, Volume 41, Issue 6, pp 681-683

Comparison of a novel micro-assay for insulin autoantibodies with the conventional radiobinding assay


Measurement of insulin autoantibodies (IAA) with a novel micro radiobinding assay which requires only 20 μl of serum was compared with that in a conventional radiobinding assay which uses 600 μl of serum. IAA were measured with both assays in samples from 94 new onset insulin-dependent diabetes mellitus (IDDM) patients, 97 control subjects, and 48 first degree relatives of IDDM patients selected for having IAA in the conventional radiobinding assay. Overall, 227 (95 %) of 239 samples tested were concordant, and IAA levels correlated well (r 2 = 0.7) between the two assays. Discordant results were obtained in 7 new onset patients, 4 control subjects, and 1 first degree relative, and these had low IAA levels in the respective assays. Sensitivity and specificity in the new onset IDDM patients and control subjects were 69 % and 98 % for the micro radiobinding assay and 72 % and 98 % for the conventional radiobinding assay. The use of the micro radiobinding assay should greatly facilitate islet related antibody screening, particularly in children. [Diabetologia (1998) 41: 681–683]

Received: 8 October 1997 and in final revised form: 26 January 1998