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L E T T E R S
OBSERVATIONS Uric Acid Indicates a High Cardiovascular Risk Profile but Is Not Closely Associated With Insulin Resistance in Obese Adolescents
W
e comment on a recent study by Dehghan et al. (1), who identified high serum uric acid as an independent risk factor for type 2 diabetes in adults. We investigated serum levels of uric acid in a large cohort of obese adolescents (n ⫽ 355; mean ⫾ SD age 13.1 ⫾ 4.1 years and age range 10 –22 years) and normal-weight control subjects (n ⫽ 200) of similar age and sex distribution (2). Uric acid levels were highly significantly increased in the obese adolescents (4.6 ⫾ 1.1 vs. 5.6 ⫾ 1.3 mg/dl, P ⬍ 0.0001). Male probands had significantly higher uric acid serum levels (P ⬍ 0.0001) in the obese and control groups. Interestingly, uric acid correlated highly significantly with systolic blood pressure (r ⫽ 0.37, P ⬍ 0.0001), increased inti-
DIABETES CARE, VOLUME 31, NUMBER 4, APRIL 2008
ma-media thickness of common carotid arteries (r ⫽ 0.33, P ⬍ 0.0001), nuchal subcutaneous adipose tissue thickness (r ⫽ 0.46, P ⬍ 0.0001), measured by lipometry (3), and waist circumference (r ⫽ 0.57, P ⬍ 0.0001). A negative association was seen with the high molecular weight–to–total adiponectin ratio (r ⫽ ⫺0.35, P ⫽ 0.01) (H. Mangge, G. Almer, H. Gruber, C. Mayer, M. Truschnig, N. Grandits, R. Mo¨ller, R. Horejsi, M. Borkenstein, S. Pilz, unpublished observations). In contrast to these strikingly significant correlations, identified as early as childhood, only weak correlations were seen between uric acid, homeostasis model assessment index (r ⫽ 0.2, P ⬍ 0.0001), and fasted insulin levels (r ⫽ 0.2, P ⬍ 0.0001). Fasted glucose levels and free fatty acids were not significantly associated with uric acid. Thus, in the earliest phases of the metabolic syndrome, as detected in obese adolescents aged ⬃13 years, uric acid indicates a high cardiovascular risk profile. However, in contrast to the observations in subjects in late adulthood by Dehghan et al., obese adolescents show a stronger association between uric acid, early vascular abnormalities, trunk-weighted obesity, and hypertension compared with markers of insulin resistance such as fasted insulin and homeostasis model assessment index.
HARALD MANGGE, MD1 STEFAN PILZ, MD2 SAMIH HAJ-YAHYA, MD1 GUNTER ALMER, MAG, MD1 From the 1Department of Laboratory Medicine, Medical University of Graz, Graz, Austria; and the 2 Department of Public Health, Mannheim, Germany. Address correspondence to Harald Mangge, MD, Department of Laboratory Medicine, Medical University of Graz, A-8036 Graz, Austria. E-mail:
[email protected]. DOI: 10.2337/dc07-2411 © 2008 by the American Diabetes Association.
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References 1. Dehghan A, van Hoek M, Sijbrands EJ, Hofman A, Witteman JC: High serum uric acid as a novel risk factor for type 2 diabetes. Diabetes Care 31:361–362, 2008 2. Pilz S, Horejsi R, Mo¨ller R, Almer G, Scharnagl H, Stojakovic T, Dimitrova R, Weihrauch G, Borkenstein M, Maerz W, Schauenstein K, Mangge H: Early atherosclerosis in obese juveniles is associated with low serum levels of adiponectin. J Clin Endocrinol Metab 90:4792– 4796, 2005 3. Moeller R, Horejsi R, Pilz S, Lang N, Sargsyan K, Dimitrova R, Tafeit E, Giuliani A, Almer G, Mangge H: Evaluation of risk profiles by subcutaneous adipose tissue topography in obese juveniles. Obesity (Silver Spring) 15:1319 –1324, 2007
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