Mel, Go with what your doctor says! It sounds as if you are a Type II Diabetic like me. My glucose levels were way out of whack. After low-carbing for well over a year, I am perfectly normal now for all tests. Your kidneys should have no problem if you drink all your water.
Ignore the nay-sayers! Remember, people used to think the world was flat and there were some who said computers were just a craze like the hula-hoop! It's not that they want you to stay fat - they are just worried about your health. I just thank folks for their concern and smile politely - no sense arguing.