Anybody Pumping U-500?

[BuffaloBenny]

Hey all. I'm new to the forums. I'm a type 1 (Dx'ed 4 years ago) and I've been on the pump for about a year, and last week I switched to U-500 (I'm insulin resistant). Is anyone else out there pumping U-500? If so, has it worked out for you? I've only been on it a few days, but I seem to be having some difficulty maintaining control...

U-500 is a type R insulin, so it takes longer to kick-in than Lispro, but has a longer duration. I guess I need to work on my bolus timing....I've been having some crazy BG spikes after eating (400+), and I have been taking correction boluses to try and get these down, but then I crash several hours later. It's strange, I'm using a lot more than 1/5th of my previous u-100 doses. E.g. instead of taking 5 "units" of U-500 for a meal that would have required 25 Units of Humalog, I need to take 7-8 of U-500

It is my understanding that a lot more endo's are prescribing U-500, but I can't find any info on people actually pumping it. I wonder if the effects vary between pumping and injecting? Any thoughts?

[Scratch]

Hey all. I'm new to the forums. I'm a type 1 (Dx'ed 4 years ago) and I've been on the pump for about a year, and last week I switched to U-500 (I'm insulin resistant). Is anyone else out there pumping U-500? If so, has it worked out for you? I've only been on it a few days, but I seem to be having some difficulty maintaining control...

U-500 is a type R insulin, so it takes longer to kick-in than Lispro, but has a longer duration. I guess I need to work on my bolus timing....I've been having some crazy BG spikes after eating (400+), and I have been taking correction boluses to try and get these down, but then I crash several hours later. It's strange, I'm using a lot more than 1/5th of my previous u-100 doses. E.g. instead of taking 5 "units" of U-500 for a meal that would have required 25 Units of Humalog, I need to take 7-8 of U-500

It is my understanding that a lot more endo's are prescribing U-500, but I can't find any info on people actually pumping it. I wonder if the effects vary between pumping and injecting? Any thoughts?
R insulin has an activity profile of 6 to 8 hours, somewhat dependent upon where it is being injected or infused. Generally the most rapid absorption occurs in the tummy area, then the arms, then legs are often the slowest.

R units aren't exactly equivalent to the analog rapid insulin units. I remember it being about needing 10% more units of R to get the same effect as the analogs. 7 to 8 would still be higher than expected.

R takes about 30 minutes to start getting going. When for a brief time I was using NPH for basal and R for bolus, I would very often try to inject my meal boluses at least 30 minutes ahead of time, although that introduces the uncertainty of never exactly what might happen to make you forget about eating on time.

If I also recall correctly and assuming a 6 hour activity profile, it takes about 2 hours after injection or bolus start for 50% of the R to be used. At 3 hours, 70% will be used. If you're testing 2 hours after eating, you will see some higher blood sugars because of less R being absorbed versus Humalog, etc. Although 400 is much higher than any of us would want.

Be careful with the administration of correction boluses, you can get a lot of stacking and bad tail effects with R due to its longer activity profile.

[BuffaloBenny]

Thanks. I was thinking about administering boluses earlier...as you mentioned there will always be some danger in doing so, but it doesn't seem like a major issue.

Correction boluses were sending me on a roller-coaster. 400+ at 3pm, and by the time i got home from work around 7pm I tested a 53. I was like "no way...I don't even feel weird." And then I instantaneously got the shakes. "Oh....there it is"

I've been slowly cranking up my daytime basals as well. (Fasting BGs have been decent)

[poodlebone]

When I was first diagnosed I was NPH + Regular (regular Regular, not U-500 regular!) and was given a chart of how far in advance to inject the R based on BG. I have no idea what the actual numbers were, but basically if my BG was in a normal range I was to inject 20 minutes before breakfast. If I was low, I was to inject and then eat right away. If high, I was supposed to inject more than 20 minutes, but I forget how much more. It probably depended on how high my BG was.

I'm pumping Humalog and even with that I've seen the benefits of bolusing in advance (I'm using CGMS as well). Even if my BG is normal I'll wait 15 minutes before I eat most times. It really cuts down on spikes. With U-500 15 minutes probably wouldn't be enough time to have it start working, you'd probably do better closer to 30 minutes (depending on BG).

[SueM]

Hiya,
I know of 2 people using U500 in their pumps.(UK)
I do use regular in my pump though.
You do need to set your basal correctly 1st as with any insulin used.
You also need to find out your insulin duration as well.
Mine is set at 4 1/2 hours and works just fine for me.
Timing of your meal bolus is also very important.
I find 1/2 hour is fine for me but others find they need up to 3/4hr.
Everything is down to the magic trial and error though.
Don't make to many hasty changes and you will get there eventually.
Best wishes
Sue

[lark 27]

I pump Humalog so don't have a lot of insight here, but I do know that when my BG is significantly high (over 250 for example) it affects my correction factor to bring BG down. In other words 1 Unit might drop me 25 pts. if I'm at 150, but at 300 1 unit will not drop me 25 points. So, if you're on the roller coaster and get to the high levels that might need to be taken into account as well. Good luck.

[BuffaloBenny]

Thanks for the responses everyone. I notice a lot of you are using CGMS... Out of curiosity does your insurance cover that or are you paying out of pocket? My insurance didn't cover it when I started pumping last year, but maybe it's time I checked again! :)