Figure 3. Acanthosis Nigricans (AN).
This hyperpigmented skin rash is usually found at the base of the neck and axilla and is highly predictive of insulin resistance in adults. Although less documented in children, recent data indicate that more than 60% of children with AN also have a homeostatic model assessment index (HOMA) ≥3. HOMA is the current gold standard of insulin resistance and beta-cell function based on fasting plasma glucose and insulin levels.