Insulin Action time

After Mondays visit to the diabetes doctor (A1c was 6.4, down from 6.8), the doctor noticed my "insulin action" time was 2.0 hours. She suggested moving it to 3.0. To me, leaving it at 2.0 is the way to go..its working! Any thoughts on why she suggested moving it to 3.0? Ive been a little higher the last couple of days since the change.


OH and a quick update on the trip I took from Houston (IAH) to Peoria, Illinois. The security line at IAH terminal A was MASSIVE at 5am on Friday 8/9/13. It took close to an hour to get to the front of the line. I had all of my pump supplies in a large plastic bag, taken OUT of my backpack. They ran my bag through the x ray 4 times...and I did have to touch my pod for the explosive test.

In Peoria, they have regular metal detectors, so the pod does NOT set that off. (almost a crisis situation when I realized that i did NOT have my PDM once i got through security...thankfully it was in the rental car) whew

I’d imagine your Endo suggested it cause I believe 3 hrs is a more “standard” insulin action time. However, if 2 has been working for you and 3 doesn’t seem to be, stick with what gets you results! Everyone’s body is different, after all, so I doubt there’s a scientific catch-all that all bodies react to synthetic insulin identically.

It seems to me with the new system...the way things calculate...that 2 works better. I'll give this a couple of weeks, and i'll show her that I was right to change it to 2...haha.

Ah interesting… I’ll be starting the new system soon so I’m interested to see if I notice changes in that area.

Thats cool..dont let all the "failure" frustration talk get to you. Ive had ONE in my first 3 boxes...and it was most likely due to filling it with too much. Im 99% sure that people with all the errors are missing a step.

Good luck!

I have mine set to 2.5 and that works well for me. My Endo also suggested 3 but I said no. I also have my target BG set to 80-90. He wanted 90-110. Again, no. :) He is a good Endo and trusts that I know what is best for me.

Thanks! I never really fill above ~180 so that isn’t really an issue for me. I’m pretty excited about it!

Haha yeah last time I changed my basal "worked" so she was fine with it. Ill try 3 for a couple weeks and go from there

Mine's at 4 hours...

My Pod tech had mine set for 4 and the endo suggested 3. He also reminded me that it is all just a guide and that I still ultimately have control over what I choose to bolus based on IOB, etc. Obviously if my sugars are high after a meal, I miscalculated. So even if the IOB is telling me to correct less, I can use my judgement about what the numbers actually mean.

My next appointment is in September. I'm pretty excited to see my A1C.

I had it set to 2.5 on the old pods and, like you, found that 2 works better with the new ones. I'm not a fan of the new IOB calculations. I have to manually change the bolus correction way more often now, but, setting it to 2 hours has helped a bit.

Thanks for asking this! I am going to change my son's from 2.5 to 2. With the old system 3 worked for us but with the new system even 2.5 subtracts too much meal insulin every time. We are chasing a lot more highs that way. But reading this makes me a little more tenacious. :)

I was running at 4.0 hours on the old PDM. That's a little long; it often lead to me having to make multiple correction boluses if I went high. With the new PDM, however, it was a disaster; because meal boluses are now added to the insulin on board it meant corrections within 4 hours of a meal simply stopped working as a result of the meal bolus knocking out the correction.

When my BS hit 300 on the first day I realized something was very wrong. I immediately reduced to 2.0 hours and, since then (so long as I never combine a meal bolus with a BG reading to avoid doing any reverse corrections to a meal bolus) things seem to be ok.

The best guess can be obtained from the data sheet with the insulin. For Humalog it is 120 minutes - the point where it stops having an effect on blood glucose on the graph they publish. As the manufacturer points out, however, different individuals might have different absorption rates and environmental factors (skin temperature, exercise) certainly have a big effect.

The problem with the number is that the Omnipod assumes linear adsorption over time, and that doesn't happen. Nevertheless I seem to be getting a lot better results with 2.0 hours than I got with 4.0 hours; before I didn't care much because the consequences of error were easily managed by repeated corrections, with the new PDM that doesn't work so I care a lot more about getting the time of action right.

John Bowler

John, thanks for that hands on post. As a 40 year Type 1, I guess I've become too used to "chasing highs", and never really thought to rely on the Pods to help more with that than they do. Also didn't even think to consider this adjustment as a tool for that goal either. I always recalled Humalog having a 4 hour window, but not given thought about how "active" is was during that 4 hours. It's worth some experimenting in my case I think now.

I just used the 4 hour value because that was the default. I was chasing highs too, it's not too much work. Despite my misgivings about the new algorithm the silver lining is that, based on the last 3 days, the 2 hour insulin action period works much better; fewer highs and I have not been seeing insulin on board when I eat.

John Bowler

How does one determine The optimal action time that works, whether it is 2, 3 , 4 or even 6 hr?
I had set mine to 6 as my BG would show no change even 2 hr after bolusing for a high.

So, taking 2hr as the start time of insulin action and adding the 4 hr as suggested in guidelines I set it to 6.

However I get the feeling it is wrong as I still run high 2-3 hr after every meal as the IOB calculation could be wrong due to wrong action time, if that makes sense?

You need to have both the basal insulin and the insulin/carb ratio correct first.

When those are correct the insulin action time is the time it takes for you blood sugar to return to your target level after eating a "high carb" meal - i.e. a meal where the carbs are absorbed relatively quickly so the carbs get absorbed much faster than the bolus of insulin.

I.e. you should *expect* to run high for the insulin action time after the meal, so long as the carbs were absorbed at a normal rate.

I've consistently found that my BGs will stick high some times if I let them get over 200. I believe this is something completely different - not a matter of delayed insulin action, rather something stopped by BG dropping back to the target.

I use humalog with the 3 hour window. For me corrections go haywire at the 3-4 hour mark if I’m not careful. Setting insulin action for 4 was too long, but 3 prevents me from overdoing it.

I love these discussion boards. So helpful!

Ditto! Our endo changed us to two hours now, just have to be a little careful with corrections…

Omg, I am so glad to see this post cause I thought I was crazy that it seemed with the new pods we are experiencing highs and once we pass 225, then we cant seem to bring the blood sugar back down for the rest of the night. I contacted our rep and insulet and they acted as if this was not an issue. They claim our basal rates needed to change which was crazy because these are exact same rates we had before the new pods and we didnt have these highs after eatng.