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The negative association between plasma ghrelin and IGF-I is modified by obesity, insulin resistance and type 2 diabetes.

Pöykkö SM, Ukkola O, Kauma H, Kellokoski E, Hörkkö S, Kesäniemi YA

Department of Internal Medicine, University of Oulu, P.O. Box 5000, 90014 Oulu, Finland. seppo.poykko@ppshp.fi

AIMS/HYPOTHESIS: Ghrelin is a natural growth hormone-releasing peptide thought to be involved in the regulation of energy metabolism. The recent studies concerning the association between ghrelin and insulin-like growth factor-I (IGF-I) concentrations have shown either negative correlation or no correlation at all. The aims of this study were to clarify the association between ghrelin and IGF-I concentrations in a large cohort and to characterize whether obesity, insulin resistance and type 2 diabetes affect this association. METHODS: We analysed fasting plasma ghrelin and IGF-I concentrations of 1,004 middle-aged subjects of the population-based OPERA study. Insulin resistance was estimated using QUICKI. RESULTS: IGF-I concentrations were negatively associated with ghrelin concentrations in the analysis of all subjects before (beta=-0.32, p<0.001) and after adjustments for BMI, insulin levels, sex and age (beta=-0.40, p<0.001). The association was particularly strong in males and in the higher BMI tertiles. The degree of association varied in relation to the glycaemic status: no insulin resistance: r(2)=6.5% (p<0.001), insulin resistance without type 2 diabetes: r(2)=21.0% (p<0.001), type 2 diabetes: r(2)=25.4 (p<0.001). IGF-I levels explained larger proportion (r(2)=9.8%) of the variation in ghrelin concentrations compared to fasting insulin concentration (r(2)=3.0%) and BMI (r(2)=1.5%). CONCLUSIONS/INTERPRETATION: There is a negative and independent association between ghrelin and IGF-I concentrations in middle-aged subjects. The interaction between IGF-I and ghrelin is modified by obesity, IR and type 2 diabetes. Further studies are warranted to elucidate the role of ghrelin in the development of these states.

Published 7 March 2005 in Diabetologia, 48(2): 309-16.
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