Metformin use may prevent immune-mediated skin diseases in type 2 diabetes patients

"Except for the need for a minor vigilance on the potential acne risk, the multiple pleiotropic effects of metformin, including a protection on skin cancer and immune-mediated skin diseases at the therapeutic doses required for hyperglycemic control provide supportive evidence for using metformin as the first-line antidiabetic drug," the study authors wrote.

Considering that the effects of metformin on non-cancer skin diseases are rarely investigated, Chin-Hsiao Tseng, National Taiwan University College of Medicine, Taipei, Taiwan, aimed to investigate immune-mediated (allergic contact dermatitis, urticaria, and psoriasis) and androgen-mediated (hidradenitis suppurativa, acanthosis nigricans, and acne) skin diseases associated with metformin use.

For this purpose, the researchers obtained data from the National Health Insurance (NHI) database in Taiwan collected between 1999 and 2009. Patients treated with metformin in the initial 12-month period were assigned to the metformin group. Those who received antidiabetic medications other than metformin in the initial 12 months were assigned to the nonmetformin group.

The researchers followed metformin initiators (n = 234,585) and non-metformin initiators (n = 125,921) within 12 months of the antidiabetic drug until December 31, 2011. Hazard ratios for metformin initiators versus non-metformin initiators were estimated using Cox regression weighted for propensity score in intention-to-treat (ITT) and per-protocol (PP) analyses.

The researchers found the following:

• Hazard ratios for immune-mediated skin diseases (allergic contact dermatitis, urticaria, and psoriasis) were 0.930 and 0.930 in ITT and PP analyses, respectively. The hazard ratios for each specific outcome were all significantly below unity.
• The ITT and PP hazard ratios for androgen-mediated skin diseases (hidradenitis suppurativa, acanthosis nigricans, and acne) were 1.110 and 0.990, respectively. All hazard ratios were insignificant for each specific outcome except for acne in the ITT analysis (hazard ratio: 1.116).

Limitations of the study include possible disease misclassification and confounding by indication. Also, the analysis did not determine whether the use of the same set of confounders was adequate.

The researchers conclude, "Metformin use is associated with a remarkably lower risk of immune-mediated skin diseases but lacks a preventive effect on androgen-mediated skin diseases."

Reference:

Chin-Hsiao Tseng; Differential Effects of Metformin on Immune-Mediated and Androgen-Mediated Non-Cancer Skin Diseases in Diabetes Patients: A Retrospective Cohort Study. Dermatology 2023; https://doi.org/10.1159/000530077