Association between thyroid hormones and diabetic complications in patients with newly diagnosed type 2 diabetes: A cross-sectional study

Abstract

Background Diabetes mellitus (DM) and thyroid dysfunction (TD) are two closely associated disorders. The coexistence of TD could adversely influence metabolic control and even increase the long-term mortality in patients with DM. The objective of the present study was to investigate the thyroid status and the relationship between thyroid hormones, diabetic complications and metabolic parameters in patients with newly diagnosed type 2 DM (T2DM). Methods This is an observational cross-sectional study, conducting on 340 patients with newly diagnosed T2DM who were admitted to ward of endocrinology department and 120 matched nondiabetic subjects. Clinical characteristics were collected and laboratory measurements were conducted. Results Levels of free T3 (FT3), free T4 (FT4) and TSH were significantly lower in patients with T2DM as compared to nondiabetic subjects. The prevalence of TD was 21.2% in patients with diabetes, higher than that of controls (4.2%). The low T3 syndrome was the most frequent TD, shown in 14.7% of patients. The presence of diabetic complications (diabetic nephropathy (DN), diabetic ketosis), metabolic and demographic factors, including age, glycemic control and insulin resistance were factors 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. Conclusions TD is not rarely seen in patients with newly diagnosed T2DM. Diabetic complications and diabetes-related metabolic and demographic factors are related to TD. Decreased FT3 is strongly correlated with the presence of DN.