Study of Efficacy of Metformin in the Treatment of Acanthosis Nigricans in Children With Obesity

Double-blind Randomized Trial Using Oral Metformin Versus Placebo in the Treatment of Acanthosis Nigricans in Children With Obesity

Obesity is often accompanied by insulin resistance and/or hyperinsulinemia. Acanthosis nigricans (AN) is a skin condition commonly present on the neck of obese children. Metformin is a useful drug for conditions characterized by insulin resistance.The aim of this study is to compare the efficacy of metformin versus placebo on AN lesions of the neck as well as their effects on metabolic and anthropometric variables in a sample of obese children. This is a 12-week randomized, double-blind randomized trial involving obese children with AN to receive either metformin or placebo. Evaluations will be performed every three weeks. Clinical, histological and colorimetric assessments of AN lesions will be compared initially and at the conclusion of the study.

Acanthosis nigricans (AN) are lesions affecting localized areas of the skin in persons with obesity and/or hyperinsulinemia. Roughening of the skin is related with histological papillomatosis and the skin darkening is due to hyperkeratosis. Biochemical mechanisms for developing this hyperplastic lesion involve local cutaneous growth factors. Nearly 40% of Native American teenagers have acanthosis nigricans, whereas about 13% of African American, 6% of Hispanic, and less than 1% of white, non-Hispanic children aged 10-19 have clinically apparent acanthosis nigricans. AN is a clinical surrogate of laboratory-documented hyperinsulinemia. The aim of this study is to compare the efficacy of metformin versus placebo on AN lesions of the neck as well as their effects on metabolic (HOMA, triglycerides, cholesterol) and anthropometric variables (BMI, waist) in a sample of obese children. This is a 12-week randomized, double-blind randomized trial involving obese children with AN to receive either metformin or placebo. Evaluations will be performed every three weeks. Clinical, histological and colorimetric assessments of AN lesions will be compared initially and at the conclusion of the study. Burke´s scale, papillomatosis and hyperkeratosis, and the L* axis of will be used to measure the AN improvement.

Initial and after intervention assessment of acanthosis nigricans using the quantitative scale of Burke (Diabetes Care 22:1655-1659, 1999). Five anatomical sites were chosen to assess the presence and extent of AN: neck, axilla, knuckles, elbows, and knees. The neck and axilla are graded for severity on a scale from 0 to 4. For AN present on the neck, texture of the affected area is also measured on a scale from 0 to 3. Knuckles, elbows, and knees are graded as AN present (1) or absent (0). Score goes from 0 to 14.

Epidermal and stratum corneum thickness of 3 mm skin samples obtained from neck will be measured using an image processing software initially and at the end of trial.

Quantification of pigmentation change of lesions by means of the L axis of the CIE system. 0 is pure white, 100 y total dark. Initially, and at the end of study.

BMI It is the measure of body fat based on height and weight. The BMI is the body mass divided by the square of the body height, and expressed in units of kg/m2, resulting from weight in kilograms and height in metres

Inclusion Criteria: Signed informed consent from children and parents. Children younger than 18 years. Clinical diagnosis of acanthosis nigricans. Obesity. Exclusion Criteria: Diabetes mellitus. Neurological diseases. Congenital diseases. Oral treatment for obesity in the last two months. Topical treatment for the last two months.

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