Medtronic pumps and 'factory set' BSL range

[kitedoc]

The other day at my endocrinologist appointment he mentioned that new Medtronic pumps have an unalterable set range of BSL.
The range was something like 3.3 to 7.0 mmol/l.
Of course the lower figure was concerning to him because of car driving regulations and the risk of hypos to the patient in general. My DNE had rung up to query this range (and why it is not alterable) to be informed that the basal rate suspend function would actually stop the BSL ever-reaching 3.3 mmol/l. (thus assuming the pump user could afford the CGM component).
But why set at 3.3. mmol/l was not answered or why the unalterable range setting.
Does anyone have any further information or any comments to make!!

 

[Cobia]

@kitedoc is this for the 640g or 670g?

All i know is the range is factory set.

Does this opinion sound right?

https://bionicwookiee.com/2019/02/11/a-closed-loop-is-not-every-closed-loop-670g/

 

[kitedoc]

Hi @Cobia, I did not find out the model. It seemed like a new thing so the 670 is the likely one.
But when I looked up the Medtronic site it said set from 3.9 to 10mmol/l as the in-range setting.
So I don't understand where the 3.3 mol/l that I heard fits in.
Even so the recommendation in South Australia is fora TI D's BSL to be over 5 mmol/l before driving. This allows for an error range in the glucose meters such that a reading of say, 4.5 mmol/l with a +/- 15% error range could be a range of 3.925 to 5.175 mmol/l.
So in Medtronic auto mode the TID driver could not rely on the pump keeping BSLs over 5 mmol/l as the the error range of the CGM has to be allowed for.
And by whose authority does Medtronics dictate that 10 mmol/l is the top of the 'in-range' BSL.? This reeks of Medtronic deciding that everyone should follow the ADA recommendations including their high carb diet.
Meanwhile some diabetics on other pumps or MDI using a very low carb diet report they achieve in-range readings (4 - 7.8) as often as or more often than 80%.
The fact that Medtronics appear to have moved the 'goal posts' on the in-range values could point also towards the inability of their system to do better.
Any loop system which performs well is a great achievement. But flexibility has to be blended with limits, not limits dictate pre-conceived out-dated concepts about acceptable blood sugar ranges.

 

[porl69]

Pretty sure thats on the 670G. Just checked my 640G and can set from 3.3 upto 13.9 for the BG range in the bolus wizard

 

[Cobia]

Hi @Cobia, I did not find out the model. It seemed like a new thing so the 670 is the likely one.
But when I looked up the Medtronic site it said set from 3.9 to 10mmol/l as the in-range setting.
So I don't understand where the 3.3 mol/l that I heard fits in.
Even so the recommendation in South Australia is fora TI D's BSL to be over 5 mmol/l before driving. This allows for an error range in the glucose meters such that a reading of say, 4.5 mmol/l with a +/- 15% error range could be a range of 3.925 to 5.175 mmol/l.
So in Medtronic auto mode the TID driver could not rely on the pump keeping BSLs over 5 mmol/l as the the error range of the CGM has to be allowed for.
And by whose authority does Medtronics dictate that 10 mmol/l is the top of the 'in-range' BSL.? This reeks of Medtronic deciding that everyone should follow the ADA recommendations including their high carb diet.
Meanwhile some diabetics on other pumps or MDI using a very low carb diet report they achieve in-range readings (4 - 7.8) as often as or more often than 80%.
The fact that Medtronics appear to have moved the 'goal posts' on the in-range values could point also towards the inability of their system to do better.
Any loop system which performs well is a great achievement. But flexibility has to be blended with limits, not limits dictate pre-conceived out-dated concepts about acceptable blood sugar ranges.

Yep i totally agree a loop system has to be flexable as we have to be... im currently mdi my target is 4 to 8.5 im 80% in range when driving find the best way to stay above 5 is vlc but can be hard to maintain for extended periods(in my case 6-7 weeks at a time). I want a system that keeps me above 5 during the day i apply this while working its safer even tho im not driving on roads every minute of the day... its a requirement i have on me all the machines here dont forgive mistakes.

I agree with the stay above 5 to drive it hits home since i have a heavy vechile licence.

Going to the nuro next month hoping to see my endo at the same time i need her to sign off on the type of pump i think i should get..,,.

 

[ringi]

I think the Medtronic automode is mostly design to keep people alive over night and in nurcing home etc, not to take over from someone who can decide for themselves how much insulin to use.

 

[kitedoc]

Pretty sure thats on the 670G. Just checked my 640G and can set from 3.3 upto 13.9 for the BG range in the bolus wizard

Thanks for that @porl69 . The plot thickens. Why would you want the extremes of that range ??

 

[kitedoc]

Yep i totally agree a loop system has to be flexable as we have to be... im currently mdi my target is 4 to 8.5 im 80% in range when driving find the best way to stay above 5 is vlc but can be hard to maintain for extended periods(in my case 6-7 weeks at a time). I want a system that keeps me above 5 during the day i apply this while working its safer even tho im not driving on roads every minute of the day... its a requirement i have on me all the machines here dont forgive mistakes.

I agree with the stay above 5 to drive it hits home since i have a heavy vechile licence.

Going to the nuro next month hoping to see my endo at the same time i need her to sign off on the type of pump i think i should get..,,.

With you @Cobia. On my Tandem pump I can set a BSL figure which I would like the pump to make correction doses towards. So for example I have it set up for 5.5 mmol/l. Of course not being closed loop it is limited in what it can achieve (something called the human factor mucks it up from time to time)!! But at least it is not likely to dose me into BSLs lower than 5 mmol/l.
I hope all goes well for both appmts and that you are as happy as you can be in your pump choice !!

 

[Cobia]

@kitedoc this might be a hornets nest.

 

[kitedoc]

How so, @Cobia ?

 

[Cobia]

@kitedoc just the vibe i got from my diabetes educator... which her opinion was i had to to go for a medtronic pump even tho there is 6 others available in australia. My endo said its entirly my choice....

There seems to be a lot of politics involved from my perspective.

If the 670g thinks an aceptable low target is 3.3 whats it high when it will run with a hba1c of around 7%?

I would have thought the low side would be higher its supposed to be from just what ive seen over at tudiabetes....

 

[kitedoc]

It is a tangled web alright!! I am hearing that not only in UK but in Oz that Medtronic pumps are getting errors, causing problems and that Medtronic actually make a lot of the other companies infusion sets. The plastic cannula ones are causing troubles and many have turned to using infusion sets with steel cannulas.
Not sure if the company is experiencing quality control issues but the increase in troubles has made my endo and nurse worried !
These 3.3 mmol/l settings seem to me to be forcing people to use Medtronics CGM so that the suspend infusion function is used. But as you point out how does that ensure you stay above 5 mmol/l?
I gather Medtronic CGM is more expensive that Dexcom. I have not priced the Medtronic CGM for Oz but Dexcom works out at
about AUD 7,000 per year.

 

[Cobia]

Mate if my info on the dexcom is right with xdrip you can extend the sensor life. i have had it runing here with the libre ive bulit it from the sources but it would be better with one type of insulin...

And dexcom.


Just from my perspective i thought we were supposed to be in control of how things are supposed to run.... being a farmer i like that illusion.

 

[kitedoc]

That is great to hear about the Dexcom sensor, Trev. Let us hope it is true.
I think doctors too will be pretty annoyed about Medtronics dictating to both patients and them !!
When Tandem gets to the semi-closed loop stage it will be interesting to see if they follow Medtronic's control
strategy.

 

[kitedoc]

I am wondering if @tim2000s would mind commenting on set ranges ?

 

[ringi]

Are the ranges for emergency alarms, not the range they think someone should be aiming at?

 

[tim2000s]

@kitedoc To be clear here, you are talking about two different things.

The range described is what you can set within the pump for alerts from the CGM system and low glucose suspend. It's not a hardcoded range for the APS system, and it's designed for use with low glucose suspend only and alerting. Overnight, for example, you may not want a high number as your threshold low level so you can set it lower and not get woken up by alarms, knowing full well that predictive suspend will kick in safely.

For removal of doubt, when in auto mode, the target is 6.5mmol/l. There is no upper and lower bound - it only targets that value and you cannot change it.

 

[LooperCat]

when in auto mode, the target is 6.5mmol/l. There is no upper and lower bound - it only targets that value and you cannot change it.

I find that unacceptably high, tbh.

 

[kitedoc]

@kitedoc To be clear here, you are talking about two different things.

The range described is what you can set within the pump for alerts from the CGM system and low glucose suspend. It's not a hardcoded range for the APS system, and it's designed for use with low glucose suspend only and alerting. Overnight, for example, you may not want a high number as your threshold low level so you can set it lower and not get woken up by alarms, knowing full well that predictive suspend will kick in safely.

For removal of doubt, when in auto mode, the target is 6.5mmol/l. There is no upper and lower bound - it only targets that value and you cannot change it.

Thank you @tim2000s. So then it becomes a matter of how well the pump system can maintain that target of 6.5 mmol/l given influences of stress, food intake etc. What do see is needed for the DVLA, for example, to ratify use of loop insulin pump systems in future ?

 

[tim2000s]

I find that unacceptably high, tbh.

It's well below the average glucose level required to achieve an Hba1C of 6.5%, (typically, average glucose of 6.5 will give you an Hba1C of 5.7%) and given that in general, 92% of the T1 population of most countries is above 6.5%, I think it's a perfectly reasonable number to aim for.

What do see is needed for the DVLA, for example, to ratify use of loop insulin pump systems in future ?

The DVLA is unlikely to care. They don't talk about insulin delivery systems (pen, syringe, pump or hybrid closed loop) in their documentation. They just care that your glucose levels are high enough that you don't crash and kill someone, and with ratification of CE marked CGM systems (which Guardian 3 is), they're happy enough for you to use it.