A Cross Sectional Study Of Evaluation Of Association Between Acanthosis Nigricans And Insulin Resistance

Abstract

Background: Acanthosis Nigricans is a skin lesion characterized by hyperpigmented velvety cutaneous thickening that can occur in flexural areas like axilla, sides of neck, antecubital and popliteal fosse or groin. Insulin resistance is a reduction in the ability of tissue cells, mainly those in muscle, to use insulin. In this condition, the pancreas is hyperactive to produce more insulin, and hyperinsulinemia develops to maintain blood sugar levels within normal limits. The body cannot use the additional insulin, and the pancreas becomes exhausted. Insulin production then decreases. At this point, a person may be diagnosed with Type 2 diabetes. Some researchers consider acanthosis nigricans to be a predictive marker for Type 2 diabetes mellitus. Many studies have been done in various parts of the world on subjects with acanthosis nigricans to determine correlations with obesity, diabetes, hyperinsulinemia, insulin resistance (IR) and other metabolic parameters. Thus, screening of patients with acanthosis nigricans for insulin levels becomes relevant and necessary, so as to advice them regarding the diet, life style modifications and weight reduction to prevent occurrence of diabetes mellitus. Aim: To determine the prevalence of insulin resistance in acanthosis nigricans patients and relation of Acanthosis Nigricans with obesity. Materials and method: This study was a cross sectional study consisting of 40 patients clinically diagnosed as having acanthosis nigricans irrespective of age or sex. Patients known to have diabetes were excluded from the study. The fasting serum insulin levels and fasting glucose levels were measured. Insulin resistance was calculated by using homeostasis model of assessment of insulin resistance (HOMA-IR), the values ≥ 2.5 were considered to be positive. Results: The prevalence of insulin resistance in patients with acanthosis nigricans was found to be 70%. The proportion of females (45%) and males (55%) were almost same. Prevalence of acanthosis nigricans was more in age group between 21 to 30 years. Prevalence of insulin resistance was seen more in the age group of 11 to 20 years.77.78% of obese patients had insulin resistance, 78.94% of overweight patients had insulin resistance and 50% of normal patients had insulin resistance. 80% of patients with positive family history had insulin resistance and 64% with negetive family history had insulin resistance. All patients (100%) had acanthosis nigricans on the neck, next commonest site being axilla (95%). The unusual sites involved were perioral, periorbital and flank regions. Conclusion: According to our study, raised insulin resistance was found in considerable number of patients with acanthosis nigricans. Prevalence was also more in obese and overweight patients when compared to normal patients. These could be the early indications of impending diabetes in these patients. Thus screening of patients with acanthosis nigricans for insulin levels becomes relevant and necessary.