Endocrine Abstracts

Background: Effects of vitamin D on immune cells might affect diabetes mellitus (DM) development since inflammatory factors have been linked to insulin resistance (IR). The aim of this study was to investigate the effect of cholesterol treatment on insulin sensitivity metabolic markers in patients with chronic autoimmune thyroiditis.

Materials and methods: In this double-blind, randomized, placebo-controlled trial, which was conducted from May to September 2019, 45 patients with chronic autoimmune thyroiditis were enrolled. They randomly allocated into two groups to receive oral cholecalciferol (28 000 IU weekly) and placebo for 12 weeks. Serum concentration of glycated hemoglobin (HbA1c), insulin, fasting plasma glucose (FPG), calcium, phosphorus, parathyroid hormone, C-reactive protein, creatinine, triglyceride (TG), total cholesterol, and high-density lipoprotein were measured in both groups before and after investigation. Homeostasis model assessment estimates of beta cell function (HOMA-B) and HOMA-insulin resistance (HOMA-IR) were calculated before and after trial in both groups.

Results: Twenty-three and twenty-two participants were allocated to cholecalciferol-treated and placebo-treated groups, respectively. Mean (standard error) level of 25(OH)D increased significantly in cholecalciferol-treated group (34.71 [1.82] ng/ml vs 14.17 [0.72] ng/ml, P = 0.002). Plasma parathyroid hormone decreased in the treatment group while remaining unchanged in the placebo-treated group (35.04 [2.24] ng/ml vs 46.83 [2.29] ng/ml respectively, P = 0.03). In between-group comparison, there was significant difference between cholecalciferol-treated and placebo-treated groups regarding measures of HOMA-B, HOMA-IR (P < 0.05). Other variables did not meet a significant change after trial (P = NS).

Conclusions: Weekly 28 000 IU oral cholecalciferol for 12 weeks improved IR and insulin secretion in patients with chronic autoimmune thyroiditis.