Relationships between baseline serum leptin levels and 2-year changes in body mass index, blood pressure and metabolic parameters in Japanese male adolescents and middle-aged men

We and others have reported that serum leptin levels are positively correlated with body mass index (BMI), blood pressure and heart rate (HR) in cross-sectional clinical studies. However, only a few longitudinal studies have focused on the relationships between leptin, BMI and blood pressure. The present study was performed to elucidate the relationships between baseline serum leptin levels and 2-year changes in BMI, blood pressure, HR and metabolic parameters in 314 Japanese male adolescents aged 16–17 years and in 225 Japanese men aged 30–63 years. Height, weight, systolic blood pressure (SBP), diastolic blood pressure (DBP), HR, fasting plasma glucose (FPG), serum lipids [total cholesterol (TC), triacylglycerols (TG), high-density-lipoprotein cholesterol (HDL-C) and low-density-lipoprotein cholesterol (LDL-C)], uric acid (UA), insulin and leptin levels were measured in the morning after an overnight fast. In the male adolescents, serum leptin levels in 1996 (log[leptin'96]) were significantly correlated with BMI, SBP, mean blood pressure and HR in 1998 (r = 0.40, 0.13, 0.11 and 0.14, respectively). The percentage change in BMI per year (ΔBMI) was negatively correlated with log[leptin'96], even after adjustment for baseline BMI (r =-0.12, P = 0.030). In men aged 30–63 years, log[leptin'96] was also positively correlated with BMI'98, SBP'98, DBP'98, FPG'98, TC'98, log[TG'98], LDL-C'98 and UA'98 (all P < 0.05), and negatively correlated with HDL-C'98, ΔBMI, ΔFPG, ΔTC and ΔLDL-C. The relationship between log[leptin'96] and ΔTC was significant, even after adjustment for initial BMI (r =-0.15, P = 0.023). These findings therefore suggest that serum leptin levels are correlated with subsequent decreases in BMI and TC in Japanese men.