Evaluating the Efficacy and Safety of Metformin in Vitiligo

Inclusion Criteria:

• Adults 18 years - 100 years of age with stable vitiligo

• Stable vitiligo is defined as no new spots of depigmentation or expansion ofany existing spots for one year;

• Total body surface area BSA >/= 1%

• Facial body surface area BSA >/= 0.25%

• Willingness to participate in the study;

• Willingness to undergo suction blistering;

• Non-English speaking adults may be enrolled with the assistance of an interpreterand the use of an IRB-approved short form in the subject's language;

• Informed consent document signed by the subject;

Exclusion Criteria:

• Adults unable to consent (adults lacking capacity);

• Active vitiligo defined by presence of confetti lesions, trichrome lesions, andKoebner's phenomenon;

• Individuals who are not yet adults (infants, children, teenagers);

• Pregnant women and/or breastfeeding, or those who have recently delivered a babywithin the past 6 months;

• Prisoners;

• Systemic immunosuppressive medication (oral corticosteroids) within prior 4 weeks;

• Topical steroids within the prior 2 weeks;

• Currently undergoing UVB light therapy or history of light therapy within the past 8weeks;

• Unable to return for follow-up visits;

• Enrolled in a clinical study of any other investigational drug or device;

• Diabetes, liver disease, or kidney disease;

• Hypoglycemia as defined by fasting blood glucose <70 mg/dL assessed at a fastingstudy visit;

• Prescription medication or cosmetics containing: retinoids, glycolic acid, salicylicacid, or any other remedies that might affect the healing process. Non-medicatedmoisturizers are allowed. If the person is unsure, they can bring in any productsfor our review;

• Self-reported history of chronic alcohol or drug abuse within 12 months prior toscreening, or any condition associated with poor compliance as judged by theinvestigator;

• Any other condition or laboratory value that would, in the professional opinion ofthe investigators, potentially affect the subject's response or the integrity of thedata or would pose an unacceptable risk to the subject.