PLASMA LEPTIN CONCENTRATIONS - GENDER DIFFERENCES AND ASSOCIATIONS WITH METABOLIC RISK-FACTORS FOR CARDIOVASCULAR-DISEASE

The cloning of the obese gene and the characterization of its protein product, leptin, has permitted the study of a new hormone potentially involved in the regulation of adipose tissue mass. The present study e xamined the gender differences in fasting plasma leptin concentration and its relationship to body fatness, adipose tissue distribution and the metabolic profile in samples of 91 men (mean age +/- SD: 37.3 +/- 4.8 years) and 48 women (38.5 +/- 6.8 years). Plasma leptin concentrat ions were strongly associated with body fat mass measured by underwate r weighing [men: r = 0.80, p < 0.0001; women: r = 0.85, p < 0.0001]. I n both genders, plasma leptin levels were also strongly correlated wit h waist girth as well as cross-sectional areas of abdominal subcutaneo us and visceral adipose tissue measured by computed tomography. Women had, on average, plasma leptin concentrations that were three times hi gher than men. Furthermore, this gender difference remained significan t when comparing men and women matched for similar levels of body fat mass. The associations between plasma leptin and lipoprotein concentra tions were dependent of adiposity. In both men and women, elevated fas ting plasma leptin levels were associated with higher plasma insulin c oncentrations, but only in women was the association maintained after correction for fat mass. Thus, results of the present study show that women have higher plasma leptin levels compared to men, independent of the concomitant variation in total body fat mass. Furthermore, our re sults also suggest that, in women, the association between plasma lept in and insulin concentrations is independent of adiposity, a finding w hich provides further support to the observation that adipose tissue l eptin secretion may be upregulated by insulin.