Beneficial Role of Vitamin D Supplementation on Thyroid Hormone Levels among T2DM Patients with Thyroid Disorders: Statistical Evaluation

Abstract

Thyroid function is impaired by diabetes, resulting into thyroid disorders, accompanied by the alteration of thyroid-stimulating hormone (TSH) and thyroxine (T4) levels. The aim of this study was to investigate the role of vitamin D supplementation on TSH and total T4 levels in serum of Libyan patients suffering from type 2 diabetes mellitus (T2DM) with thyroid disorders. A total of 180 subjects were recruited and distributed into two groups: 80 participants in control group (43 females and 37 males), with an age range of 26-72 years, and 100 participants in T2DM patient group (54 females and 46 males), with an age range of 26-63 years. Each T2DM patient received a monthly intramuscular injection of 200000 ng/ml vitamin D for three months. Glucose, vitamin D, total T4 and TSH levels were determined in serum samples of healthy subjects and of T2DM patients (pre- and post-administration of vitamin D). After the T2DM group received vitamin D supplementation, the mean of vitamin D level increased in the T2DM, while the mean of glucose level decreased. Most importantly, the mean of total T4 level for patients increased significantly (p ˂ 0.05) from 1.34 to 8.23 mg/dL, both of which were lower than the control group mean 10.99 mg/dL. In contrast, the mean of TSH level for patients decreased significantly (p ˂ 0.05) from 11.77 to 2.71 mU/L, and both values were greater than the control group mean 2.01 mU/L. ANOVA results showed that age, gender, and body mass index had no significant individual interactions (p > 0.05) with vitamin D supplementation on total T4 and TSH levels. Vitamin D supplementation had a beneficial role on total T4 and TSH levels in serum of Libyan T2DM patients with thyroid disorders. Keywords: T2DM, thyroid disorder, total T4, TSH, vitamin D supplementation, ANOVA, t test.