Bacitracin attenuates haemolysis‐induced insulin degradation during insulin sensitivity testing: Repurposing an old drug for use in metabolic research

Abstract

Aims: Hemolysis of serially‐collected insulin serum samples frequently causes falsely‐low measured concentrations due to release of intracellular insulin degrading enzyme (IDE). We investigated if bacitracin, an in vitro IDE inhibitor, could prevent hemolysis‐induced insulin degradation during insulin sensitivity testing. Materials and Methods: Blood samples were collected from adults undergoing serial sampling for insulin sensitivity. A dose‐finding study measured insulin from experimentally‐hemolyzed samples containing five bacitracin concentrations (0‐2.5g/L) and from non‐experimentally‐hemolyzed samples. To confirm utility of bacitracin in the clinical setting, we compared insulin in samples collected with and without 1g/L bacitracin from a frequently sampled intravenous glucose tolerance test (FSIVGTT), where hemolysis often occurs accidentally. Results: In the dose‐finding study, bacitracin 0.25g/L, 1g/L, and 2.5g/L all maximally prevented insulin degradation in experimentally‐hemolyzed samples. Among FSIVGTT unintentionally‐hemolyzed samples, insulin concentrations from bacitracin‐containing samples were significantly higher than from those without bacitracin (p<0.01), and not different from non‐hemolyzed samples obtained simultaneously from a second intravenous catheter (p=0.07). Bacitracin did not alter insulin concentrations in non‐hemolyzed samples. Conclusions: Bacitracin attenuates hemolysis‐associated insulin degradation in clinical samples, enabling a more accurate assessment of insulin sensitivity and glucose homeostasis.