Endocrine Abstracts

Introduction: Recently, vitamin D3 (cholecalciferol) deficiency has been considered as one of the factors for the development of type 2 diabetes mellitus (T2D) and metabolic syndrome (MS), which contributes to increased insulin resistance (IR) and reduced insulin secretion. The most pronounced vitamin D deficiency is observed in persons suffering from morbid obesity. The aim of this study was to assess IR, b-cell functional activity and metabolic profile parameters according to the 25 (OH) vitamin D3 (vitD3) status in patients with T2D.

Materials and methods: The study included 109 patients with T2D. All patients were divided according to the Endocrine Society clinical practice guideline for vitD3 status on 3 groups as follows: group 1 (n=11) – no deficiency, with optimal level vitD3 (>40 ng/ml); group 2 (n=38) – vitD3 insufficiency (21–29 ng/ml); and group 3 (n=60) – vitD3 which was determined as less than 20 ng/ml. The IR, b-cell functional activity were assessed as change C-peptide and HOMA-β (homeostasis model assessment-estimated β-cell function) which calculated using HOMA2 calculator (Diabetes Trials Unit, University of Oxford). Continuous variables were analyzed using one-way ANOVA with Tuckey Post Hoc test. Data with non-parametric distribution was analyzed using Kruskall-Wallis test. The significance level was considered significant at P<0.05. Association between vitD3 amount and metabolic changes was assessed with univariate Pearson’s correlation analysis.

Results: In patients with vitD3 deficiency we observed significantly higher C-peptide as compared to both other groups. The HOMA2 (3.29±1.89 vs. 2.12±0.71; P=0.049) and HbA1c (9.11±1.63 vs. 7.75±1.06; P=0.016) levels changes significantly only in vitD3 deficiency group as compared to patient with optimal vitD3 (group 1). Furthermore, in univariate Pearson’s correlation analysis, only in vitD3 deficiency group we observed significant association between vitD3 amount and C-peptide (r=−0.461, P<0.001), insulin sensitivity (r=0.370, P=0.004), HOMA2 (r=−0.292, P=0.023), triglyceride-glucose index (r=−0.318, P=0.013), HbA1c (r=−0.317, P=0.014) and BMI (r=−0.285, P=0.027) respectively. B-cell functional activity changes insignificantly and we did not found significant associations between vitD3 amount and metabolic parameters across all groups.

Conclusions: Our study demonstrated that vitD3 deficiency in patients with T2D associated with more severe IR, obesity and poor glycemic control as compared to optimal value or vitD3 insufficiency. From the other hand, we did not found significant relationships between vitD3 status and β-cell functional activity.