The Efficacy of Metformin as a Therapeutic Agent in the Treatment of Acne Vulgaris: A Systematic Review

A large portion of the world's population is affected by acne vulgaris (AV), with many of these individuals being adolescents. The underlying mechanism of AV is hyperkeratinization and Cutibacterium acnes infection of the pilosebaceous follicle secondary to excessive stimulation of sebaceous glands by androgens. Metformin is a biguanide medication primarily used in efforts to lower patients' sugar levels in the management of type 2 diabetes. It has been proven to reduce levels of circulating androgens in patients with insulin resistance, indicating its potential for treating AV. A search strategy was developed and performed using the databases Ovid Medical Literature Analysis and Retrieval System Online (MEDLINE), Excerpta Medica database (EMBASE), Cumulative Index to Nursing and Allied Health Literature (CINAHL), Cochrane Controlled Register of Trials (CENTRAL), and Web of Science. The keywords "metformin" and "acne" were searched, along with related Medical Subject Headings (MeSH) and other subject headings. Studies that met the inclusion criteria were controlled trials, published after 2010, and in the English language. Participants with and without comorbidities such as polycystic ovary syndrome (PCOS) were considered. Two independent reviewers screened studies based on predefined criteria and extracted data from each study, which were quantitatively combined. A total of 15 studies were included in this systematic review. Across the 15 studies, there were 1,046 participants, with 13 studies looking exclusively at women with PCOS. Of the remaining two studies, one examined males with altered metabolic profiles, while the other included men and women with moderate AV. Notable risks of bias included studies that did not exclusively state the blindness of the study. Of the studies that were examined, 13 showed that metformin reduces AV, with seven studies showing statistical significance. Acne vulgaris is an inflammatory condition that has plagued patients for years due to the limited treatment options available. The hyperglycemic medication metformin, used in the management of type 2 diabetes, is being explored as a novel therapeutic that can possibly be repurposed for the treatment of AV. The use of metformin in AV is hypothesized to disrupt the proposed linkage between insulin resistance and AV proliferation. This proposed research could offer physicians a new option for the treatment of AV as well as render an alternative AV treatment for patients.