title: Metformin Decreases Thyroid Volume and Nodule Size in Subjects with Insulin Resistance: A Preliminary Study.
abstract: OBJECTIVE
  The aim of this study was to investigate the effects of metformin on thyroid volume and nodule size.
  
  
  METHODS
  Prospective data were gathered on 100 newly diagnosed subjects with insulin resistance (68 female, 32 male) between August 2008 and May 2010. Each subject followed a standard diet and exercise program, and received 1,700 mg/day of metformin therapy for 6 months. The height, weight, waist circumference (WC) and thyroid hormone levels of each subject were measured. Additionally, the dimensions of the thyroid lobes and maximum diameter of each thyroid nodule were determined by ultrasonography. BMI and thyroid volumes were also calculated. Insulin resistance was estimated by homeostasis model assessment. All these parameters were measured at the beginning and at the end of the treatment period.
  
  
  RESULTS
  BMI and WC decreased significantly after metformin therapy (34.5 ± 5.1 vs. 32.7 ± 4.8, p < 0.0001, and 106.3 ± 11.8 vs. 101.8 ± 19.0 cm, p = 0.008, respectively). Insulin resistance also decreased after metformin therapy (4.5 ± 1.9 vs. 2.9 ± 1.7, p < 0.0001). The mean thyroid volume (22.5 ± 11.2 vs. 20.3 ± 10.4 ml, p < 0.0001) and mean thyroid nodule size (12.9 ± 7.6 vs. 11.7 ± 7.2 mm, p < 0.0001) also decreased after treatment.
  
  
  CONCLUSIONS
  In subjects with insulin resistance, metformin therapy significantly decreased thyroid volume and nodule size.
authors.affiliation: Department of Endocrinology and Metabolism, Baskent University Faculty of Medicine, Ankara, Turkey.
authors.forename: Cuneyd
authors.initials: C
authors.lastname: Anil
authors.forename: Altug
authors.initials: A
authors.lastname: Kut
authors.forename: Berna
authors.initials: B
authors.lastname: Atesagaoglu
authors.forename: Asli
authors.initials: A
authors.lastname: Nar
authors.forename: Neslihan
authors.initials: N
authors.lastname: Bascil Tutuncu
authors.forename: Alptekin
authors.initials: A
authors.lastname: Gursoy
mesh_terms: D000328:Adult; D000368:Aged; D015992:Body Mass Index; D001837:Body Weights and Measures; D004032:Diet; D015444:Exercise; D006801:Humans; D007004:Hypoglycemic Agents / Q000627:therapeutic use*; D007333:Insulin Resistance; D008297:Male; D008687:Metformin / Q000627:therapeutic use*; D008875:Middle Aged; D011446:Prospective Studies; D013961:Thyroid Gland / Q000000981:diagnostic imaging / Q000187:drug effects*; D013963:Thyroid Hormones / Q000097:blood; D016606:Thyroid Nodule / Q000000981:diagnostic imaging / Q000188:drug therapy*; D055815:Young Adult
chemical_list: D007004:Hypoglycemic Agents; D013963:Thyroid Hormones; D008687:Metformin