Effect of Intranasal Insulin on Olfactory Recovery in Patients with Hyposmia: A Randomized Clinical Trial.

Objective Hyposmia is a sensorial disorder in which patients have a reduced sense of smell. However, there are no effective regimens for the management of this disorder. Therefore, the aim of this study is to evaluate the therapeutic effect of intranasal insulin on olfactory recovery in patients with hyposmia. Study Design This is a double-blinded, randomized controlled trial. Setting Intervention. Subjects and Methods This study was administered on 38 patients with hyposmia according to the inclusion and exclusion criteria. Patients were randomly divided into 2 parallel groups. The intervention and placebo groups underwent endoscopic placement of intranasal insulin gel foam (40 IU) and saline-soaked gel foam into the olfactory cleft, respectively. The procedure was performed twice a week for 4 weeks with butanol threshold testing initially and 4 weeks after treatment. Results The Connecticut Chemosensory Clinical Research Center score in the intervention group was significantly higher compared to that of the placebo group after 4 weeks ( P = .01). Moreover, no adverse effects were reported in both groups. Conclusion Our findings indicated that intranasal insulin (40 IU) administration may trigger the improvement in the olfactory sense and also appears to be free of significant adverse events in this small cohort. However, due to limited research regarding this topic, further studies using a larger population are required.