U500 and correction factor time

Is anyone else on U500 and a pump? Because of the amount of insulin I take (9 units at breakfast which would be 45 regular units, 5 x9, 5 at lunch (25 regular units) and 7.5 (37 units) I am on U500.

The problem is that it seems forever to have the correction factor work for high blood sugars. Is anyone using a fast acting insulin like Humalog with their U500?

I don’t have experience with u500, but I know that large doses and concentrated doses of insulin take longer to absorb than small doses.

So it makes sense that it takes a long time to see the effect.

Some people take large doses of Regular insulin to work as an intermediate insulin, because it slows down absorption so much it becomes a longer acting insulin.

I assume you are taking some insulin resistance meds, if not you might want to
Talk to your doctor about it. Because smaller doses of insulin is generally easier to predict than high doses

Good points! I see the doc next week.

Nine units of U500 insulin contains the exact same amount of insulin, nine units, as U100 insulin. U500 insulin is concentrated, so the volume of the same insulin dose is 1/5 the volume of the same dose of U100 insulin.

I don’t have any experience with U500 insulin but I suspect the challenge that you’re up against is the increased insulin resistance of high blood sugars. In other words, for many of us, the correction factor needs to be increased as the level of hyperglycemia goes up.

For example, correcting a 300 mg/dL level down to 200 mg/dL will take more insulin than correcting a 200 mg/dL level down to 100 mg/dL. If you’ve tested a correction factor and found it to be 1:25 (1 unit of insulin will drop glucose by 25 mg/dL) for correcting below 200 then you might find that you need to make it stronger to correct at higher levels. It might take a correction factor of 1:15 (1 unit of insulin will drop the glucose level by 15 mg/dL).

How do you know your correction factor (also known as insulin sensitivity factor)? Did someone tell you what number to use or did you experiment to discover your correction factor?

Doctor set the correction factor at 1 unit for every 50 points over 120, I think.

That number is just a guess, one that’s likely heavily weighted to ensure you don’t come anywhere near hypoglycemia. In other words, the corrections are likely to be a weak sauce for treating actual high blood sugar.

Your doctor’s correction factor recommendation is just a starting point for you to experiment and find what your actual number is. This requires some work but if you do it and find your actual correction factor, you corrections will be more effective while also safe from driving you into hypoglycemia.

Does your doctor’s office have someone with a diabetes educator credential on staff? This would be a good person to help guide you in this effort. You could also home in on your actual insulin to carbohydrate ratio as well as your pump’s basal rate schedule.

Better yet, you could do some study to find out how to intelligently change these settings yourself. Diabetes is with you all day, every day but your doctor can’t cover all that time.

I recommend that you adopt a longer term goal to learn how to experiment safely with your pump so that you can discover what your body needs. Check out the book, Think Like a Pancreas by Scheiner for instruction about how to properly set your pump for your unique needs. There are other books that cover this topic but this one is good starter.

Dosing insulin to treat diabetes is not a set-it-and-forget-it business. Diabetes is dynamic, not static. It remains in motion and our challenge is to somehow align our insulin delivery to that ever-changing need.

It’s not easy, but it can be done. If you depend on your doctor for all your pump settings, it’s likely you will fail to engage the power of a customized insulin delivery plan. I make insulin pump setting changes every week.

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U-500 insulin is concentrated Regular insulin. Therefore it will work much more slowly than Humalog or other fast-acting insulins. So maybe it is worth a try to add an injection of Humalog when your BG levels are high. But it will certainly complicate your insulin regimen since you will not have the Humalog reflected in your pump statistics. Since a prescription is required for any of the fast-acting insulins, you’ll need to discuss this with your doctor and get his/her input.

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When I search for U500 insulin I come up with U-500 Humulin R, it is a concentrated version of Humulin R which is an intermediate acting insulin. Humulin R is not the same as the rapid acting (Humalog, Novolog , etc.) normally used in pumps.

It surprises me that you are being prescribed U500 Humulin R to use in a pump because I know of no pump that is calibrated for U500 insulin. While it is possible to use conversion factors to obtain proper set up it does not end there, this conversion must happen with every interaction with the pump, there is a constant chance for serious error. It can be done but please be careful.

Like @Laddie said Humulin R 500 is regular insulin. Its action time is slower and it stays in your system longer. Your pump settings need to reflect these longer action times.

I have not used regular insulin but on the surface it looks like it is not an ideal insulin for making corrections because of it slow action time, perhaps @Laddie is right, maybe you need a fast acting insulin pen for corrections.

We have many members that lived through the days of regular insulin, it would be nice to hear what were the strategies for making corrections while using regular insulin.

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I used to take regular and nph. Regular was the fastest insulin on the market.
The reality is, it wasn’t really that different.
I would prebolus 30 min ahead instead of 20 w humalog.
It also would hang around longer. I wasn’t testing much back then so it’s hard to say.

With an algorithm, speed is everything. When you are only guessing in the dark, like the old days, it was a very different experience. That was back when a 7.5 a1c was considered pretty stellar.

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I have heard people in the past say the U500 is really slow in acting.

Indeed, Humulin U-500 is rather slow acting, with its action peaking 4 to 8 after delivery. If that’s all you have, prebolusing by 4 or more hours may be your only tool.

Humalog is faster acting and isn’t available in U-500 but is available in U-200 Kwikpen.


Thanks everyone. Like I say, I see the endo Tuesday.

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This is why user needs to do conversion. In first post, mentions 45 “units” of insulin (assumed in U100 liquid volume) units.

If pump is filled from U500 pen, (concentrated), would get smaller volume of insulin (similar to volume of 9 “units” via U100 syringe). So pump assumes U100 units, and user has to do conversion to deliver U500 insulin from “dumb” U100 based pump.

But unlikely doctors would prescribe.
And only U100 is available in vials, but in theory a pump could be filled from pen insulin and user responsible for correct dosing calculations.


Here is study of U500 via pump.

I am heavily insulin resistant, I overcame the limitation of bolus size of the average pump by purchasing a Tandem T-flex pump which allows bolus sizes up to 60 units, if not for this pump I would be wanting to do what @Dennis4 is doing and that is use a more concentrated insulin.

My T-Flex pump is no longer available for purchase, I will eventually have to look at other options. I have looked at U-500 as an option but find their website says it is not to be used in a pump. Thats why I was surprised @Dennis4 was prescribed it, I would do as he is doing if allowed.

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I pay a lot of attention to all of Tandem’s investor into, and they 100% believe the future in expanding their business lies in catering to Type 2 market, who generally want discreet dosing and often require high volume doses. They’ve commented quite a few times now that this will require branching out into concentrated insulins and say they’ve been experimenting with it already.

In fact, the T:sport that many of us are looking forward to is supposed to be marketed to the Type 2 audience, even though it only has a 2mL (200 unit) capacity. I wouldn’t be surprised if it launches with concentrated insulin approval next year. (Darn thing keeps getting postponed because they’re waiting for the mobile bolus software to get approved first.)

They’re also doing studies now to expand the T:slim X2 w/Control-IQ to be indicated for Type 2s, so hopefully that too will bring the inclusion of concentrated insulins.

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I saw a tsport at a JDA event , just before the shutdown started.
It has stamped on the back “u100 insulin only”
That’s what my tslim says too. Of course they can change that.
I have heard of a few people who use u200 insulin in insulin pumps.
It makes sense especially if they are going to shrink the reservoir
I use 5o units a day, total. So I fill my cartridge to 175. I can go all the way to 300.
I could easily see using u200 and filling 80 or so.
I only ever go to half units, I don’t split more than that.
More importantly, if it is the same price, it would save money.

If that’s the case why would thy pull the T-flex from the market. T-flex is merely an original T-slim pump with a larger cartridge and altered software to allow the higher volumes that an insulin resistant T2 might need.

Market share and dividends. It costs a lot of money to produce, evolve, and support a line of equipment. There’s just wasn’t a big enough market for the T:flex in their existing ecosystem, when they were marketing to Type 1s and their Endos, and the smaller capacity was suitable for that audience. When product lines lose money, they get cut.

I’m summarizing from a bunch of different telecasts, as they all offer different little tidbits of information. One of the biggest problems they face with the Type 2 market is actually establishing a line of communication between Tandem, doctor, and patient… Because the overwhelming majority of Type 2s are treated by their general practitioner, not an endocrinology team. It’s been much easier to reach out and train the select few endocrinology offices, than it is to support and train each and every single GP out there… Which pretty much cuts the potential supply line of Type 2s off at the ankles. As of yet, their Type 2 patient base has been largely limited to those with special insulin needs who have been transferred to an Endocrinologist, who is comfortable prescribing the pump off-label, and even then only to those patients who have insurance who will cover an off-label pump for Type 2s.

That’s a lot of hurdles to overcome! And that’s not even including the stigma which often comes attached to Type 2. Many Type 2s actually feel ashamed of needing insulin, because society in general judges them poorly, as if they did this to themselves and have failed in some major way. There’s a big demand for discretion, and the giant pump with tubes and flashing lights just didn’t meet that criteria.

Tandem has recently partnered with a new patch-pump company called Cequr. They think that it will provide powerful insight into his to actually get these devices into Type 2 hands. Once the market is established, then there’s more money for product support and you’ll get all these specialized pieces of equipment designed for high volume insulin dosing. We’re still at the starting line, though.

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Do you know % T2s using insulin? I thought majority were on meds only.