Are dietary protein requirements altered in diabetes mellitus?

Authorities in the United States and Canada have recently advised persons with diabetes to limit their protein intake to the level recommended for normal adults, and consider further reductions in the presence of incipient renal disease. This recommendation ignores metabolic data indicating that conventional insulin therapy fails to fully normalize the abnormal protein metabolism characteristic of untreated diabetes. The residual abnormality is an increased or poorly regulated rate of amino acid catabolism. It is proposed in this review that the large amount of protein in the customary diet compensates for this increased amino acid catabolism, and thus protects many diabetic individuals from protein malnutrition. If this is true, protein restriction to a level that still meets the requirement of an individual with normal insulin metabolism could be too little for someone with diabetes. The current assumption that the protein requirement in diabetes is equal to the value set for normal individuals should be reconsidered.