Skin Manifestations of Insulin Resistance: From a Biochemical Stance to a Clinical Diagnosis and Management

Worldwide, more than 1.9 billion adults are overweight, and around 600 million people suffer from obesity. Similarly, ~382 million individuals live with diabetes, and 40–50% of the global population is labeled at “high risk” (i.e., prediabetes). The impact of these two chronic conditions relies not only on the burden of illnesses per se (i.e., associated increased morbidity and mortality), but also on their increased cost, burden of treatment, and decreased health-related quality of life. For this review a comprehensive search in several databases including PubMed (MEDLINE), Ovid EMBASE, Web of Science, and Scopus was conducted. In both diabetes and obesity, genetic, epigenetic, and environmental factors overlap and are inclusive rather than exclusive. De facto, 70–80% of the patients with obesity and virtually every patient with type 2 diabetes have insulin resistance. Insulin resistance is a well-known pathophysiologic factor in the development of type 2 diabetes, characteristically appearing years before its diagnosis. The gold standard for insulin resistance diagnosis (the euglycemic insulin clamp) is a complex, invasive, costly, and hence unfeasible test to implement in clinical practice. Likewise, laboratory measures and derived indexes [e.g., homeostasis model assessment of insulin resistance (HOMA-IR-)] are indirect, imprecise, and not highly accurate and reproducible tests. However, skin manifestations of insulin resistance (e.g., acrochordons, acanthosis nigricans, androgenetic alopecia, acne, hirsutism) offer a reliable, straightforward, and real-time way to detect insulin resistance. The objective of this review is to aid clinicians in recognizing skin manifestations of insulin resistance. Diagnosing these skin manifestations accurately may cascade positively in the patient’s health by triggering an adequate metabolic evaluation, a timely treatment or referral with the ultimate objective of decreasing diabetes and obesity burden, and improving the health and the quality of care for these patients.