A Systematic Review on Clinical Evidence for Topical Metformin: Old Medication With New Application.

Background and Aims: Metformin is a widely used oral agent for controlling diabetes mellitus, but it also has other therapeutic benefits for various conditions. In addition, conventional oral metformin, and topical metformin have been used in, in-vitro studies in the treatment of acne, psoriasis, wound healing, and and so forth. While topical metformin has shown promising results in animal studies, there is limited data on its effectiveness in humans. Our study aims to summarize the clinical findings of human studies on the efficacy of topical metformin. Methods: This review followed the PRISMA standards and systematically searched multiple databases using specific keywords. The relevant articles were selected according to the inclusions and exclusions criteria. Results: Our search strategy yielded 1831 articles, after screening, 27 articles met our inclusion criteria which were: human studies, articles published before the start of the search, and topical forms of metformin. We also identified three additional relevant articles through reference checking. Therefore, our systematic review included a total of 30 articles. Conclusion: Most commonly, topical metformin has been studied in dentistry and dermatology. In dentistry, it has been found effective in treating periodontitis when used with scaling and root planning. Combining metformin with platelet-rich fibrin can provide better benefits for furcation-involved teeth, and coating dental implants with metformin improves osseointegration. In dermatology, studies on melasma have had inconsistent results. Topical metformin has also shown promising results in promoting hair regrowth, wound healing, and acne vulgaris, suggesting it could be a potential treatment option for these conditions.