Cutaneous Manifestations of Nutritional Excess: Pathophysiologic Effects of Hyperglycemia and Hyperinsulinemia on the Skin

Steven A. Svoboda, BS; Bridget E. Shields, MD

Disclosures

Cutis. 2021;107(2):74-78. 

In This Article

Acanthosis Nigricans

Acanthosis nigricans (AN) is a highly prevalent cutaneous finding in individuals with insulin resistance that clinically presents as thickened, hyperpigmented, velvety plaques on the intertriginous and flexural surfaces. The most frequently involved sites include the neck, axillae (Figure), and inframammary and inguinal folds. Black and Hispanic patients most commonly are affected. Although classically associated with T2DM, AN also can be observed in normoglycemic individuals.[7,8,9] One recent study reported the rate of AN to be 36% in a cohort of middle-aged patients (N=320) with normal fasting blood glucose levels, while the rate of AN in matched patients with hyperglycemia(prediabetes and T2DM) was approximately 50%.[7] Quantification of insulin resistance was performed using the homeostatic model assessment of insulin resistance index. Interestingly, the specificity for insulin resistance in normoglycemic and hyperglycemic subjects with AN was 85% and 90%, respectively.[7] These findings suggest that AN may serve as a convenient surrogate marker for subclinical insulin resistance, a conclusion that has been reported in a series of previous studies.[8,9,10]

Figure 1

Acanthosis nigricans of the axilla with associated acrochordons in a patient with poorly controlled type 2 diabetes mellitus.

Although the pathogenesis of AN has not been fully elucidated, it is known that persistently elevated blood glucose triggers continual secretion of insulin and insulinlike growth factor 1 (IGF-1), which results in the overstimulation of insulin and IGF-1 receptors on keratinocytes and dermal fibroblasts through direct and indirect pathways.[11,12] The resultant cellular proliferation canbe observed histologically in the forms of orthokeratotic hyperkeratosis and papillomatosis, as occurs in AN.[11,13] Further supporting the association between elevated insulin and AN are reports of AN developing at sites of repeated insulin injection as well as genetic mutations in the insulin receptor resulting in severe AN in children.[14,15,16]

The treatment of AN ultimately focuses on improving glycemic control and reducing insulin resistance through lifestyle modification and pharmacotherapy with agents such as metformin.[11,13] Dermatologic treatment with oral and topical keratolytic agents such as isotretinoin and other retinoids, salicylic acid, urea, or ammonium lactate may be used, but their efficacy generally has been limited.[11,13,17,18]

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