Short Report Cross-reactivity of 12 recombinant insulin preparations in the

Background: Insulin analogues used in the treatment of insulin-dependent diabetes may result in hypoglycaemia; however, these preparations show variable cross-reactivity in many insulin assays. In order to investigate a suspected insulin overdose, it is therefore essential to characterize the cross-reactivity of these preparations in insulin assays. Methods: The cross-reactivity of 12 commercial insulin preparations was assessed on the Beckman DxI analyser, by comparison with the insulin calibration curve corresponding to the midpoint of the dose–response curve. This was achieved by manually plotting the relative light units generated by the analyser for each preparation. Results: All 12 insulin preparations examined showed significant cross-reactivity with the Beckman DxI insulin assay, with 11 of the insulin preparations demonstrating cross-reactivity of 83 % or greater. The lowest cross-reactivity was observed with detemir with a value of 47.6%. Conclusion: When investigating hypoglycaemia it is important to be aware of the cross-reactivity of the recombinant insulin analogues in insulin assays. This study has established the cross-reactivity of 12 preparations in the Beckman DxI insulin assay. Ann Clin Biochem 2010; 47: 264–266. DOI: 10.1258/acb.2010.01000