High-Concentration Insulin Glargine Overdose: Polyphasic Patterns of Blood Insulin Levels

In the treatment of diabetes mellitus, there is a growing trend towards using high-concentration insulin, with Lantus XR (Bridgewater, NJ: Sanofi-Aventis U.S. LLC), which has a drug concentration three times higher than that of conventional Lantus (100 U/mL; Bridgewater, NJ: Sanofi-Aventis U.S. LLC), being a prominent example. This type of high-concentration insulin is known for its smaller injection volumes, leading to a slower absorption rate and maintenance of more consistent blood insulin levels. When administered in high doses, the pharmacological effects of insulin are generally prolonged; however, insulin glargine overdose rarely occurs, and its pharmacokinetics remain unclear. We encountered a case of an insulin overdose in a 19-year-old female patient, who had self-injected glargine (Lantus XR) 1,350 units and aspart (NovoRapid; Bagsværd, Denmark: Novo Nordisk A/S) 600 units. We measured blood glucose and insulin levels over time. Bimodal peaks in blood insulin levels were observed, and we adjusted high doses of intravenous infusion with a 50% glucose solution until the blood insulin levels returned to the normal range. Consequently, the patient was treated without inducing severe hypoglycemia. U300 glargine overdose may lead to both a multimodal elevation in blood insulin levels and prolonged hypoglycemia compared to U100 glargine. Therefore, monitoring blood insulin levels and adjusting treatment accordingly may contribute to safer patient management. This study represents the initial documentation of blood insulin levels measured in a U300 glargine overdose patient, revealing a bimodal peak.