Insulin amount calculations

@Old_Dave Do you have Type 1 or Type 2? What insulins do you take?

Your basal dosage doesn't depend on your current blood glucose reading. So that's a strange question that kind of implies you might not understand what your basal insulin is for or how to work out the dosage. Have a look at basal testing.

There's no point working out a bolus dose for a meal in the future based on blood sugar readings hours in advance. Bolus wizards/calculator use the following information to work out a bolus dosage:

• The carb content of your meal
• Your insulin to carb ratio
• You current blood sugar
• Your blood sugar target
• Your correction factor

So it will work out how much insulin you need to cover your meal and then add a bit on or take a bit off dependent on your blood sugar with the aim of keeping you in target.

Lots of blood sugar monitors have bolus calculators in them.

Old_Dave said:

Wow thanks for getting back so fast everybody.
I'm Type 2 on Basal/Bolus (NovaRapid/ Levemir) but eminently going for a change/addition in conjunction with my Diabetes Nurse.
I use a spreadsheet at the moment but I can't believe that everybody else does the same so I was wondering how they calculate quantities.

Click to expand...

A basal test will check if your basal is at the right level. That's the place to start as it's the foundation you build on.

Once that's ok, you can look at your insulin to carb ratio for meals.

Changes to your diet, loosing weight, increasing exercise can impact upon your insulin requirements. Really whether your basal is too great a quantity depends upon what your blood sugar control looks like and would require some basal testing to assess - https://mysugr.com/basal-rate-testing/

A basal bolus regime and carb counting does require calculating for every meal. As stated above you can get monitors with inbuilt bolus calculators to do the calculating for you.

An alternative to carb counting, to address your concerns about making a mistake with the numbers, would be to switch to fixed doses of bolus with meals. But this would require keeping your meals at fixed carb content values.

Old_Dave said:

Thanks Catapillar but you haven't answered my question. Out of all the thousands of people with diabetes what are the most common ways they have to calculate bolus quantities.

Click to expand...

Usually, a bolus dose is calculated by carb counting. If you know your insulin to carb ratio is 1unit to X grams of carbs you divide the carb content of your meal by X and that gives you your bolus dose.

The bolus dose can be adjusted for circumstance, heat, exercise, illness and to take account over current blood sugar levels. Please see post #3 for a discussion of bolus calculators.

Yes, as mentioned above.
Basal should keep your BG flat over time if you're not eating/drinking(alcohol/carbs), or doing unusual amounts of exercise. (Eg your BG shouldn't change much while asleep)

You have to figure this out first, otherwise it interferes with the bolus calculations.

Once you have figured out how much basal you need, then you can figure out your bolus. You do this with an insulin:carb ratio and a correction ratio. I'd recommend keeping a diary (for each meal - carbs eaten, insulin and blood sugar before meals). It's easier if you can skip snacks while trying to collect this info, if you can manage it. They can interfere otherwise.

For insulin:carb ratio, basically, you need a period during which you:
1) eat a meal with a known quantity of carbs.
2) leave enough time after eating and taking your insulin for all carb and bolus insulin effects to wear off (approx 5 hours for novorapid)
3) end up at roughly the same blood glucose as you started at (eg right before meal/insulin, and 5hrs after).

For example, 24u lantus keeps me flat. That's my basal.
One day from my diary, I started at 13.4. I took 6u novorapid and had 65g carbs for breakfast. I ended up at 12.9, 5 hours later.
65g/6u = 11.8g per unit.

Then you need to figure out your correction ratio, which is how much 1u of bolus reduces your blood sugar (with no effects of food interfering).

Eg if my BG was 15, and taking 2u novorapid took me to 5, 2 units dropped it by 10, so 1unit drops me by 5.

Old_Dave said:

Thanks Catapillar but you haven't answered my question. Out of all the thousands of people with diabetes what are the most common ways they have to calculate bolus quantities. I know everything in your first sentence is correct but I just feel that I'm filling up on insulin. I have more lumps and bumps under my skin than a really lumpy thing so I was just wondering.
Mahola - its been quite a while since I had a hypo - just the opposite. I think you must be some sort of super hero or have a cast iron bum - ha.

Click to expand...

You calculate your bolus using your insulin to carb ratio basically. Eg if you have a ratio of 1 unit of insulin to 5g of carbs, you count the carbs in your meal then use your ration to calculate your bolus dose. So if your meal contained 30g of carbs, that would mean you needed 6 units of insulin (30g divided by 5g is 6).

Please note - those are example figures only. Your ratio may be very different.

That's a very simple explanation.

@catapillar has given you a link to basal testing above. She's also mentioned fixed doses. These give less flexibility and require more routine, but you may find them less hassle. It's something to think about anyway.

I really need to get to grips with this myself I just don't have the time need a week off work week off from life!