That "flipping of the switch" change in your gut sounds like a dietary enzyme problem, based on my body doing the exact same thing several times (with different enzymes deficiencies).

It is a case of "all of a sudden, wham"!

It could be protein or fat enzymes (or carbs) and is easy to check by purchasing a relatively inexpensive pancreatic enzyme supplement.

I use the Pure brand Pancreatic Enzyme Formula based on the good Amazon reviews, but a few other brands of the same get good reviews too.

Dealing with protein and fat digestion is the icing on the cake for me, as my largest deficiency is in the carbohydrate area (and I take other enzymes for that).

I would try the pancreatic enzyme route (even if, like me, you don't have the symptoms of pancreatic insufficiency). Even if it helps a bit, that is something to consider and build on.

Also, I am sure you know that Type 1 Diabetes causes constipation for some. There are several studies on it, posted on the NIH website. So just Google "NIH diabetes constipation" and take a read.