Relative potencies of human and pork insulin during i.v. and oral glucose tolerance test in lean and obese persons.

The biological efficacy of biosynthetic human insulin (BHI) of recombinant DNA origin was compared with that of highly purified pork insulin in subjects with normal (lean persons) and decreased (obese persons) sensitivity to insulin. Sequential i.v. administration of glucose with increasing insulin doses under somatostatin coverage was used to establish the dose-response characteristics of insulin-induced glucose clearance [insulin vs. Kg (glucose disappearance rate, %/min). Insulin was also given s.c. prior to an oral glucose tolerance test (OGTT) performed under somatostatin blockade; the appearance of insulin in serum and the modification of glucose levels were followed. The insulin vs. Kg dose-response curve was flatter and shifted to the right in obese persons compared with lean persons, demonstrating insulin resistance. In both lean and obese subjects, BHI and pork insulin had comparable effects on glucose clearance. Similarly, the effect of s.c. insulin on the serum glucose values during OGTT was the same when BHI or pork insulin were used. The absorption characteristics from the injection site were similar for both insulins. Thus, in man, human and pork insulin have similar pharmacokinetic and biological characteristics.