One website says diabetes mellitus is the most common single cause of kidney failure. This is why medical treatment to try to slow kidney disease is so important, particularly so in your case with only one kidney! Are you getting treatment for your diabetes? Have you had kidney function tested to see if you have kidney disease in the kidney you do have? If so, and if you do, have they told you dietary steps you need to take about that?
I'm confused... are you saying you have only one kidney, and you have type-2 diabetes?
Or are you saying that you have 2 kidney's and have type-2 diabetes in one of them?