Association between Subclinical Hypothyroidism and Albuminuria in Patients with Type 2 Diabetes Mellitus: A Cross Sectional Study in Iran

Introduction: Studies have shown the association between subclinical hypothyroidism and type 2 diabetes. However, the common complications of type 2 diabetes, such as diabetic nephropathy and albuminuria with subclinical hypothyroidism, are not fully clear yet. This study thus aimed to determine the association between subclinical hypothyroidism and albuminuria in patients with type 2 diabetes mellitus. Methods: This was a cross-sectional study, of 140 individuals diagnosed with type 2 diabetes mellitus (DM) admitted to the internal clinics of Kosar Hospital in Semnan, Iran in 2017-2018. The participants were selected, and were compared based on having 2 TSH levels above normal (>4.2 mIU/L) 3 months apart, as well as patients were divided to two groups including, subclinical hypothyroidism group (n=40) and euthyroid group (n=100) based on demographic information, laboratory information and indicators such as albuminuria, and urinary albumin-to-creatinine ratio (UACR). Findings: The mean and standard deviation of UACR in patients with subclinical hypothyroidism were significantly higher than those of euthyroid patients (46.09 ± 27 9.27 vs. 3.94 ± 0.24 and P = 0.015, respectively). In patients with subclinical hypothyroidism, there was a statistically significant and direct relationship between UACR values with primary TSH level (r = 0.555, P< 0.001) and UACR values with secondary TSH level (r = 0.563, P< 0.001). Conclusion: Among type 2 DM patients, the rate of albuminuria in subclinical hypothyroidism group was significantly higher than that of euthyroid patients and with increasing initial and recurrent TSH levels, UACR values and consequently albuminuria increased.