Change of insulin dosage, circulating free and bound insulin and insulin antibodies on transferring diabetics from conventional to highly purified porcine insulin.

Fifty-eight patients on long term conventional mainly bovine insulins have been transferred to highly purified porcine insulin preparations. There was an overall reduction of 22% in daily insulin dosage and improved diabetic control as shown by decreased blood glucose concentration. Increased concentrations of serum free insulin and falls in serum bound insulin levels were also found. There were reductions in the serum binding capacities and affinity constants on changeover from conventional to highly purified insulin due to a combination of the effects of differential conventional/purified porcine binding and the substitution of a low antigenicity insulin. However, 12 of the patients receiving higher doses of insulin experienced marked hypoglycaemic reactions immediately on insulin changeover despite initial dosage reductions of 30% and prior to any changes in antibody characteristics.