Immunologic Improvement Resulting from the Transfer of Animal Insulin–treated Diabetic Subjects to Human Insulin (recombinant DNA) Free

To study the immunologic effects of transfer of patients from animal insulins to human insulin (recombinant DNA), a double-blind comparative trial was begun in over 300 patients. Preliminary results are reported in 116 individuals. After maintenance on purified pork or mixed beef-pork insulins (PPI or MBP) for a minimum of 6 mo, 116 patients were either switched to human insulin or maintained on their previous insulin. Antibody levels were assessed at a baseline visit and then monthly. In PPI-maintained individuals as well as those switched to human insulin there was a significant decrease in qualitative antibody binding as indicated by species-specific binding of ¹²⁵I beef and human insulins (SBB and SBH), both P < 0.005. Quantitative binding, as indicated by bound insulin levels, decreased to a much greater extent in patients switched to human insulin, 52% versus 31%, P < 0.005. Parameters derived from formal antibody titration did not change. In patients maintained on MBP, bound insulin decreased (− 36% at 6 mo, P < 0.002). When switched from MBP to human insulin, there was a marked reduction in all parameters of binding, both qualitative and quantitative: SBP, −68%; SBH, −61%; SBB, −57%; bound insulin, −67% (all P < 0.001) and decreases in high- and low-affinity binding capacities (P < 0.02). Thus, for patients treated previously with nonhomologous insulins, transfer to human insulin may result in significant immunologic improvement in anti-insulin antibody levels.