A Case of Surreptitious Glargine Overdose Confirmed by Insulin Pharmacokinetic Time Curves

Case: A 49-year-old man presented with recurrent altered conscious state suggestive of encephalitis. This was followed by an episode of severe hypoglycemia requiring protracted intravenous glucose administration. Comparing the pharmacokinetic time curves of serum insulin levels on two insulin immunoassays with different insulin analog cross-reactivity allowed the likely diagnosis of surreptitious glargine overdose to be made rapidly. Discussion: The differing insulin analog cross-reactivity of serum insulin immunoassays, in this case the Abbott ARCHITECT and Roche Elecsys, allows the presence of insulin analog to be detected. Through comparison of time curves the characteristic signature of the specific causative insulin analog can be identified. This information confirms surreptitious insulin overdose in a timely manner, therefore avoiding the expensive and time-consuming investigations required to exclude alternate causes of severe hypoglycemia.