Ghrelin and leptin levels in obese adolescents. Relationship with body fat and insulin resistance.

OBJECTIVE Ghrelin and leptin levels are influenced by body fat (BF%), pubertal stage and possibly insulin resistance (IR). The aim of our study was: 1) To compare fasting ghrelin and leptin levels between obese and non-obese, adolescents, 2) to investigate possible correlations of these hormones with BF %, as well as IR. DESIGN Twenty obese insulin resistant (IR) adolescents, twenty obese non IR (NIR) and fifteen healthy non-obese, age-matched adolescents were studied. In all participants, height, weight, body mass index (BMI) and BF % were measured. Fasting glucose, insulin, ghrelin and leptin levels were determined. IR was assessed using HOMA-IR index. RESULTS BMI, BF %, insulin and HOMA-IR values were positively correlated with leptin and negatively with ghrelin levels. A negative correlation between circulating leptin and ghrelin levels was found. A suggestive positive correlation between leptin levels and BF %, independent of BMI, was also observed (P=0.075). Ghrelin levels were significantly correlated with insulin levels and HOMA-IR, independent of BMI (P=0.077). CONCLUSIONS Obesity and IR may play an important role in the release of ghrelin as well as in the negative correlation between ghrelin and leptin.