This topic is widely debated in a similar blog.The outcome of the debate was heated one.-- by one who is a non diabetic and other a diabetic who is still relatively young and diabetic for less than 5 years.Both denigrate the other's view causing harm to the healthy debate..
As far as I know protein helps build body tissue and all cereals,vegetables and even fish meat dairy products etc.,have this in some measure..The kidney is not expected to throw this nutrition out in the urine but filter and retain in the blood while throwing waste through urine.
whereas in case of corbohydrate in our food in excess of our energy requirement circulates in the blood as sugar and discharged through kidneys as a waste material and in case of diabetics results into frequent urination consequently overloading the kidneys and causing it finally to fail in its function.called renal failure.This is what practising nephrologists opine.
Even in case of non diabetics or well controlled diabetics excess use of oral drugs and pain killers is supposed to cause kidney failure.similar to what happens in case of corbohydrates..
When renal failure occurs it is no more possible for the kidney to filter and retain protein in the blood but it is also discharged through urine as waste.That is how additional intake of protein as suppliment is advocated by nephologists treating kdney patient.