Hacker News Reader

Comment by RPLong | Hacker News Reader

One thing I'm worried about WRT switching to a pump is the impact of heat on insulin. I can't have a Humalog pen exposed to 80+ degree heat for more than a few minutes without it losing efficacy. I live in Texas. What will stop the summer heat from cooking all the insulin in my pump's reservoir while I'm walking down the street?

Do you have any thoughts on this? I'd love to have more flexibility.

View on HN

Insulin efficacy isn't really an issue until you are about 90+ F, anything below 90 and it will take long enough to breakdown the proteins that you would already be due to swap your infusion set (every 3 to 4 days). But being in Texas, you might exceed 90F at which point, yeah it could go bad really fast. Not a big deal though, just get a cooling wallet for your pump; FRIO seems to be the popular choice https://www.frioinsulincoolingcase.com/frio-pump-wallet.html

Thanks for the pointer. I have a FRIO, and love it. I wasn't aware that they made FRIOs for pumps.

I use the Tandem t:slim X2 pump in conjunction with the Dexcom G6 continuous glucose monitor. The one thing I hate about the pump is that it's always clipped on or in a pocket. Literally, I'm always plugged into this thing. So that part does suck, but otherwise it's just a lot better than manual injections.

It keeps track of my insulin on board so I don't have to worry about stacking and getting a low nearly as much. It's programmed with my carb ratios so I just type in the carbs and it doses accordingly, it will even take your current BG into consideration and increase/lower the insulin dosage to help get you at target BG.

With manual injections, you have to give 1 full unit of insulin; the pump can give doses as small as .04 units of insulin so the dosing is much more precise. You are no longer saying, "Well should I round up or down..."

The pump has a closed loop with the CGM, so the pump knows if my blood sugar is going to be low BEFORE I'M LOW. So it just automatically quits giving insulin to help prevent the low before it ever happens.

Honestly, it's pretty amazing to me how far these things have come from just 10 years ago.

Agreed with the other user's assessment of pumps. I've had T1D since 1990; been wearing a pump since 2004. My A1C has averaged 6.3 since 2000 (so I was in control before I started on the pump) - and I lived in Los Angeles from 2000 to 2008 (so I've dealt with the heat).

Personally, I've rarely had an issue with the heat affecting my pump's reservoir - except when I would go skydiving up in the Mojave desert, where temps would reach north of 110 degrees F. Would simply pack it in a bag with a cool pack when I was outdoors, then put it back on once I got to the ground and was back inside.

Since I was in good control, my biggest reason for transitioning to the pump was convenience. I was up to taking 7 injections a day (when I was working from home and couldn't resist the urge to snack). Once I made the switch, I was amazed at the convenience - I could eat almost anything and take the insulin to cover it (of course, moderation is the key here - and knowing how quickly and persistently some foods elevate your blood sugar. For instance, I'd much rather have a snickers bar than Chinese food. The high fat content and the rice carbs wreak havoc on my BG).

Point being, it's well worth looking into it, if you have the means and the desire.

I've been on a Medtronic pump since making the switch, but will likely be jumping over to a Dexcom CGM and compatible pump once my latest pump warranty is up. (I've stopped using the Medtronic CGM due to some hassles with calibration issues; the Dexcom is supposedly more reliable overall).

Regardless, good luck!

Yeah; it's really too bad that the Medtronic CGM is not better. I think Medtronic's pump is slightly ahead of the Tandem pump today on the closed loop, but I'm hoping Tandem catches up this summer if they get their new predictive algorithm approved for automating correction dosing for high BG.

Our 7 year old lays on top of his pump regularly when he sleeps and despite it making the entire pump way hotter than 80 degrees, it’s never caused any efficacy issues. He’s played soccer for 3+ hours in the 95+ degree heat (4 days in a row), no problems with the insulin on board.

From the context of your message, I think I correctly understood you to mean you have had no problems with the insulin that is in the insulin pump's infusion set reservoir?

Trying to help and I don't want to come off as rude, so please forgive me in advance. The term "insulin on board" has a very specific meaning and it refers to the fast acting insulin that is currently in one's body and still active.

So let us say you are using fast-acting insulin, like Humalog, and it stays active in your body for 2.5 hours.

You take 3 units of insulin at Noon

1 hour later you take another 3 units of insulin

1 hour later you take another 4 units of insulin

At 2:00 you have 10 units of insulin on board

At 2:30 you have 7 units of insulin on board

At 4:30 you no longer have any insulin on board

You're right - I'm sorry, I shouldn't have been so careless with my words. What I meant was, we've never had a problem with the insulin in his pump's cartridge/reservoir even in 90+ degree heat for 3+ hours with him running and sweating.

Reply on news.ycombinator.com