And what about whey protein, branched-chain amino acids (BCAA's) plus glutamine taken after workouts?
Most diabetics don't really need protein powder supplements. There are always exceptions, but it's mostly professional athletes who happen to be diabetic who may (or may not) benefit from protein powders.
For elite athletes doing resistance training every day to put on muscle, these supplements do make a difference, about half a pound (225 g) of muscle in 10 weeks for whey powder, and 1-1/2 pounds (750 g) of muscle in 10 weeks for elite athletes using the BCAA's plus glutamine. Protein shakes, protein powders, and protein bars taste good and may be OK for you, too, but they won't help you put on muscle or take off fat.
There is one supplement that can help you put on muscle, and that supplement is creatine. The way creatine works is that it incorporates water into muscle, literally pumping it in to pump you up. But don't use creatine before you have achieved the weight you want. Creatine not only incorporates water into muscle cells, it also incorporates water into fat cells, and water in fat cells is the main reason weight loss diets fail.