Acanthosis Nigricans
Acanthosis nigricans is a skin condition causing dark, velvety patches — a visible sign of insulin resistance linked to excess weight.
Plain English
Patient-Friendly Explanation
Acanthosis nigricans appears as dark, thick, velvety patches of skin, most commonly on the back of the neck, armpits, or groin. It is not dangerous or contagious, but it is an important visible sign that your body may be struggling with insulin resistance — a precursor to type 2 diabetes. The patches usually improve when the underlying insulin resistance is treated through weight loss and lifestyle changes.
Medical
Clinical Definition
Acanthosis nigricans is a cutaneous marker of hyperinsulinaemia, presenting as symmetric, hyperpigmented, velvety plaques typically affecting intertriginous areas (neck, axillae, groin). Elevated circulating insulin binds to insulin-like growth factor 1 (IGF-1) receptors on keratinocytes and dermal fibroblasts, stimulating epidermal proliferation. It is strongly associated with obesity, insulin resistance, metabolic syndrome, and polycystic ovary syndrome (PCOS). Resolution typically parallels improvement in insulin sensitivity through weight reduction and physical activity.
Key Insight
Why It Matters
Spotting acanthosis nigricans during a physical examination at Accord Medical provides an early warning that metabolic health needs attention — often years before blood tests show abnormalities.
Sources
Reviewed against standard medical references.
Medically reviewed by
Family Physician & Registered Acupuncturist, Accord Medical Clinic. MBBS (NUS), Graduate Diploma in Family Medicine (NUS), Graduate Diploma in Acupuncture (Singapore College of TCM).
Last reviewed: August 2026
This page is general health education, not medical advice. Whether any treatment is appropriate for you is a decision made in consultation after assessment.
