Immunogenicity of human and bovine insulin in type 1 diabetes mellitus patients.

BACKGROUND: The advantages of synthetic insulin (human insulin) over bovine insulin in the treatment of type 1 diabetes mellitus (DM) are much debated in terms of potency and purity. Immunogenicity is one of several factors that determine potency and safety. This study was designed to investigate and study the difference in immunogenicity of human and bovine insulin. We investigated anti-insulin antibody (AIAB) status in 69 type 1 DM patients receiving insulin therapy. Group 1 had 33 patients treated with bovine insulin, and group 2 had 32 patients treated with human insulin. All patients had received their respective insulin therapy for a minimum period of 1 year and had no history of change in insulin type. Forty-three subjects from the normal population were the control group. METHODS: AIABs were assayed in serum samples of all subjects using a semiquantitative radioimmunoassay kit. The Kruskal-Wallis non-parametric and Mann-Whitney U tests were used to study the difference in immunogenicity of human and bovine insulins. RESULTS: The Kruskal-Wallis test showed that antibody titers in the three groups significantly differed (P<0.001). The Mann-Whitney U test showed no significant difference in AIAB titer between the treatment groups. AIAB titers in the two treatment groups differed significantly from that of the control group, independently (P<0.001). High titers of AIABs are present in patients receiving bovine and human insulin compared to that of the normal population. CONCLUSIONS: Bovine and human insulins are antigenic, and there is no significant difference in AIAB titer. Prospective studies are required to determine the long-term clinical significance of these antibodies.