I was diagnosed with diabetes type 2 just over 20 years ago. Luckily I believe it had only just be established so with Metformin it has been kept under control for all this time. Whether the IBS D came along at the same time I'm not sure but possibly there is a connection.
I've managed the IBS by noting toilets en route when going out and taking spare underwear just in case. I have a very understanding DH who has had to take diversions as I need the loo NOW.
Strange as it sounds, I never connected what I was eating with the IBS. After a bit of research I went with the Fodmap diet and this did help but not completely. I then tried not eating any fruit and this is what made such a enormous difference. Fodmap will tell you, you can eat certain fruits but for me that wasn't the answer.
Since giving fruit up I am so much better as I was a big fruit eater. I miss it, but it's no-brainer.
If anyone here experiences the same, give it a go.
Passports not in the drawer I always keep them in. Turning the place upside down.