Effectiveness, safety, and preference of transdermal insulin compared to subcutaneous insulin in the treatment of diabetes patients: a systematic review of clinical trials.

Background: Several studies were performed on transdermal (TD) insulin delivery in vitro and in vivo, and recently, the study groups included a clinical trial in humans. Therefore, this systematic review was conducted to get summary information about the effectiveness, safety, and preferability of TD insulin in comparison with subcutaneous insulin delivery.

Methods: We conducted a thorough search to find studies in the databases Cochrane Library, MEDLINE via PubMed, Web of Science Core Collection, EMBASE, Scopus, Hinari, Medlib, and Magiran until January 2024. We included 18 randomized clinical trials.

Results: Although there are various types of TD delivery methods, the TD insulin delivery methods that have undergone clinical trials are the TD patch, micro needle TD insulin delivery, and TD insulin jet injector. Eighteen studies were conducted on TD insulin delivery, which showed either superior or comparable effectiveness, safety, and preferability of TD insulin in comparison with SC insulin. About eleven out of eighteen studies (61.1%) showed more effective blood glucose control than SC delivery, and the remaining seven studies showed comparable effectiveness with SC delivery. Eleven studies (61.1%) showed equal tolerability of TD insulin versus SC insulin, and seven studies (38.9%) showed more tolerability of TD insulin over SC insulin. In most studies, eleven out of eighteen (61.1%) showed a higher preference for TD insulin delivery over traditional SC delivery; sixth out of eighteen (33.3%) showed equal preferability for TD insulin versus SC insulin; and only one study (5.6%) showed that TD insulin delivery was less preferable than SC insulin.

Conclusion: The review revealed that clinical trials have demonstrated the effectiveness of TD insulin delivery methods such as TD patches, MN-based insulin delivery, and insulin jet injectors compared to traditional SC routes of administration. The studies showed the superior or comparable effectiveness of TD insulin in controlling blood glucose levels. Additionally, TD insulin delivery was found to be equally or more tolerable than SC insulin delivery in all studies. Overall, the majority of studies favored TD insulin delivery over traditional SC delivery methods, highlighting its potential as a preferred option for insulin administration.