[The role of tumor necrosis factor alpha and leptin in obesity and insulin resistance].
OBJECTIVE
To investigate the effect of TNFalpha and leptin in obesity and insulin resistance.


METHODS
84 patients of type 2 diabetes mellitus and 84 nondiabetic persons were included in this study. Those two groups were further divided into subgroups according to their body mass index (BMI). TNF alpha, leptin, lipid level, fasting and postprandial blood glucose and immunoreactive insulin (IRI) were measured. Blood pressure, body height, body weight and the circumferences of waist and hip were also documented.


RESULTS
The levels of TNFalpha and leptin were significantly higher in the obese than those in non-obese subjects. Serum leptin level in women was 2 times higher than that in men. Pearson correlation analysis showed that TNFalpha was positively correlated to HOMA-IR, waist-to-hip ratio (WHR) and fasting IRI (r = 0.43, 0.53 and 0.59, respectively, P < 0.01), and negatively correlated to high-density lipoprotein cholesterol (r = -0.35, P < 0.01). Leptin was positively correlated to HOMA-IR and fasting IRI (r = 0.31, 0.29, P < 0.05), while leptin level in men was significantly correlated to WHR. There was also a positive correlation between TNFalpha and leptin (r = 0.29, P < 0.05). Multiple stepwise regression analysis demonstrated that HOMA-IR was most closely correlated with TNFalpha, with leptin the next. Serum TNFalpha was also positively correlated to fasting blood glucose.


CONCLUSIONS
Serum levels of TNFalpha and leptin in obese subjects are closely related with insulin resistance, indicating that high level of TNFalpha may promote release of leptin for the modulation of adipocyte. The synergistic effect of TNFalpha and leptin may induce insulin secretion, which in turn leads to insulin resistance.
Sun
Qi
Q
Department of Endocrinology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing 100730, China. sunqi@pumch.ac.cn
Yang
Guo-hua
GH
Wang
Heng
H
D001786:Blood Glucose / Q000032:analysis; D015992:Body Mass Index; D003924:Diabetes Mellitus, Type 2 / Q000097:blood / Q000503:physiopathology; D005260:Female; D006801:Humans; D007328:Insulin / Q000097:blood; D007333:Insulin Resistance / Q000502:physiology*; D020738:Leptin / Q000502:physiology*; D008055:Lipids / Q000097:blood; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000097:blood / Q000503:physiopathology*; D014409:Tumor Necrosis Factor-alpha / Q000502:physiology*
D001786:Blood Glucose; D007328:Insulin; D020738:Leptin; D008055:Lipids; D014409:Tumor Necrosis Factor-alpha