Dont know where you got we "MUST" eat carbs. simply aint true. Lots of diabetics control there BG with low cab diets. also known as a ketogenik diet.
Go to Harvard medical school and look up "essential nutrients " essential nutrients are ALL the nutrient we need to live. they dont list carbohydrates for a very simple reason our body make carbs we dont need to eat them.
just because you hear "we need carbs" ... a lot, does not make it true.
Google "food: american diabetes association". This ADA website covers food & fitness: what you can eat, planning meals and recipes. At the bottom of the page you will find a link devoted to weight loss, plus more.
HTH
Seeking a weight-loss diet for diabetics is also my goal. However, I found your explanation a bit choppy and indecipherable. For example, type 2's must eat carbs; it is inadvisable to cut them out of a healthful diet for diabetics.
Does anyone have a proven weight-loss diet for diabetics?
There is no "diabetes" diet
Many diabetics fallow the "eat to your meter diet" (Google it)
Test before you eat test 1 hour after you eat if your BG goes up more than 40 Pts (US) (2.3 for the rest of the world) you eat too many carbohydrates.
carbohydrates raise BG ALL carbs raise BG
If he is T1 (type 1) he has to take insulin. (some T2 take insulin too)