Correlations Among Glycemia and Glucose Variability, Thyroid Hormones, and Albuminuria in Patients With Type 2 Diabetes Mellitus

Hyperglycemia, glucose fluctuations, and thyroid dysfunction contribute to the progression of diabetic nephropathy. This study aimed to investigate the associations of glycemia, glucose variability, and thyroid hormones with albuminuria in patients with type 2 diabetes mellitus (T2DM). In total, 451 T2DM patients were included. The data of continuous glucose monitoring system (CGMS)-generated indices, thyroid hormones, and the ratios of urine creatinine to urine microalbumin (URCA) were collected. There were 152 patients with normal URCA (< 30 mg/g), 230 patients with microalbuminuria (30 mg/g ≤ UACR < 300 mg/g), and 69 patients with macroalbuminuria (UACR ≥ 300 mg/g). Free triiodothyronine (FT3) was negatively correlated with hemoglobin A1C (HbA1C), glucose, and glucose variability in T2DM patients (most p < 0.05). HbA1C (p = 0.002), the standard deviation (SD) of glucose (p < 0.001), the coefficient of variation (CV) of glucose (p < 0.001), the time below range (TBR) (p = 0.002), and the mean amplitude of glycemic excursions (MAGE) (p = 0.033) were positively associated with albuminuria. Moreover, FT3 was negatively associated with macroalbuminuria (p = 0.003). According to multivariate logistic regression analyses, HbA1C, SD, and CV of glucose, the TBR, and the MAGE were independently associated with a greater risk of albuminuria after adjustment for demographics, duration of T2DM, biochemical indices, and medications for T2DM and hypertension (all p < 0.05). Moreover, the associations of HbA1C, SD, and CV of glucose, TBR, and MAGE with albuminuria were partially mediated by FT3, FT3, and TSH, but the weight of mediation was low. In conclusion, glycemia and glucose variability derived from the CGMS are correlated with a lower level of FT3, and they are positively associated with albuminuria in patients with T2DM.