Carb Counting Maths Question

[KookyCat]

Hi all
I've just started on my carb counting and dosage adjustment journey. To start with I was using foods where I could easily find a carb reference per 100g and I'm still struggling a little bit with my evening ratio (I seem to have a much higher tolerance after five), but on the whole I'm getting it about right the majority of the time. I have a guilty pleasure food however, that I just can't seem to get right. This guilty secret is a cheese pasty, which has potato mixed in with the cheese and delightful shortcrust pastry (which it now occurs to me may also have potato in the pastry 😱). Right so here's my maths question.

If I know where my blood sugar was before I ate it, and how much insulin I took, and how much the rise was, can I work out the actual carb in the beautiful/evil food stuff? Or more to the point the correct bolus dose.

So if estimated that it was 50g of carb for which I would need four units of insulin, but five hours later my blood sugar was five points higher than previously can I assume that since 1 unit of insulin would lower my bs by 2.5, then 2 more units were needed to effectively bolus for it?

Any advice welcome if anyone is still with me, because I think I may have just pickled my own brain. 😱

I was going to ring my specialist nurse but I'm not sure I'd explain it very well, and given that this is an infrequent pleasure I can't do a lot of practicing!

 

[Pumper_Sue]

Pastry and cheese = fat so even if you got the carb content right you would still need more insulin later on as that's when the high would hit you well and good. Perhaps think about a split dose of insulin. 🙂

 

[Redkite]

If there was a mathematical algorithm that worked for all foods in all people we would've solved the artificial pancreas problem!

You had the right idea working out your ratios at different times of day by sticking to simpler meals at first. Now you're adding high fat foods into the mix, as Sue said. Did you see what your level at the 2/3 hour mark was? What tends to happen with this type of meal is that the fat content slows down digestion, AND also some of the fat gets metabolised into glucose - so you need to give insulin for all the carbs AND a bit extra for the high fat. With my son's pump, we can split the insulin, giving part up front and the rest over a few hours. On injections, we used to approach it similarly - part as one injection upfront (after eating to allow for the slow digestion) and part as a second injection a couple of hours later. You will need to experiment, as there's a lot of trial and error involved, and we STILL haven't got it right for all foods, after all these years! It's frustrating when his levels are spot on 2 hours after eating, only to rise into orbit after another couple of hours. 🙂

 

[KookyCat]

Ah that would make sense! I don't generally eat high fat foods very often, and if I do I tend not to combine them with starchy carbs. This might also account for the spaghetti carbonara incident last month. I didn't do the post meal reading because my specialist nurse said I should just do four readings, I think she thought I was a bit obsessed and my control might be too tight (fairly sure she did). Right so next time I indulge in my guilty pleasure I'll test two hours after to see how it's progressing and then consider a split dose. When splitting do you just half what you would have dosed or is there a formula?

I could just give it up, but I have so few guilty pleasures I don't want to

 

[trophywench]

LOL - Carbonara is a great (or the worst depending on how you look at it LOL) example of when you need to split the dose.

Think I did more 60/40, but you really have to play it by ear - could be 40/30/30. Or any combination of numbers which total 100 .......

 

[Redkite]

When splitting do you just half what you would have dosed or is there a formula?

You have to experiment with different splits to find what suits you - so this is a good excuse for repeatedly eating it 😉

For pasta, my son would normally do a 60:40 split (60% upfront). For a tomato or bolognese sauce, only the carbs need counting, but for a cheesy sauce he would need to add more insulin for the fat, and it would effectively end up as a 50:50 split if he was injecting (slightly different tactics with his pump though). If it's proper carbonara (ie beaten egg and a little Parmesan coating the spaghetti), then he doesn't need extra insulin for the fat - it's only for those British versions that are swimming in thick cheesy sauce!