I'm Type 2, controlled by pills. I also take a diuretic pill for high blood pressure. I walked from Sarria in May. Everybody is different, I'm not your doctor, ask your doctor what's right for you, blah, blah, blah, but here's what worked for me.
First thing: take along your twice-a-day finger poke machine and USE IT. At home, my readings averaged 150 but after walking 10 miles a day on the Camino, I had readings in the 90's. You know what? I can afford a bite of carbs with readings like that.
Second thing, the finger-poke machine measures sugar as a percentage of blood volume. If you allow yourself to get dehydrated, you have the same amount of sugar but less water in the blood stream so as a percentage, your reading goes through the roof. Mine scared the pants off me the second day, before I did the on-line research to realize the issue wasn't the carbs, it was the water. I stopped taking the diuretic pill and drank a lot more water after that - readings dropped back where they belong, and even below. Don't discontinue taking medicine on your own - ask your doctor - but remember the old hiker's adage: if you don't need to pee, you're not drinking enough water. Applies to diabetics, too.
Third thing, the daily menu typically started with soup or salad. I picked out the potatoes and the rest was okay for low-carb diets. Second course was generally fried food but scrape off the breading, ignore the French fries, eat the fish and you're good.
Dessert: man, they were killing me there. It all looked so good and really, it's part of the Camino experience so . . . yes, I will put my hand up to having "just a taste." One fewer beer, one more forkful, you'll figure it out.
Buen Camino!