Basal Insulin

hi everyone im not sure if its my basal or bolus my sugar was (10.4mmol 12.57pm)before meal injected 11 units novorapid normally i inject 10unit for 40grams of carbs but i injected 1 extra unit as sugar level was high (10.4mmol 12.57) (2.30pm 10.3mmol) (12.1mmol 2.54pm) (10.8 mmol 3.22pm) then 5.09pm 6.2mmol) (5.40pm 5.4mmol) and sugar just went to (4.4mmol 6.06pm)also im taking split dose of levemir 13unit morning and 13 units night i wanted to do a basal test but found my sugar level was going low so didnt. trying to figure out if its my bolous or basal any sugesstions can someone suggest easiest way to test basal as i feel like im going in circles lol

In an ideal situation your basal doses would hold your glucose level steady and in-range when you fast. For bolus insulin, it would completely counteract the meal in both intensity and timing. The real world is a little more fuzzy. For many of us bolus insulin sometimes does the work of the basal and sometimes the basal insulin works in a bolus fashion.

It’s preferred, however, that we keep these two functions separate as much as possible. It makes future analysis and adjustments easier to make.

The classic method begins with setting basal insulin doses first and then once that is adjusted, work on the bolus insulin. Basal adjustments are often done by skipping a meal so that the effects of the bolus insulin do not obscure the basal insulin action. One basal adjustment system that I’ve used successfully is posted at Integrated Diabetes Services. It takes some time and effort to work your way through this process. I would budget a week or two to get this right. As you’ve already acknowledged, basal tests must be ended if the blood sugar is out of range.

Once your basal doses have demonstrated the ability to hold your glucose steady when missing meals, then you can address meal dosing. Bolus doses are usually calculated using an insulin to carb ratio (I:C). A 30 gram carbohydrate meal with a 1:10 insulin to carb ratio will need 3 units of insulin (30/10).

Another important aspect of dosing meal insulin that is often tossed aside is the idea of a pre-bolus. Pre-bolusing is all about timing. Since injected insulin does not go to work immediately, if you inject right at mealtime then a food/insulin timing mismatch occurs and your blood glucose will often spike high.

Pre-bolus times are an individual thing and are best arrived at by carefully testing to see what works for you. Common pre-bolus times usually range between 15-60 minutes. I use a continuous glucose monitor and will watch my glucose trace after I inject my meal dose. When the trace bends downward, that’s the time I want to eat. You could approximate this using a closely spaced in time series of fingersticks following the meal injection.

You mentioned also that you ate a meal when your blood glucose was at the 10 mmol/L level. That is a high blood sugar to start eating. When my blood glucose is that high and I still want to eat, I’ve found that I have to take much more insulin to metabolize the same level carb meal. High glucose levels increase insulin resistance. It’d best to wait to eat, if possible, until your blood glucose level is at least under 8 mmol/L (144 mg/dL), lower is better. I like to start eating when my glucose is < 5.6 mmol/L (100 mg/dL) and the trend is heading down.


That’s a great tutorial @Terry4!

@static192 you might see if your endo’s office has a library with some resources that elaborate on this. You can search the forum here for a few highly regarded books. As a T1/LADA you’ll probably find yourself nodding in agreement and appreciation when reading them!

And remember, every day is different. There is no set formula.

A note on Levemir: I liked Levemir, which I split 2x/day. I’ve heard here from people who divide even more to 3x a day. If I went back to Levemir, I think I’d do that too. It doesn’t have such a long activity, but that can be used to your advantage if you, like most people, have a variable basal requirement. That’s also likely a big reason many people prefer a pump.

Lantus and Levemir both remain active for less than 24 hours. Hence the need of double or tripple dose. But Tresiba DIA duration of insulin action goes beyond 24 hours. This might be a good choice if your body will tolerate it. Remember YDMV.


I had to draw this out so I understood what you were saying. I put it into US units. This calculation looks perfect, to me. You don’t like it? I think it looks like a perfect calculation.

What might be confusing is that the meal bolus insulin lasts 2 hours, but the correction lasts 4 hours. So, you have to verify each dosage independently.

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Your correction insulin should possibly be a little less than a unit because you go a little low around 6pm, but it seems like your using syringes, so that just might not be possible. Keep a couple little pieces of candy with you for four hours after you take correction. I also tend to go a little low after delivering correction sometimes. Sometimes that correction insulin hangs around in your body for a little longer than four hours. We call that, ‘having a long tail’ on correction bolus. It just goes a little longer than it should.


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Thanks for the link on how to set basals…

It might be worth mentioning, too, that basal rates change over time and can be impacted by all kinds of external / internal factors like stress, illness, work conditions, and other things that aren’t just food and insulin.

I need to go through the basal setup process again, as I haven’t in a long time and I’m fairly confident my basal rates are not where they should be.


Its on my To-Do list, as well, @CaM2.

Basal rates, like the insulin to carb ratios and insulin sensitivity factors, all move, sometimes for reasons you can’t identify. You don’t have to know the reason why. What matters is acknowledging this dynamic action and moving with it. Ponder’s surfing metaphor is perfect for living well with diabetes.


Can somebody else comment, directly, on the dataset he provided? So that there’s a second opinion. It wouldn’t hurt to have someone comfortable with british units look it over, too. He went to great effort to provide us with data. That’s a lot of work. He deserves some more feedback.

@static192, can you give us a basal test when you have the opportunity? We’ll look at it.