The effects of human insulin on antibody formation in pregnant diabetics and their newborns.

We studied the immunogenicity of human insulin in 11 diabetic mothers and their newborns. Serum antibody formation was assayed by two different methods. Upon switching four patients from beef/pork insulin to human insulin, we found that elevated baseline antibody levels in three women decreased, in two to undetectable levels at term. The fourth patient had undetectable antibody levels at baseline and borderline levels at term. Only one of their four newborns had antibodies. Upon initiation of insulin treatment in another five diabetics without detectable antibodies at baseline, only two developed antibodies, and only one of their newborns developed antibodies. Two other patients, initially not on insulin, had baseline elevations of antibody that decreased with administration of human insulin; both of their newborns had antibodies. Overt diabetes evolved subsequently in both mothers after pregnancy. We conclude the following: 1) Upon transfer from beef/pork insulin to human insulin, mothers and their newborns show a decrease in insulin antibodies; 2) new patients initiated on insulin develop low levels of antibodies, if any, and their newborns also have low levels of antibodies if any; and 3) the decreased or absent immunogenicity of human insulin supports its use in pregnant diabetics.