Topical Insulin in Atrophic Acne Scarring: A Systematic Review of Efficacy, Safety, and Patient Satisfaction

Background: Atrophic acne scars are challenging to treat and have a negative psychological impact. Insulin has been tried as a topical adjuvant and stimulates fibroblast activity, collagen deposition, and keratinocyte migration. Objectives: To evaluate topical insulin for atrophic acne scars in terms of its effectiveness, safety, and patient-rated results. Methods: Five databases were searched for research on topical insulin, either alone or in conjunction with a procedure, without regard to the date. Records were screened, extracted, and evaluated in duplicate (RoB 2 or ROBINS-I) each by two independent researchers, using Covidence. Results: Fourteen studies with 619 patients, seven randomized and seven non-randomized, were qualified. All insulin arms improved from baseline (35.8% to 55.4%), but comparator arms mostly improved similarly; five studies, none at low risk of bias, favored insulin. Adverse effects were mostly local, minor, and transient, although one study reported systemic hypoglycemia-related symptoms; glucose monitoring was inconsistent, and satisfaction was high. Limitations: Meta-analysis was not possible due to heterogeneity in design, dosage, and outcome scales, and the small number of patients precludes certain conclusions. Conclusions: Although its superiority over current adjuncts has not been demonstrated, topical insulin appears to be an affordable, well-tolerated adjunct that may have a function where traditional therapies are unavailable; larger studies are needed.