Type 1 Testing insulin activity length

MisterMints

Well-Known Member
Messages
49
Type of diabetes
Type 1
Treatment type
Insulin
Hi all,

Is there a way to test how long bolus insulin remains active in my system?

I'm having a few problems getting my insulin to work correctly and the dosage right, and one of the things I think I should understand is how many hours my NovoRapid remains active, at least while sedentary.

Thanks
 

rmz80

Well-Known Member
Messages
332
Type of diabetes
Type 1
Treatment type
I do not have diabetes
I just use NovoRapid prior to a meal based on a “carb count” of the meal. This insulin is used to break down any consumed carbs. It may be an idea to read up on this if not come across it before.
 

MisterMints

Well-Known Member
Messages
49
Type of diabetes
Type 1
Treatment type
Insulin
I just use NovoRapid prior to a meal based on a “carb count” of the meal. This insulin is used to break down any consumed carbs. It may be an idea to read up on this if not come across it before.
I'm completely aware of carb counting, and I do that, but that isn't what I'm asking.

NovoRapid is rated to last between 3 and 5 hours. I want to know how to test whether it lasts 3, 4 or 5 hours in my body
 

Scott-C

Well-Known Member
Messages
2,474
Type of diabetes
Type 1
NovoRapid is rated to last between 3 and 5 hours. I want to know how to test whether it lasts 3, 4 or 5 hours in my body

I suppose the most common way is to wait until you're running a level line on cgm for a few hours (if I remember correctly from other posts, you're using a blinged libre and xdrip?), inject 1u, watch the line to see how far it drops and when it levels out again.

Tells you correction factor and broadly speaking when the novo has stopped doing its stuff.

I tend to wing things a bit, but if I'm looking to do experiments like that, I'll usually just have a long lie in on a Saturday morning before going for a late brunch about 3pm, so I can check whether basal is holding me ok, and then see what 1u or 10g does while I'm settled watching a box set and not moving too much.

Stephen Ponder's book Sugar Surfing, couple of quid on kindle, is pretty good for this stuff. He's T1 and also an endo and early user of cgm, so covers a lot of bases.
 

sninge

Well-Known Member
Messages
67
Type of diabetes
Type 1
Treatment type
Pump
I noticed years ago that novorapid stops working after 2hrs for me, simply put, if I correct and test after 2 hrs then my sugars won't drop any lower than they have. I knew this because if i checked again half hr/ hr or 2 after then it wouldnt drop any lower. This is now confirmed by using libre. Obviously you need to be confident that your basal are correct and you haven't eaten any carbs that you could still be digesting.
 

tim2000s

Expert
Retired Moderator
Messages
8,934
Type of diabetes
Type 1
Treatment type
Other
This is always an interesting point. Put simply, most observational attempts to determine how long insulin lasts in the body come up with an answer that is way too short, for a number of reasons. I've written about it here but it comes down to clearance time, and the studies that have been done on insulin clearance all show that subcutaneous insulin has a half life of roughly 55 minutes. This appears to be reasonably consistent across adults and children and doesn't seem to vary very much. So the story that we get from HCPs about insulin lasting 3 to 5 hours is generally wrong.

The observable effects often stop showing up after around 3-5 hours (dependent on dose) simply because of the way decay works, but for the vast majority of people, there is still insulin on board at 5+ hours, and this really becomes noticeable when we exercise.

The other aspect of this is that because we have been told that insulin lasts three hours, we tend to set up our basal dosing with this expectation in mind and also observe with this in mind, so the overall effect is that when we try and observe duration, we aren't starting from a technically correct place.