Changes in thyroid volume and function after treatment in patients with newly diagnosed type 2 diabetes mellitus

Objective: It has been shown that thyroid volume increases and there is a higher nodule prevalence in patients with impaired glucose metabolism. There are studies showing serum TSH level, thyroid gland volume, nodule diameter and presence of nodules decrease after treatment of diabetes mellitus. The aim of this study was to demonstrate the effect of treatment on thyroid function, thyroid volume and presence of nodules in patients with newly diagnosed and treated type 2 diabetes mellitus. Patients who received metformin were included in our study to obtain a more homogeneous group. Material and Method: Recording of age, sex, fasting plasma glucose, HbA1c, body mass index, additional diseases, drugs used, complete blood count, serum creatinine, AST, ALT and metformin dose; at the beginning and 6 months later serum TSH, fT4, fT3, Anti-TPO, Anti-Tg was planned to be monitored in euthyroid and hypothyroid newly diagnosed diabetes mellitus type 2 patients who started to receive treatment in our internal medicine outpatient clinics. Thyroid volume, presence of nodules, maximum nodule diameter, and presence of multinodularity were evaluated by thyroid ultrasonography. Exclusion criteria were drug use which may affect serum TSH level such as oral contraceptive use, chronic renal disease, chronic liver disease, sepsis, pregnancy and Type 1 diabetes mellitus. Results: One hundred and one patients with type 2 diabetes mellitus (37 males, 64 females) were included in the study. The mean age of the patients was 53.02 ± 11.9 years. The mean of body mass index of the patients was 29,60 ± 3,9 kg/m2 and 52 (52%) patients were classified as obese. The body weight, body mass index, serum TSH, ALT and anti-TPO level and thyroid volume were significantly decreased in the baseline and 6th month evaluation (p values, p = 0,000; p = 0,000; p = 0,011; p = 0,000; 0.022; p = 0.000). Anti-Tg, fT4, fT3 and the number of thyroid nodules did not differ significantly (p values; p = 0.086; p = 0.593; p = 0.380, respectively). The number of nodules and multinodularity of the patients did not change significantly. Anti-TPO levels were significantly decreased in both patients with obesity and non-obese groups at the end of 6 months (p values; p = 0.003; p = 0.009, respectively). Serum TSH level was statistically reduced in non-obese subjects (p = 0.004) and thyroid volume was statistically decreased (p = 0.000) in patients with obesity only. Conclusion: The results show that metformin treatment significantly reduced body weight, body mass index, thyroid volume and serum TSH, ALT, and Anti-TPO levels in newly diagnosed type 2 diabetes mellitus patients. In addition, serum TSH levels were significantly reduced in non-obese patients and thyroid volume reduced in obese patients. Keywords: Type 2 Diabetes Mellitus, Metformin, TSH, thyroid volume, thyroid nodule