Correlation between subclinical hypothyroidism and renal function in patients with diabetes mellitus

To evaluate the incidence of and risk factors for subclinical hypothyroidism (SCH) in patients with type 2 diabetes mellitus (T2D), and determine the association of SCH with renal function.

T2D patients hospitalized between June 2007 and July 2008 were cross-section ally assessed. Clinical indicators and renal function were compared between the SCH and normal thyroid function groups. Risk factors for SCH and diabetic renal injury (albuminuria) were evaluated by univariate and multivariate analyses.

Subclinical hypothyroidism prevalence was significantly higher in women, with a male to female ratio of 1:2.7. Age (62.56 ± 10.79 vs. 59.09 ± 10.82 years, P = 0.008), systolic blood pressure (138.80 ± 18.85 vs. 131.29 ± 16.97, P = 0.000), TC (5.22 ± 1.20 vs. 4.83 ± 1.03 mmol/L; P = 0.008), LDL-C (3.35 ± 0.96 vs. 3.06 ± 0.87 mmol/L; P = 0.007), creatinine (84.54 ± 47.05 vs. 74.49 ± 29.96 µmol/L; P = 0.01), urinary albumin excretion rate [18.6 (7.58-326.78) vs. 10.69 (5.79-40.8) µg/min; P = 0.001], and thyrotropin [4.92 (4.37-6.27) vs. 1.4 (0.92-2.09) μIU/mL; P = 0.000] were significantly higher in the SCH group; meanwhile, TBIL (12.05 ± 5.20 vs. 13.98 ± 5.32 µmol/L; P = 0.008), DBIL (2.54 ± 1.20 vs. 2.88 ± 1.17 µmol/L; P = 0.033), IDBIL (9.51 ± 4.62 vs. 11.10 ± 4.72 µmol/L; P = 0.013), and total glomerular filtration rate [46.96 (35-68.26) vs. 71.74 (50.13-83.36) mL/min; P = 0.000] were significantly lower in SCH patients. Macroalbuminuria prevalence was significantly higher in the SCH group (18.2 vs. 11.4%; P < 0.001). Interestingly, SBP (OR = 1.050; 95%CI 1.034-1.066; P = 0.000), DR (OR = 5.248; 95%CI 2.816-9.777; P = 0.000), SCH (OR = 2.256; 95%CI 1.184-4.299; P = 0.013), and TC (OR = 1.389; 95%CI 1.108-1.742; P = 0.004) were found to be independent risk factors for macroalbuminuria.

These findings demonstrate an association of SCH with renal injury in diabetic patients.