Correlation of serum vitamin D and glycosylated hemoglobin levels with thyroid function in type 2 diabetes mellitus

Abstract

Two hundred and seventy two type 2 diabetes mellitus (T2DM) patients with negative anti-thyroid autoantibody were enrolled in Shanxi Provincial People′s Hospital from November 2016 to September 2017. According to serum vitamin D levels, patients were classified as serious deficiency of vitamin D group([25(OH)D]<25 nmol/L, n=119), vitamin D deficiency group (≥25~<50 nmol/L, n=124) and normal vitamin D group (≥ 50 nmol/L, n=29) . There were significant differences in total T4(P=0.04), TSH (P<0.01), parathyroid hormone (P=0.03) among these groups (P<0.05). After adjusting gender, age, BMI, glycosylated hemoglobin (HbA1c) and duration of diabetes, serum 25(OH)D level was negatively correlated with TSH (r=-0.24, P<0.05). After adjusting gender, age, BMI, duration of diabetes and serum 25(OH)D level, HbA1c level was negatively correlated with free T3 (r=-0.18, P<0.01) and TSH (r=-0.20, P<0.01). Multiple linear regression analysis revealed that TSH was correlated with 25(OH) D (β=-0.224, P<0.01) and HbA1c (β=-0.206, P<0.01). In conclusion, the serum vitamin D and HbA1c levels are independently correlated with thyroid function in patients with T2DM. Key words: Diabetes mellitus, type 2; Vitamin D; Hemoglobin A, glycosylated; Thyroid function