Acne vulgaris (AV) is a common chronic inflammatory disease of skin that develops from sebaceous glands associated with hair follicles. Typically AV begins at puberty and may continue through adulthood affecting the comedogenic areas of face, back and chest .~One of the undesirable outcomes of acne is acne scars that are divided into two main types based on a loss (atrophic) or gain (hypertrophic) of collagen. Atrophic type is the most common type, further subdivided into three subtypes: icepick, boxcar and rolling scar .~Post acne scars occur in nearly 75% of patients with acne affecting both male and female equally . Acne scars impair quality of life and may be a risk factor for depression, suicide, low academic performance and unemployment .~There are different therapeutic modalities for atrophic acne scars including microneedling, chemical peeling, laser, filler, surgical procedures (punch excision, punch grafts) and fat transfer.~Microneedling is considered safe for all skin types. It is performed by dermapen or dermaroller to induce new collagen formation that remains for a few months after the procedure.~Microneedling enhances the effect of topical preparations when used combined with them due to increasing their absorption by creating small channels through the epidermis to the dermis .~It was reported that combination of glycolic acid (GA) with microneedling gave excellent results in treatment of post acne scars compared to microneedling alone.~Glycolic acid is an alpha hydroxy acid that decreases corneocytes cohesion leading to increasing keratinocytes turnover rate and faster desquamation .~It was found that glycolic acid increases dermal hyaluronic acid and collagen gene expression through increasing the secretion of IL6 .~the administration of topical human insulin was investigated for the treatment of atrophic post-acne scars and concluded that topical insulin following microneedling was associated with significant improvement.~Topical insulin induces collagen formation and neovascularization through synthesis of transforming growth factor (TGF b1) and vascular endothelial growth factor (VEGF).
To examine the anti-scarring effect of topical glycolic acid 35% combined with microneedling against that of topical insulin combined with microneedling for post acne scars