How long for extra insulin

[Charl]

For some reason 3 hours after taking my morning insulin, breakfast etc my readings are still running high, dont think it's my insulin dosage as breakfast plus insulin was the same as usual,how long should I be waiting to take a bit extra as I don't like to be starting lunch with high numbers. Thanks

 

[helli]

The concern with taking extra insulin between meals is "insulin stacking" - as fast acting insulin tends to remain active for about 4 hours, if you take extra in this time, you risk going low. Therefore, 4 hours is often given as the recommended time between bolus.
However, this does not mean you cannot eat again (and dose for what you eat) in that time. Or a make a correction if you do not think you have enough "insulin on board" to bring your levels down.
Calculation of "insulin on board" is always an estimate because the action profile of insulin differs from person to person and it is not linear over the active period. The usual simplification used is to assume a quarter of your dose is used every hour. So, if you took 4 units for breakfast. you now have about 1 unit active which you need to take into consideration when calculating your correction dose.
Or you could wait another hour and then calculate the correction assuming you have no insulin on board.

As a slight aside, I am not a fan of the term "insulin on board" because to me it implies all insulin. However, it is only referring to your fast acting insulin. You do not have to consider the basal (slow acting insulin).

 

[Proud to be erratic]

Depends what your bolus insulin is, since different insulins have different profiles. NovoRapid is supposed to last 4-5 hrs; the exact duration depends on individuals plus time of day, weather and numerous other factors.

Traditionally, before CGM, we were strongly advised to not "stack" insulins, ie to not take extra insulin when there was already Insulin On Board (IOB). Personally, because I trust my current CGM (Dexcom G7) to give me an accurate sense of what is going on I will stack insulin - cautiously.

But I also find in the mornings my body seems to behave unexpectedly in respect of bolus. Sometimes I can go low and that just seems to "stick" almost goading me into eating more carbs and then catching up and bouncing me too high. But often it's the reverse: I don't get the correction I'm anticipating and I'm being inconvenienced by that (delaying starting to eat) - so I eat anyway and get a bit of exercise activity (ideally in the fresh air). Frequently this change provokes a favourable reaction and my BG then drops. Its not easy this D malarkey and you will read from time to time that D is "fickle". Well it certainly can be for me.

 

[Proud to be erratic]

@helli got here before me.

 

[SimonP]

I stack bolus insulin all day, I use XDrip+ to keep track of how much bolus insulin is in my system (with the understanding that the curve it produces is only an estimate for the reasons mentioned above, but it does allow me to easily refer to something when I make decisions about whether/how much to stack rather than needing to resort to pen and paper/memory).

I also suffer from dawn phenomenon and my subsequent BG response can be a bit erratic (which I think is down to how much I'm doing that morning, i.e. an activity link, so sitting down to WFH needs more insulin, while heading into work needs less).

 

[rebrascora]

Can you give us more detail on your breakfast situation?
ie What your waking reading was and how long you prebolused and what your levels were when you ate breakfast and what they are now and how much bolus insulin you used and how many carbs. For me these are some of the things I take into consideration before I start stacking insulin, which is generally discouraged by HCPs because if the risk of causing a hypo, although like @Proud to be erratic, I trust my CGM and my own experience to do it regularly with good effect. I however use Fiasp which for me acts over a shorter period than NR and I mostly use small doses, plus a keep a tally of when and how much insulin I stacked so that I can roughly do a mental tally and figure out if what I have on board will bring me down into range or if I need more.

There are lots of things to consider and one important one being, have you got time this morning to monitor your levels closely or will you be busy and/or very active at work perhaps, when you could potentially take your eye off the diabetes ball game and get caught out with a hypo as a result of stacking that correction. If you have time to monitor things closely and have hypo treatments close to hand, then experiment with a modest correction taking into account how much insulin you stil have active from your breakfast bolus. So if you injected 5 units 2 hours ago there are probably about 2 units left active and those 2 units might drop your levels 2- 3mmols each, so that would mean that there is enough insulin still in your system to drop your levels by 4-6 mmols. So if you are up at say 15mmols, that is still going to leave you high at lunchtime at about 9-11mmols, so 1-2 units might just help bring you back down into range by lunchtime. You do however need to be aware that unless lunch is 4 hours later, some of that stacked correction will still be working, so if you are still a bit high at lunchtime, you would not include another correction.

I know it probably seems really complicated, but you do get used to just glancing at your CGM, perhaps doing a finger prick to confirm if levels are really that high and then calculating roughly how much is left and if that is enough to bring those levels down or if you need more. I log all my injections on Libre so that I can look back and tot up how much insulin is stacked at any one time before I decide if I need more or if perhaps some exercise will bring it down. I have recently started running up and down stairs 20x if I am in the house and my high alarm goes off and that will bring me down a couple of mmols. Sometimes if levels are rising fast, I need to add a correction plus the exercise.

 

[helli]

I however use Fiasp which for me acts over a shorter period than NR

Not wanting to derail this thread but that's interesting.
Although Fiasp starts working quicker than NR for me, I find it remains active for as long.

 

[Charl]

No extra needed, Readings have decided to drop, maybe I wasn't walking about as much as I usually do, will save those numbers regarding stacking etc. Thanks

 

[rebrascora]

Not wanting to derail this thread but that's interesting.
Although Fiasp starts working quicker than NR for me, I find it remains active for as long.

I see very, very minimal activity after 2.5 hours with Fiasp and nothing worth considering after 3hrs. I think it was one of the things which made it really difficult for me to adjust to and it may be linked to my low carb way of eating, but now that I have adjusted to it, I find I manage with it much better. So for instance if my levels are high when I wake up and I calculate a correction plus my breakfast bolus, if I wait 2 hours for it to come down before eating and it doesn't, then I need to hit it with more. I can wait and wait and wait after that but it just sits there.
Also something that I was thinking about last night which seems to be another quirk of Fiasp. I can substitute prebolus time for units. So if I am in the 7s or 8s and I want to eat straight away, then if I add another unit of Fiasp to my actual dose ( including any correction), I will get away with eating straight away and not go low afterwards, whereas if I inject the usual amount and wait the usual time the normal insulin dose works. I really don't know if this is just me being odd, and I have only done it for small 10-20g snacks, if 10g I would just add 0.5 units extra and only if my levels are above 7. If it was 15-20g carbs, 1 extra unit seems to do it. I may be misinterpreting the results I am seeing and because we don't see or have control of all the things affecting our BG levels I may be wrong, but it is becoming an increasingly common result, the more I experiment with it, so I don't think it is a coincidence. I try to always eat when my levels are in the 4s and 5s and very rarely above 8, but I can get away with mid 8s with a 10-15g carb snack, plus correction plus an extra unit and get to where I want to be in the 6s and not go above 10mmols.

 

[rebrascora]

Glad that you have found levels have come back down without intervention @Charl Even just being a bit dehydrated can stall their descent a bit, so worth just having a cuppa or glass of water or a bit of exercise before you reach for more insulin.

 

[helli]

I see very, very minimal activity after 2.5 hours with Fiasp and nothing worth considering after 3hrs. I think it was one of the things which made it really difficult for me to adjust to and it may be linked to my low carb way of eating, but now that I have adjusted to it, I find I manage with it much better. So for instance if my levels are high when I wake up and I calculate a correction plus my breakfast bolus, if I wait 2 hours for it to come down before eating and it doesn't, then I need to hit it with more. I can wait and wait and wait after that but it just sits there.
Also something that I was thinking about last night which seems to be another quirk of Fiasp. I can substitute prebolus time for units. So if I am in the 7s or 8s and I want to eat straight away, then if I add another unit of Fiasp to my actual dose ( including any correction), I will get away with eating straight away and not go low afterwards, whereas if I inject the usual amount and wait the usual time the normal insulin dose works. I really don't know if this is just me being odd, and I have only done it for small 10-20g snacks, if 10g I would just add 0.5 units extra and only if my levels are above 7. If it was 15-20g carbs, 1 extra unit seems to do it. I may be misinterpreting the results I am seeing and because we don't see or have control of all the things affecting our BG levels I may be wrong, but it is becoming an increasingly common result, the more I experiment with it, so I don't think it is a coincidence. I try to always eat when my levels are in the 4s and 5s and very rarely above 8, but I can get away with mid 8s with a 10-15g carb snack, plus correction plus an extra unit and get to where I want to be in the 6s and not go above 10mmols.

I find both last about 3 hours for me.
Because Fiasp peaks earlier, there is less Fiasp "on board" after 2.5 hours but I still need to consider it with my "stacking" calculations.
I have mentioned before how the speed of Fiasp depends very much on my BG. The duration may be related to when it starts working: if I bolus when in the 4s, it works immediately and has little affect 2.5 to 3 hours later. If my levels are higher (in the teens), it can take an hour to start working and is active 2.5 hours after that.
As I don't "sugar surf" in the way you do, I do not find increasing the dose when high makes it work any faster. In fact, my long hypo at the weekend was probably related to a large bolus when my pump failed which took a long time to take effect and I over compensated for my insulin resistance when high.

 

[rebrascora]

I find both last about 3 hours for me.
Because Fiasp peaks earlier, there is less Fiasp "on board" after 2.5 hours but I still need to consider it with my "stacking" calculations.
I have mentioned before how the speed of Fiasp depends very much on my BG. The duration may be related to when it starts working: if I bolus when in the 4s, it works immediately and has little affect 2.5 to 3 hours later. If my levels are higher (in the teens), it can take an hour to start working and is active 2.5 hours after that.
As I don't "sugar surf" in the way you do, I do not find increasing the dose when high makes it work any faster. In fact, my long hypo at the weekend was probably related to a large bolus when my pump failed which took a long time to take effect and I over compensated for my insulin resistance when high.

I absolutely agree with you about Fiasp working quicker when levels are lower and more resistant/sluggish to work when levels are higher, but even with that consideration, I find it is gone much quicker than NR and increasing my dose to account for no prebolus time when levels are 7-9 mmols seems to be a strategy that is consistently working for me.
My sugar surfing does give me the mentality that I can always deal with it later by having 5g carbs if my levels are heading low but I don't find that I need to on these occasions.
Most of my frustrations with Fiasp were that it didn't do what I expected it to do and I needed to be more heavy handed with it. I am slowly learning the nuances of how and when I need to be more heavy handed and the more I can keep it in the 4-7 range, the less heavy handed I need to be and I am discovering extra little strategies to help keep it there as much as possible.

 

[Proud to be erratic]

So for instance if my levels are high when I wake up and I calculate a correction plus my breakfast bolus, if I wait 2 hours for it to come down before eating and it doesn't, then I need to hit it with more. I can wait and wait and wait after that but it just sits there.

That is my experience also with NR.

..... which seems to be another quirk of Fiasp. I can substitute prebolus time for units. So if I am in the 7s or 8s and I want to eat straight away, then if I add another unit of Fiasp to my actual dose (including any correction), I will get away with eating straight away and not go low afterwards, whereas if I inject the usual amount and wait the usual time the normal insulin dose works.

When I was on my Dafne course and I indicated that I would sometimes need to wait a very long time for my BG to correct before eating (and how that was tolerable when I was on my own but a real nuisance when we had company) the DSN leading the course challenged this practice and was expecting me to put in an extra dose to "force" that correction. We discussed this a bit involving the others - but they weren't really identifying with my scenario. But, I struggled with the principle, since the inference is if you are already high then one's bolus correction ratio is in effect being changed. The discussion didn't resolve the issue for me, but it was truncated and as far as I'm concerned unresolved. The DSN was in effect saying sometimes use one correction ratio and at other times don't - OR have a sort of sliding scale and use one correction ratio if only a little elevated and use a different (stronger) ratio for correcting when a lot elevated.

It does reinforce how muddling and confusing bolus dosing can be!

 

[rebrascora]

That is my experience also with NR.

When I was on my Dafne course and I indicated that I would sometimes need to wait a very long time for my BG to correct before eating (and how that was tolerable when I was on my own but a real nuisance when we had company) the DSN leading the course challenged this practice and was expecting me to put in an extra dose to "force" that correction. We discussed this a bit involving the others - but they weren't really identifying with my scenario. But, I struggled with the principle, since the inference is if you are already high then one's bolus correction ratio is in effect being changed. The discussion didn't resolve the issue for me, but it was truncated and as far as I'm concerned unresolved. The DSN was in effect saying sometimes use one correction ratio and at other times don't - OR have a sort of sliding scale and use one correction ratio if only a little elevated and use a different (stronger) ratio for correcting when a lot elevated.

It does reinforce how muddling and confusing bolus dosing can be!

I definitely need a larger correction factor ie more insulin when levels are high than when under 10, but even then I often find that it seems to be more effective, particularly with Fiasp, to stack 2 or 3 smaller corrections than to hit it with a much bigger one straightaway. I am guessing it will absorb from several smaller sites slightly quicker than one larger amount in one site, but I may be wrong. I also feel a little more in control stacking smaller corrections over a period of time than shoving in one big one which will have a peak of activity all at once, so if I got it wrong it will cause a more dramatic drop than 2 or 3 smaller corrections over an hour or so. I may be mistaken and that could just be a psychological benefit. I suppose it also depends how you feel about extra injections. Another 2 or 3 doesn't bother me and I reuse needles (naughty I know 🙄 ) so no financial impact to the NHS in doing so.

Really surprised that a DAFNE DSN would suggest an additional correction to "force" the correction.

It doesn't surprise me at all that other people on the course didn't relate to the issue, as I am sure most people just inject, wait however long their DSN told them to prebolus with their particular insulin and then eat and be oblivious of their levels spiking or assume there was nothing they could do about it.