Post Prandial Highs

IainB

IainB

Member
Relationship to Diabetes
Type 1


Iain Byrne​

​

Hi all,
I am a long standing type 1 and have been on Lantus and Novorapid for 28 years. I have only recently started CGM with Dexcom 1+ and would like a little advice.
Post prandial highs - I regularly get highs of around 12 - 13 post meals, how soon should you react to these events with a control dose if at all as these are causing me a few issues.
I have been tending to give control doses quite soon but this sometimes results in a corresponding low.
I have been unable to speak to my DNS about this as they have some staffing problems but have arranged an insulin review for October as my GP thinks my insulin is not ideal.
Thanks Iain
 
Post prandial spikes are usually an issue of timing of the insulin rather than dose, if you have carb counted and used the correct ratio and your levels have mostly come back down into range by the next mealtime.

How far in advance of eating do you inject your Novo(not so 🙄)Rapid before you eat?

My situation is a bit extreme, but I found that I needed to inject NR as much as 75 mins before breakfast, about 30 mins before lunch and about 15-20 mins before my evening meal, but it depended on what I was going to eat. I now have Fiasp which is quicker but I still need about 45 mins between injecting my Fiasp and eating breakfast to prevent spikes.

I am not suggesting you do the same as me, because many people would hypo waiting that long but clearly my body is pretty slow to absorb insulin and my digestive system is very fast.
The way to go about it is to experiment by increasing your prebolus time by 5 mins each day until you find the "sweet spot" timing for your body with NovoRapid and remember that it will likely be different timings at different times of day and may also vary with your premeal BG level. So if I am in the 4s when I wake up, I will need less time than if I wake up at 8mmols or above. If I am eating something which is going to release very quickly then I need more time than if I am going to have something slow like a pizza.

Generally I inject my breakfast bolus before I get out of bed and then keep an eye on my CGM and eat my breakfast when I see my levels starting to drop, rather than actually timing it like I had to before CGM.
 
I discovered a link to an American doctor discussing this issue. He recommended if BG is within normal range inject 15 mins before meal, if above 30 mins and if below inject then eat so I have been using that. I will try your system thanks.
I agree with your description of Novorapid as “not so rapid”
Thanks for your advice
 
Hi @IainB I still my surprise when I first used a sensor. I had no idea just how spiky my levels were after meals and had never heard of pre-blousing at that time. I was back in target by the following meal so finger pricks did not show a problem. Once I saw the evidence on the sensor output of what was happening in between I looked for changes that I needed to make.

Like @rebrascora I took a bit of time to work out my pre-bolus timings for each meal. These are lower in the evening than first thing. I also spotted that certain foods were more spiky for me than others. Porridge oats are a no for me now.

Worth using the sensor to identify patterns and find changes needed.
 
That doctor's advice is good guidance, but as with all guidance it is generalised and you need to find the timings for your body with your insulin when you are above range, in range or low. I did lots and lots of finger pricking before I got LIbre to find what worked for me as I used to spike up to 15 or more every morning after breakfast and then came crashing back down again later to about 5 but it felt horrid because I went so high and then dropped and that sort of variability long term is not good for your body, so getting your timing right is a really good diabetes management skill.
If my levels are above 10 on a morning when I wake up, I can be waiting 2 hours before I eat breakfast otherwise I will be high most of the day. That said, Fiasp is only quicker when my levels are nicely mid range, once I get above 10, it is like injecting water and even above 8 it becomes more sluggish.
 
rebrascora said:
That doctor's advice is good guidance, but as with all guidance it is generalised and you need to find the timings for your body with your insulin when you are above range, in range or low. I did lots and lots of finger pricking before I got LIbre to find what worked for me as I used to spike up to 15 or more every morning after breakfast and then came crashing back down again later to about 5 but it felt horrid because I went so high and then dropped and that sort of variability long term is not good for your body, so getting your timing right is a really good diabetes management skill.
If my levels are above 10 on a morning when I wake up, I can be waiting 2 hours before I eat breakfast otherwise I will be high most of the day. That said, Fiasp is only quicker when my levels are nicely mid range, once I get above 10, it is like injecting water and even above 8 it becomes more sluggish.
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That’s all very interesting thanks. I did read that some new insulins are in development and close to clinical trials. One is a very fast acting one and one they are calling “smart insulin” where you inject once a week and the insulin reacts to your body’s glucose levels
 
I have been tending to give control doses quite soon but this sometimes results in a corresponding low.

How soon is “quite soon”? If you inject too early then you’re not giving the Novorapid a chance to work fully. We used to be told to correct at the next meal. I don’t always do that but I never correct closer to a meal than 2hr15 or so and then only if it’s obvious something has ‘gone wrong’, eg a major carb miscalculation, and I’m really high. I wouldn’t correct a 12 at 2hr+ post-meal as it would probably come down.

Finding the best time to pre-bolus is the answer as then you can keep the rises controlled. If you correct too early you risk an unwanted ride on the unpleasant Type 1 rollercoaster, veering from high to hypo and back again.
 
I have been allowing 1-1.5 hours before giving a control dose but now realise that timing my pre dose is more important. Thanks
 
@IainB, just a passing thought: have you done a basal test recently (these days it's more simple with scrutiny from your CGM). It's easy to forget that if your basal isn't right then your bolus is having to compensate for that first.
 
Great basic explanation in this link. But it doesn't make clear that there are fundamental differences in what to do when the different actual basal insulins can vary so much - from one extreme of very flexible and changeable Levermir, often taken 2x daily, to Tresiba the seemingly inflexible 1x daily and with a 40 hr profile.

Firstly the reality is our body generates uneven internal glucose releases throughout any 24 hr period.
Extremely few people require or need a very steady and even basal 24 hours a day. Our basal insulin is there to help us manage that irregular internal glucose production leaving our bolus for the food we eat, when exercise and general activity has already played its part. With a pump, people can programme their insulin releases from the pump to match their basal needs 24 hrs a day. On Multiple Daily Injections (MDI) our basal can only provide a fixed degree of cover to match the requirement of any one part of a day.

The user needs to be clear about which part of a 24 hour period they require their basal to be matching their internal glucose releases. Levermir is pretty unique, in that the user gets 2 bites at the cherry and can have very different basal doses between am and pm. Tresiba has to be optimised for just one portion of the 24 hr day. That doesn't mean Tresiba is doing nothing for the rest of the 24 hrs, but whatever it is providing then is a fixed background entity and does not need to be thought about - it is just there quietly having its own private party. At such times bolus along with exercise and activity are the key, changeable, BG management tools for Tresiba.

So basal needs to be optimised for specific parts or part of a 24 hr period. Levermir for 2 parts, single dose basals for one part. The MySugar video makes clear that basal assessment needs to be done in time blocks under tight conditions of both fasting and BG stability. If events such as a low intervene then that fasting session becomes void.

Before CGM this was a tricky process to set up, needing a 24hr period to be split into 3 or 4 parts and done probably across many days, with fine adjustments and repeats. Using fp and meter testing it was both demanding and potentially stressful to get a clear understanding of how one's basal was doing. CGM is a significant aid to this analysis - just look at the relevant bit of the graph! (And keep good notes!). But of course, other than for 2x daily basal doses, most of the basal analysis (testing) needs to be looking at the one part of the 24hrs that basal needs to be optimised for.

I have optimised my Tresiba to cover the late evening into the night and until I wake and get up. My evening meal can be as late as 8 pm, so from midnight (after that meal is digested and my NovoRapid has essentially gone) until 8am (+/- an hour or 2) I can fall asleep at 6.7mmol/L and wake still at 6.7mmol/L, with negligible BG movement during this natural fasting period. I don't seem to get much Dawn Phenomenon (DP) but if I do my Tresiba doesn't manage that; I often get some Foot on the Floor (FotF) syndrome about an hour after I wake, but by then my breakfast bolus is already in my system. If my BG regularly falls during the night I conclude my basal is too much and if it rises it is too little. Thanks to CGM I never make a decision from one fasting test, but after 3 or even more overnight graphs.

With Lantus it's profile is to last a nominal 24 hrs and it's release is not perfectly even across those 24 hrs. So more attention is needed to how one's Lantus is behaving in the period of keen interest - and unlike Tresiba it's quite possible that the time of that 1x daily dose is also critical to get the optimum performance at the time when needed.

At the other end of the spectrum with Levermir it is possible to look back at a succession of 24 hr periods and spot those times in fasting and BG stability when a Levermir dose is pushing you out of kilter, both am and pm. I was taught how to do this during my DAFNE course and while I understood the mechanisms being explained, it felt to me that stable nights would be possible from well tuned evening Levermir, but for the rest of a day there was too much variety from hormone triggered internal glucose releases to make Levermir match that variety across a potential 12 hour period. So I concluded that Levermir could only be optimised for just part of the am period; there is too much internal glucose release variation during the am period so "one size still couldn't fit all that variable period".

Is this all too much faff to bother with? Well remember that "If our basal insulin isn't adjusted properly, nothing else works properly. When basal rates are off, it's like walking through quicksand – doing a lot of work without much progress, or sinking even deeper into trouble.".

Also, never change 2 things at the same time. If you've tweaked your basal don't be tempted to adjust anything else in that period.
 
Not just Levemir @Proud to be erratic As a pump user, I use an isophane insulin as basal twice daily when I take a pump break. The biggest difference in basal rates is between day and night so a twice daily basal allows me to get closest to what my pump does.

Of course another alternative, which no-one mentions much here, is to use a regular (non-analogue) insulin as bolus as that can give cover across the day if you eat three meals (it lasts longer and has a different profile) meaning that a basal is only needed at night, just like years ago when MDI was first introduced.

@IainB If your Lantus isn’t working for you, you could consider a twice daily basal and give that a trial to see which you prefer.
 
IainB said:
I discovered a link to an American doctor discussing this issue. He recommended if BG is within normal range inject 15 mins before meal, if above 30 mins and if below inject then eat so I have been using that. I will try your system thanks.
I agree with your description of Novorapid as “not so rapid”
Thanks for your advice
Click to expand...
As @rebrascora mentioned, this is a good guideline but it missing subtleties. It assumes our insulin resistance/sensitivity is the same 24x7x52; it assumes all food is digested and all carbs absorbed at the same rate; it assumes you have not done anything like exercise that may cause your BG to fall.
Breakfast is often mentioned as the first meal to start working out pre-bolus times because, for most people, it is eaten around about the same time every day and there is little variety. However, insulin resistance is higher for most people in the morning so pre-bolus time is often greater.
With other meals, it will take some trial and error and decision on your part how good is good enough for you. But generally, foods higher in fat will affect your BG later. For example, pasta with a creamy/cheesy sauce can affect my BG 4 hours after eating. This doesn't mean I need to bolus 4 hours after my meal but it may need a split bolus - part of he bolus before/with food and the rest after an hour or two.
If I have done intensive exercise which raises my heart rate for 30 minutes or more, I know my BG is likely to fall so I never pre-bolus after exercise.

@Inka mentions basal testing which is a great idea. Before switching to a pump, I used Lantus (and still have it as a back up). When I started on it 20 years ago, it was the new shiny long acting insulin but it has been superseded by the next generation for many. The "problem" with Lantus is that it is not as flat as advertised and may not last a full 24 hours. Some people see it become a little more "potent" after about 5 hours which can result in a drop in BG. But then, if it runs out after 22 hours, you may see a rise in BG.
I mention this as somethings you may spot during your basal testing and could be a reason to ask for a different newer basal insulin.
 
To pick up on both replies from @Inka and @helli, if you end up feeling a different basal may be more helpful then the 2x daily Levermir has its place, but needs regular (almost daily) decisions about the dose size am and pm. Conversely the newish but seemingly inflexible Tresiba also has its virtues. Once set up it really only needs tweaking between summer and winter and the CGM graphs clearly show when that is necessary. It's so simple for the basal review.

I am a huge fan of Tresiba; the DSN who arranged for my change from Levermir offered no explanation or guidance, nor did she get the Tresiba dosing after Levermir even near correct - I needed to work that all out for myself, which is fine because I ended up understanding that Tresiba required a very different mindset. As a 75yr old male, my growth hormones are very dormant and because I'm fully retired I can pace my lifestyle and avoid pressure; all of which helps to reduce the daytime unscheduled glucose releases (reduce, but not stop).

Now, knowing my basal is sorted I can play with my bolus ratios and pre-bolus timings (with split boluses quite often) to fend off the post prandial highs. I think mine are probably caused by delayed digestion after my high fat breakfasts (plenty of double cream with any fruit and yoghurt). So self-inflicted!

I meant to ask you @IainB, are you familiar with Gary Scheiner's book "Think Like a Pancreas"?
 
To be fair @Proud to be erratic I find my isophane basal (Hypurin) doesn’t need any adjustment. When I take a pump break, I work up to the right doses and then they stay there. My longest pump break was months.

I was trying to find an up-to-date list of basal insulins but I couldn’t so please add to the list below if you’d like as these are just the ones that sprang to mind:

Abasaglar (thanks @silentsquirrel )
Humulin i
Hypurin isophane
Insulatard?
Is Insuman still available?
Lantus
Any Lente ones still available?
Levemir
Is Monotard still available?
Semglee
Toujeo
Tresiba

My consultant automatically picked her ‘favourite’ but I asked for my isophane and it suits me well. I’m a big fan of having a variety of insulins available. We’re all individual and sometimes people are only offered one basal or just a choice of two when others out there might suit them better for a number of reasons.
 
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Proud to be erratic said:
if you end up feeling a different basal may be more helpful then the 2x daily Levermir has its place, but needs regular (almost daily) decisions about the dose size am and pm. Conversely the newish but seemingly inflexible Tresiba also has its virtues. Once set up it really only needs tweaking between summer and winter and the CGM graphs clearly show when that is necessary. It's so simple for the basal review.
Click to expand...

I think the need to vary basal depends on the variability of your lifestyle and the way your body reacts to it.
My days vary from slovenly working at my desk through stressful meetings one day to 8 hours of hiking up and down mountains the next. While the hike may be planned the stressful meetings are often not. My body needs significantly different amounts of basal on each of those day and I cannot plan ahead for them.
If my days were more "stable" and predictable, a longer active basal like Tresiba would suit me. Instead, I adjust my basal on my pump most days and, when I was injecting, my Lantus dose would change based on exercise 4 days out of 7.

In other words, it is the nature of the person taking the insulin that results in the need to vary the dose, not the nature of the insulin.
I guess it is a bit like the mixed insulins - not everyone needs the flexibility of MDI and 2 injections a day are better for them.
 
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Inka said:
To be fair @Proud to be erratic I find my isophane basal (Hypurin) doesn’t need any adjustment. When I take a pump break, I work up to the right doses and then they stay there. My longest pump break was months.

I was trying to find an up-to-date list of basal insulins but I couldn’t so please add to the list below if you’d like as these are just the ones that sprang to mind:

Humulin i
Hypurin isophane
Insulatard?
Is Insuman still available?
Lantus
Any Lente ones still available?
Levemir
Is Monotard still available?
Semglee
Toujeo
Tresiba

My consultant automatically picked her ‘favourite’ but I asked for my isophane and it suits me well. I’m a big fan of having a variety of insulins available. We’re all individual and sometimes people are only offered one basal or just a choice of two when others out there might suit them better for a number of reasons.
Click to expand...
abasaglar
 
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