Last time I saw my dietician she told me that if I am having a meal that contains over 50g of carbs I should be doing a square wave bolus over an hour. This is something I have never considered doing (I would do it if the meal was above 100g), I was just wondering if anyone else does this and if they find it results better then just doing a normal bolus.
I always use the square wave bolus – in fact, the only time I use anything else is when (a) I’m also giving a correction does, when I use the Multiwave (so the correction goes in immediately, and the rest over 30 mins) or (b) if I’m eating something that I know acts fast and is under about 10 grams cho. Admittedly, I have slow digestion, so my tolerance is about 10-15 grams (rather than 50 grams). An hour sounds quite a long time just for a standard meal though.
I think there is a formula that says if you are eating more than (half your weight in pounds) carbs in one go, then your carb ratio may well break down. Another says that you can only digest 60 grams of glucose (and another 60 grams of fructose) per hour, so if you eat more than that, it wont absorb – where a square wave bolus comes in, I guess. (That last comes from the manufacturers of a sports energy gel, trying to sell its fructose based gel – ie you you absorb more energy using their gel than normal glucose based gels. Whether thats true or not I dont know, but maybe – no smoke without fire and all that.)
And for the record, I never eat more than 50 grams in one go (in fact, I rarely eat more than 40 grams in one go) because my innards just give up the ghost and refuse to work altogether if I give them too much to do. With resulting low bgs that wont react to glucose. Not nice. 100g? I’d be comatose…
I use dual wave much more than square wave, but to do the same thing.
If I’m below a 5 before the meal, I use dual wave to take some insulin 15 mins (approx 20%) before I eat and then spread the rest over the following 30mins. This stops me going hypo before the food kicks in, without waiting til I’ve finished eating to inject it all and then going high.
Large meals – over about 60g carbs I would do a dual wave. If I did square wave over an hour I’d be high as I wouldn’t have enough insulin in early enough. I’d generally do 50% of the insulin up front, then 50% over the next hour for something like pasta (those timings assume you start the bolus about 20mins before you start eating, so the last of the insulin goes in 40mins after you started eating). For pizza, I do 40% upfront and 60% over 2 hours.