@CatLady, do you usually wear your more than 10 days? Does the 10 day limit impact you?
@CatLady @Eric, there has been some discussion about whether or not the sensor could be hacked to go beyond the 10 days… In the FAQ’s posted on the Dexcom site they reference a sensor serial number that needs to be entered to get the pre-calibrated values. They also talk about what to do if you “lose” the sensor serial number. Without the serial number the process is the same as the G4/G5 systems. Why would you not be able to run the sensor initially as a lost code for 10 days, then run as a coded sensor to get 20 days instead? Is there something I’m missing?
This might be possible, but at this point it is still speculation, since nobody has tried it yet.
I was just asking because not everyone will want to go through whatever is required to hack the 10 day limit.
If CL wants to hack it and can hack it, that’s great. But if she doesn’t want to, then she has to make a choice about the upgrade.
If someone does not want to do that, then the question becomes if getting the new G6 is worth the 10 day limit. So my question is simply how important a 10 day limit is to people.
It is worth about $150 a year to me. Not too much, but enough to care. This is based on my cost for 3 boxes of sensors. We usually get by with just three shipments a year. Not to mention the cost of not having the pain of extra insertions. For us, this isn’t worth that much, but for many of our dia friends that use pain numbing cream and hate the insertions, that is probably worth much more than the money.
Are you getting 12 sensors (3 boxes) in each shipment x 3 shipments? That is about 10 days per sensor. So the sensor life is about equal. But another thing we don’t know is if the cost is the same per month. Who knows, right?
I consistently get 2 weeks per sensor and best ever was 24 days. As for the G6, I am wondering if “improved accuracy” includes reduction of the time lag many of us experience, especially after correcting a bad low. That might be an acceptable trade-off for shorter sensor life.
I doubt it does anything like that. The delay in reaction between blood glucose and how long it takes for your interstitial fluid to reflect the BG is just one of the limitations.
They may change the algorithm and try to be better at predicting your BG, but they can’t make your interstitial fluid any faster in picking up your BG. That will always be a limitation of this type of system.
Here is some stuff about it if anyone is interested.
the equation characterizing IF glucose was described as follows: dV2G2/dt = K21V1G1 − (K12 + K02)V2G2, where G1 =plasma glucose concentration, G2 = IF glucose concentration, K12 = forward flux rate for glucose transport across the capillary, K21 = reverse flux rate for glucose transport across the capillary, K02 = glucose uptake into the subcutaneous tissue, V1 = volume of the plasma, and V2 = volume of the IF.
Lönnroth et al.25 was the first to use this method to show that IF glucose was almost identical to venous plasma glucose in healthy individuals during steady state. Jannson et al.26 demonstrated an increase in lag time between IF and plasma glucose when there is a rapid rise in the plasma glucose level.
Very interesting. One line in particular caught my attention from the mentioned article:
The time required for glucose to diffuse from the capillary to the tissue plays an important role in the lag time between changes in plasma and interstitial glucose levels, but the lag during rapid changes of blood glucose is likely due to the magnitude of concentration differences in various tissues at a time of rapid change.
I tried looking up the footnote associated with this for the related article but it seems to only point to a single line abstract? Maybe I am not looking in the right place? But the concept of the lag being related to the difference in BG seemed worth reading more about.
And this also was very interesting:
Interstitial glucose levels have been shown to remain below plasma glucose concentrations for prolonged periods of time after correction of insulin-induced hypoglycemia.36 These findings could be explained by the push–pull phenomenon during which the glucose is pushed from the blood to the interstitial space at times of increased blood glucose, and later on glucose being pulled from the IF to the surrounding cells during decreasing blood glucose levels.37 This phenomenon has been a matter of debate for some time, in light of data failing to support the push–pull phenomenon and instead reporting compensation of enhanced uptake of glucose in the IF by increased plasma glucose delivery and lack of glucose removal effect of insulin in the adipose IF.
And an explanation of the “warm up” other than a stupid FDA thang. Looks like real science at work !!!
Despite the advances in the making of sensors with new and improved designs and materials, sensor insertion causes trauma to the insertion site. It can disrupt the tissue structure, provoking an inflammatory reaction that can consume glucose followed by a repair process.38–40 The interaction of the sensor with the traumatized microenvironment warrants the need for a waiting period for the sensor signal to stabilize, and that period varies depending on the sensor type.21
This assumption will not be valid if sensors are calibrated during rapid changes in plasma glucose, which is a major source of sensor error. The effect of sensor lag on performance is most obviously seen during periods of rapid glucose rate of change (either up or down). Sensor levels may trail glucose levels by 5–10 min during periods of rapid change, but the most important effect on lag is to introduce error during calibration, which affects long-term sensor performance.
@Eric - This is a really good article !!!
Thanks for posting the relevant pieces. The whole thing was interesting. It was a little bit old (9 years), but the science is still relevant.
This was one of the things I meant to quote, but I got distracted and forgot to put it in my post! Thanks for highlighting it.
It depends on what mechanism they’ve chosen to enforce the 10-day wear restriction. Your work-around could succeed if the issue is the sensor ID as stored in the receiver/app. On the other hand, it has been suggested that the transmitter may insist on detecting an electrical disconnection from the sensor before a sensor start, and disconnecting appears to require breaking the base of the sensor. So the work-around in that case could be to pre-break the transmitter base before inserting the transmitter the first time, then taping well to maintain the transmitter connection during each 10-day wear period.
In any case, if a work-around is possible I’m sure it will be discovered quickly when the device actually becomes available. Then we’ll all decide what decision is best in our own circumstances.
I pay for the Dex out of pocket, and generally run the sensor until I see jitter (which for me is evidence of increased inaccuracy and impending sensor failure,) typically around day 14. Given equal pricing from Dexcom, the increase in annual sensor cost for me would be about $750 if we can’t evade the 10-day limit. In that case the G6 would need to be quite wonderful before I’d voluntarily switch from the G5.
The upgrade to G6 is automatic and can’t be declined?
I hope it can be declined. I run my sensors 25 to 50 days depending on insertion location. G6 only makes financial sense for me if my DME is greater than 80%. Also not crazy about how limited their Android selections are, which is why I primarily use Xdrip.
Same. Currently, we get a minimum of 14 days and we have gone as much as mid 20’s before, with Liam. It would make no sense for us to pay twice the money on sensors each year with the G6. So, I hope there is an “opt out” or “decline” option for users of previous G4/G5 systems.
I haven’t seen any indication of the “can’t be declined” part. My understanding of it is just that if you are on auto-refill of your sensors, they’ll switch you to the G6 when they can. If you call in to place your order, I’m confident that you can order the kind of sensor you want. Dexcom still will make G4 and G5 sensors because of the insulin pumps that use those sensors and that may not be upgradable to accept the G6.
I was trolling the Tandem site, and their stated timeline for integration with the G6 is first half of 2019. The timeline stated was for the Hybrid Closed Loop, and considering Medicare has not approved the G6 as yet I believe the G5 system will be around for awhile yet. Personally I am in no rush to upgrade - the G6 does not currently integrate with my pump, and it outwardly appears to be a more expensive system since currently there is no way to restart sensors. As the system gets out in the wild and people more clever than myself (almost everyone, lol) figure a way to extend the life of the sensors I may make the leap.
Their FAQ links to an updated compatibility page. For the G5, the Apple Watch section says “(watches require compatible smart device to use app),” but in the G6 section it does not say anything about that.
I guess this could just be an omission, but I really hope this means that the G6 is approved to talk to my iPhone and Apple Watch simultaneously, which was promised for the G5 but never delivered.
I look forward to being able to swim in the pool or ocean with my kids and have my blood sugar on my wrist while my phone is safely in the hotel room. Or to go for a run without my phone.
Of course I did all those things for 15 years before I had a CGM but it’s hard to go back to constantly guessing and testing.
I definitely agree. They are not going to pull support any time in the near future. The G6 will most likely be an optional upgrade.
I talked to a Dexcom rep a couple of days ago just to see how the upgrade would work since we get our daughters Dexcom from pharmacy rather than direct from Dexcom thanks to insurance . While speaking I asked if the G6 would communicate directly with the Apple Watch. I was told not at this time.