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Confused about how insulin is working

C

CoolUserName

Well-Known Member
Messages
52
Hello all,

I have been hovering in the background since last year when our son was diagnosed with T1 but would really appreciate some advice from all of you with the years of experience I don't have.

Since diagnosis our sons basal insulin has reduced from 14 units down to 6 units and bolus is 1:9 units (b'fast) 1:11 units (lunch) and 1:10 (tea) which I assume is neither high or low?

He wears a Libre2 sensor.

He takes bolus insulin 15 minutes before eating, his blood sugar rises typically up to about 7.5- 8.5 mmols, sometimes 9.5 mmols but then it quickly drops down. Unfortunately about 1.5 - 2 hours after eating he is hypo and having to eat just to keep his blood sugar up. Monday was particularly bad as his blood sugar went down to 3 mmols!! It is as if his insulin works nicely on his food but then won't stop!!

What I don't understand is if he has less bolus then his blood sugar will go above 10 (bad) but if he has the amount he is having now which stops his blood sugar going too high, he goes hypo later on. How do you all balance this effect? What are we doing wrong??

I assume his basal is okay as he is typically 4.6 mmols first thing.

Any advice would be welcome as I'm getting pretty weary!!

BTW he isn't taking lots of exercise - he is a typically lazy teenager. If he does take any exercise - eg walking more than about a mile then his blood sugar can drop very fast which is also a worry.
 
Injected insulin follows a fixed curve over 5 hours and does not match the food you are eating. If you eat normally you are to ignore the spike and as long as it comes down to the same level before your meal 5 hours later the dose was correct.

Some follow Typeonegrit which is a facebook group that chooses to eat low carb to avoid spikes. The DN's and consultants push for eating normally.
 
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ert said:
Injected insulin follows a fixed curve over 5 hours and does not match the food you are eating. If you eat normally you are to ignore the spike and as long as it comes down to the same level before your meal 5 hours later the dose was correct.
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But I thought the whole idea of carb counting was to make the amount of insulin match the amount of food/carbs as close as possible and that if you kept spiking above 10 mmols it wasn't good news long term?

From what you say our son could use next to no insulin, let his blood sugar spike high and this would be okay as long as his BS was the same premeal level 5 hours after eating? Wouldn't doing that repeatedly cause untold damage long term?
 

Hi @CoolUserName ,

Welcome to the forum. I have to agree with @ert .
Insulin has a working profile. The digestive system has "other ideas" regarding the workload on what's been eaten?
Fats for instance may slow down digestion? Other stuff may peak faster.

Using insulin is a little like good comedy.. It's all about the "timing." In this case the timing of the dosage.
The rule of thumb for bolus insulin is 20 minutes prior, but your son may need to try a little sooner?
 
Reactions: ert
We digest different foods at different rates. This is obvious when we hypo - we take fast acting carbs. Some fatty foods (such as pizza and curry) are very slow acting.
However, injected fast acting insulin works at the same rate regardless how much we inject and what we eat.
If you Google something like "NovoRapid profile graph" you will see the speed at which NovoRapid works over time - it has a peak and lasts for 4 or 5 hours.
Ideally, we want to match the peak of the NovoRapid activation with the peak at which the carbs that we have just eaten are digested. Assuming we carb count correctly, the only variable we have to adjust is when we inject.
If your son is hypoing after eating and his insulin to carb ratio is correct, he may be taking his insulin too early for the food he is eating so you could try delaying his insulin until after he has finished ... or just before he eats rather than 15 minutes before.
As with everything diabetes related, we are all different so it may take some trial and error to find the best timing for your son's dose.
 

Yes, we've noticed that eating fats with carbs slows things down and that white rice is the devils work (even without diabetes in my opinion as I prefer brown).

The maximum time he's tried pre-bolusing is 20-25 minutes before a meal but by doing that typically his blood sugar will drop as he is eating before picking up a bit to about 6 mmols so I think if he left it any longer he'd be on the floor.

I was thinking about raising his bolus ratio so he has less insulin at each meal. The trouble is that his insulin requirements seem to change on week basis but these hypos have really got me worried.
 
There's actually a lot of ways of approaching this problem.

One) Adding mandatory midmeal snacks which will help prevent late hypos. This is a carry-over from Mixed Insulin days.

Two) Changing the food that's eaten at the meals to include more slow-acting carbs to help prevent those late drops.

Three) Using Half Unit Insulin Pens to increase the preciseness of doses.

Four) 15 minute Pre-Bolusing is a rough guide, rather than the optimal timing for taking your Insulin. You can use the Libre to gauge modest changes timing of Insulin. For instance, I wait at least twenty minutes before eating in the morning, whilst I wait 0 minutes to eat my lunch.

Five) This list isn't even exhaustive, there are probably other methods which I'm not thinking of.
 
I hadn't considered taking his insulin later. The reason he takes it 15 minutes before is that I know that it's the general amount of time it takes to start working and up until relatively recently it worked really well. Being 17 he hoovers his food up rather than eats it slowly for maximum enjoyment!!
TBH I'm not 100% sure his insulin ratios are spot on.
 
On DAFNE we learn that since the spikes come back down after 5 hours, you can still achieve the NICE recommended HbA1c by ignoring them. It's running your blood sugars high for consistently long periods of time that does damage.
 
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ert said:
On DAFNE we learn that since the spikes come back down after 5 hours, you can still achieve the NICE recommended HbA1c by ignoring them. It's running your blood sugars high for consistently long periods of time that does damage.
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This is one of those DAFNE claims I’d be extremely sceptical about. There a number of assumptions at play in this claim that aren’t mentioned.

1) If you took insufficient Insulin for your Carbs there’s no reason to assume a Spike at hour 2 will be gone by hour 5.

2) It assumes a Basal rate that’s “doing you favours” as DAFNE also claims taking a <15 gram snack in between meals won’t raise you blood sugar. The only reason that would be the case is if the Basal is set at such a level where it could take care of it on its own.

3) It assumes if you go out of target during the first two hours the rest of the remaining dose will bring it down. The majority of fast acting insulins out there will have done the majority of their work in the first two hours and will begin tapering off at approximately 2 hours, if not earlier. So clearly they are assuming the Food will have been fully digested in the first two hours, which not all foods will have. This is mostly likely to be the case on High GI foods.

None of this is to say this won’t happen, but it is by no means guaranteed due to a lot of unexamined variables. For instance in the DAFNE course I was on, if any of us were high at hour 2 it was almost certain we would be even higher later.
 

I have similar issues. I can't tell you what to do for your son obviously (against the rules) but if I have a meal with carbs that I KNOW from previous experience is going to raise me to 9/10 in the first hour and then after 2 hours is going to drop rapidly to hypo levels, I take a unit or two less at the start of the meal. Yes, it may mean a rise to 10 but if I know that rise is only for an hour or so then that's fine, generally speaking it's the spikes that STAY up for hours on end that can cause the problems. You will NEVER get a carb/insulin ratio that is 'spot on', it is not possible. A non diabetic's pancreas releases the exact amount of insulin at the exact right time every second of every day, even using the correct amount of basal is tricky as it pops into action at any given moment. Add that to the fact your son may still be in the honeymoon period thus still producing some of his own insulin and you can see why it's difficult. Also, injected insulin can take a different path to its destination for every injection, sometimes it takes the scenic route (takes forever to work) and sometimes it gets there speedily. If I have a low carb meal of course then the initial rise does not happen or is kept very low, that's another option. One other thing re his libre, with them being 15 minutes behind, do you finger prick when it shows very low (hypo) or very high (hyper)? x
 

The thing is though, NOTHING is guaranteed, and EVERYTHING depends on many variables. Assumptions have to be made sometimes as it is definitely not mathematical as in 2 plus 2 is 4. Of course you don't know whether a spike is gone after 5 hours, that's why you test. You can take an educated guess that any bolus injected 5 hours ago is pretty much gone, but you don't know when exactly your basal might kick in. I was told the same as ert and it has worked out for me, in fact they said on this type 1 course that if you correct a 'high' reading around hour 2, then this may take you low quickly (as it meets the bolus you've already taken), your body panics and thinks it's going too low too fast, so drops out glucose and sends you higher! I think we'd all agree that it's all a right pain!
 
The DAFNE science is sound. The 5 hour dosing curve worked for everyone on my DAFNE course. If your blood sugars do not come down after 5 hours, then your dose wasn't correct and you needed a correction with your next meal and to look at your CHO ratio over a few days for that meal.
 
CoolUserName said:
From what you say our son could use next to no insulin
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I use 'next to no insulin', 6 units of basal a day and only 1 unit of bolus for every 20 carbs (ish), as long as the amount of insulin your son DOES use keeps him in a safe range then it matters not whether it's 1 unit a meal or 20. So yes, your son may be able to use lower amounts which will still work. From my own experience, if I did not use ANY insulin for a 30 carb meal my levels would rise, so I use 1 unit and even that small amount stops the rise. x
 
I feel we also have to throw in the "mix" this sounds like a young chap going through that growing hormonal thing..

I don't know about everyone else here, but I left that hell in a handcart behind years ago...
 
Look guys, I don’t want this to become an argument but if you make definitive statements like that you’re increasing the likelihood of them I personal try to avoid them for that very reason.

Diabetes is an extremely complex condition with countless variables. There are many disagreements precisely because of this. No two individuals using the same insulin and same diet would have the same experience because there are many more factors beyond just those two highly influential ones.

Even DAFNE educators wouldn’t be as definitive as you have. I know this because I had a conversation similar to this one with the Educator that ran my course.

If these particular guidelines work for you that’s great keep following them, but it is worthwhile exploring the possibility they might not work for everyone because quite frankly they don’t. Again like I say it didn’t work for anyone on my course.

I will speak only for myself but my HBA1C and Blood Glucose Variability was much worse following these particular guidelines than when I changed to a different style of Diabetes Management.
 
And I follow these DAFNE guidelines and have an HbA1c of 5.3% and rarely hypo. You need to understand how insulin works and human physiology to have a platform to manage your blood sugars. It isn't just chaos theory like you are suggesting.
 
ert said:
And I follow these DAFNE guidelines and have an HbA1c of 5.3% and rarely hypo. You need to understand how insulin works and human physiology to have a platform to manage your blood sugars. It isn't just chaos theory like you are suggesting.
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Whoa, whoa, whoa. I’m not saying that at all.

What I am saying is there are many countless factors in Diabetes Control. There are many Doctors that will agree with me on that. It is not a controversial statement. DAFNE itself acknowledges this. All the other Diabetic Literature I have read cites this as “complicating factor”.

DAFNE makes assumptions for simplicity which means it will work for a lot of different people but when you make assumptions you preclude the possibility of it working for those who do not fit those criteria.
 
The fact that the OP mentioned that the problem with his son's glucose levels only began recently, makes me wonder if the rising temperatures af this time of year are making a difference to his insulin's action. My levels drop like a stone as it gets warmer. My consultant says that in warmer weather insulin 'potentiates' faster, ie it works faster and more efficiently. The result can easily be a hypo.

There are so many variables to consider that if can make our lives difficult. Some people need more insulin in warmer weather. We are not all the same.
 
Sure there is variability, but if you are able to understand dosing bolus and basal you can be mostly stable. Understanding how insulin works and some basic physiology are the cornerstones of our treatment. This is what I understood from DAPHNE. We were taught to follow our blood sugars and make adjustments.
 
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