Insulin pens

When I inject with an insulin pen there is always a droplet at the end of the pen after I take it out. I always wait and count to ten after giving the dose before I withdraw from the injection site yet the droplet and a bit of insulin is always there. Is this normal ??

Pretty much. As long as it’s not dripping out or squirting back out of the injection site then you are fine. I don’t know why pens do this and old fashioned needles don’t but that has been my experience for as long as I’ve been using pens.

Thanks :smile:

Drove me nuts when I was using pens too. I’d wait 20-30 seconds, tried gently rotating the needle while it was still inserted to kinda wipe it off, then pull it out and… d’oh! there’s the little drop! Don’t think there’s any way to avoid it.

There’s a juvenile rhyme that guys have about a similar situation, but I’ll spare you…

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I’ve seen that in all pens and doesn’t seem to matter what company manufactured it.

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It happens with all pens I’ve ever used, and many package inserts say it’s nothing to worry about. (From the NovoPen Echo insert: “You may see a drop of insulin at the needle tip after injecting. This is normal and does not affect your dose.”)

Here’s an explanation from a paper published in Practical Diabetes International in 2000.

When injecting with an `ordinary’ insulin syringe, the pressure on the rubber plunger ceases when the injection is finished. If the plunger has become compressed it can move backwards when the pressure has ceased. The liquid will therefore not continue to be pressed through the needle.
When injecting with an insulin pen, there is a locking mechanism making the piston unable to move backwards. Any pressure that has been accumulated in the system is able only to be equalized by the liquid being pressed through the needle. Thus at a fast injection, liquid may continue to be pressed through the needle long after the pressure on the piston has ceased.

It doesn’t explain why the drop appears after you remove the needle from the skin rather than while it’s still under the skin.

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I would guess the last little droplet gets stuck to the opening of the needle due to surface tension.

One possibility - if you are priming the pen with the needle pointing up, the priming drop will fall down to the base of the needle. When you inject, you may see the priming drop on your skin after you remove the needle.

If that is the case, it isn’t insulin that leaked out of the injection, just the remains of the priming drop!

Try priming with the needle pointing down so it does not land on the needle base, and see if you notice less insulin on your skin when you remove.

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Good idea Eddie. The instructions have always said to prime holding upwards but I’ll try with the needle pointing down as you suggest.

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Let us know what you see.

I tested this idea once by priming pointing up and then inserting the needle in my thigh but NOT injecting any insulin. When I removed the needle, I saw what looked like a leak. But since I had not injected, I realized it really was the priming drop.

I have primed pointing down ever since.

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actually i do get a bit of a squirt of insulin out of the injection site in addition to the droplets from the pen.
do you think it’s better to use the vials and needles ?

I don’t think one is better than the other but I have always preferred vials and needles although pens are more convenient when out and about. Are you using proper protocol when injecting with the pen? Do you hold the plunger down for ten seconds and then just keep the pen needle injected for ten more seconds to give the insulin a chance to absorb a bit before removing it?

When I do it this way I only get one drop of insulin remaining on the needle when I withdraw it and if any were to squirt back out I would worry that I hadn’t gotten the full dose.

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It annoys me too. Air bubbles in the pen will inevitably result in droplets; they’re under pressure until you pull the pen out.

Nevertheless the instructions are correct; it doesn’t matter. This is because the amount of insulin involved is truly minute. For example even a 1mm drop (that would look pretty big) only contains 1/20th of a unit of insulin (0.05IU).

The main issue here is that we are born useless at judging volumes; we vastly overestimate the volume of a small drop and vastly underestimate the volume of a large amount (e.g. a swimming pool or a small pond). We can train ourselves to get very close to the right answer but we typically don’t get the opportunity and the training only works over a small range; cooks are typically good over the 5ml to 1 litre range.

Here’s a list of sphere (drop) diameters that may help. For older Americans, 1mm is 5/128th of a US inch, which is about 1/32nd of an inch:

Diameter (mm) IU (insulin) Volume (ml)
0.5 0.01 7.E-05
1.0 0.05 5.E-04
1.2 0.10 1.E-03
2.1 0.50 5.E-03
2.7 1.00 1.E-02
3.4 2.00 2.E-02
4.6 5.00 5.E-02

thanks @Firenza that totally did it , i have been doing this for a couple of days and i no longer got insulin gushing out of the injection site and i get only one small droplet on the novorapid pen after retraction, weird thing is it doesn’t happen with Lantus at all i don’t see droplets on the needle afterwards.