Table 2. Summary characteristics of the included studies.
QoL: quality of life
| Study | Country | Time frame | Study design | Patients, n | Type of acne lesion | Inclusion criteria | Exclusion criteria | Study findings | ||
| Total | Intervention | Control | ||||||||
| Ali et al. 2024 [13] | Pakistan | April-Sept 2023 | Split-face comparative study | 30 | 30 | 30 | Atrophic post-acne scars (ice pick, boxcar, rolling, mixed): 60% ice pick, 20% boxcar, 13.4% rolling, 6.6% mixed | Post-acne atrophic scars, age 18-60, Fitzpatrick IV-VI | Active acne, diabetes, bleeding disorders, pregnancy/lactation | Insulin + microneedling showed superior improvement (grades II-III in 100% of patients) vs. microneedling alone (grades 0-I in 100%) |
| Abdelhay et al. 2025 [14] | Egypt | 2022- 2023 | Randomized controlled trial, split-face | 21 | 21 | 21 | Atrophic post-acne scars (types not specified in detail; likely ice pick, boxcar, rolling based on context) | Facial atrophic post-acne scars, ≥18 years | Active acne, infection, systemic disease, recent retinoid/laser, anticoagulants, keloid tendency, pregnancy/lactation | Both sides showed significant improvement, but no significant difference between insulin + microneedling and placebo + microneedling |
| Karkour et al. 2025 [15] | Syria | July 2021-Sept 2023 | Prospective cohort | 158 | 119 | 39 | Atrophic scars from multiple causes: (1) post-acne scars (ice pick, boxcar, rolling), (2) post-leishmaniasis scars, (3) striae alba, (4) postoperative scars | Atrophic scars (acne, leishmaniasis, striae alba, postoperative) | Active infection, keloid history, diabetes, pregnancy, refusal | Significant improvement in acne and leishmaniasis scars with insulin + microneedling vs. placebo. Better QoL outcomes |
| Malik et al. 2024 [16] | Pakistan | Jan-July 2021 | Prospective split-face comparative trial | 50 | 50 | 50 | Atrophic acne scars (ice pick, boxcar, rolling): study focused on atrophic types, but specific distribution not detailed | Atrophic acne scars, age 18-50, Goodman and Baron score ≥30 | Active acne, bleeding disorders, keloid tendency, recent retinoid/laser, pregnancy/lactation | Both treatments were effective, but insulin + microneedling showed greater improvement and faster healing |