Insulin autoantibodies in the pre-diabetic period: Correlation with islet cell antibodies and development of diabetes

Abstract

IgG and IgM class insulin autoantibodies were measured by an enzyme-linked immunosorbent assay in sera from members of the Barts-Windsor-Middlesex prospective family study for Type 1 (insulin-dependent) diabetes. One hundred and twelve individuals from 28 families were selected for study on the basis of a clearly defined islet cell antibody status. IgG insulin autoantibodies were found to be significantly associated with islet cell antibody positive (n=30) versus islet cell antibody negative (n= 57) first degree family relatives (p=0.002), with increased significance (p=0.0003) if complement-fixing (CF)-islet cell antibody individuals (n=20) only were considered. In addition, a significant association of IgG insulin autoantibodies with subsequent development of diabetes was observed within the CF-islet cell antibody positive group (p<0.0003). No such associations were found for IgM insulin autoantibodies, but a higher prevalence of these autoantibodies was observed in islet cell antibody negative first degree relatives (n=57) compared with a control group of 73 Blood Bank donors (p=0.00007), and they were significantly associated with siblings (n=48) rather than parents (n=39), (p=0.001). We conclude that the presence of IgG insulin autoantibodies and CF-islet cell antibodies confer more risk for future development of diabetes than the presence of either marker alone. © 1986 Springer-Verlag.