More on (no, not moron!) IM injections -- some data

I've been posting about IntraMuscular injections over the past weeks, experimenting with this technique for corrections. For anyone that's been interested, here's what I've found:

  • About 2x faster in my body. I can get a nasty high (>200) back down in range in about 2 hours. Doing it just with my pump subQ it takes about 4 hours to get back down from a bad one like that.
  • I can see it start to work on my Dexcom in about half the time too. 15-20 minutes and BG starts dropping. Via subQ its always 30-40 minutes before I see anything happen.
  • Peaks in about half the time as well: 45-60 minutes. SubQ, I generally peak around 90 minutes.
  • Oddly, however, seems to have a longer "tail" than half the subQ result. I get about 4.5 hours out of a subQ injection. Getting 3-3.5 out of IM injection. SOOOOOO... I'm finding I am going lower with IM than with the same amount of insulin subQ. Scratching my head on this one
  • Side-benefit: My 200U reservoir is making it 3 days now instead of 2 because I'm direct injecting corrections when its convenient and easy to do so.
  • Been using my thighs exclusively.
  • Downside: Have to manage all IOB via smartphone app, can't use pump. Not as big a deal as you might think -- only doing IM to correct "bad" situations. Minor corrections (anything under 150 or so) I'm still doing subQ via pump.

All said, it's a technique that is working well for me in yet another tool for tight control, keeping that time "in range" greater, and the a1c lower.

How painful are you finding it? Are you getting much bruising? Obviously I've gotten IM shots at the doctor, but I've never actually delivered one into myself (at least not intentionally :).

IMs are a standard part of my "toolkit", been using them for years now. I find nothing else to be anywhere near as efficacious when I need a correction NOW. I use the deltoids exclusively, and I find them no more uncomfortable than the "ordinary" subQ injections. That's my experience, yours may vary.

Not painful at all. The only thing I've found I have to be careful of is not to allow the syringe to angle at all after insertion -- keep it nice and straight parallel to the entry angle -- and there's no pain.

No bruising at all.

I'm using a disposable 50U syringe with a 29 gauge, 12mm needle. Easily penetrates well into the muscle on the thigh.

I'm T2 with IR, IC 1:4 so my correction boluses are large relative to a typical T1 dose.

I've done 4 this week already -- one of them actually a meal bolus that was taken after eating (forgot to mention I use IM's in that circumstance too if possible).

I tried it the other day to correct a bad high. Injected it straight into the deltoid, but noticed a bruise about half a day later, even though the injection felt painless and there was no bleeding at the time of injection.

Yeah, that happens to me once every 30 or 40 times. But it happens with subQ's, also. Just goes with the territory, seems.

I think you mean perpendicular. I jab it straight into my quad.

Yes perpendicular (normal) to the skin surface.

However, once all the way in, important to keep it straight. With that long needle, any deviation from the straight-in jab angle is felt, painfully, down in the muscle.

That's what I was referring to -- not very well :-)

David -- have you seen a significant difference in "potency" of IM injections vs. subQ? I'm having some really big differences in my "ISF" when correcting IM vs subQ. It's caused hypos every time when I'd get right to where I should be via subQ.

It seems my ISF for IM injections is about 2x what it is for subQ. I get about a 10 pt drop per unit for subQ, 20pt for IM. And twice as fast.

This 2x factor seems to be showing up in many parameters comparing the two. Got me wondering if my IC would be affected as well, bolusing IM for meals. I don't, because I'm worried the faster action will throw everything off. I plan to play with it this weekend and get some solid characterization for IC, ISF, duration, etc. -- basically abandon the pump for 48 hours and use IM for all my insulin boluses, meal and correction.

If these differences hold, I could cut down on my TDD, and get better control, faster. If this can be reliably nailed, I might go all-IM for a week and see how it goes.

Too bad there isn't any way to practically put an infusion cannula down in muscle tissue...

Using IM to correct is a tool I seldom use but think I'll try it more often. So, you're using a 12 mm depth needle or about 1/2 inch. When I got my flu shot at Costco, I asked the pharmacist what depth he was using. He said 1 inch. My sub-q syringes are about 1/4 inch; I wonder if that's deep enough.

I don't think 1/4 will reliably get you into muscle unless you're crazy lean, and even then maybe not.

1/4 inch is iffy, very iffy. Half inch (12.7 mm) is normally preferred. I use the BD 30 unit 30 ga. 12.7mm ones and they work perfectly every time.

I agree with the others -- the 4 or 8mm needles won't do it. You need the ~12mm (1/2 inch) to fully penetrate muscle. Also, inject in a very lean place, like side of thigh, deltoid.

I've been using IM injections a lot this week (hence all my talk about it :-)). All large corrections (anything over 120) I've been doing IM.

The results are consistently much faster. The thing that's puzzling me is the apparent greater potency -- yesterday and today I went seriously hypo (as in, had to counter-correct three times yesterday, 20g total, twice today, again 20g total); I never go low administering corrections subQ.

I'm hooked. It's forcing me to do most of my IOB accounting with Glucosurfer and using the pump as just a delivery device, but it's not really that much extra work. The benefit, for me, far outweighs the extra hassle.

Here's some actual Dexcom data:

I had taken a subQ correction right after I woke up. An hour later, based on my stubborn BG, dosing calculations in the pump said to take another correction. I administered that one IM instead. The graph above is what happened.

The IM slope is about 2x the subQ slope. The IM worked quickly, and finished absorption relatively quickly (about 2.5 hours). The subQ correction was still working when the IM quit, hence the transition to a shallower slope.

In theory, the total amount of the two corrections should have got me right to where I wanted to be, and when I only administer subQ, that's what would have happened. I do this all the time.

What puzzles/surprises me is that the IM portion seems to have worked more potently, pushing me down more than my 1:10 ISF says it should for the amount of the dose, leaving the remaining subQ from earlier continue to drag me down in to hypo territory.

I think what's going on is the slower availability/action of the subQ injection is giving the factors causing increased IR in the morning "more time" to sabotage the insulin action. With the faster, more available insulin from the IM injection, those factors are "overwhelmed" and not as effective at messing with action of the insulin.

Just a speculative theory. However, I love everything about these IM corrections, so I've adopted the practice of correcting that way any time it's reasonably possible to do so.

IM injections are no more difficult than subcutaneous ones, and -- short of an IV -- there is no faster way to deliver exogenous insulin to where it's needed. IMHOP they deserve to be in every PWD's toolkit.


I've known this for a while. Now I'm sold. Sometimes it takes me a few exposures to an idea for it to stick. I need to pick up some longer needles.

Where do you get 12mm pen needles? I got 8mm ones from the pharmacy and the pharmacist repeatedly tried to convince me to get the 4mm ones (I tried them, just didn't like them as I've always used 8mm or 12mm needles).

I haven't seen 12 mm pen needles. I use a syringe with a 12 mm needle (take the insulin out from the pen), if needing a IM correction.

Hmm. Just guessing here since I don't use pens, but it's possible that no one makes them. 12mm syringes are relatively easy to find, but that may not be the case with pen needles. Many doctors and nurses are still schooled in the traditional straitjacket of "subcutaneous only" when it comes to insulin. So the pen manufacturers may not be considering the possibility at all. Just an educated guess.

How do you inject IM? Can you do it with a pen or do you have to have a syringe? I too sometimes have highs that are SO LONG (at least 4 hours! sometimes more)to bring down. I think I missed some information, sorry if you have to repeat .