Tslim "low toner" syndrom

You know how many printer manufacturers set a limit on your ink or toner and force you to replace the cartridge long before the ink or toner runs out? I was wondering about Tslim and the 0 units left indicator to see if it performed the same way. Now I know why this is done in printers. They want to sell more cartridges. I cant imagine this would be the case for Tandem but was curious about the accuracy of the 0 units left indicator.

Today when I got this warning, I went to change cartridge, and proceeded to fill the tubing as if I had replaced and refilled the cartridge, except it was the same empty cartridge.

I was surprised to see the empty cartridge expel 10.2 units. So there is insulin still in there. Then upon resuming insulinm the indicator went to 60+ units. I let it run all morning with my basil (about 10 units) and before linch the indicator changed to 30 units left. So maybe there was still about 40 units in teh cartridge+the 10.2 that I used to fill the tube.

It is now close to dinner and I did my lunch Bolus of 8 units and the pump is showing 18 units left.

I would be curious if anyone else has tried this and f they see similar results. I am essentially getting a full days use out of what Tslim said was an empty cartridge.

Somewhat disturbing given the cost of insulin.

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I use medtronics minimed pump, and similar thing occurs. I measured about 5 units are left in reservoir when status shows 0. A warning is given based on user setting of units or time.

Many times bubbles accumulate at end of minimed reservoir, so I tend to change soon after warning. Tslim may be different regarding bubbles.

I am sure that it is a safety factor.

I have noticed this, to keep from wasting this insulin I will remove it from the spent Tandem cartridge with a syringe.

My Tandem T-Flex pump cartridge holds 480 units after my pump says it is empty I can usually remove 40 to 60 units from the cartridge. This is partly my fault since I tend to overfill by about 10 units but not 40 to 60 units.

I have theory as to why this happens, its only a theory concocted in my pea brain. I believe Tandem does this due to their cartridge design which is a flexible bag inside a hard shell. As insulin is used the bag collapses, as the bag collapses it gets harder to draw insulin from the bag causing occlusion alarms. I believe they sacrifice insulin to prevent these alarms. Like I said just a theory.


According to Tandem, there is 20-30 units worth of “dead space”. I have never seen an explanation for this, but I believe it’s because some of the pump function relies on pressure. Kinda like how there’s a minimum water level on pressure cookers. I know the fill volume at least is detected that way. Maybe it’s a margin of error or something.

I knew this before I choose the X2, though, and I’ve always sucked that remaining insulin out with the syringe, too. Just suck it out the same way you put it in. It was easier when they still used the luer lock connector.

I, too, had a pump that had way too much insulin remaining in the cartridge. I usually get that 20-30 expected units back out (plus anything remaining on the readout), but on that pump I was seeing closer to 60 units. I also had unexplained highs. I wound up having that pump replaced under warranty. It never threw an error code, though, so we had to jump through a few loops to get it replaced. They set me up with an appointment to discuss the problem with a diabetes educator who was then able to authorize the replacement.

I always thought I damaged the pressure sensor myself, though. I used to inject air back INTO the cartridge (that was still mounted in the pump), to make it easier to withdraw the remaining insulin. Don’t do that! If you’re n going to remove the insulin, just draw it out with minimum pressure and no boost. It’s possible your pressure sensor may also be bad. It might be worth a call to technical support to see about troubleshooting that. I wouldn’t tell them you did anything contrary to the written manual, though, it might void your warranty. Just explain you checked the empty cartridge (while not in your pump) and found nearly 60 units in a supposedly empty cartridge, which is out of spec. I’ve always had a great experience with their Tech Support!

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The X2 is about 15-20 units. I also draw the remaining insulin out with the syringe.

II have always removed the cartridge first before drawing out the remaining insulin and have never used the boost method.

What I am recovering is insulin that is not recognized by my pump. This has been the case since day one. If I fill with exactly 480 units that my pump holds and after using 11 to 12 units to prime tubing I should still have well over 400 units but I do not, my pump will say I have 300+ units which will adjust itself out as time goes by to the upper 300’s. The remaining insulin is lost in the electronics.

I am wondering if the spec is the same for my much larger capacity T-flex pump. Is this published spec and if so where can I find it.

Yeah. I know doing it while the cartridge is still installed is bad, but the X2 annoyingly alarms if you don’t complete the load processes fast enough. It was just one thing to speed the process up while I was still a newbie and slow at changes. Never really broke the bad habit. Haven’t had the pressure sensor issue again since I stopped injecting air into the pump, though.

The 20-30 unit dead space in the X2 thing isn’t actually in the user manual, but it has been mentioned in many of their training videos. I couldn’t really wager a guess if it’s the same in the t:flex or not.

I have always known that the dead space in my T-flex cartridge is more I have always chalked it up to the larger size of the cartridge. I have had this pump for almost 3 years and plan to keep it as long as it is working in a satisfactory manner. They don’t make the T-flex anymore, I’m not sure I could get a warranty replacement.

There is no advantage for me to get a new pump, They don’t sell the T-Slim X2 with Control IQ to type 2s, nor do they sell a Medtronic 670. The algorithms are not designed for T2.

I’m curious as to what you said about them not selling the Tslim to T2 or the 670G. I have the Medtronic 630G, it’s still under warranty but I had to come off all medication for about a year due to no insurance and couldn’t afford it. Anyway, my new CGM (Dexcom G6) isn’t compatible with Medtronic. I was hoping I could get my new Endo (whom I won’t see until July 7th) to switch me to the Tslim X2. We are also testing to see if I’m LADA aka T1.5.

I am Type 2 and have the T-Slim X2. I was also using Dexcom G6 and was about to open the X2 and get the Control IQ sw update but after getting a new job/insurance, I no longer have coverage for CGM. Now I am stuck with Libre from costco using the Costco Members Prescription program. Tandem never said they would not sell or that the algorithm is not designed for Type 2.

I suspect this increases the change of bacteria growing in your insulin. The folks at Tandem told me that bacteria can clog the tubing and can cause occlusion alarms. In my case I had lots of occlusion alarms and was told that Humalog is not meant to last in their cartridge for more than 2 days. I contacted Lilly and they said it should last for 3 days. But anyway, extracting old insulin and injecting into a new cartridge seems like a good way to introduce bacteria. Something to think about.

In my case, I am using an old pump that is out of warranty. I have had an X2 for over a year but have not bothered to use it since I cannot afford to pay for Dexcom G6. I didnt see any advantage to switching pumps but if there is a sensor problem, maybe I should try the new pump to see if the problem goes away.

If Control IQ is available for a T2 I will be pleasantly surprised, I will not contradict anything said because I have not found written yea or nay if it is available to T2’s

I base my belief that it isn’t on a statement on Tandem’s site that say that Control IQ technology is intended for persons over the age of 14 with type 1 diabetes mellitus.

I would love to be proven wrong, when I need to replace my pump I will check in to it. I would also like to hear from any type 2 that is currently using Control IQ.

You can use the cartridge long after low toner message - how to do it is on the net.

Easily hundreds of pages

When I switched to the tslim I noticed straight away that it seemed to waste insulin. They automatically have a 20 unit “buffer” of insulin that won’t get used but there is typically more in the cartridge. I have sometimes extracted the extra but I find that the insulin has lots of air bubbles and I worry about contaminating the fresh insulin that I am putting into a new cartridge. Like an earlier person posted, I think the waste of insulin is due to the design of the cartridge.

I only put 150 units in my tslim. It lasts 5 days (I use approx. 24 units a day). The tubing takes 12 units. The plastic bag needs some insulin to operated correctly. I don’t try to remove old insulin as I don’t want to keep mixing the old with the new. In theory and anecdotal observation, I believe the longer insulin is heated up via body heat the less potent it becomes.

Encourage you to check again with your insurer. In my experience, the call center employees are not trained about “standards of care” in the treatment of T1D or T2D; they “don’t know what they don’t know” and again and again (in my experience) give false or incomplete information. In other words, verify, verify, ask again. CGM is often covered under a pharmacy benefit, usually with mail-order fulfillment. The Pharmacy Benefit Manager (PBM) employees may also be oblivious about CGM, but you can guide them with the NDC (National Drug Code) numbers that Dexcom provides here: https://provider.dexcom.com/education-research/clinic-resources/prescribing-info/how-fill-dexcom-g6-pharmacy-prescription Dexcom or a 3rd party distributor like Edgepark can also help you navigate your insurance better than the insurer’s “customer no-service reps.”

Likewise, be aware that Dexcom started a new “Patient Assistance Program” that may be helpful and is described here: https://www.dexcom.com/covid19-assistance

Another concern with harvesting insulin from a Tandem cartridge is that the potency may be diminished, with greater risk for hyperglycemia or even ketoacidosis. Insulin in the cartridge is exposed to higher than “room temperature,” especially with the Tandem battery is charging.

With some states implementing price caps on insulin and both Lilly and Novolog rolling out programs to reduce insulin costs, the risks of harvesting insulin from Tandem cartridges or infusion sets may not have the expected benefits.

My son routinely used to use cartridges for 7-9 days, with no evidence of the insulin losing potency.
However, this changed about 2-3 months ago, and now if he we don’t change his cartridge on day 6 or 7 at the latest the insulin is dead as a doornail (typically it stops working overnight between day 6-7 and I’m up at 2-3am changing the cartridge and trying to get his BG down again!).
I don’t know if this is due to a change in the cartridges or a different batch of insulin.

Could it be your son’s hormones / growth / activity level is / has changed?

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