, ,

Basal Insulin Testing – Why, How & When?

Do you have frequent low blood sugars? Or high? And they all seem to come out of nowhere?

It could be something wrong with your basal insulin, dose or timing! Learn all about basal insulin testing in today’s Type 1 Thursday!

When was the last time you checked you basal insulin settings?

Type 1 Thursday – Basal Insulin Testing – Hanna Boëthius


If you prefer to read all about basal insulin testing, you can do so below. Enjoy!

Basal Insulin Testing

‘I want to ask you this first, do you perhaps experience frequent hypos or frequent highs that seem to come out of nowhere? They are not really connected to when you’re eating and your bolus insulin, and it’s not really connected to anything else either. So maybe it is something else, could it be? (As we all know, with diabetes, chances are it could be…)

Butt first, hypos, or low blood sugars, never, ever happen because you’re not eating enough food! Hypos always, always, always happen because you’re taking too much insulin for that particular circumstance. That actually leads us back to today’s topic, basal insulin settings and how to check that your basal insulin settings, like your long acting insulin, or basal settings on your pump, are correct for you. Not for anyone else, never ever compare insulin dosages with anyone else. It is what it is for you and if it is correct.

Basal insulin is really key, either is dose or the timing. If you are on MDI, timing of the basal insulin could be a problem. So let’s figure out what it is, how we do it and all this stuff when it comes to basal insulin testing. It’s not necessarily fun, but hey, you know, it needs to be done if you want as good of a control as you can have on your Type 1 Diabetes. Having your basal set properly also helps you bolus correctly for your food or it makes it a lot easier to calculate.

What is a basal insulin test?

The point of basal insulin is to keep your blood sugar stable when you’re not eating, when you’re exercising when you’re not doing anything. It works the same in healthy people, the ones that don’t need to add insulin from the outside. Basal insulin is there to keep your blood sugar very stable during the whole day when you’re not eating, not exercising, not doing anything of the few things that actually help lowering your blood sugar, or any of the 42 or 45, or whatever things that can increase your blood sugar.

What is a basal test? Well, it’s basically to determine what your proper basal setting is, whether you are on a pump or taking long acting insulin. Without the influence of food and without bolus insulin, without exercise.

How to basal insulin test?

How do you do it? Well, trick number 1 is to start at a normal blood sugar level. Don’t start if you’re too high, don’t start if you’re too low, start at a normal that is the baseline of basal insulin testing.

You can either do it in two ways. Either you fast the full 24 hours and get it all out of your system and you have done in one go or you divide it up on 4 days and divide the 24 hours into 6 hour increments, where you fast for 6 hours and then check your blood sugar’s hourly to see what happens to them.

This is also where a CGM is very helpful, although I would not trust it to be exact for all of that, I would also prick my finger a couple of times in those 6 hours or those 24 hours, just so you can actually see what is doing what. If you choose to do it in four days, then you do overnight in one go and then you do a morning session, followed by a day session and then an evening session, so that you get those 24 hours all checked.A suggestion is that you basal insulin test one week and then the next week you do the same, to just double check and fine tune and really tweak your basal insulin (because this is really key for good blood sugar management)

Do & Don’t when Basal Insulin Testing

Don’t eat or take insulin (bolus) 4 hours before you start the test.

You can have water and herbal tea during your fasting hours, anything that’s not caffeinated and nothing that will do a number on your blood sugar. Anything that is neutral is fine.

Don’t eat unless you go too low, if you’re having a hypo. Also, don’t correct unless you go too high. (If you go too low during your your basal insulin testing, it means that you’re taking you’re taking too much basal insulin, whether it isn’t a pump or injections. If you go too high, your basal insulin is sett too low.)

Make sure you’re not sick or on your period or have something going on that you know influences your blood sugars.

It is completely okay to break the test if you have to! If you have a hypo, you have to correct it. It’s fine to break the basal insulin test, you just do it another day instead. And the same if you go too high, it’s fine to break the test, you have a bolus and get on with your day. The main point is that you take care of yourself! The basal insulin test can be done another day instead.

Also, one, one very important tip, is to write down the results, so you have them on paper. It makes it a lot more easy to overview instead of having it in some app and you have go back and forth between resources. Good old pen and paper works the best in this case, I would say.

What are the results of basal insulin testing?

If your blood sugar drops too much, you’re taking too much insulin. You’re taking too much basal for your needs. If your blood sugar goes up too high during the basal insulin test, you’re taking too little basal insulin, and you need to increase it.

If you are an MDI and notice something could be better during these 24 hours, perhaps you need to split to your dose? This is something you can discuss with your doctor. And if you’re on a pump, remember that it’s usually the basal setting that is about an hour to 2 hours before that impacts your blood sugar’s right now, so you have to be a little bit flexible in adjusting this, if you need to.

That was my very short run through on how to basal test your insulin properly.

I want to know from you, when was the last time you basal tested your settings or your dose or timing for that matter?

Let me know in a comment below. I’ll be so happy to chat with you there.

Ps. Want to learn more about basal insulin testing? Check out Dr. Richard Bernstein’s video here!