Rate of Insulin Absorption

Hello! I recently joined this forum, but I’ve had T1 for 20 years. In the past couple of years I had some real problems with my infusion sites (MiniMed pump). The rate at which I absorbed/processed the insulin highly depended on which day of the site I was on. If the site actually inserted properly and worked, then the first day was the best. By the third day, I was processing maybe 1/2-2/3 the amount of insulin as the first day. Where I placed my site also really affected how well I absorbed the insulin.

When you factor in all the other unpredictable things diabetes brings (such as reactions to food), this became incredibly frustrating. So I told my doctor I wanted to go back on Lantus. I feel like I’m able to predict my reactions to insulin so much better now that I’m on Lantus and humalog than when I was on the pump.

However, I’ve noticed that (as with the infusion sites) where I do my bolus injections affects the rate of insulin absorption. I could simply adjust how long I wait to eat after an injection (or all the other things we do to try and limit post-meal spikes), EXCEPT sometimes injections in my thighs simply never kick in. So while I’m no longer stuck with an infusion set in my leg that isn’t absorbing at the right rate, I’m still left wondering if I’ll ever be able to use my thigh again as a good spot.

Do any of the other T1s on here have spots that simply don’t work anymore? I thought that I alternated pretty well between my arms and my legs (the stomach infusion sites never worked well), but maybe it doesn’t matter?

Has anyone else experienced variance in insulin absorption while on the pump vs injections? Or any other related thoughts?


I haven’t experienced the same variance you describe but there are locations that simply don’t and have never worked well for me. I do worry that over time the sites I regularly use will begin to exhibit the same thing you’re seeing and wonder if there is anything I can do to prevent it. I’ve also thought maybe using a longer canulla when I begin to see the degradation might be a solution although temporary.
One thing I’d like to know is why we can’t have a permanent infusion site inserted into a vein? Seems to me it would be a one time cost and then no more infusion sets, just refill the insulin reservoir in the pump.


I never use my thighs for injections or infusion sites. I’ve just never gotten good absorption there at all. Not enough fat on my legs. I think legs tend to be more muscular sites, and insulin tends to be absorbed most predictable in areas of fatty tissue. I have always used my abdomen or arms (lol since I have no matter how hard I try flabby arms). Also when I insert my infusion site I always pinch the skin up to make sure the cannula ends up in fatty tissue and not resting against muscle. I am just extra careful to make sure I really rotate sites well, but 30 plus and still no significant problems with abdomen and arms. What insulin are you using in your pump? I use Humalog in mine and it seems not to degrade much at all over the 3 days. I think Apidra is a little less stable in a pump.

An infusion site directly into a vein would make the insulin hit harder and faster since it is directly in the blood stream. While that is useful short term insulin drip in the hospital, it’s not an ideal solution for day in and day out use. Plus there is always a risk of more serious infection when you have a direct access site going directly into a vein. DEF not worth it in the long run.

My sites never worked as well on day 3. I use a 2-day rotation which helps. One common reason for site degradation is denaturation of insulin around the area of the site and in the cannula. This results in the formation of insoluble fibrils which inhibit absorption of insulin. There is evidence that of the three commonly used rapid acting analogs, Apidra is by far the most prone to denaturation - Humalog is better and Novorapid/Novolog slightly better still.

As well as rotating my sites every two days, I also switched from Apidra to Humalog which seemed to help. I sometimes have sites that just don’t work properly from the start. Thigh sites seem to be more prone to this problem.


Thanks for the responses guys! Kitkat2, I also used humalog in my pump. I’d only been using the pump for 8 years (I used Lantus and humalog for the 12 years before that).

Maybe I’ll switch back one day. I’m crossing my fingers that Viacyte will pull through for us in the next few years. In the meantime, I am enjoying not being tethered to a pump, even though there are some drawbacks as well.