I've started accounting for fat and protein in my bolus calcs as discussed in that TuD group I can't remember. Basically, total the grams of fat and protein, divide by 2, add as additional "carbs" to the bolus calc, then do an extended on that extra juice.
I extend it for 2-3 hours usually, depending on the size of the meal.
Now, the main point of this post: If you're using percentage as the means to specify the break between immediate and extended bolus, it can get a bit annoying to try and figure it out on the fly.
So, I did some surveying of fast-food nutrition menus and worked up a spreadsheet to see what the ratios are for carbs vs. 50% by weight fat+protein. I used fast food only because the detailed nutrition information is readily available.
The key point: What I found is the ratio between insulin for the meal carbs, and insulin for the fat+protein generally runs between 60-80% carb.
This was across a wide range of menu items, from Taco Bell regular tacos to Burger King whoppers. Same for healthier fare, like TB's fresco chicken soft taco. Salads that contained meat were in the same ballpark.
BOTTOM LINE: A quite good rule of thumb comes out of this. First, if you know or can estimate the carbs in an "ordinary" meal, you can conservatively approximate the extra carb equivalent insulin need from the fat+protein at 1:4 to 1:3. Then, simply deliver 75-80% of the total bolus immediately, extending the balance for 2-3 hours.
Example: Meal has 24g carb, 20g fat, 16g protein (2 crunchy tacos at TB). Total "carb equivalence" would be 24+20/2+16/2 = 42g. Actual carbs are 24/42 = 57%. So, bolus for 42g, use extended bolus with immediately delivery of 60% (omnipod only supports 5% increments).
The approximate way for this same meal would be 24g carb; using the 1:3 rule of thumb, there's roughly another 8g "carb-equivalent" BG loading from the fat and protein, slow digested. So, bolus for 32g, deliver 75% initially, extend the rest for 2 hours.
I've been doing this now for a week, and my control is quite a bit better! I am flirting with lows more, so some experiment/learn/adjust is necessary as I work this out.
Thought I share this with people who are having trouble getting their BG down after meals, even when the count carbs and do everything right. Fat and protein get converted to glucose to some degree by the liver, so not accounting for this may be the reason your sugars don't come all the way back down after eating, and you have to correct.
With that, I'm off to go have two Taco Bell crunchy tacos for lunch