Insulin to Inhibit Protein Catabolism after Injury

Abstract

Using patients with varying degrees of trauma as their own controls we compared three isocaloric regimens in three-day crossover studies; 9.4 g of nitrogen as l-amino acids was also given daily. The urea production rate was used as an index of protein breakdown. We found that in catabolic patients, insulin and glucose produced a strikingly greater inhibition of protein breakdown than glucose alone, and that glucose alone was marginally more protein sparing than a regimen containing mainly fat (Intralipid and sorbitol). These differences were not seen in non-catabolic patients (urea production rate <15 g daily). In the catabolic patients (urea production rate >15 g daily) the protein-sparing effect of insulin was proportional to the initial urea production rate.

We therefore concluded that insulin has important protein-sparing effects in severely ill traumatized patients, but little effect when there is no increased catabolic rate. (N Engl J Med 300:14–17, 1979)