I have a PDF of a recent download of Dexcom readings as I've been trying to figure out my insulin action time.
Based on how it's read, it could be anywhere from 2.5 to 3 to 4 hours.
How do I get help figuring this out?
Unless you are super active (like spend all your time moving like small children do), your insulin action time is 4 hours. It's how these insulins are made and they are all the same with respect to pharmacodynamics. People say Apridra peaks faster, but I think it is more that they are told it's supposed to. They do differ somewhat on heat sensitivity, but they are all pretty stable to heat. The reason insulin action time is 4 hours is the physiology of injecting into subcutaneous tissue which is the same process in everyone. Once insulin gets into the circulatory system (slow process) it goes to the cells at effectively the same speed in everyone too, unless they are especially active because circulation of blood goes up as heart rate does. I can go into more detail about how the speed of insulin leaving the system is also the same, but that process gets a little complicated.
There is some variation. I do much better with mine set at 3 1/2 than 4 hours. For me it was trial and error with some input from my dexcom data.
Wow, thanks for the post...hope you can become an Endo, we need more smart doctors...i have a question for you, sometimes when my sugars are high..i will inject insulin into a muscle area so it will react quicker and lower my sugar within sometimes as fast as 30 to 45 min...so even though the injection was subcuntaneous, the blood circulation inside the muscle somehow got the insulin into the blood quicker or was it the fact that the blood was circualting the insulin quicker ??.. also, what is ur opinion on this statement, usually insulin comes 35% in the first hour, 35% in the second hour and then 20% the third and the final 10% in the last hour...this is just something i learned being diabetic...is this is pretty accurate in trying to figure out how much insulin is on board ??
If you inject straight into muscle (you'll get some blood when you pull out the needle), the absorption and elimination is much faster because muscle tissue is highly perfused with blood vessels. I've never tried it, so I'm not sure how much faster. If you inject still into the subQ but in a muscly area, it can definitely kick in faster simply because the injection is closer to the highly perfused muscle tissue. Moreover, if you move that muscle which will increase circulation to the muscle, that will speed it up further. When I'm high and need to come down fast, I inject subQ lower down on the top of my thigh, then go on a walk. Because that muscle is so active during a walk, it absorbs faster. Cool trick, huh?
About the % activity, I imagine it more as a normal (symmetrical) curve because absorption into and elimination from the blood happens at relatively the same rate. It's hard to see that on a dexcom because rates of food absorption vary so widely.
Thank you, my dream is to be an endo...that actually understands what it's like. :)
Hey, all! Thanks for your responses! I learned a lot.
Did you say what kind of insulin you use? It can vary a little by type. My endo insists that Humalog, what I use, should be set for 3 hours. But to be honest, I did not see any difference from when I had it set at 4 hours. But then, I am not meticulous in record keeping. I have had no problems with the 3hr duration set, so I will stick with it.
Individual responses vary. For me the fast acting insulins are still going a bit even up to 5 h. I'm hoping for the faster acting insulins (currently being tested) maybe coming to the market soon. Also, in addition the local blood flow, the delay is also partly related to how quickly the insulin ring structure breaks down. Insulin molecules are bound together in a ring, and the long acting insulins (like NPH) break down more slowly after injection. However, there is little difference in this breakdown rate between the 3 fast acting insulins we use in pumps.
For me, it can vary widely, even always injecting to the same SubQ near a muscle area, and eating the exact same meals and doing the same activities (I was testing to see if I could determine the timing). Unless my digestive system is varying its processing of food (which could also be happening), my only recourse is frequent blood sugar testing. I think you will find that every body works differently.
By the way, Wil Dubois posted a reply to a question about this yesterday on Diabetes Mine:
Calculating Insulin Action Time
I thought that might be helpful on this thread. :)