Biologic and Immunologic in Vivo and In Vitro Studies with Biosynthetic Human Insulin

A preliminary study was performed to estimate the effect of biosynthetic human insulin (BHI) produced by the Eli Lilly Company in comparison with purified pork insulin (PPI) from the same manufacturer. Immunologic studies were done using an intradermal skin test with both insulins and in vitro studies binding with sera containing preformed antibodies against bovine and pork insulin. The studies were undertaken in eight healthy volunteers aged 24–31 yr. Insulin was given subcutaneously in an amount of 0.1 U/kg and 3 days later intravenously in an amount of 0.03 U/kg injected slowly over 1 min. Blood glucose, insulin, C-peptide, and growth hormone were measured at different times between 0 and 360 min. It was shown that BHI and PPI behaved similarly in lowering blood glucose, suppressing C-peptide, and increasing growth hormone via hypoglycemic action. After s.c. injection, BHI was found to reach higher serum concentrations after 60 min than PPI. Correspondingly, the blood glucose curve was significantly lower after BHI than after PPI. This difference was not observed after the i.v. application of both forms of insulin.