Evaluation of 25-hydroxy Vitamin DSerum Levels and Thyroid-related Parameters in Patients with Type 2 Diabetes Mellitus and Healthy People in Shiraz, Iran

The prevalence of type 2 diabetes mellitus (T2DM) is increasing globally. There is increasing evidence in the correlation between altered vitamin D levels, thyroid dysfunction, and T2DM. The goal of this study was to evaluate the association between serum 25-hydroxy vitamin D (25(OH)D), lipid profile, glucose and thyroid-related parameters among patients with T2DM and non-diabetic individuals.

This case-control studywas conducted on 228 individuals (110 type two diabetics and 118 healthy controls). The serum concentration of 25(OH) D was determined by chemiluminescence assay. Photometric methods measured serum levels of fasting blood glucose (FBG), calcium, phosphorous, total Cholesterol (TC), triacylglyceride (TG), high-density lipoprotein (HDL). Low-density lipoprotein(LDL) and VLDL levels were estimated from the Friedewaldequation (LDL-C=TC–HDL-C–(TG/5)).The Elisa kit measured serum T4 and TSH.

80% of Patients with T2DM and 71% of healthy individuals were suffering from vitamin D insufficiency. A non-significant relationship between TG (P=0.36), HDL (P=0.33), VLDL (P=0.36), T4 (P=0.56)calcium (P=0.39) and phosphorus (P=0.41) levels were showed in control and diabetic groups. The levels of FBG (P=0.000), TC (P=0.001), LDL (P=0.004), TSH (P=0.000) were significantly higher, and the levels of 25 (OH)D (P=0.001) was significantly lower in the T2DM group compared to the non-diabetic group.

We revealed that the serum level of 25 (OH)D is lower in patients with T2DM, and the TSH level is significantly higher compared to the non-diabetic group. Thyroid dysfunction and a low level of 25 (OH)D are associated with a high risk of T2DM