title: The influence of body mass index and low-grade systemic inflammation on thyroid hormone abnormalities in patients with type 2 diabetes.
abstract: Previous reports highlight the role of systemic inflammation in the genesis of non-thyroidal illness syndrome and type 2 diabetes mellitus (T2DM). Our objective was to assess whether body mass index and the low-grade systemic inflammation would be associated with changes in thyroid hormone metabolism in patients with type 2 diabetes. This was a cross-sectional study of 104 subjects; 52 patients with type 2 diabetes and 52 in a control group, paired by age, gender and body mass index. We measured total (T) and free (F) thyroxine (T4) and triiodothyronine (T3), reverse T3 (rT3), the ratios FT3/rT3, FT3/FT4 and FT4/rT3, clinical parameters (age, gender, diabetes duration and complications, body mass index, waist circumference, hypertension, HbA1c), and high sensitivity C-reactive protein. Patients with DM presented lower levels of TT4 (p=0.006), TT3 (p<0.001) and FT3 (p<0.001) and higher of FT4 (p<0.001), waist circumference (p=0.047) and C-reactive protein (p<0.001). Body mass index was inversely correlated with FT4 (p=0.036) and TT3 (p=0.008). C-reactive protein was positively correlated with rT3 (p=0.001) and inversely with FT4/rT3 (p<0.001) and FT3/rT3 (p=0.014). Body mass index was an independent predictor for FT4 (B=-0.011, p=0.029) and TT3 levels (B=-1.118, p=0.003). Inflammation predicted the FT4/rT3 ratio (B=-0.190, p<0.001). C-reactive protein (B=0.235, p<0.001) and body mass index (B=-0.008, p=0.047) were independent predictors for rT3. In conclusion, type 2 diabetes was associated with a low T3 state. Body mass index and the low-grade systemic inflammation are related to the non-thyroidal illness syndrome in these patients, possibly by altering the activity of peripheral deiodinases.
authors.affiliation: Endocrinology Division, Clinical Medicine Department, Faculty of Medical Sciences, University of Campinas, Campinas, Brazil.
authors.forename: Arnaldo
authors.initials: A
authors.lastname: Moura Neto
authors.forename: Maria Candida Ribeiro
authors.initials: MC
authors.lastname: Parisi
authors.forename: Marcos Antonio
authors.initials: MA
authors.lastname: Tambascia
authors.forename: Sarah Monte
authors.initials: SM
authors.lastname: Alegre
authors.forename: Elizabeth Joao
authors.initials: EJ
authors.lastname: Pavin
authors.forename: Denise Engelbrecht
authors.initials: DE
authors.lastname: Zantut-Wittmann
mesh_terms: D015992:Body Mass Index; D002097:C-Reactive Protein / Q000032:analysis; D016022:Case-Control Studies; D003430:Cross-Sectional Studies; D003924:Diabetes Mellitus, Type 2 / Q000097:blood* / Q000150:complications* / Q000453:epidemiology / Q000378:metabolism; D005260:Female; D006801:Humans; D007249:Inflammation / Q000150:complications* / Q000453:epidemiology / Q000473:pathology; D008297:Male; D008875:Middle Aged; D012016:Reference Values; D013960:Thyroid Function Tests / Q000592:standards; D013963:Thyroid Hormones / Q000097:blood*
chemical_list: D013963:Thyroid Hormones; D002097:C-Reactive Protein