DERANGEMENTS IN PROTEIN-METABOLISM INDUCED BY TYPE-I DIABETES-MELLITUS

In poorly controlled diabetics, the whole-body protein flux is increas ed by 20-30% in comparison to well-controlled type I diabetes (IDDM) a nd normal subjects. Intensive insulin administration completely revers es these abnormalities. In poorly controlled IDDM, the primary effect of insulin administration is to reduce the increased protein catabolic rate by suppressing the accelerated rate of protein breakdown. Studie s in humans have demonstrated that the increased rate of protein synth esis observed in these patients is the consequence of elevated plasma amino acid levels. When IDDM subjects develop renal complications, a p rotein-restricted diet may be recommended to preserve the remnant kidn ey function. However, it has been demonstrated that in IDDM patients, metabolic adaptation to protein restriction is incomplete because supp ression of endogenous proteolysis is impaired. Since this component of protein metabolism is very sensitive to insulin action, maintaining s trict metabolic control during the protein restriction regimen has bee n suggested. The major studies on the effects of amino acid and insuli n on protein metabolism in patients with diabetes mellitus are reviewe d.