Prevalence of acanthosis nigricans in newly-diagnosed type 2 diabetes

Objective: To determine the prevalence of acanthosis nigricans in a population of patients with newly-diagnosed type 2 diabetes mellitus. Methods: Chart review of men and women treated for newly diagnosed type 2 diabetes at the University Diabetes Treatment Center at Parkland Health and Hospital System in Dallas, Texas between January 1998 and December 1999. The presence of acanthosis nigricans was evaluated on the posterior neck of each individual. Results: Of 216 patients identifi ed with newly diagnosed type 2 diabetes, 78 individuals (36.1%) presented with acanthosis nigricans involving the back of the neck. Most subjects were obese, with the mean BMI of the subject population at 32.7 ± 5.8 kg/m² (mean ± SD). Prevalence of acanthosis nigricans increased with degree of obesity, with fully 54.1% of the population with a BMI of ≥ 30 kg/m2 manifesting the skin lesion. The prevalence of acanthosis nigricans differed notably among ethnic groups, as the lesion occurred in 50 (52.6%) of 95 African-American subjects and 28 (35.9%) of 78 Latin-American subjects. Patients with acanthosis nigricans required markedly higher insulin doses (82.3 ± 7.2 units/day) to achieve euglycemia compared to those without the disorder (50.2 ± 5.7 units/day). Conclusion: These results suggest that acanthosis nigricans is a readily visible marker of hyperinsulinemia and is frequently encountered in patients with type 2 diabetes. Prevalence of acanthosis nigricans is influenced by ethnicity and BMI in this patient population.