title: The effects of metformin and diet on plasma testosterone and leptin levels in obese men.
abstract: OBJECTIVE
  The aim of this study was to investigate the effects of combined hypocaloric diet and metformin on circulating testosterone and leptin levels in obese men with or without type 2 diabetes.
  
  
  METHODS
  Twenty obese men with type 2 diabetes (mean body mass index [BMI]: 35.5 +/- 1.1 kg/m(2)) and 20 nondiabetic obese men were enrolled in the study. We measured serum follicle-stimulating hormone, luteinizing hormone (LH), total testosterone (TT), free testosterone (FT), sex-hormone-binding globulin (SHBG), dehydroepiandrosterone sulfate (DHEAS), and plasma leptin levels before and 3 months after metformin treatment. Both groups were placed on a hypocaloric diet and 850 mg of metformin taken orally twice daily for 3 months.
  
  
  RESULTS
  Metformin and hypocaloric diets led to decreases in BMI and waist and hip circumferences in both groups. A significant decrease in TT levels in the diabetic group and FT levels in the control group was found, whereas follicle-stimulating hormone, LH, and DHEAS levels were not changed significantly. A significant increase in SHBG levels was observed in the control group but not in the patient group. Leptin levels also decreased after treatment in both groups. Decreased testosterone levels were not correlated to changes in waist and hip circumference, waist-to-hip ratio, BMI, and levels of fasting blood glucose, leptin, SHBG, or DHEAS in the diabetic group. However, a decrease in FT was correlated to changes in the levels of SHBG (r = -0.71, p = 0.001) and LH (r = 0.80, p = 0.001) but not to other parameters.
  
  
  CONCLUSIONS
  We conclude that metformin treatment combined with a hypocaloric diet leads to reduced FT levels in obese nondiabetic men and to reduced TT levels in obese men with type 2 diabetes. Increased SHBG levels may account for the decrease in FT levels in the former group.
authors.affiliation: Department of Endocrinology and Metabolism, Gulhane School of Medicine, Etlik-Ankara, Turkey. mozata@obs.gata.edu.tr
authors.forename: M
authors.initials: M
authors.lastname: Ozata
authors.forename: C
authors.initials: C
authors.lastname: Oktenli
authors.forename: N
authors.initials: N
authors.lastname: Bingol
authors.forename: I C
authors.initials: IC
authors.lastname: Ozdemir
mesh_terms: D000328:Adult; D001824:Body Constitution; D015992:Body Mass Index; D019314:Dehydroepiandrosterone Sulfate / Q000097:blood; D003920:Diabetes Mellitus / Q000097:blood / Q000628:therapy; D003924:Diabetes Mellitus, Type 2 / Q000097:blood / Q000628:therapy; D004038:Diet, Reducing; D002149:Energy Intake; D005260:Female; D005640:Follicle Stimulating Hormone / Q000097:blood; D006801:Humans; D007004:Hypoglycemic Agents / Q000494:pharmacology* / Q000627:therapeutic use; D020738:Leptin / Q000378:metabolism*; D007986:Luteinizing Hormone / Q000097:blood; D008297:Male; D008687:Metformin / Q000494:pharmacology* / Q000627:therapeutic use; D008875:Middle Aged; D009765:Obesity / Q000097:blood* / Q000628:therapy; D012738:Sex Hormone-Binding Globulin / Q000032:analysis; D013739:Testosterone / Q000097:blood*
chemical_list: D007004:Hypoglycemic Agents; D020738:Leptin; D012738:Sex Hormone-Binding Globulin; D013739:Testosterone; D019314:Dehydroepiandrosterone Sulfate; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone; D008687:Metformin