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Skin signs of endocrine and metabolic disease
The skin reflects hormones and metabolism: insulin resistance produces acanthosis nigricans and skin tags, diabetes causes necrobiosis lipoidica and bullosis diabeticorum, thyroid disease changes the skin and hair, and lipid disorders appear as xanthomas.
Why it matters in the exam
Exam stems show a yellow-brown plaque with an atrophic centre and prominent vessels on the shins of a woman with diabetes — necrobiosis lipoidica — or an obese teenager with dark thickening of the neck, or yellow papules erupting suddenly on the buttocks of a patient with very high triglycerides (eruptive xanthomas), or a pink waxy thickening on the front of the shins in Graves disease (pretibial myxoedema). The question tests matching the sign to the disease and the next test, for example glucose and HbA1c, thyroid function or a lipid profile. Remember also the "diabetic back" — scleredema of Buschke with thickened skin on the upper back — and the link between vitiligo and autoimmune thyroid disease. The key understanding is that treating the underlying disease improves some signs, but necrobiosis lipoidica does not parallel glucose control. Patients with diabetes also have a greater tendency to skin and fungal infections.
Key points
- Acanthosis nigricans usually signals insulin resistance and requires glucose and lipid testing.
- Necrobiosis lipoidica is an atrophic yellow-brown plaque on the shins of patients with diabetes and does not parallel control.
- Diabetic dermopathy is the most common skin sign of diabetes, and bullosis diabeticorum causes benign blisters.
- Pretibial myxoedema appears in Graves disease, usually together with ophthalmopathy.
- Eruptive xanthomas signal high triglycerides and a pancreatitis risk, and tendon xanthomas signal familial hypercholesterolaemia.
Summary table
| Skin sign | Appearance | Underlying disease | Note |
|---|---|---|---|
| Acanthosis nigricans | Dark velvety thickening of the neck and axillae, with skin tags | Insulin resistance, obesity, PCOS, type 2 diabetes | Improves with weight loss; check glucose and HbA1c |
| Necrobiosis lipoidica | Yellow-brown plaque, atrophic centre with telangiectasia, on the shins | Diabetes (often type 1) | Does not parallel glucose control; may ulcerate |
| Bullosis diabeticorum and diabetic dermopathy | Tense non-inflamed blisters on the feet; small brown macules on the shins | Long-standing diabetes | Benign; dermopathy is the most common skin sign of diabetes |
| Pretibial myxoedema | Pink waxy "orange-peel" thickening on the front of the shins | Graves disease | Usually with ophthalmopathy; potent topical steroids |
| Xanthomas | Eruptive: yellow papules on the buttocks; tendinous: in the Achilles tendons; palmar: in palm creases | Eruptive: high triglycerides; tendinous: familial hypercholesterolaemia; palmar: dysbetalipoproteinaemia | Eruptive xanthomas signal a pancreatitis risk |
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Sources
- American Diabetes Association Standards of Care in Diabetes, 2025 — Comprehensive medical evaluation — skin
- Fitzpatrick's Dermatology, 9th edition (2019) — Diabetes and other endocrine diseases
- European guideline on xanthomas and lipid disorders (ESC/EAS dyslipidaemia guideline), 2019 — Physical signs
Sources are given for further reading; the text is written afresh and not copied from them.
Reviewed by the Examqo AI Professor · 2026-11-06. The text may contain errors; when in doubt, check the source.