Research ArticleOriginal ResearchA

Acanthosis Nigricans and Diabetes Risk Factors: Prevalence in Young Persons Seen in Southwestern US Primary Care Practices

Alberta S. Kong, Robert L. Williams, Melissa Smith, Andrew L. Sussman, Betty Skipper, Andrew C. Hsi, Robert L. Rhyne and ; On behalf of RIOS Net Clinicians
The Annals of Family Medicine May 2007, 5 (3) 202-208; DOI: https://doi.org/10.1370/afm.678

Article Figures & Data

Figures

  • Figure 1.
    Figure 1.

    Prevalence of acanthosis nigricans by number of diabetes risk factors.

    Note: Risk factors included family history of type 2 diabetes mellitus, overweight/obesity, hypertension, and minority ethnicity.

Tables

  • Table 1.

    Characteristics of the Study Sample (N=1,133)

    Characteristic% (No.)
    * Other race/ethnicity included Asian, black, Pacific Islander, or mixed. Five of the 155 patients were not Hispanic or Latino and reported “other race.”
    Age, years
        7–1115.8 (179)
        12–1926.8 (304)
        20–2926.4 (299)
        30–3931.0 (351)
    Sex
        Female61.6 (698)
        Male38.4 (435)
    Race/ethnicity
        American Indian35.7 (405)
        Hispanic30.6 (347)
        White, non-Hispanic16.9 (192)
        Other*13.7 (155)
        Missing data3.0 (34)
  • Table 2.

    Prevalence of Type 2 Diabetes Mellitus Risk Factors and Acanthosis Nigricans by Demographic Variables

    Prevalence*
    VariableFamily History of Type 2 Diabetes MellitusOverweight or ObeseHypertensionHyperlipidemiaAcanthosis Nigricans
    Note: total numbers of patients for each variable are given in Table 1.
    * Cell entries show percentages with risk factor present followed by (number positive/number for whom information was available).
    † P<.001 for χ2 comparing all categories for indicated variable.
    ‡ P<.05 for χ2 comparing all categories for indicated variable.
    § P <.01 for χ2 comparing all categories for indicated variable.
    Total69.2 (761/1,100)60.5 (685/1,133)8.9 (97/1,087)16.6 (85/513)19.2 (218/1,133)
    Age, years
        7–1167.4 (118/175)41.3 (74/179)†1.8 (3/165)†7.7 (5/65)†19.0 (34/179)‡
        12–1967.2 (195/290)44.4 (135/304)4.5 (13/291)7.5 (8/106)15.8 (48/304)
        20–2971.8 (211/294)71.9 (215/299)7.2 (21/293)11.6 (15/129)17.4 (52/299)
        30–3969.5 (237/341)74.4 (261/351)17.8 (60/338)26.8 (57/213)23.9 (84/351)
    Sex
        Female71.8 (491/684)‡59.9 (418/698)6.1 (41/671)†12.9 (41/318)§19.3 (135/698)
        Male64.9 (270/416)61.4 (267/435)13.5 (56/416)22.6 (44/195)19.1 (83/435)
    Race/ethnicity
        American Indian77.6 (305/393)†71.4 (289/405)†10.4 (40/386)16.6 (32/193)28.1 (114/405)†
        Hispanic68.8 (234/340)59.1 (205/347)7.4 (25/340)20.6 (27/131)19.0 (66/347)
        White, non-Hispanic54.9 (100/182)43.2 (83/192)7.2 (13/181)12.2 (10/82)3.1 (6/192)
        Other60.9 (92/151)56.8 (88/155)9.6 (14/146)13.8 (12/87)16.1 (25/155)
  • Table 3.

    Prevalence of Acanthosis Nigricans by Type 2 Diabetes Mellitus Risk Factor

    Aged 7–19 YearsAged 20–39 Years
    Type 2 Diabetes Risk FactorNo.% (95% CI)No.% (95% CI)
    BMI=body mass index; CI=confidence interval.
    * P <.001 for comparison of prevalence of acanthosis nigricans between those with and without the risk factor.
    † For children, normal is defined as less than 85th percentile; overweight but not obese is defined as 85th to less than 95th percentile; and obese is defined as 95th percentile or higher. For adults, normal is defined as 25 kg/m2; overweight but not obese is defined as 25 to 30 kg/m2; and obese is defined as ≥30 kg/m2.
    Family history of type 2 diabetes
        Yes31321.4 (17.0–26.4)*44825.2 (21.3–29.5)*
        No/unknown1708.8 (5.0–14.1)20211.4 (7.4–16.6)
    BMI category†
        Normal2742.6 (1.0–5.2)*1743.4 (1.3–7.4)*
        Overweight, not obese8011.2 (5.3–20.3)18712.3 (8.0–17.9)
        Obese12951.2 (42.2–60.1)28937.0 (31.4–42.9)
    Hypertension
        Yes1668.8 (41.3–89.0)*8137.0 (26.6–48.5)*
        No/unknown46715.2 (12.1–18.8)56918.6 (15.5–22.1)
  • Table 4.

    Type 2 Diabetes Mellitus Prevalence Ratios for Factors Related to Type 2 Diabetes Mellitus, by Log-binomial Regression Analysis

    FactorPrevalence Ratio (95% CI)P Value
    CI=confidence interval; BMI = body mass index.
    * Risk factors included family history of type 2 diabetes mellitus, hypertension, and minority ethnicity.
    Age, years
        7–191.00<.001
        20–397.64 (3.17–18.42)
    Acanthosis nigricans
        No1.00.01
        Yes1.97 (1.18–3.27)
    BMI category
        Normal or overweight1.00.004
        Obese2.25 (1.29–3.91)
    Number of risk factors*
        0–11.00<.001
        2–33.41 (1.65–7.06)

Additional Files

  • Supplemental Figure

    Supplemental Figure. Acanthosis nigricans on the posterior neck.

    Files in this Data Supplement:

  • The Article in Brief

    Acanthosis Nigricans and Diabetes Risk Factors: Prevalence in Young Persons Seen in Southwestern US Primary Care Practices

    Alberta S. Kong, MD, MPH , and colleagues

    Background This study looks at the relationship between acanthosis nigricans, a skin condition, and type 2 diabetes, the most common form of diabetes. More than 1,000 patients from 7-39 years old took part in the study.

    What This Study Found Patients with acanthosis nigricans (AN) were almost twice as likely as other patients to have type 2 diabetes. Children and adults with a family history of type 2 diabetes had higher rates of AN than other patients. Identifying AN often led doctors and patients to discuss lifestyle changes that can lower the risk of diabetes.

    Implications

    • AN can be used to quickly identify patients with risks for type 2 diabetes.
    • Diagnosing AN may help doctors identify patients who would benefit from lifestyle changes that can reduce the risk of diabetes.

  • Annals Journal Club Selection:

    May/Jun 2007

    The Annals Journal Club is designed to encourage a learning community of those seeking to improve health care and health through enhanced primary care. Additional information is available on the Journal Club home page.

    The Annals of Family Medicine encourages readers to develop the learning community of those seeking to improve health care and health through enhanced primary care. You can participate by conducting a RADICAL journal club, and sharing the results of your discussions in the Annals online discussion for the featured articles. RADICAL is an acronym for: Read, Ask, Discuss, Inquire, Collaborate, Act, and Learn. The word radical also indicates the need to engage diverse participants in thinking critically about important issues affecting primary care, and then acting on those discussions.1

    Article for Discussion

    • Kong AS, Williams RL, Smith M, et al, on behalf of RIOS Net Clinicians. Acanthosis nigricans and diabetes risk factors: prevalence in young persons seen in Southwestern US primary care practices. Ann Fam Med. 2007;5(3):202-208.

    Discussion Tips

    This article presents opportunities for many levels of learning about diabetes, diagnostic testing, and practice-based network (PBRN) research. (See the article by Tierney et al in this issue of Annals2 for an overview of US PBRNs). You can examine Supplemental Figure 1 online to see what acanthosis nigricans looks like.

    Discussion Questions

    • What are the research questions and why are they important? What already is known about acanthosis nigricans and diabetes risk factors?
    • What are the limitations of the cross-sectional study design for answering the different study questions?
    • To what degree are the findings affected by:
    1. How participants (practices, clinicians,3 patients4,5) were selected?
    2. How critical variables were measured and/or defined?
    3. Missing data?
    4. Confounding (false attribution of causality because 2 variables discovered to be associated actually are associated with a third factor)?
    5. Chance?
  • What are the main findings? How do they advance current knowledge?
  • How do you interpret the �unanticipated finding�?
  • How transportable are the findings to your setting and patients? How might the information be used to change practice?

    • References

    1. Stange KC, Miller WL, McLellan LA, et al. Annals journal club: It�s time to get RADICAL. Ann Fam Med. 2006;4:196-197. Available at: http://annfammed.org/cgi/content/full/4/3/196.
    2. Tierney WM, Oppenheimer CC, Hudson BL, et al. A national survey of primary care practice-based research networks. Ann Fam Med. 2007;5(3):242-250.
    3. Nutting PA, Baier M, Werner JJ, Cutter G, Reed FM, Orzano AJ. Practice patterns of family physicians in practice-based research networks: a report from ASPN. Ambulatory Sentinel Practice Network. J Am Board Fam Pract. 1999;12(4):278-284.
    4. Gilchrist V, Miller R, Gillanders W, et al. Does family practice at residency teaching sites reflect community practice? J Fam Pract. 1993;37(6):555-563.
    5. Green LA, Miller RS, Reed FM, Iverson DC, Barley GE. How representative of typical practice are practice-based research networks? A report from the Ambulatory Sentinel Practice Network (ASPN). Arch Fam Med. 1993;2(9):939-949.
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