RESEARCH - Inflammation-associated insulin resistance: differential effects in RA and SLE define potential mechanisms

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Arthritis Rheum. 2008 Jun 24;58(7):2105-2112.

Inflammation-associated insulin resistance: Differential effects in

rheumatoid arthritis and systemic lupus erythematosus define potential

mechanisms.

Chung CP, Oeser A, Solus JF, Gebretsadik T, Shintani A, Avalos I,

Sokka T, Theodore Pincus PR, Stein CM.

Vanderbilt University School of Medicine, Nashville, Tennessee.

OBJECTIVE: Insulin resistance is increased by inflammation, but the

mechanisms are unclear. The present study was undertaken to test the

hypothesis that decreased insulin sensitivity is differentially

associated with mediators of inflammation by studying 2 chronic

inflammatory diseases of different pathogenesis, systemic lupus

erythematosus (SLE) and rheumatoid arthritis (RA). METHODS: We

measured fasting insulin, glucose, and lipid levels, erythrocyte

sedimentation rate (ESR), C-reactive protein (CRP), interleukin-6

(IL-6), tumor necrosis factor alpha (TNFalpha), and coronary artery

calcification in 103 patients with SLE and in 124 patients with RA.

Insulin sensitivity was measured using the homeostasis model

assessment (HOMA) index. RESULTS: The HOMA value was higher in RA

patients (median 2.05 [interquartile range (IQR) 1.05-3.54]) than in

SLE patients (1.40 [0.78-2.59]) (P = 0.007). CRP and ESR did not

differ significantly in RA and SLE patients. Body mass index (BMI) was

significantly correlated with the HOMA index in both RA (rho = 0.20)

and SLE (rho = 0.54), independently of age, sex, race, and current use

of corticosteroids. In RA patients, the HOMA index was also

significantly positively correlated with IL-6 (rho = 0.63), TNFalpha

(rho = 0.50), CRP (rho = 0.29), ESR (rho = 0.26), coronary

calcification (rho = 0.26), and Disease Activity Score in 28 joints

(rho = 0.21); associations adjusted for age, sex, race, BMI, and

current use of corticosteroids remained significant (P < 0.05). In SLE

patients, the HOMA index was also significantly correlated with ESR

(rho = 0.35) and CRP (rho = 0.25), but not with other variables. The

association between the ESR and the HOMA value in patients with SLE

remained significant after adjustment for confounding covariates (P =

0.008). In multivariable models, the major contributing factors to the

HOMA index were the BMI in SLE patients, and IL-6 and TNFalpha levels

in RA patients.

CONCLUSION: The pathogenesis of insulin resistance and its

contribution to atherogenesis varies in different inflammatory

settings.

PMID: 18576352

http://www.ncbi.nlm.nih.gov/pubmed/18576352

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