See Richard K. Bernstein's books on diabetes. Low-carb is the way to go.
Carbs affect blood sugar a lot and more or less quickly--even so-called "complex carbohydrates."
Protein affects blood sugar some but not as much as carbs.
Fat has very little effect on blood sugar... before insulin was discovered, the only way to keep diabetics alive was to put them on high-fat diets.
The American Diabetes Association is massively out of date.
The ancestor’s diet is the way to go. Humans originally did not drop by a fast food joint for a chocolate shake and fries after hunting mammoth all day.
Beef, chicken, fish, pork, all vegetables (even potatoes), salad greens and tomatoes, some fruit - like berries and melons - but nothing battered and deep fried.
I allow myself a small glass of red wine with dinner and milk in my coffee in the morning - these aren’t exactly what one would expect to find in the cave’s pantry but hey! A little will not hurt.
It may well be that early man brewed beer but no potato chips, no clam dip, and no football. Those ice age winters were hellish.
A great book is the “The GI (Glycemic Index) Diet by Rick Gallop. It is basically set up using the traffic light system. Stay away from foods listed as red colored foods, eat yellow foods in moderation, eat all the green colored foods you like. No need to starve!
I’ve been Type II since June 2005 and have been controlling my diabetes with this diet and exercise (hiking mainly) without drugs since.