[The changes in plasma leptin, insulin and proinsulin levels in obese adolescents]

To investigate the metabolic changes in obese adolescents and the relationship between obese adolescents and metabolic syndrome.

198 obese adolescents [body mass index (BMI) >/= 25 kg/m(2)] and 78 normal adolescents (BMI 18.5 approximately 23.0 kg/m(2)) were chosen from 2 217 middle school students of 14 approximately 16 years. The levels of serum leptin, insulin, proinsulin, glucose and lipids of these adolescents were measured and compared.

(1) There was significant gender difference of serum leptin levels in adolescents of 14 approximately 16 years. The level of serum leptin was higher in female than that in male [(18.53 +/- 1.41) microgram/L vs (6.33 +/- 1.79) microgram/L]. (2) The levels of serum leptin, insulin and proinsulin of obese adolescents were significantly higher than those of normal adolescents [(19.94 +/- 1.91) microgram/L vs (11.27 +/- 2.04) microgram/L, (15.34 +/- 1.66) microIU/L vs (13.17 +/- 1.43) microIU/L and (16.19 +/- 1.64) pmol/L vs (11.79 +/- 1.70) pmol/L respectively]. (3) The levels of blood glucose and triglyceride of obese adolescents were significantly higher than those of normal adolescents [(4.63 +/- 0.50) mmol/L vs (4.13 +/- 0.33) mmol/L and (1.20 +/- 0.56) mmol/L vs (0.90 +/- 0.32) mmol/L respectively], but the levels of serum high-density lipoprotein cholesterol (HDL-C) of obese adolescents were significantly lower than those of normal adolescents [(1.14 +/- 0.24) mmol/L vs (1.38 +/- 0.26) mmol/L].

It is suggested that there are leptin resistance, insulin resistance and potential disorders of blood glucose and lipid metabolism in obese adolescents. Our study indicated that adolescent obesity would be related with early occurrence of type 2 diabetes.