Evaluation of the Thyroid Characteristics and Correlated Factors in Hospitalized Patients with Newly Diagnosed Type 2 Diabetes

Yanli Li,1,* Min Yi,1,* Xiaoyi Deng,1 Wangen Li,1 Yimei Chen,2 Xiaodan Zhang1 1Department of Endocrinology, The Second Affiliated Hospital of Guangzhou Medical University, Guangzhou, People’s Republic of China; 2Health Examination Department, The Second Affiliated Hospital of Guangzhou Medical University, Guangzhou, People’s Republic of China*These authors contributed equally to this workCorrespondence: Xiaodan Zhang, Department of Endocrinology, The Second Affiliated Hospital of Guangzhou Medical University, 250 East Changgang Road, Haizhu District, Guangzhou, 510260, People’s Republic of China, Email sysuzhangxd@163.comBackground: Diabetes mellitus (DM) and thyroid dysfunction (TD) are two closely associated disorders. The objective of the present study was to investigate the thyroid status and the relationships between thyroid hormones, diabetic complications and metabolic parameters in hospitalized patients with newly diagnosed type 2 DM (T2DM).Methods: This was an observational cross-sectional study, conducting on 340 patients with newly diagnosed T2DM who were admitted to ward of endocrinology department and 120 matched individuals without diabetes. Anthropometric, clinical and biochemical data were collected. Spearman correlation coefficients were calculated to evaluate the correlations between thyroid hormones and other variables. Factors associated with diabetic nephropathy (DN) was analyzed with multivariate logistic regression.Results: Levels of free triiodothyronine (FT3), free thyroxine (FT4) and thyroid stimulating hormone (TSH) were significantly lower in patients with T2DM as compared to control group without diabetes. The prevalence of TD was 21.2% in patients with diabetes, higher than that in controls (4.2%). The low T3 syndrome was the most frequent TD, shown in 14.7% of patients. The presence of diabetic complications DN, diabetic ketosis or ketoacidosis), metabolic and demographic factors, including age, glycemic control and insulin resistance were factors significantly associated with levels of thyroid hormones. FT3 level was inversely correlated with the level of urinary total protein (mg/24h) and the presence of DN. Multivariate analysis indicated low FT3 level as a strong independent risk factor (OR = 0.364, P = 0.001) for DN.Conclusion: TD is not rarely seen in hospitalized patients with newly diagnosed T2DM. Diabetic complications and diabetes-related metabolic and demographic factors are related to thyroid hormone levels. Decreased FT3 is strongly correlated with the presence of DN.Keywords: type 2 diabetes mellitus, thyroid dysfunction, thyroid hormones, diabetic complication, diabetic nephropathy