Biosynthetic human insulin: effect in healthy men on plasma glucose and non-esterified fatty acids in comparison with highly purified pork insulin.
Biosynthetic human insulin (BHI) produced by recombinant DNA technology was administered subcutaneously and intravenously at two dose levels to two groups, each consisting of six normal men. Responses were compared with those for purified pork insulin (PPI) given by the same routes at the same dose levels to the same two groups. The glycemic response to the insulins was similar with a suggestion (seen both with intravenous and subcutaneous administration) that the glycemic depression with BHI was slightly greater at low dose and less at high dose. No significant difference between insulin types was found in the depression of non-esterified fatty acid (NEFA) concentrations, although significant differences between types with low-dose subcutaneous injection emerged during the later phases of the experiment. After termination of high-rate infusion with both insulins, NEFA concentrations rose more rapidly with some overshoot, suggesting that the rate and depth of blood glucose fall in these experiments might have triggered a brisker counterregulatory response. The small differences found between human and pork insulins, although in some cases significant, are unlikely to be of clinical importance.