We measured plasma
sex hormone-binding globulin (SHBG),
corticosteroid-binding globulin (
CBG), and total
cortisol, and calculated free plasma
cortisol in 1 137 subjects attending a hospital outpatient
lipid disorders clinic to investigate whether or not these analytes correlated with the degree of
insulin resistance and the presence of the
metabolic syndrome. In both males and females, plasma SHBG correlated inversely with anthropometric measures and with fasting
glucose,
insulin,
insulin resistance, and
triglycerides, and positively with
HDL-cholesterol. However, in males with the
metabolic syndrome, unlike females, the relationship between SHBG, some anthropometric measures, fasting
glucose,
insulin, and
HDL-cholesterol were lost, which suggests that in males SHBG may not co-cluster with other components of the
metabolic syndrome. In males and males with the
metabolic syndrome, total plasma
cortisol and calculated plasma free
cortisol correlated positively with fasting
glucose.
Corticosteroid-binding globulin correlated inversely with percentage body fat and positively with
HDL-cholesterol in males with and without the
metabolic syndrome.
CBG correlated negatively with age in both sexes. Overall, the results confirm the finding that SHBG is a marker of
insulin resistance in males and females and that SHBG is associated with fasting
triglycerides in males with the
metabolic syndrome. Importantly, SHBG could be considered a stronger component of the
metabolic syndrome in females than in males. However, the aetiological role of
CBG and
cortisol in
insulin resistance is uncertain, although in males,
cortisol and
CBG could be subtly related to the degree of
insulin resistance.