Why does my body react to shots differently than the pump?

I’m 23 years old and I’ve been a type one diabetic for 19 years. I’ve been on an insulin pump for about 13 years. Last night, I had a problem with my pump and took a shot to treat a high instead. I went to bed and woke up with it still around the same high number. I’ve done this a few times in the past when I’ve had problems with my pump but I’ve never understood how my body reacts so well to my pump giving me insulin and so poorly to insulin being given via shot. Does anyone know why this happens?

Because insulin is absorbed differently from pump and injections. Usually, insulin form the pump cannula is absorbed better.


Do you know why it absorbs differently? Shouldn’t it be the same?

Needles and cannulas are different in the way they fit into your fat layer and form canals.


This is common, I know many who observe widely disparate results between the two. Just a short time in these forums should convince you that no two physiologies react the same way to anything. For some people, pumps are the only way to get good control. For others, it doesn’t matter that much. My absorption may not (probably won’t) be your absorption.

That said, I get excellent results with MDI . . . which is lucky, because unless I hit the lottery there is no pump in my future. Ordinary MDI plus the occasional IM correction works great. Thankfully.

There are differences between a pump and MDI. Usually people need less total dose from a pump due to insulin being more efficiently delivered. And insulin may absorb differently when you inject or pump into different parts of your body. That may explain some of the variation. But you have also had diabetes for nearly two decades so you may have built up some scar tissue as well. Was your injection site different that you pumping site and is it possible that you have some scar tissue where you injected?

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This is the opposite of how it works for me… a shot is always faster than a bolus through the pump. For very high corrections I’ll even inject in 2-3 places to speed up the absorption of insulin… that same insulin bolused through my pump would take MUCH longer to work.

I’ve had to do that occasionally–split a bolus into sections, injected together, to get faster or more predictable action. I also find that IM injections are quicker still, though I don’t have a pump to permit comparison.

I often give pump corrections an extra “push” by turning up my basal after I do the correction. I don’t know if it’s just the extra insulin or if it gives some sort of fluid dynamic shove to get it going but it seems to help. I’ll set a 200% basal for an hour or two and kind of keep an eye on my CGM and kill the upped basal when the numbers start heading down, or when they are getting back where I want them.

For me, I get faster response from an IM shot, which I never used until I saw that you were doing it @David_dns (thanks!). It has saved me a few times in the past year when my BG wasn’t responding to pump delivered insulin.

I’m glad that’s helping. They certainly make a difference for me in those situations. Simply a case of the right tool for the right job.

Just for the record, I learned about IMs from Bernstein.

EEK! I guess that’s why they didn’t work as well for me! (Just kidding).

Seriously, though… I generally get better absorption from the pump after the first couple hours from inserting an infusion set. Maybe the continuous “drip” of basal insulin makes the area more attuned to absorbing insulin (or “softened”). I believe that I read somewhere that “improved absorption” is one of the benefits of using a pump for some people. It seems to be so for me, as less insulin goes a lot farther for me with the pump than it ever did with MDI.

IM shots - at least in muscles like calves or biceps that I then used/flexed a bit shortly after injecting - were still a bit quicker for correcting big spikes.

@Ginger_Vieira mentioned in some article or other a few years ago that new sites tend to be inflamed for a while. Until this settles/ heals, the absorbtion is slowed/ impaired.