Dealing with reduced insulin “efficiency” at high BG?

Although I can’t find a specific thread, I recall on several occasions seeing someone mention when talking about dealing with high BG something like: “Of course, you need to remember that insulin isn’t as efficient at high BG …”

I don’t know if this phenomenon has a name, but I do know that my pump and I DON’T factor this in when trying to bring down high BG.

Do any you have any tips, tricks, or a reference for dealing with this? Do you, in effect, over correct to try to bring down high BG?

Note: I use a G6 and a t:slim with C-IQ that has a correction factor that changes over 24-hours, but doesn’t have a built-in mechanism for lowering the CF at high BG.

Thanks for your consideration



Not sure when it comes to t-slim, but in general for me I’ll get aggressive with the insulin dosing when blood sugars are high.

I use Android APS and if I notice the number spiking I will temporarily raise the basal profile by 40 percent for around 30 minutes which in turn promotes additional bolus due to less IOB calculations.

Or, sometimes I’ll manually dose a couple of units. I don’t have any alarms for rapidly rising BGs, but I think they could be useful for this purpose. My high alarm is set to 150 during the night and 125 during the day that way I can tend to these things faster.

If it seems as though the number is going up for certain parts of the day, I will make slight shifts to the basal profile prior to when that is happening.


It’s absolutely true for my body that when my BG is over 160 for any length of time I develop significant insulin resistance, so I need much more correction insulin than normal.

Yes. Some call it a “rage bolus” which suggests an emotional component, as in “I just can’t get my BG to come down, by golly I’m going to force it down with an enormous blast of insulin.” But since I expect the insulin resistance, there’s no emotion, it’s just about giving an effective bolus. If my BG rises over 160, I’ll take double the expected correction, and if I don’t see a response within a half hour, I’ll take maybe quadruple the expected correction (possibly using a syringe to rule out the possibility of an infusion site failure.) When I do this, I’m depending on a trustworthy CGM to help keep me safe, (or fingersticks every half hour would work) because there is a significant likelihood that I will have overdosed insulin by the time I see the response, so I will need fast carbs to catch the falling BG and prevent a low. I have lots of glucose tablets available, so it’s routine and not dangerous for me, but this approach does require attention and fast carbs to be safe.


@MarkP I’m only a year old T1, but actually 67. Recently went on the pod and the Insulet rep and doc initially record a 63 correction factor, even though my own experience showed more like a 40 was needed. I haven’t corrected unless I’m 160+ and usually go for 2 units, depending on IOB, 3 for 180+, 4 for 200+.

I’m hopeful of someday getting the point where I can set an alarm for 125-150. Currently mines set for 160 daytime and 200 nighttime (I really hate getting woken up when sleeping, perhaps not the best approach).

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I also do this on tandem pump. And if notice quick falling bg, can cancel temp and set a reduced basal if dropping really fast and CIQ hasn’t reduced.


@TomH I have a different alert set for sleeping as I like my sleep too!

@bkh Yes,I call it rage bolusing also. You want your levels to come down and you don’t want to spend hours higher. So I have a tendency to be more aggressive if I have gotten up to a “too high number” for me. BG just seems more stubborn at a higher number. So I usually put my BG level in my pump and then add to it. It’s a toss up because sometimes I still need more insulin and sometimes I am eating something. I usually have some pineapple to offset a drop too much, so I don’t mind.

I know others that are of the same opinion, that highs are more irritating than lows. For some reason, but we all know the reason, we are stuck with highs longer. Lows might be more dangerous so it shouldn’t be that way but…


Thank you all for sharing your tips and experience. As I struggle getting my TIR much above 80%, I would clearly benefit from being a bit more aggressive about correcting highs …

Stay safe!



The phenomenon doesn’t have a name because no one understands it.

It may be an indirect correlation; for many of us high BG happens at night when we are inactive, so maybe lack of activity reduces the immediate effects of subcutaneous insulin on BG.

I did 15IU last night with no noticeable effect on my blood sugar, it stuck at 200+. It wasn’t a total pump failure, but my pump was up for replacement in the morning. Maybe end-of-life on the inject site?

I’m also getting very, very, suspicious of Fiasp; these effects seem to be getting worse. I’m not saying they weren’t before I swapped to Fiasp but on Humalog any increasing effects were happening more slowly. (So there is a correlation with my swap to Fiasp, but there is also a correlation with the length of time I’ve been using the Omnipod.)

As of this moment the only suggestion that I have seen that works consistently is rage bolusing. Of course it is treating the symptom, so it has to work, but in the absence of an underlying rational and completely demonstrated explanation treating the symptom is all we can do.


@jbowler A lot of us have issues with fiasp. The first time I used it, great! The second time not so much, and by the third time, it was water. Most people that notice a problem with it, it’s after more time though. I think I even tried to use it again months later and it still was like injecting water.


I can be stuck high (200+) with a fair amount of insulin on board then add some activity (walking) to get my BS headed in the right direction. I’ll get things in the 160 range, still have plenty of active insulin on board and once I stop the activity my BS will gradually go back to 200+.

Never really understood that and very frustrating.


@jim26 I’ve experienced the same thing, but it isn’t consistent; seems counter intuitive, though I’ve read it depends on the type/severity of the exercise.


Exercise is so important in getting the insulin into your system, so I’m not surprised that it goes down when you exercise.

It is strange that it goes back up after you stop exercising. Have you tried adjusting your basal rate?


I literally just popped on to see if anyone had any experience with this. I restarted Dexcom this morning, so had 2 blank hours of no data and didn’t even think to finger stick. Dexcom ran out at 134 and then came back in at 250 (ugh) at 12pm. I took 3u Humalog (and 7u Lantus, which I take mid-day) and got on the treadmill for a 30 min walk/hike (w/incline). Blood sugar increased slightly during treadmill time, then has been slowly decreasing over past 3.5 hours and I’m back to 133. I haven’t eaten anything all day. I’m not even sure what I’m asking for here; I’m just really frustrated. The 250 also shouldn’t have even happened b/c I woke up at 4am with rising blood sugar and took 2u, which should have covered my DP or FOTF or whatever the @#$ my body is calling it these days. UGH! Jessica


It can depend on the type of exercise. Aerobic exercise will help you use insulin better …but given some time your body needs fuel and your liver will dump glucose for fuel. I was swimming for 2-3 hours and after about an hour my blood sugars would start climbing. Supplying it with fuel before I swam helped offset the huge climb I was having. I learned that from @Eric! But then there is also anaerobic which is more intense exercise and you will start to have a BG climb pretty quickly to help to fuel the body. Some people notice this more like with weight lifting that after they stop their BG level goes up. And as you get used to certain exercise your response can change.

Of course a “normal” makes insulin and uses it appropriately to constantly utilize that BG and the system runs pretty smoothly.

So it’s also possible that once you have stopped the activity, you are back to needing more insulin at that point. Once you stopped exercising you aren’t either utilizing it as well if you are a type 1 or 2 or there is a lack at that point in time of insulin.

I would be curious if it is/was a higher fat or a higher protein meal you ate when you did an easier exercise like walking? Because the carbs or protein hit later with higher fat and sometimes higher protein. So you burned off a bunch of carbs but then maybe some of the carbs, protein is hitting after you walk?


Hi @JessicaD,
Are you wondering about the exercise part, or the other stuff?

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Sounds possible, though I don’t know how much ControlIQ/BasalIQ allow the base rate to be adjusted.

It’s all going to depend on the rate of rise or fall that ControlIQ sees. With @jim26’s numbers and a BG at 160 ControlIQ is meant to “increase the basal rate” but above 180 it’s meant to “give a correction bolus” (I’m quoting from, I don’t use ControlIQ).

So in the “stuck high at 200” scenario the pump has already delivered a correction and it isn’t working, then exercise gets it back to 160, maybe by getting the insulin into the right place, but the basal ControlIQ is delivering is still not enough?

@Eric I am curious about the exercise part. I am hoping for a “magic” formula that would get me to using “gentle” exercise to boost my insulin efficiency. That noontime 250 + 3u Humalog + 30 min hike still took 3.5 hours to get me down to only 133 (3:30pm). By 5pm I was in the 70s. I hadn’t eaten anything all day; had a cup of coffee with cream in the early am.

At minimum I’m on the treadmill for a 30 min hike every day (am in a 30 min/day workout challenge w friends and no one is more competitive than I am about keeping a streak) or I do a bike class or yoga. I don’t have a set time during the day that I do any of these things, though.

Thanks for any thoughts! Jessica


There really is no magic formula. Just like everything else it takes work and practice.

There are a lot of things you can do. There are tactics that make it easier. Tactics we share. But everyone has a unique profile. What someone else does may not work for you. Your “magic formula” will be different than someone else’s.

So many times when I see a post and someone is looking for exercise help, the first thing I do when I reply is offer them…a ton of questions. Because really, for each person, the answer just depends on all of their unique needs.

If you want to make exercise easier, I promise we can do that. And I can also promise that the more you exercise, the easier all of your BG stuff gets.

So we can do this, but we gotta start at zero.


@JessicaD Eric really is the best at exercise and understanding how BG levels are affected. You can’t ask for better help! He helped me and has helped several others!


Back to the OP question. There was an article published in DiabetesCare (?) on how to correct for highs based on the angle, and number, of the arrow in Dexcom. They gave a table with the information. I will try to see if I still have the article.
I give incrementally higher doses for every 30 min I remain high. If high for several hours I will inject 7-10 U, thinking the insert may have gone bad.