Serum C3 Is a Stronger Inflammatory Marker of Insulin Resistance Than C-Reactive Protein, Leukocyte Count, and Erythrocyte Sedimentation Rate

Comparison study in an elderly population

  1. Antonio Muscari, MD1,
  2. Serafina Antonelli, MD2,
  3. Giampaolo Bianchi, MD1,
  4. Giulia Cavrini, PHD3,
  5. Susanna Dapporto, MD1,
  6. Amedeo Ligabue, MD2,
  7. Cosimo Ludovico, MD1,
  8. Donatella Magalotti, MD1,
  9. Guido Poggiopollini, MD1,
  10. Marco Zoli, MD1 and
  11. on behalf of the Pianoro Study Group
  1. 1Department of Internal Medicine, Cardioangiology, and Hepatology, University of Bologna, Bologna, Italy
  2. 2Laboratory of the Azienda Unità Sanitaria Locale Bologna, Bologna, Italy
  3. 3Department of Statistical Sciences, University of Bologna, Bologna, Italy
  1. Address correspondence and reprint requests to Antonio Muscari, MD, FESC, Internal Medicine, Cardioangiology, Hepatology, University of Bologna, S.Orsola-Malpighi Hospital, Via Albertoni 15, 40138 Bologna, Italy. E-mail: amuscari{at}


OBJECTIVE—This study was performed to ascertain the relative relevance of some inflammatory markers in insulin resistance.

RESEARCH DESIGN AND METHODS—Four inflammatory markers (leukocyte count, erythrocyte sedimentation rate [ESR], high-sensitivity C-reactive protein [CRP], and C3 complement) were assessed as possible determinants of the homeostasis model assessment (HOMA) index, together with the five elements of the metabolic syndrome (National Cholesterol Education Program Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults [Adult Treatment Panel III] definition), total cholesterol, physical activity, and four indicators of adiposity (BMI, waist circumference, percent body fat, and hepatic steatosis) in an unselected population of 990 subjects aged 65–91 years (the Pianoro Study).

RESULTS—In univariable analysis, C3, CRP, and leukocyte count, but not ESR, were significantly correlated with HOMA index. In multivariable analysis, C3 remained associated with insulin resistance with the highest partial R2 value (0.049), independently of all other covariates. The other most significant (P < 0.0001) determinants of HOMA index were total cholesterol (inverse association, R2 = 0.026), waist circumference (R2 = 0.023), triglycerides (R2 = 0.022), and hepatic steatosis (R2 = 0.021) (R2 = 0.450 for the whole model).

The adjusted relative risks of having the metabolic syndrome for the subjects with inflammatory markers in the high tertile, with respect to those with lower values, were (prevalence ratio [95% CI]): 1.77 (1.41–2.22) for C3, 1.38 (1.12–1.70) for leukocyte count, 1.17 (0.94–1.46) for CRP, and 1.13 (0.91–1.40) for ESR.

CONCLUSIONS—Of the four inflammatory markers simultaneously assessed in our elderly population, only C3 was strongly associated with insulin resistance, independently of the components of the metabolic syndrome and the main indexes of abdominal and general obesity.


  • Published ahead of print at on 26 June 2007. DOI: 10.2337/dc07-0637.

    Additional information for this article can be found in an online appendix at

    A table elsewhere in this issue shows conventional and Système International (SI) units and conversion factors for many substances.

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    • Accepted June 11, 2007.
    • Received April 2, 2007.
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  1. Diabetes Care vol. 30 no. 9 2362-2368
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