Intermittent sensor with loose silicon llubricant

Diabetes Technology Glucose Monitoring
1

Has anybody else seen this issue on a Dexcom sensor on first day of service:

1.After initial install sensor was bouncing around +/- 5 units on individual readings.

2. By Midnight \, readings were dropping from 150 to 120 every half hour. Testing immediately with Caveman fingerstick showed no such instability and in fact readings there continued stable.

3. AT midnight; I stopped the sensor and removed the sensor and popped off the transmitter.

4. Looking at back of transmitter was a covering of a oily substance I assume was Silicon lubricant
that coated the back of the transmitter and matched the well of the sensor. No bath, no wash , no greases, ointments had been used by me whatsoever. I also noted that the elastomer electrical connectors of the wire sensor where shiny with the same substance when in fact in past they has always were a dull color.

5. I immediately replaced a new sensor from this new batch and had back up by 3:13 am. Readings then seemed stable throughout rest of early morning till noon when I saw another instance of marginal behavior. I gently pushed down on the transmitter a couple of times and then sensor continued working normally.

6. I did speak with Dexcom's technical services and was under impression that they did add a silicon lubricant.

7. Given that the electrical connection is a low voltage low current connection, I am deeply worried out the use of a low temperature lubricant that melts at body temperatures and can run around the sensor cavity and contaminate the electrical connections. Worse yet, the connections on the back of the transmitter appear as some form of tin lead solder - at least not gold, nor am I aware of any additional metal gold fibers that might be in the elastomer connection to ensure a gas tight seal and firm electrical connection, puncturing any oxide on the transmitter solder bumps, and prevent wandering silicon lubricant from contaminating and interrupting the electrical connection and causing the intermittent behavior I saw on my receiver causing heart stopping behavior.

8. Ignoring other issues I have with Dexcom that I have had to work around, this issue with the sensors seems extremely unacceptable, possibly incompetent and/or a change/mistake in the assembly of sensors. I may need to get a professional opinion on this matter from a PHD/expert on connector systems and contamination. Why anybody would use a low temperature melting substance/grease and in sufficient quantities to wander around the whole cavity of the sensor platform and leave thick coatings on the bottom of the transmitter. I always clean very carefully my arm, the transmitter bottom to ensure clean and this is the first time in 10 months that I have ever seen a thick coating left on the bottom of the transmitter on the first day of installing a new sensor.

9. Dexcom did swap out this first sensor of this new batch and I have asked for the whole batch to be swapped out and I am adding that any sensors shipped me better be devoid of the low temperature melting compound/grease interfering with the stable operation of my Dexcom unit.

10. I have used sensors since Jan 2011 and this is the first instance of unstable - intermittent behavior.
I am curious if any of the other users have seen this recently. This batch where the first bad sensor was seen was shipped in October 2011.

Please advise.

2

this is very interesting...can you send this as an email to somebody at Dexcom and get a full technical report? This would be nice to have thier written explanation and then you can post thier answer.

3

I’ve seen it! I didn’t realize that could be why Dex was reading so wacky though. Thanks! In the future I will call for a replacement!

4

Will do. c annot guarantee any response. Thank you for responding.

5

I cannot speak for Dexcom and nor for their recommended action.

That said, I use the wipes withe\ the isopropl alcohol that I use to clean hands and mounting location for sensor and also
clean off back of transmitter carefully to remove ALL residue and ensure the electrical pads are wiped clean as well prior to mounting on the new sensor plate.

Thank you for your data and response.

6

Today is teusday. November 22, 2011 and still no response to what I feel are legitamate concerns about a fowled sensor. I would have expected at least an email and possibly a courtesey call from Dexcom. Unfortunately they seem to have attirude they do not have to respond to me, a valid customer and type 2 diabetic 64 years old with serious issues.

I have logged a complaint with the FDA as well and will continue to press for a response.

Yes, they replaced the original sensor and they indicated they were using silicon grease on sensor. That does not end story especially when the temperature of melting, the quantity used and the extent the grease moved all around the sensor platform cavity, coated the back of transmitter, and appeared to fowl the elastomer electrical contacts.

I have also asked for proces best to clean up the excess grease on back of transmitter as well as flushing the sensor plate cavity to remove excess grease.

I would be most appreciative of a morer extensive caring and prompt dilligent response.

7

This just happened to me also yesterday. I was about 18 hours into a new sensor and the numbers were jumping around a bit. All of a sudden the number dropped 60 points from one reading to the next. When I checked with a fingerstick there was no drop in blood sugar. A few minutes after that happened I got the dreaded ???. I waited about an hour and decided to change the sensor because I wanted the 2 hour waiting period during a stable time in blood glucose.

When I removed the sensor there was clear gel on the bottom of the transmitter. I cleaned it off with alcohol swabs and inserted new sensor. Of course Dexcom was closed due to the holiday so I sent them an email asking for an explanation of the gel and a replacement sensor. This was the second sensor I had fail from one box.

If I get any sort of response from Dexcom, I will post here.

8

Thank you most kindly for sharing your experience and your data.

I am amazed and quite frankly shocked. If you have opportunity and feel so inclined, you might file a Voluntary online Medwatch report with the FDA detailing your data, experience CGMS serial number and sensor numbers as well.

Hope you had good thanksgiving or good holiday as well.

9

URL for FDA online form is:

https://www.accessdata.fda.gov/scripts/medwatch/medwatch-online.htm

10

I have been using Dexcom since March 2011, and have never noticed any 'goo'.

I've had only 2 sensors with bad readings and were replaced by Dexcom. In the first case, I think I didn't have the transmitter firmly snapped in on both sides.

11

Not including this latest batch, and in 10 last months; I have also had a few sensors drop out early and fail but never like this and NEVER any loose goo, silicon lubricant running around in sensor cavity under the transmitter..

I would normally not pester the good folks of tudiabetes over a few early sensors that failed In a non suspicious manner in the past months. I have also in the past been in hot environments here at Big Pine including wood stove burn the air out of the room - but no failures as these latest sensors ref 9500-03 lot 5023981 and dated 2012-05-17.

I have always carefully checked the transmitter every time when installing a new sensor and cleaning each time.
Today I was shocked over the grease left behind that seemed to melt at low body temperatures and contaminating contacts and the repeated intermittent sudden drop in readings.

So far two sendors of the new batch have failed with the grease showing and sudden drops in readings.
The third sensor - I cleaned out excess grease carefully on new sensor platform and under and over the contact platform that sits at an angle till trasmitter installed. The third sensor worked stable with no intermittent readings for 3 days from startup and then on Sunday at 10:45 had a sudden drop from 190 and reading stopped at 147 there odd and I had to enter new BG readings to get it back to where it was supposed to be.. Handheld had shown no drop during time Dexcom reported BG as 147 while fingerstick was 190. I gently pressed on trasmitter and sensor continued working after that incident till today without any incidents and still running.today. Touch wood.

I have sent polite courteous reports to Dexcom since November 18, 2011 without any return report or call fromn Dexcom.

Apparently, purchasing and using a $ 1000 Dexcom for the last 10 months and boxes of sensors at $3xx a box of 4 and having serious type 2 issues that require a cgms to manage liver carefully do not warrant a response from Dexcom. notwithstanding my polite reporting and detailing the exceptional difficulties on these latest sensors not seen in the past 10 months on prior sensors.

One might think I had bought a 19.95 Timex at Target and expexting gold plated service. I wonder what it takes to qualify a person to get prompt and respectfull service at Dexcom. Some folks say they are very happy and have so reported at tudiabetes.

12

Third sensor after hickup on Sunday worked without incident till to day which I stopped and restarted same sensor to see how long it would run after the seven days with one hiccup.

Other then the drop hickup on Sunday at 10:45 am approx, this sensor that I cleaned out the goo-grease - whatever in the sensor cavity has worked the best of this new batch and no apparent intermittent activity on the trend line before and after the hickup.

I still have no report nor response from Dexcom as to why would there be a substance in the sensor cavity that clearly shows signs it can melt and wonder around the cavity and coating the rubber/plastic elastomer connector to the transmitter.

13

I am surpised by the drop off in responss and traffic on tudiabetes over the thanksgiving holiday weekend and
now first week of Christmas. I assume this is normal but given the 2x,xxx number of members that is interesting.

Dexcom finally responded today this afternoon PST time while I was out picking up meds. It was an email and I have deleted the names to protect privacy and message was as follows:

Hi Mr. Snell,

We are sorry for not answering your question on the sensor substance directly and immediately. Michelle is out of the office indefinitely and in order to help you in a timely manner please email us at TechSupport@Dexcom.com .

We are looking into the matter and we will respond back by today or early next week. Let us know if you have any questions in the mean time.

Happy Friday!

Thanks,

Website: www.Dexcom.com

To Good folks at Tudiabetes - thank you all for your comments, experiences and time as well as good patience..

14

What of what you have described is worthy of a report to FDA ? Unless you had a sensor wire brieak off under the skin or a skin infection I dont understand what meets the criteria.

"report serious adverse events for human medical products, including potential and actual product use errors and product quality problems "

If I reported every unreliable or ??? or sensor that showed my BG To be 100% higher than it was I would be reporting more that 50% of the sensors. The accuracy of Dexcom and Minimed sensors is not great for most people. Thats not news and reporting it to FDA isnt going to do any good. Dexcom doesnt and the FDA doesnt see the accuracy issues as quality problems, certainly not "serious adverse events" . If you spend any time on the phone with them you will understand that they have no hard and fast rules for ANYTHING related to accuracy or reliability.

Ive not experienced any GOO as its been described. What adhesive are you using to attach the dex ? Maybe its the adhesive.

It looks like you have been emailing an ExEmployee or one that is on short term disability at least. Were you sending emails to a specific person at Dexcom or to a department mailbox like Support ?

With all the problems you have been having the right thing to do is CALL - Not email.

My $0.02

15

Thank you for responding and sharing your two cents.

If assembly issues and use of products that compromise the connectoring system cause system to go intermittent is in fact a very serious issue and I disagree with your comments.

I have called Dexcom about this on Novemeber 18 and I do not have satisdactory answer at all here on Dec 5, 2011. I have attached a picture of the latest hit on the 4th sensor of a group.

The adhesive pad I was referring to was the one provided by Dexcom on the back of their sensor platform that had failed and the stains of the leaking melted substance could be seen on the pad and the back of the transmitter.

I cannot agree with your defense of unacceptable behavior and response.

[3713-scan0006.jpg|attachment](upload://eH8zzUFRBqHzUim6IP5SgPWwpHG.jpeg) (756 KB)
16

Not defending - simply stating that they wont care.
Your scan shows remarkable consistency. If mine looked like that I would be thrilled.

Here is a graph from mine - Dexcom sees all these gaps as perfectly acceptable


All these gaps in data and the jumping around are completely within acceptable ranges according to them. Some of these gaps are when the sensor showed "???"and some was when it was "out of range" - the sensor reported out of range when the receiver was in my pocket. Again - Dexcom considers this normal.

And you can be pretty sure that they are in compliance with FDA in saying that.

As far as call VS email - I would be willing to bet that calling creates an FDA trackable event and email does not. Which is why I suggested calling rather than email.

17

My read of the gaps are due to the receiver/transmitter no longer connected as shown by the width of the gaps in your dump.

I assume spacing between transmitter/receiver, interfering RF signals and startup intervals are probably responsible for the gaps as shown here.

The issue that drives me nuts is the sudden drops that the fingerstick machine and its test strips cannot prove. I do not worry about sea changes where the delays of interstitial and filtering delays on the Dexcom end up with difference in readings.

18

Doug:

While I await to hear back from Dexcom; I thought it appropriate to respond to the possible concern I am inflating a hot air balloon making a big deal in a hand basket. Some of the well meaning comments on tudiabetes are suggestive of that to me.

My situation involves using the Dexcom to yes monitor trends as well as monitor BG going to low and arresting. That requires catching the BG before it gets to sub 120 and adding sugars/foods to stop BG going sub 100. In fact on my large body, if my glucose gets to 110 it is moving very fast and can be sub 70 in a heart beat.
Due to interstitial delays and filtering delays on the Dexcom, while my Dexcom is showing 120, my caveman fingerstick machine is showing reliably across both hands 110/112.

As the low level alarming has a max of 100 – useless, I have to monitor closely and manually as glucose readings drift sub 130. If my liver was working properly and could do the bottom end glucose adds as blood glucose goes sub 70 without ramming my BG to 511/Hi sliding back to 278/311 as heart pumps crap around system diluting it; this all would be academic.

The end result if I get these dumps, is to immediately walk 2 to 3 miles to burn the glucose out. Insulin DOES NOT get rid of the crap – it only stores it elsewhere.
This is NOT helpful to me.

Through use of metformin, CGMS proactive monitoring; my glucose of this 30 year + type 2 diabetic is under control and A1C is 6.4 and weight down from 330 lbs to 260 pounds and rot stopped.

Having a CGMS stall out due to receiver heated up, intermittent contacts on sensor and RF communication that causes receiver to display prior old readings without any alarms or indication is not adequate in my opinion.

Each time I have one of these fracas, I end up using a 50 barrel tub of fingerstick test strips in 2 days flat. AT $ 77 dollars at the pharmacy and $ 30 at the mail order wholesale this is still an added expense.

Sometimes we as humans make sometimes necessary assumptions and conclusions that are in fact wrong and on the simplest situations , underlying behavior can be very complex and not as we assume.

As a retired engineer, I am most concerned about this issue having worked 40 years plus on complex digital electronics and ensuring/fixing designs to work worst case from -40 degrees C to 120 degcrees C.

More importantly, the lessons from the 51D Challenger Shuttle disaster are extremely important and salient.

In this case, a metal cylinder stackup on therocket boosters used a lap joint sealed with a caulking and O rings to protect against 1500 degrees F exhaust from burning solid fuel rocket fuel from escaping from the joints and burning the shuttle up.

Cutting to chase, the lap joints allowed the o rings to move out of their grooves. 32 degree F weather hardened the rubber o rings so they were no longer flexible and pliant. Failure to seal and the o rings burned up in seconds.

Next the testing regimene of compressed air to test the o ring seals in fact pushed the o rings out of their seat. Next the o rings did not reseat until the booster lit so that the exhaust pressure pushed o rings back in position and as long as they were at normal room temperature flexible still did their job mostly.

It turns out we were bloody lucky not to incinerate the astronauts every time we launched the shuttle.

Going back over prior launches did show abrading and some destruction of the o-rings.

Back to our Dexcom sensors; these sensors are using a non gold contacts on the transmitter, an elastomer connector to connect the sensor wires to the transmitter. This is a low voltage/low current sensor circuit where one asks how is the oxide of the metal contacts pierced to ensure reliable, 7 day contact or better without going intermittent. Secondly the presence of a goo/silicon grease substance that appeared to melt at body temperatures and possibly too much had been added that wanders all around the sensor cavity and onto the back of the transmitter and electrical contacts is a great concern. I may be wrong, but my understanding that silicon grease does not enhance the conductivity of the elastomer contacts in any way and if conductive would as I saw it short out/load down the sensor contacts.

My concern is simple, I just want to ensure – me/Dexcom are doing this right and if their opportunities to improve the situation; the correct engineering disciple/effort is being followed and done to get us the best possible product.

I have no interest is shutting down Dexcom, nor trashing them or their good people.

I hope all of you understand that, readers, tudiabetes, Dexcom et all.

Thank you most kindly for your patience, time and understanding and nor is this an attempt to panic or worry Dexcom users. I have been using 24/7 for the last 10 months and getting good help from the Dexcom product. Prompt timely response to my concerns would greatly help me in this matter.

19

As of Saturday, December 10, 2011; Dexcom has not responded diretcly to my concerns and only sent emails that they are working.

I see my last response has no reply capability at TUdiabetes.

I consider this most unfortuante and unwarranted.

20

I meant to add the following positive comments:

At all times as a diabetic knowing the complexity of the disease and technical issues, I try at all times to accomodate, adapt and live with.

Regarding the sensors I have taken to cleaning out the sensor cavity of excess goo/substance /silicon grease with cue tips and isopropyl alcohol - 70 % and cleaning back of transmitter.

With the last two sensors of this batch, I have not seen any leakage from the bottom of the sensor that stains the mounting pad and that that causes the adhesive pad to go non sticky and release nor any coatings on back of transmitter.

I also have found that gentle pushing on transmitter when installed and during installed seems to stop an intemittent activity - perceived.

Should I have to do this and is this the best approach? I do not know without a timely and prompt response from Dexcom. Verbal communicatiosn I use to check on orders, chat about the weather and ask general questions.

As a retired engineer, I use written communications to more accurately convey my observations, data and concerns.

I hope I get a response soon. Start Novemebr 18, 2011 and Dec 10, 2011 still politely waiting.