A Double-Blind Crossover Trial Comparing Human Insulin (recombinant DNA) with Animal Insulins in the Treatment of Previously Insulin-treated Diabetic Patients

Ninety-four diabetic patients established on treatment with pork (N = 47) or beef insulin (N = 47) took part in a double-blind crossover trial in which 6-wk treatment periods of their animal insulin were compared with similar periods on human insulin (recombinant DNA). Six patients withdrew during the trial—in three cases for hypoglycemia while taking human insulin. In patients initially treated with beef insulin there was no significant change in the mean blood glucose, the ‘M’ index, the total daily insulin dose, or the frequency of hypoglycemic attacks after the change to human insulin. Home blood glucose sample values were greater before the morning and evening insulin injection on human insulin (morning: 12.8 mmol/L [beef] versus 14.2 mmol/L [human insulin] [P < 0.05]; evening: 10.0 mmol/L versus 11.6 mmoi/L [P = 0.05]). In pork insulin-treated patients greater values while on human insulin were found for mean glucose (9.0 mmol/L [pork] versus 9.7 mmol/L [human insulin], P = 0.05), ‘M’ index (65.0 [pork] versus 79.6 [human insulin], P < 0.025), and total daily insulin dose (50.9 U/day [pork] versus 52.5 U/day [human insulin], P < 0.001). The early morning glucose sample was also greater on human insulin (9.6 mmol/L [pork] versus 12.1 mmol/L [human insulin], P < 0.001). No significant differences in either insulin antibody levels or E. coli protein antibody levels were found between either of the animal-insulin treatment periods and human insulin treatment periods. While human insulin appears to be a safe alternative to beef and pork insulins, it seems likely that pharmacokinetic differences may account for the apparent differences in glycemia and insulin requirement. It may be necessary to adjust the dosage and proportions of short-acting and long-acting insulin formulations in order to obtain maximum benefit from human insulin.