Very careful insulin dilution instructions

These instructions will seem ridiculously over-the-top detailed and meticulous to many of you. That’s fine. They are intended to be as ultra-cautious and careful as possible.

It’s one thing if you go low or high. You know what’s happening and know what to do. It’s an entirely different thing when it happens to a 9-month-old infant, who can’t tell anyone if they are low or high, and doesn’t even know.

Insulin and diluent look the same. And you can’t tell if you have 100% or 10% or anything in-between. So these steps are designed to make it mistake proof. When you have your vial labeled 10%, you need to know with absolute certainty that the vial contains 10%. There can be no question about it.

Let’s start with a few rules. You don’t do this at 4am when you are tired. You don’t have the TV on. You don’t have your phone with you watching TikTok.

There is no multi-tasking here. You only do this when you are wide awake and you are doing nothing else. You treat this procedure with as much focus as you’d want a surgeon to have when they are operating on you.

With me so far?


The “One Vial at a Time” rule

These steps are not the most efficient. They are not designed to be easy, they are designed to be safe. Someone could say, “Wouldn’t it be easier if you did it this way…

Sure. But we are not trying to make it as easy as possible. We are trying to be very safe and meticulous.

I could just say - “Put 10 units of insulin and 90 units of diluent into the mixing vial.” Those would be very simple instructions. But they would also leave a lot of room for possible mistakes.

So I am giving you instructions that are methodical and purposeful. Bear with me and read through it all carefully…

By design we are using 2 different types of syringes to make it easier to differentiate them. Only one of the syringes can hold 90 units of diluent! So that makes it easier to not make mistakes. We don’t want 2 syringes that contain diluent or 2 syringes that contain insulin.

Once something is in a syringe, you can’t tell what it is! So using 2 completely different types of syringes will help you be more careful.

On your working table, clear it out. Remove all the clutter. And you will sit at that table to do your work - to draw out the insulin and diluent, and put it in your small diluted vial (the mini-vials I sent you).

I am recommending a “One Vial at a Time” rule. This rule helps prevent mistakes. It is methodical.

The rule is that there can only be one vial on that table at a time. Never more than one. This prevents mistakes, because the diluent and the insulin vials look very similar. Both have a white label, both are from Lilly Pharmaceuticals, both are 10ml vials, etc…

We don’t want to make a mistake picking up the wrong vial, so only one vial is ever on that table at any time.

Gather all of your stuff:

  • alcohol swabs
  • 2 of your larger syringes (the 1ml, 100-unit syringes)
  • 1 of your smaller syringes (the 0.30ml, 30-unit syringes)
  • your vial of diluent
  • your vial of insulin
  • your small mix vial
  • 2 pieces of notebook paper, a pen, and some clear tape

Put all of those things on a different table or shelf somewhere, not on your working table.


I am writing this all out for a 10% diluted mix. As this changes over time, you will adjust the amounts to change the concentration. But as a rule, if we always do it in 100 unit TOTAL quantities, the math will always be super simple. You add the units of diluent to the units of insulin, and it should always equal 100 units total.

On our PM, you said your baby is taking between 1.4-1.7u diluted Humalog every day. So 100 units of the mix is going to last 50 days. You now have 3 vials of diluent (1,000 units in each vial), so that means you have about 4 years worth of diluent!
(That stuff lasts forever, don’t pay attention to the expiration dates on there. It is inert, all it does is dilute. And it will always dilute. Follow sterile techniques, swabbing the vial, and only using a new sterile syringe, and you will have a 4-year supply of diluent.)

I know the dosage and dilution amounts will change as your son grows, but you have a pretty good stash of the stuff to start with! :+1:


Okay, let’s get started…

On one of the pieces of paper, write “90 units of diluent” and put that on a different table (not your working table). On top of that piece of paper, set one of the larger syringes and your diluent vial. Check that vial. What does it say? Check it again. Make sure it says “diluent”. Check it one more time.

On the other piece of paper, write “10 units of insulin”, and put that on a different table than the working table. On top of that piece of paper, set the smaller syringe and the insulin vial. Check what it says on that vial. Make sure it is the insulin vial. Check it again.

Get your tape, pen, and the mini-vial. On the piece of tape, write “10% insulin mix” and the date. Put that tape on the vial. We always want to label it! And then put a clear piece of tape over the label so it does not smudge off.

We have to make room for the mix to go in the mini-vial. Swab the top of the mini-vial and get a large syringe. Remove 100 units of air from the labeled mini-vial. Set the mini-vial somewhere, away from your working table.

Always follow the same order for drawing the diluent and insulin and mixing it. Drawing and mixing it in this order only matters because following the same steps with intention and purpose prevents mistakes, rather than doing things randomly. Always follow the same order.

Your working table should have nothing on it right now except alcohol swabs. Take the piece of paper that says “90 units of diluent”, and the diluent vial and the syringe that is on top of it. Move this to the working table. Make sure it is a large syringe, and the vial is the diluent vial. Swab the top of the vial, add 90 units of air, and then remove 90 units of diluent from the vial, making sure there are no air bubbles in the syringe.

Cap your syringe. Put the diluent vial back in the fridge! We are done with it for now. Don’t leave it out where you might pick it up by mistake! Take the syringe that now contains the 90 units of diluent and the “90 unit” paper, and set this aside somewhere, no longer on the working table.

Now we do the same steps for the insulin vial…

Take the piece of paper that says “10 units of diluent”, and the insulin vial and the syringe that is on top of it. Move this to the working table. Make sure it is a small syringe, and the vial is the insulin vial. Check that name again! Swab the top of the vial, add 10 units of air, and then remove 10 units of insulin from the vial, making sure there are no air bubbles in the syringe.

Cap your syringe. Put the insulin vial back in the fridge now. We are done with it and do not want to leave it out where you might get it by mistake. Take the syringe with the 10 units of insulin and the “10 unit” paper, and set this aside somewhere, no longer on the working table.


Take a breath, we are almost done…

Your working table should be empty except for alcohol swabs. Let’s get your stuff.

  • Get your labeled mini-vial and put that on the working table.

  • Get the piece of paper that says “90 units of diluent” and the syringe that is on top of it, and put that on the working table.

  • Get the piece of paper that says “10 units of insulin” and the syringe that is on top of it, and put that on the working table.

Let’s check our math.
90 +10 =100 :white_check_mark:
10 / 100 = 10% :white_check_mark:

Math is good.

Swab your labeled mini-vial.

Get the syringe with the 90 units of diluent. Take a look at it. Does it have 90 units? Put that in the mini-vial.

Get the syringe with the 10 units of insulin. Check it. Does it contain 10 units? Put that in the mini-vial.

Hold the mini-vial in your hands horizontally and roll it back and forth for a few seconds to make sure it is mixed. It will stay mixed, because the diluent is designed for this purpose.

You are done. Put your mini-vial in the fridge.

(Don’t store it near the insulin or diluent that is in the fridge! We don’t ever want to pick up the wrong vial. Put it on a different shelf!!

FUD community, please check this. Let me know if I missed anything. We always want to check our work!


This is exactly the proper procedure. I suggest getting these Vial Safes. Use red for undiluted insulin, blue for the dilutent and violet for the diluted insulin.

Reading your procedure @Eric reminded me of when my wife made up IVs with medications in them at the hospital.


Thanks @CarlosLuis!

And good call on the VialSafe. Here is a link:


Someone forgot to post the link, oh my! Good catch @Eric

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In addition to helping identify various bottles, they work wicked well when you drop your precious insulin vial on the floor. I have yet to have one shatter and fingers crossed hope to continue to avoid that calamity with these nifty little silicone sleeves.


I have a question regarding the mixing procedure, will making 100 units of U-10 be enough to last for a decent time?

I ask this because when you insert the insulin syringe into the U-10 mini vial there would have to be enough fluid to cover the tip of the needle to withdraw the fluid, so in this case should I make more than I intend to use?

For example, should I put 180 units of diluent and 20 units of U-100 into a mini vial?

Or is that too much?

The tip of the needle doesn’t need to be pushed all the way into the vial. To finish off an almost empty vial, insert the needle, then pull it part way out until just the very tip is through the stopper, so it’s possible to extract nearly all the liquid that’s in the vial.


Ditto on what @bkh said!

When you get down to the last few units in the vial, just push the needle up into the vial far enough so that the tip of the needle is inside the vial, past the rubber stopper. You don’t need to push it all the way in.

This will help you get the last little bit out of the vial instead of wasting it.

Yes, you can mix it in bigger quantities if you wish. You just have to be very careful and meticulous. Like if you are doing it, make sure you don’t do twice the insulin but forget to do twice the diluent, etc.

But since you said your son is using less than 2 units per day, doing it in 100 unit quantities will last you a pretty long time.


Okay good point, thank you!

Another question I have:

Throughout the mixing process and even the drawing of the diluted insulin to inject, if the first draw has bubbles is it okay to push the diluent or insulin or diluted insulin back into the respective vials to remove the bubbles then draw again? without removing the needle of course.


Yes, absolutely! That is the way you are supposed to do it!

Did they not give you training on all of that stuff when Henry was diagnosed?

Also, see my note above on mixing it double. :arrow_up:


They did give us training at the hospital when he was diagnosed, however like I mentioned earlier, every diluted insulin vial the compound pharmacy at that hospital has ever given me (5 in total) has turned cloudy within 7-14 days of me picking it up.

When I have brought this issue to their attention they are questioning my methods and how I’m treating the vial. So I just wanted to make sure I am doing it correctly and I’m not the reason my diluted insulin up to this point turns cloudy!

I mean even on my syringe packages it gives a step by step guide on how to draw and inject it.

I will admit, sometimes I forget to swab the vial with alcohol before drawing it, but I talked about this with my clinic and they said they still don’t think that would cause the diluted insulin to go cloudy.

Does anyone have any thoughts on this? Is it really possible for me to make clear diluted insulin turn cloudy?

I never subject them to higher temperature than room temp, and I always keep the diluted insulin in the fridge, unless travelling (no more than 2 hours) then its in a freeze pack case and covered with a tissue to protect from freezing.

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It does not sound like you are doing anything wrong!

I took a very close look at my diluted vial. I’ve never really noticed it before. At a quick glance I would not say it looks cloudy. But if I look at it very closely, I guess you could say it looks a little bit cloudy.

Is this what you are seeing?

(It was hard to get a picture and a background that actually shows it! This was the best I could do!)


This is one of my older vials.

Not only does it become cloudy but there are little stringy clumps of white stuff that floats to the top after you move the fluid around abit.

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It’s hard to say. Mine seems like maybe it’s a bit cloudier than it is when not diluted. But it still works fine for me. I don’t see any clumps in it.

I suggest trying it yourself for a few months and seeing if there is a difference. Mixing it in the small 100 unit batches might be helpful, since it would be used up faster than a larger amount.

On a different topic, what type of blood glucose meter do you use?

@ClaudnDaye, do you recall at what age children are approved for CGM?

Yeah it will be good to see how my own diluted insulin goes compared to the ones I was being supplied!

We use the OneTouch Verio for blood tests and we just switched from the Libre to a Dexcom G6 2 days ago.

CGM are approved for over 2 years old, but it seems pretty accurate with him, when comparing the Dexcom reading with the blood test from the OneTouch, its usually within 5-10%

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2 years or older. Although if Liam was younger than 2 when he was diagnosed (he was diagnosed at 2), I’d have probably fought tooth and nail to get it approved for him anyway because imo <2yo could have / use the unit just the same as 2 yo’s…this is just their cut-off based on their testing or whatever, I’m fairly certain.

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