Correlation between serum thyroid hormones and lipid profile in type 2 diabetes mellitus patients

AIM To evaluate the correlation between serum thyroid hormones and lipid profile in type 2 diabetes mellitus patients.METHODS A total of 478 diabetic patients aged from 20 to 87 years and hospitalized from January 2008 to October 2009,were enrolled in this study.The blood pressure and body mass index were recorded.The total cholesterol(TC),triglycerides,high density lipoprotein cholesterol(HDL-C),low density lipoprotein cholesterol(LDL-C),glycosylated hemoglobin A_(1c)(HbA_(1c)),free tri-iodothyronine(FT_3),free thyroxine(FT_4),and thyroid stimulating hormone(TSH)were measured in each patient.The patients were categorized by thyroid function and TSH level.Variance analysis,t test and multiple stepwise regression were used for data analysis.RESULTS In this study cohort,110 patients had hypothyroidism(23.0%)and 168 patients had subclinical hypothyroidism(35.2%).The mean age of female was significantly lower than that of male(P0.05).However,female patients had higher level of FT_4,TC and HDL-C than male patients(P0.05).TC and LDL-C levels of the control group were significantly lower than those of hypothyroidism and subclinical hypothyroidism group(P0.01),but there was no significant difference between the hypothyroidism and subclinical hypothyroidism group(P0.05).TC and LDL-C levels increased with TSH level.TC and LDL-C showed negative correlations with FT_3(r=-0.134,-0.112,P0.05),positive correlations with TSH(r=0.195, 0.247,P0.05)and HbA_(1c)(r=0.298,0.308,P0.01).HbA_(1c),FT_3,TSH and LDL-C were independent risk factors for TC according to multiple stepwise regression analysis.FT_3,TSH and TC were independent risk factors for LDL-C.CONCLUSION FT_3 and TSH influence the levels of TC and LDL-C in type 2 diabetic patients,regardless of glycemic control.