Bolus converter question

[sweetlife]

The target range we fix ex.130 is for after 2 hrs BS or for 3 or 4 hrs BS as effect of fast acting insulin lasts for this time frame,me little confuse so requesting a feedback.

[BlueSky]

I think that target of 130 at 2 hours after eating is more of a T2 thing. Setting a 2 hour target when the insulin acts over 4 hours doesn't really make sense. Whether BG is less than 130 at 2 hours depends on the amount of carbs eaten and the size of the bolus used. If a large enough bolus is used to cover a carb feast and produce 130 at 2 hours, there is likely to be a hypo at 4 hours.

[Gary_W]

OK, these are opinions and how I do it rather than all-out science....

First, you need to understand how long the bolus insulin remains active for, and if you can get some idea of the 'curve' then this will help.

Most modern bolus insulins have a lifespan of 4-5 hours, but this time varies a fair bit from person to person. I use Apidra, and with my body, 65% of a bolus is used up after 2 hours, 90% used at 3 hours and the last 10% is gone by hour 4. For this reason, I always blood test at hour 2 but the result I expect will vary depending on what I ate. If I'm too high at the 2 hour point, I will correct with more insulin. If I'm too low, I'll keep an eye on it with another blood test in 1/2 hour to see how it's going and correct with food if needed to head off the hypo.

I short, what you want is the lowest possible 2 hour reading WITHOUT GOING HYPO DUE TO THE 'TAIL' OF THE INSULIN RESPONSE.

[sweetlife]

Exactly and if a person who is not strict in diet and taking average carb may go into hypo at 4 hrs if dose is high hence for T1 kids atleat I think that we should check BS after 3 hrs .
If a large enough bolus is used to cover a carb feast and produce 130 at 2 hours, there is likely to be a hypo at 4 hours.


I short, what you want is the lowest possible 2 hour reading WITHOUT GOING HYPO DUE TO THE 'TAIL' OF THE INSULIN RESPONSE.

[Subby]

First, I think it's much more useful and sensible to talk in terms of relative BG levels rather than absolute. It's not always practical to be "exactly" on a particular figure at the start of the meal, so absolute numbers become incorrect. Instead of aiming for absolutes/immediately begging the question to factor in corrections or sliding scales, establishing a consistently replicated mealtime BG profile from the 0 hour to the 4th hour should be the first base.

Adjustments for achieving BG correction/aiming for more absolute numbers throughout the mealtime scenario, can be looked at once a baseline consistency has been established.

I think a two hour target is very important, in conjunction with a four hour target.

The two hour target checks the scenario "mid way" and would normally factor in some upward rise, due to the fact that carb/insulin matching is not an exact science and an error margin upwards rather than downwards is more likely to result in a successful overall result, considering the insulin may often lasts longer than the carbs and also that moving low might afford more danger than moving high.

I've understood a reasonable 2 hour target to be around 2 mmol/l upwards (35 mg/dl). Your standards may differ, either tighter in the aim to achieve better control, or looser in the aim to be more realistically achievable in the short term, given a more volatile BG reactivity.

What does the two hour really tell you? The BG result of the food/insulin combo in mid-scenario, and it provides a plotting point to make much more sense of the 4 hour, providing a picture rather than a point.

The 4 hour would be the one you want to see return to zero base as the action of both food and insulin should be pretty much finished, and you are back on your basal to keep you level.

Again, I highly recommend a test at both, at least while information is being collected. Neither give you a complete enough picture to get a birds eye view how the mealtime has played out.

The two hour target is particularly useful for eliminating high GI, quick spike carbs, and identifying successful low carb or low GI options. Often at the 4 hour point such foods may well have run their course and/or been defeated by the insulin, and you may be none the wiser that you spiked.

It can also help to inform whether pre-bolusing may be a useful technique to use. If BG is spiked at the 2 hour mark despite being a low carb or definitely low GI/energy release food, and yet a much lower figure is found at the 4 hour, it may well be showing that the insulin is taking a little too long to kick in. (There are other potential explanations of course, but this is a useful avenue of investigation).

Gary, I agree that these time points can and should be modified to suit the particular insulin action and/or diet (low carb low GI might suggest other more pertinent points), if they significantly deviate from these gross generalisations.

All this stuff is purely my way of putting what I've used in practise or discussed with my doctors, I'm sure there are far more elegant descriptions of targets out there.

[sweetlife]

Nicely summed up Subby,what happens is in most children that if we strictly follow 120-130 ppbs and IF their carb ratio is lower i.e requires more insulin than other T1,they get hungry around 4 hours and in some cases BS go down below 80 if dose is high.

[hodgsonsurvivor]

I usually test after 2hrs and my goal is for a target range <150. I am currently trying to get in more frequent tests at the 1 hr mark with a target range of <180. (These were targets my doctor told me to aim for.) If I'm testing at 4 hrs, it's because it's about time for me to eat again, since my meals are about 4-6 hours apart (and sometimes a snack in between). Those I like to see at <120. Truth be told, I aim for about 10-20mg/dl less than my targets when calculating how much insulin to take and that's been helping with my awful carb counting! lol