Saturday, June 09, 2007

Acanthosis Nigricans May Be a Risk Factor for Type 2 Diabetes

June 8, 2007 — Acanthosis nigricans is an independent risk factor for type 2 diabetes, and its presence may help primary care clinicians identify high-risk patients with diabetes sooner, according to the results of a cross-sectional study published in the May/June issue of the Annals of Family Medicine.
"Evidence shows acanthosis nigricans is often associated with hyperinsulinemia and may indicate increased risk of type 2 diabetes mellitus," write Alberta S. Kong, MD, MPH, from the University of New Mexico School of Medicine in Albuquerque, and colleagues from Research in Outpatient Settings Network. "The purpose of this study was to determine the association of acanthosis nigricans with type 2 diabetes risk factors and disease in young persons."
At the Research in Outpatient Settings Network, a practice-based research network in southwestern US communities, 96 participating clinicians collected data on 1133 children and adolescents (aged 7 - 19 years) and young adults (aged 20 - 39 years) who were seen during a 2-week sampling period. Primary endpoints were the prevalence of acanthosis nigricans, type 2 diabetes risk factors (ethnicity, family history of type 2 diabetes, hypertension, and overweight/obesity), type 2 diabetes, and the relationships among these.
Risk factors for type 2 diabetes were common in this sample: 69% had a family history of type 2 diabetes, 3% of children/adolescents and 12% of adults had hypertension, 43% of children/adolescents and 73% of adults were overweight or obese, and 80% were members of ethnic minorities.
Acanthosis nigricans was identified in 17% of children/adolescents and in 21% of adults. For both age groups, the more type 2 diabetes risk factors that were present, the higher the prevalence of acanthosis nigricans (P < .001). In patients with acanthosis nigricans, the prevalence ratio for type 2 diabetes was 1.97 (95% confidence interval, 1.18 - 3.27; P = .01), after controlling for age, body mass index, and the number of type 2 diabetes risk factors.
Clinicians noted that identifying acanthosis nigricans often allowed discussions about lifestyle modification to decrease the risk for type 2 diabetes.
"Patients with acanthosis nigricans are likely to have multiple risk factors for type 2 diabetes," the authors write. "Acanthosis nigricans may be an independent risk factor for this disease. Detection of acanthosis nigricans may help clinicians more rapidly identify high-risk individuals for diabetes counseling."
Study limitations include self-reported health history, cross-sectional design, lack of blood sampling for diabetes, underestimate of the prevalence of known hyperlipidemia, and overrepresentation of Hispanic and American Indian persons in the sample.
"Detection of acanthosis nigricans may also enhance patient and clinician receptivity to discussing risk reduction for type 2 diabetes," the authors conclude. "Studies are needed to investigate the natural history of acanthosis nigricans, its relationship to the development of type 2 diabetes, and how its presence influences screening and counseling for this disease."
The American Diabetes Association and the Agency for Healthcare Research and Quality supported this study. The authors have disclosed no relevant financial relationships.
Ann Fam Med. 2007;5:202-208.

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