Your question is a bit difficult to answer because the same supplement could be safe or unsafe to different diabetics depending on their situation and needs.
People with damaged kidneys should probably avoid excess protein consumption for example.
Ultimately, if your goal is to gain weight you need to give your body a reason to grow. In my opinion, the most effective way of doing that is heavy weight training and it's been tremendously effective for me throughout my life.
The most important aspect of weight gain is your diet. While it is possible to gain muscle with minimal carbohydrates in your diet, it's not easy and it's a very slow process. Consequently, most people will need to maintain a caloric surplus and and maintain a diet rich in protein and carbs.
Now, that obviously makes it tough for us because carbohydrates aren't always very kind to us. For me, the key is to consume carbs at the right times and avoid EXCESS carbohydrate consumption.
We can discuss it more in-depth, but let's pause for a second and let me ask you to share a bit more about what you're hoping to accomplish, what your current approach looks like, and what (if any) barriers you're trying to overcome.