Ghrelin and the metabolic syndrome in older adults

Ghrelin may be one of the pathophysiological mechanisms underlying risk factor clustering observed in the metabolic syndrome, but this has not been investigated.

The objective of this work was to study the association between ghrelin and the metabolic syndrome and identify social and behavioral determinants of ghrelin.

This was a cross-sectional study.

The setting of this work was the Rancho Bernardo Study.

Study subjects included 1513 men and women, aged 51-90 yr in 1984-1987.

Total ghrelin, measured by RIA, and the metabolic syndrome, defined using Adult Treatment Panel III diagnostic criteria, were the outcome measures.

Levels of ghrelin (mean +/- SD) did not differ between the 848 men (1451 +/- 532 pg/ml) and the 665 women (1459 +/- 672 pg/ml) or by age. Education, alcohol intake, and smoking history were each significantly and positively associated with ghrelin in a dose-related manner, independent of body mass index (BMI). Compared with participants with the lowest third of ghrelin levels, the age- and sex-adjusted odds of having the metabolic syndrome were 18% lower in the middle third and 53% lower in the highest third. This corresponds to a 21% decrease per SD increase in ghrelin (odds ratio, 0.79; 95% confidence interval, 0.69, 0.89; P < or = 0.001); this was attenuated to 13% (odds ratio, 0.87; 95% confidence interval, 0.75, 1.01; P = 0.07), after adjustment for BMI. Of the five metabolic syndrome components, only the association between ghrelin and high-density lipoprotein cholesterol was independent of BMI. A significant association independent of BMI was also observed between insulin and ghrelin.

Ghrelin levels are influenced by lifestyle factors. The inverse association between endogenous ghrelin and the metabolic syndrome is largely explained by the strong ghrelin-BMI association.