Sex hormone-binding globulin and insulin-like growth factor-binding protein-1 as indicators of metabolic syndrome, cardiovascular risk, and mortality in elderly men.

Two binding proteins, SHBG and IGF-binding protein-1 (IGFBP-1), are both down-regulated by insulin and therefore could serve as potential indicators of the metabolic syndrome and hyperinsulinemia-related cardiovascular risk. We compared serum SHBG and IGFBP-1 as potential markers of abnormal glucose tolerance, the metabolic syndrome, diabetes mellitus, cardiovascular risk factors, and total, cardiovascular, and coronary heart disease mortality in elderly men. Of the original cohort of 1711 men, 524 were alive on January 1, 1989, and 413 participated in the 30-yr examination, of whom 335 men, aged 70-89 yr, formed the study group for the present analysis. Low SHBG and IGFBP-1 were both associated with an increased prevalence of abnormal glucose tolerance and the metabolic syndrome, but only SHBG was associated with diabetes mellitus. SHBG was less influenced by body mass index than IGFBP-1. Low SHBG indicated increased cardiovascular and coronary disease mortality; the association remained after adjustment for abnormal glucose tolerance, but not after adjustment for prevalent cardiovascular disease. IGFBP-1 had no association with mortality. It is concluded that low SHBG is a better indicator of increased cardiovascular mortality than low or high IGFBP-1.