Type 1 Bs testing

Diabeticmum1982 said:

Hi I'm type 1 diabetic and not sure as to when I need to take my bs, I was taking it before every time I eat and 2hrs after I had eaten, but my dn told me to check it 4hours after I eat because the insulin takes around 4hours for it to reach its peak, (I'm on novo rapid fast acting, and levimer for slow acting) I've seen on this forum that a lot of people are testing 2hours after every meal, so I'm feeling a little lost, could someone please help me out with this? Thanks in advance.

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I can't help with the Type 1 and insulin issue, but it is the Type 2s that test before and 2 hours after eating to spot post meal trends so they can tweak their carbs next time.

Your DSN needs educating.

Ideally you will test before a meal and 2 hours after...before bed, during night occasionally and before getting up.
I also do basal testing which I will test every hour during the basal test time, and of course additional for driving.

Your nurse is correct to say that Novarapid typically stays in your body working for up to four hours.
This does not mean you should not test after two hours. But it does mean you need to consider the Novorapid still active in your body if you are going to take a correction dose.
I understand the reason many people test two hours after eating is to review the impact their meal has had on their BG. This may help you decide to inject earlier next time you eat something similar or avoid eating it all together if you feel your two hour peak is too high.

the first question you should ask yourself is not how often or when to test. It is why you test. Then you can decide what the answers are to how often and when.

Diabeticmum1982 said:

Hi donnellysdogs, how can you have an accurate reading after 2hrs when novo rapid takes 4hours to fully work? Sorry I'm just totally lost with it all.

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hi there @diabeticmum
I always test before a meal , 2 hours post meal and again at 4 hours post meal

the reason ?? to get an accurate picture of what my BG is doing relative to the carbs I have consumed.

so as an example 4.9 pre meal 68 carbs for the meal ( 13.6u bolus dose on a pump) 2 hours post meal 7.8 ( no correction )
4 hours post meal 6.1 -- again no correction as within target for 4 hours post bolus --- this is only an example and sometimes if my bloods are not within range at these timed BG 's -- I would take a correction

it is an ever evolving scenario and one with which we adjust to every day .


all the best !!!!!

Hi @Diabeticmum1982 - it probably helps to think of your blood glucose as a continuum rather than a series of unrelated points. If you were to plot the numbers on a graph every five minute, they'd look a little something like the picture below:



So what can we take from this information? Well, not a lot really, but if I overlay the food and bolus insulin on it, you can see a lot more:


If we focus on the time period around 8am, you can see that I took a pre-bolus of 2u, then a slightly later bolus of 3u, which was around 15 mins before eating. You can then see I ate at about 9.10 and that my glucose level rose, from about 7 to about 9.5, at about 10.30ish. It then fell back to just under 7 at 1pm when I ate again.

What does this show? It shows that with normal fast acting insulin (this is Novorapid) that the insulin action takes about four hours in total to take effect, and that if you don't do prebolus, your glucose levels rise with eating.

If you equate this to using finger pricks, testing just before eating would be the 7 at 9am just before eating, and that your two hour one would be the 9.5 at 11am. The two hour one is important as it shows you how high your peak is. This can be reduced by doing your bolus in advance of the meal - what's known as a prebolus, and this may need to be anywhere between 15 and 45 mins ahead of eating. The only way to find out is to test.

We've then mention of a four hour one, which is at 1pm, and that would be the ~6.5 I mentioned. That one's important because it identifies that your insulin to carb ratio is correct, as at four hours, your glucose level should be approaching the level it was before the meal. If it isn't, you need to adjust that ratio.

Additional tests throughout the day can be undertaken to ensure that you remain within the best range, and of course a test before bed is to confirm that you aren't too low to go to bed.

Hopefully the visuals help you to understand what's happening and why the testing is required. As always, if there's anything there you want clarification on, we're always here to help!

Some people find their fast acting insulin can last 5-6 hours...
If having food, to find out your carb ratios are right it is best (if you can) to bolus and eat-then test 2 hours, 4 hours and if you can test at 5 hours and six hours it would give you a good idea how long your quick acting lasts in your body. You must have any accurate carb measured meal to do this and not eat (unless hypo) for 6 hours.

You dont need to do this daily.. preferably though a couple times initially for breakfast to late lunch and again on another day for lunch to evening meal and evening meal til bedtime.

Testing at 2 hours and 4 hours is the only way to see if you get back to target levels (4-5hours) after any bolus is given. Whether its for food or corrections.