Bacitracin Attenuates Hemolysis-Induced Insulin Degradation during Insulin Sensitivity Testing: Repurposing an Old Drug for Use in Metabolic Research.

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. This article is protected by copyright. All rights reserved.