Intranasal Insulin for the Treatment of Persistent Post-COVID-19 Olfactory Dysfunction

ObjectiveTo investigate if intranasal insulin could be a treatment option for those suffering from recalcitrant olfactory dysfunction due to COVID-19. Study DesignProspective interventional cohort with a single group. SettingSixteen volunteers with anosmia, severe hyposmia, or moderate hyposmia for more than 60 days as sequelae of severe acute respiratory syndrome coronavirus 2 infections were selected for the study. All volunteers reported that standard therapies, such as corticosteroids, have failed to improve their olfactory function. MethodsOlfactory function was assessed by the Chemosensory Clinical Research Center test of olfaction (COT) before and after the intervention. Changes in qualitative, quantitative, and global COT scores were investigated. The insulin therapy session consisted of placing into each olfactory cleft 2 pieces of gelatin sponge soaked with neutral protamine Hagedorn (NPH) insulin, 40 IU on each side. The procedure was repeated twice a week for 1 month. Glycaemic blood level was measured before and after each session. ResultsThe qualitative COT score rose 1.53 points, p = .0001, 95% confidence interval (CI) (-2.12 to -0.94). The quantitative COT score increased by 2.00 points, p = .0002, 95% CI (-3.59 to -1.41). Global COT score had an improvement of 2.01 points, p = .00003, 95% CI (-2.7 to -1.3). Glycaemic blood level dropped on average 10.4 mg/dL, p < .00003, 95% CI (8.1-12.8). ConclusionOur results suggest that the administration of NPH insulin into the olfactory cleft yields a rapid improvement in the sense of smell of patients suffering from persistent post-COVID-19 olfactory dysfunction. Moreover, the procedure seems to be safe and tolerable.

Automated summary

This study aimed to investigate the effectiveness of intranasal insulin as a treatment for recalcitrant olfactory dysfunction in patients with COVID-19. The study included 16 volunteers with persistent olfactory dysfunction, and their olfactory function was assessed before and after the intervention. The results showed that intranasal insulin treatment significantly improved the sense of smell in these patients.