Acanthosis Nigricans: High Prevalence and Association with Diabetes in a Practice-based Research Network Consortium—A PRImary care Multi-Ethnic Network (PRIME Net) Study

Alberta S. Kong; Robert L. Williams; Robert Rhyne; Virginia Urias-Sandoval; Gina Cardinali; Nancy F. Weller; Betty Skipper; Robert Volk; Elvan Daniels; Bennett Parnes; Laurie McPherson

doi:10.3122/jabfm.2010.04.090221

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Figure 1.
Acanthosis nigricans presenting on the posterior neck of a young woman.

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Table 1.

Characteristics of the Study Sample (N = 1730)

Characteristic	n (%)
Age (years)
7–19	143 (8.3)
20–39	497 (28.7)
40–65	1090 (63.0)
Sex
Female	1204 (69.6)
Male	526 (30.4)
Race/ethnicity
African American	362 (20.9)
Hispanic	714 (41.3)
Non-Hispanic white	531 (30.7)
Other^*	123 (7.1)

* Other race/ethnicity includes American Indian/Alaska native, Asian, and mixed.

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Table 2.

Type 2 Diabetes Mellitus Prevalence by Age and Race/Ethnicity

Age (years)	All patients (n/N [%])	Patient Race/Ethnicity
Age (years)	All patients (n/N [%])	African-American/Black (n/N [%])	Hispanic/Latino (n/N [%])	Non-Hispanic White (n/N [%])	Other Minorities (n/N [%])
All ages	354/1680 (21.1)	87/349 (24.9)	169/698 (24.2)	68/516 (13.2)	30/117 (25.6)
7–19	3/140 (2.1)	0/53 (0)	1/54 (1.9)	2/29 (6.9)	0/4 (0)
20–39	39/481 (8.1)	6/79 (7.6)	23/232 (9.9)	5/132 (3.8)	5/38 (13.2)
40–65	312/1059 (29.5)	81/217 (37.3)	145/412 (35.2)	61/355 (17.2)	25/75 (33.3)

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Table 3.

Prevalence of Selected Risk Factors for Type 2 Diabetes Mellitus and of Acanthosis Nigricans by Sex, Age, and Race/Ethnicity

Age (years)	Family History of T2DM					Overweight or Obese					Hypertension					Dyslipidemia					Acanthosis Nigricans
Age (years)	All races/ ethnicities	African American	Hispanic/ Latino	Non-Hispanic White	Other^*	All races/ ethnicities	African American	Hispanic/ Latino	Non-Hispanic White	Other^*	All races/ ethnicities	African American	Hispanic/ Latino	Non-Hispanic White	Other^*	All races/ ethnicities	African American	Hispanic/ Latino	Non-Hispanic White	Other^*	All races/ ethnicities	African American	Hispanic/ Latino	Non-Hispanic White	Other^*
All	1072/1684 (63.7)	248/351 (70.7)	458/703 (65.1)	291/513 (56.7)	75/117 (64.1)	1294/1730 (74.8)	292/362 (80.7)	565/714 (79.1)	363/531 (68.4)	74/123 (60.2)	669/1701 (39.3)	187/356 (52.5)	240/706 (34.0)	198/521 (38.0)	44/118 (37.3)	(37.7) 578 /1535	105/318 (33.0)	230/638 (36.1)	197/478 (41.2)	46/101 (45.5)	336/1730 (19.4)	97/362 (26.8)	186/714 (26.1)	32/531 (6.0)	21/123 (17.1)
7–19	88/142 (62.0)	35/53 (66.0)	35/55 (63.6)	13/29 (44.8)	5/5 (100)	70/143 (49.0)	27/53 (50.9)	32/55 (58.2)	9/30 (30.0)	2/5 (40.0)	5/139 (3.6)	0/52 (0.0)	2/53 (3.8)	3/30 (10.0)	0/4 (0.0)	(0.0) 0/128	0/51 (0.0)	0/48 (0.0)	0/28 (0.0)	0/1 (0.0)	26/143 (18.2)	9/53 (17.0)	16/55 (29.1)	1/30 (3.3)	0/5 (0.0)
20–39	296/484 (61.2)	55/81 (67.9)	142/233 (60.9)	74/132 (56.1)	25/38 (65.8)	361/497 (72.6)	72/85 (84.7)	185/237 (78.1)	81/135 (60.0)	23/40 (57.5)	83/490 (16.9)	23/84 (27.4)	25/234 (10.7)	26/132 (19.7)	9/40 (22.5)	(18.3) 76/416	7/68 (10.3)	41/203 (20.2)	20/117 (17.1)	8/28 (28.6)	111/497 (22.3)	25/85 (29.4)	68/237 (28.7)	10/135 (7.4)	8/40 (20.0)
40–65	688/1058 (65.0)	158/217 (72.8)	281/415 (67.7)	204/352 (58.0)	45/74 (60.8)	863/1090 (79.2)	193/224 (86.2)	348/422 (82.5)	273/366 (74.6)	49/78 (62.8)	581/1072 (54.2)	164/220 (74.5)	213/419 (50.8)	169/359 (47.1)	35/74 (47.3)	502/991 (50.7)	98/199 (49.2)	189/387 (48.8)	177/333 (53.2)	38/72 (52.8)	199/1090 (18.3)	63/224 (28.1)	102/422 (24.2)	21/366 (5.7)	13/78 (16.7)

Values provided as n/N (%). T2DM, type 2 diabetes mellitus.
* “Other” race or ethnicity including American Indian/Alaska Native, Asian, or Mixed ethnicity/race.

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Table 4.

Prevalence of Acanthosis Nigricans by the Number of Type 2 Diabetes Risk Factors, Stratified by Age

Age (years)	Number of Risk Factors
Age (years)	0	1	2	3	4	5
All	1/62 (1.6)	3/173 (1.7)	43/330 (13.0)	100/455 (22.0)	84/299 (28.1)	64/168 (38.1)
7–19	0/10 (0)	0/32 (0)	4/42 (9.5)	18/39 (46.2)	1/1 (100)	0/0
20–39	1/25 (4.0)	1/68 (1.5)	21/110 (19.1)	38/146 (26.0)	18/41 (43.9)	11/15 (73.3)
40–65	0/27 (0)	2/73 (2.7)	18/178 (10.1)	44/270 (16.3)	65/257 (25.3)	53/153 (34.6)

Values provided as n/N (%).

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Table 5.

Prevalence of Diabetes by Presence of Acanthosis Nigricans (AN)

Age (years)	All Patients		African American/ Black Patients		Hispanic/Latino Patients		White, Non-Hispanic White Patients		Other Minority Patients
Age (years)	AN	No AN	AN	No AN	AN	No AN	AN	No AN	AN	No AN
All	116/328 (35.4)	238/1352 (17.6)	34/94 (36.2)	53/255 (20.8)	58/181 (32.0)	111/517 (21.5)	13/32 (40.6)	55/484 (11.4)	11/21 (52.4)	19/96 (19.8)
7–19	0/26 (0)	3/114 (2.6)	0/9 (0)	0/44 (0)	0/16 (0)	1/38 (2.6)	0/1 (0)	2/28 (7.1)	0/0	0/4 (0)
20–39	21/105 (20.0)	18/376 (4.8)	2/23 (8.7)	4/56 (7.1)	13/64 (20.3)	10/168 (6.0)	3/10 (30.0)	2/122 (1.6)	3/8 (37.5)	2/30 (6.7)
40–65	95/197 (48.2)	217/862 (25.2)	32/62 (51.6)	49/155 (31.6)	45/101 (44.6)	100/311 (32.2)	10/21 (47.6)	51/334 (15.3)	8/13 (61.5)	17/62 (27.4)

Values provided as n/N (%). Patients were not included if the response for type 2 diabetes mellitus was “don’t know.”

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Table 6.

Prevalence Ratios of Diabetes by Risk Factor Using Multivariate Models by Race/Ethnicity

	Race/ethnicity (ratio [95% CI])
	Non-Hispanic White	Minorities	All Patients
Age (years)
20–39	1.00	1.00	1.00
40–65	2.35 (0.90–6.13)	2.37 (1.64–3.44)	2.35 (1.67–3.30)
Acanthosis Nigricans
No	1.00	1.00	1.00
Yes	2.10 (1.25–3.52)	1.47 (1.21–1.80)	1.51 (1.25–1.82)
BMI category
Normal	1.00	1.00	1.00
Overweight	1.13 (0.47–2.73)	1.10 (0.80–1.51)	1.14 (0.84–1.54)
Obese	1.92 (0.89–4.15)	1.09 (0.81–1.46)	1.24 (0.94- 1.63)
Family history of diabetes
No	1.00	1.00	1.00
Yes	2.31 (1.31–4.05)	2.00 (1.51–2.65)	2.06 (1.60–2.66)
Hypertension
No	1.00	1.00	1.00
Yes	1.94 (1.14–3.31)	1.72 (1.34–2.21)	1.79 (1.42–2.25)
Dyslipidemia
No	1.00	1.00	1.00
Yes	3.54 (1.85–6.76)	1.94 (1.53–2.45)	2.10 (1.69–2.62)
Sex
Female	1.00	1.00	1.00
Male	1.53 (1.00–2.35)	1.21 (1.00–1.48)	1.28 (1.07–1.53)
Minority
No			1.00
Yes			1.73 (1.37–2.19)

Bolded values indicate statistically significant risk ratios, controlling for all other listed risk factors. BMI, body mass index.

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Table 7.

Differences in Biophysical and Metabolic Parameters among Matched Pairs of Patients (n = 11) with and without Acanthosis Nigricans (AN)

	No AN	AN	Difference	P^*
Body mass index^†	36.2 (1.6)	38.2 (1.6)	2.0 (1.0)	—
Waist circumference (9 pairs)	112 (3)	113 (4)	1 (3)	.71
Systolic blood pressure (8 pairs)	128 (5)	128 (9)	−0 (13)	.99
Diastolic blood pressure (9 pairs)	85 (2)	87 (4)	2 (5)	.66
Glucose	91 (3)	94 (4)	3 (5)	.56
Triglyceride	135 (22)	145 (13)	10 (24)	.70
Cholesterol	197 (8)	190 (6)	−7 (12)	.59
High-density lipoprotein	44 (4)	42 (3)	−2 (5)	.74
Low-density lipoprotein	127 (8)	120 (6)	−7 (12)	.57
Insulin^‡	13.1 (1.5)	23.0 (4.0)	9.9 (3.9)	.02
Free fatty acids (10 pairs)	0.57 (0.04)	0.53 (0.07)	−0.04 (0.08)	.63
Homeostasis model assessment^‡	2.98 (0.37)	5.57 (1.12)	2.58 (1.07)	.03

Values provided as mean (SE).
* P values for insulin and homeostasis model assessment are from Wilcoxon signed rank tests. All others are paired t tests.
† Body mass index was a matching variable so was not tested for significance.
‡ Geometric means of insulin: 12.3 for no AN; 19.7 for AN. Geometric mean of homeostasis model assessment: 2.7 for no AN; 4.6 for AN.