Abstract

Background
Atrophic acne scarring is a prevalent and psychologically distressing sequela of acne vulgaris, often resulting from insufficient matrix remodeling and collagen loss. While microneedling is a safe treatment, its efficacy as a monotherapy is often limited. Autologous platelet-rich plasma (PRP) is the current gold standard adjuvant, but its high cost and invasiveness restrict its use. Topical insulin has emerged as a cost-effective, non-invasive alternative to promote wound healing.

Methods
A comprehensive search was conducted across PubMed, Web of Science, CENTRAL, Scopus, and Google Scholar for comparative studies published up to January 2026. Risk of bias was assessed using the RoB-2 and ROBINS-I tools. The primary outcome was significant clinical improvement (>50%). Secondary outcomes included changes in scar severity scores and adverse events. Risk ratios (RRs) and standardized mean differences (SMDs) were pooled with 95% confidence intervals (CIs). Trial sequential analysis was also performed.

Results
Five studies involving 256 patients were included. Microneedling with topical insulin was associated with a significantly higher rate of significant clinical improvement compared to PRP (RR = 1.96, 95% CI [1.30–2.95], p < 0.0001). However, the pooled analysis of changes in scar severity scores showed no significant difference between groups (SMD = − 0.52, 95% CI [− 1.44, 0.39], p = 0.26), with high heterogeneity. Regarding safety, there was no significant difference in the risk of post-inflammatory hyperpigmentation (RR = 0.72, 95% CI [0.14–3.62], p = 0.69), and no episodes of hypoglycemia were reported.

Conclusion
Microneedling with topical insulin may achieve a higher rate of significant clinical improvement than PRP, with a comparable safety profile. However, given the inconclusive trial sequential analysis, high heterogeneity, and low overall certainty of evidence, these findings should be interpreted with caution. Further adequately powered trials are required to confirm this preliminary signal.