while for it to be absorbed and distributed. Cells don’t “drink” from the blood stream directly. They absorb and release everything through the interstitial fluid. So… There’s a chance that the cells close to the infusion site will get more insulin, and therefore absorb more sugar. So if you put the glucose sensor too close to that, the readings could be lower than they would in the rest of the body.

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Paul-Gabriel @WearsHats, the theory you explain is what I had logically assumed to be correct. I’ve since proven to myself that the theory doesn’t really hold - I did very little testing.

I had the opportunity to use multiple sensors [Dexcom G6] simultaneously, and I currently place all insulin infusion cannulas and G6 sensors on my abdomen - mapped A-D for sensors and 1-8 for insulin infusion. The sensor readings between the two readers were very close. The manufacturer who makes devices for multiple devices is working on this project.

A factor not often understood s that since the readings are sent to the pump in a radio signal we can’t put the 2 out of the line of sight. When the sensor is too far over to 1 side and the pump is placed too far on the other side the signal will often be blocked. Rather much like listening to your car radio when you drive under a bridge: reduced signal strength cuts the music volume or quality down until you get out the other side.
I have trouble at times if my pump is to 1 side of my pocket full of change, belt buckle, or keys that I hang on the belt. Keep it on the same side without interfeance will serve you well.

Interesting, Dennis. Good to know. But that doesn’t actually disprove the theory.

“Theoretically, this could happen, and that would be very unsafe, so we should tell people to avoid creating that circumstance. The odds may be low, but there are millions of people doing this every day and one error could be catastrophic.” “Well, I’ve done it a few times, and it’s always been fine for me.”

It could be placing the sensor too close to the infusion site, or smoking a lit cigarette while pumping gas, or keeping your phone on while the pilot is depending on radio signals to help land the plane. It’s fine until it isn’t. The rule is there so you don’t roll the dice, however unlikely a critical failure may be.

It is cool that you’re running a test like that, and good to know the data for you has been consistent. But that doesn’t mean it’s not possible. It may be more of a risk in someone else, or in a different site. Poor circulation (either due to a chronic medical condition or just body position and/or constrictive clothing) could make it more likely.

@Dennis , Dexcom, in the USA restricts G6 placement to the belly. See this link.
Dexcom site location (USA):
Where can I insert my Dexcom G6 sensor? | Dexcom
Otherwise, the pump sites and injections should be at least 3 inches away.

Of interest and importance, in several posts on the Child Welfare Information Gateway
(https://www.childwelfare.gov/) child protective services have been notified by ‘mandatory reporters’ of children observed with the Dexcom G6 worn outside of approved locations.

The second concern seen in other social media sites are reports of insurance denying claims for sensor wire removal if it is in a ‘wrong’ location. In a post from Kentucky, the wire was surgically removed, all was thought well until the insurance company asked for the chart notes of the wire removal. The insurance company denied the claim because the G6 had been used inappropriately & negligently.

Bottom line, read an follow the instructions with your devices.

I’m with you, Diane. I’m brand new to all of this and my head is spinning still!

Well I have to rant.
First off, I wonder how many people outside of the diabetes community know what the “approved” locations are.
Second, after decades on insulin I was needing to expand my sites. At one point I contacted Dexcom and was told that so long as my doctor approved, I could use alternate sites and they would replace problem sensors (this is what I was told a few years ago - I urge you to check this out for yourself).
And third, some people do in fact have better readings on those alternate sites,

Reporting to CPS is extremely serious; and while the intention may be good people should mind their own business and not jump to conclusions. In all likelihood they don’t know whether or not the parent is doing this with approval from their doctor.


Thanks for the comments.

The actions of Dexcom reps are inconsistent.

My endo’s nurse pump trainer & local Dexcom educator provided information that “Letters of Variance” were highly recommended continuing endo instruction was not sufficient to deviate from published standards.

Mandatory reporting laws have been enacted to remove the dilemma of “do I or don’t I” in the jurisdictions with them. The report is, “ I see something”, and then trained individuals can sort out details.

Conversely, I have learned the insurance claim denial for CGM wire removal surgery was sustained by the state insurance commissioner on appeal. Absence of a letter of variance was given as the reason for the claim denial.


Thanks @987jaj . I see what you’re saying. My personal opinion - and it’s only that - is that the FDA gives guidelines based on studies and that’s fine as far as it goes; but our bodies in general and our diabetes in particular are not one size fits all. What works for someone may not have the FDA’s blessing but that does not necessarily mean it’s bad, wrong or dangerous - just that they may not have yet gone through the testing needed to approve it.
I was aware that alternate sites could prevent you from getting a replacement in case of a problem (at least without doctor approval, as I was told), and it makes sense that would extend to other coverage. But if you decide to use an alternate site that’s part of the risk analysis that goes into making your decision.
As for reporting, what you share makes sense in cases of endangerment, but reporting to CPS seems extreme when the report-er does not know the facts of the medical situation: say they saw a parent giving their diabetic child candy and reported them for that - not realizing it was because their sugar was low and they allowed it as a special treat, or because nothing else was readily available. Wearing a CGM in an alternate site is not life threatening, and they simply don’t have the facts to take an action that can have such serious consequences. I don’t have children but from what I hear (famous last words), dealing with CPS can be a nightmare even if you’ve done nothing wrong. It’s overkill in my opinion.

@wadawabbit ,

You have some great points. More and more, the “standard of care” is surfacing in USA health care. The 1950-60 thalidomide fiasco is the most glaring. This is the reason behind FDA approval.

I have check both Tandem & Medtronic pump warranties as an example of “thou shalt follow the…” inorder have a warranty. “…valid only if the t:slim X2 pump is used in accordance with Tandem’s instructions for use…” is taken from the latest pump USER GUIDE.

Dexcom raised the ante in their fine print to “… prescribed in accordance with Dexcom’s instructions of use, which may vary from country to country.” This wording is the weight behind the insurance denial for all intents and purposes.

As far as the mandatory reporting, the incident reported in the ChildWelfare.gov bulletin was instigated by an ER doc reporting a Dexcom CGM on a patient’s arm. We are all open to read between the lines. My thought is the doc or another person close to the doc was a CGM user. Under the laws of the jurisdiction where I live, once a mandatory reporter, always a mandatory reporter. The statutes are clear in many jurisdictions, shall report 'possible or suspected harm or injury related to…" One of the phrases frequently found across jurisdictions is misuse of prescription drugs or devices.

The one that is getting scary outside the realm of diabetes is possibly close to home for both of us. If an elderly couple go to a store, one goes in the store and the other remains in the vehicle, in many jurisdictions leaving an elderly person in a parked vehicle is criminal.

Our laws are tying us in knots.

Hi @987jaj . Thank you for engaging me in this discussio… I’m typically very pragmatic and defer to the necessity of things being a certain way, but this one struck a particular nerve.
Thank you for letting me vent and for reminding me of the “why.” As you say, our laws are tying us in knots!

@wadawabbit , You have hit the nail square on the mark. There is one more episode of tying knots. In the 1980s, in a large metropolitan community, an elderly couple were eating in an establishment that served breakfast and enticed LEOs (law endorcement officer) as well.

As many do, the elderly couple pulled out two pillboxes, one for her, one for him. They started laying out their pills on a couple of napkins. Some of the pills were Controlled Substances & were outside pharmacy containers. The couple were arrested, booked, jailed, bailed, and subsequently to trial for controlled substances outside pharmacy containers. They were not convicted. The trial made a big dent in pharmacy patient education to the point of many pharmacies including handouts about the law of keeping controlled substances in their pharmacy containers.

The bottom line from my perspective is to illuminate the proper, supportable, & documented procedures & actions, especially for the folk new to this DIABETIC nightmare.


Oh for heavens sake. I’m shaking my head so much I might get whiplash! Yes, document so people can make informed decisions.