Still don't understand!

[heasandford]

I have recently been reading 'Pumping Insulin" (still hopeful!) which has reinforced a concept which I still cannot properly get my head round. It doesn't just apply to pumping.

This is what I read -
"..only half (of rapid acting insulin's) glucose-lowering action is seen two hours later, with about 90% of its action gone after 5 hours."

Surely if half the action is remaining after it has dealt with however many carbohydrates, then by definition an equal reduction will then take place over the next 2-3 hours, leading to an almost guaranteed hypo? It is so dependant on the rate at which carbohydrates convert to glucose and enter the bloodstream? This also seems to vary, I can have the same breakfast every day with the same amount of insulin, one day it will spike, another it will be perfect!

 

[Pumper_Sue]

I have recently been reading 'Pumping Insulin" (still hopeful!) which has reinforced a concept which I still cannot properly get my head round. It doesn't just apply to pumping.

This is what I read -
"..only half (of rapid acting insulin's) glucose-lowering action is seen two hours later, with about 90% of its action gone after 5 hours."

Surely if half the action is remaining after it has dealt with however many carbohydrates, then by definition an equal reduction will then take place over the next 2-3 hours, leading to an almost guaranteed hypo? It is so dependant on the rate at which carbohydrates convert to glucose and enter the bloodstream? This also seems to vary, I can have the same breakfast every day with the same amount of insulin, one day it will spike, another it will be perfect!

What it's saying is that at the 2 hour mark the insulin and food digestion should have peaked then the rest just slowly ebbs away. A bit like a battery running down 🙂
If it stayed at full strength for the 5 hrs you would be flat on your back in hypo land 😱
Hence why pumps have a feature called insulin duration, the pump has it's own formula as to how it works out whats left and at what time.

 

[MaryPlain]

I have recently been reading 'Pumping Insulin" (still hopeful!) which has reinforced a concept which I still cannot properly get my head round. It doesn't just apply to pumping.

This is what I read -
"..only half (of rapid acting insulin's) glucose-lowering action is seen two hours later, with about 90% of its action gone after 5 hours."

Surely if half the action is remaining after it has dealt with however many carbohydrates, then by definition an equal reduction will then take place over the next 2-3 hours, leading to an almost guaranteed hypo? It is so dependant on the rate at which carbohydrates convert to glucose and enter the bloodstream? This also seems to vary, I can have the same breakfast every day with the same amount of insulin, one day it will spike, another it will be perfect!

I read it the same as you, and for me it simply boils down to a choice - either put up with spikes after meals, or spread meals out to match the insulin's action. I try to do a bit of both! I'm sure others will say that another option is to cut out carbs, but for me as a vegetarian, that's not an option!

 

[Pumper_Sue]

I read it the same as you, and for me it simply boils down to a choice - either put up with spikes after meals, or spread meals out to match the insulin's action. I try to do a bit of both! I'm sure others will say that another option is to cut out carbs, but for me as a vegetarian, that's not an option!

The simple solution is to time your bolus with the type of food eaten.
Please note the word simple......... as this doesn't always work out. 🙄

 

[heasandford]

I read it the same as you, and for me it simply boils down to a choice - either put up with spikes after meals, or spread meals out to match the insulin's action. I try to do a bit of both! I'm sure others will say that another option is to cut out carbs, but for me as a vegetarian, that's not an option!

Thank you! Sometimes these statements are too straightforward, even in the books which seem 'mostly' right. (I am struggling as much now, 12 years after diagnosis, as I did at the beginning)

 

[heasandford]

The simple solution is to time your bolus with the type of food eaten.
Please note the word simple......... as this doesn't always work out. 🙄

Understatement of the century!

 

[schmeezle]

I have recently been reading 'Pumping Insulin" (still hopeful!) which has reinforced a concept which I still cannot properly get my head round. It doesn't just apply to pumping.

This is what I read -
"..only half (of rapid acting insulin's) glucose-lowering action is seen two hours later, with about 90% of its action gone after 5 hours."

Surely if half the action is remaining after it has dealt with however many carbohydrates, then by definition an equal reduction will then take place over the next 2-3 hours, leading to an almost guaranteed hypo? It is so dependant on the rate at which carbohydrates convert to glucose and enter the bloodstream? This also seems to vary, I can have the same breakfast every day with the same amount of insulin, one day it will spike, another it will be perfect!

I think John's trying to make a point insulin has fair amount of work to-do after the 2 hr mark. I wouldn't get to hung-up on the 50%/2hr statistic, as it (and duration of insulin action) are influenced by size of bolus.......smaller boluses don't last as long as larger ones. From personal experience, and small boluses (2-3 units) I'd say my 50% mark occurs before 2 hrs.

It is so dependant on the rate at which carbohydrates convert to glucose and enter the bloodstream?

Only from cgm usage, I've learned how efficient.....extremely efficient, in fact.....the body is at converting carbs to glucose.......so-much-so, it's changed how I eat - slow and cautious around fast and medium paced carbs - except for yesterday where a choco-milk took me to 11

CGM has also helped paint picture how slow "rapid-insulin" really is. For the most part, it's not uncommon for bg's to remain level 40-45 minutes after a bolus. It's from there to the 2 hr mark where rapid insulin (humalog anyway on small bolus) has it's strongest pull.

 

[everydayupsanddowns]

Very interesting Brian - and while I've not had the benefit of a cgm it very much backs up my own limited observations.

I really must look into how carbs are metabolised a bit more, but it seems to me that there is often a big initial push and then a gradual fade away. And that sometimes the push in BG is not linear with the actual amount of carbs eaten(or is it that parts of some boluses just never get absorbed?!)

Lol at Sue for the 'simple'! I think that's why I've ended up with trying to stick to a fairly limited number of combinations of carb type/amount (always eating the same measured amount of pasta/rice etc) so as to limit at least *some* of the variables. I also have a little rolling 'cheat sheet' of dual and square wave bolus attempts at various meals and how effective they were.

 

[schmeezle]

And that sometimes the push in BG is not linear with the actual amount of carbs eaten(or is it that parts of some boluses just never get absorbed?!)

To the sometimes non-linear point - I'm with you and I don't see it as a vanishing bolus - I've been thinking carbs can be "amplified" by fast intake, but not all carbs, slow are exempt or at least negligible in the big picture.

If that's way off the mark, then it could be a case of missed timing (meal peaks before insulin) resulting in high insulin-resistant bg's and time for correction.