Hud 1992: Acanthosis Nigricans as Hyperinsulinemia Marker

Background

Dr. John A. Hud Jr. and colleagues from the University of Texas published this study in Archives of Dermatology (PMID: 1626961), examining acanthosis nigricans as a marker of hyperinsulinemia in obese adults.

Study Design

Design: Cross-sectional observational Population: 34 obese adults (BMI >30) Measurements: Skin examination for acanthosis nigricans, fasting insulin, glucose, OGTT Analysis: Comparison of insulin levels between those with and without acanthosis

Key Findings

Finding	With Acanthosis	Without Acanthosis	P value
Prevalence	74% (25/34)	26% (9/34)	—
Fasting insulin	47.4 μU/mL	18.8 μU/mL	<0.01
2-hr insulin (OGTT)	269 μU/mL	85 μU/mL	<0.01
Insulin AUC	Markedly elevated	Normal range	<0.001

Key finding: Acanthosis nigricans was present in 74% of obese patients and marked significantly higher insulin levels.

Distribution: Most commonly neck, axillae, groin, knuckles

Mechanistic Insights

Acanthosis nigricans develops when high insulin levels stimulate:

1. •Insulin-like growth factor-1 (IGF-1) receptors on keratinocytes
2. •Epidermal proliferation
3. •Increased melanin deposition

It is a cutaneous marker of tissue-level insulin excess, not obesity per se.

Clinical Implications

Acanthosis nigricans on physical exam should prompt:

• •Fasting insulin measurement
• •HOMA-IR calculation
• •Metabolic syndrome screening
• •Early intervention for insulin resistance

Metabolic Health Perspective

This study established acanthosis nigricans as a visible sign of hyperinsulinemia that predates diabetes. Its presence in normal-weight individuals indicates metabolically obese normal weight (MONW) phenotype.