Metabolic predictors and vitamin D deficiency in patients with type 2 diabetes mellitus

Abstract

Background. Recently, vitamin D deficiency is considered one of the factors for the development of type 2 diabetes mellitus. The purpose of this study was to eva­luate changes in anthropometric parameters, indicators of carbohydrate and lipid metabolism in patients with type 2 diabetes mellitus depending on vitamin D status. Materials and methods. According to the recommendations of the European Society of Endocrinology, all patients were divided into 3 groups: group 1 — optimal vitamin D level (30 ng/ml); group 2 — vitamin D deficiency (21–29 ng/ml); and group 3 — vitamin D deficiency (< 20 ng/ml). Insulin sensiti­vity and β-cell functional activity were evaluated using the HOMA-2 calculator. Results. The ave­rage body mass index increased in parallel with a decrease in the serum vitamin D concentration. The highest body mass index and prevalence of obesity, including morbid obesity (16.7 %), were observed in the vitamin D deficiency group. HOMA-2-IR (2.12 ± 0.71 vs 2.25 ± 0.95, p = 0.963) and insulin sensitivity (S% — 57.11 ± 32.07 vs 54.69 ± 32.5, p = 0.965) in the group of the optimal level of vitamin D and its insufficiency (group 2) were almost identical. In vitamin D deficiency, HOMA-2-IR was statistically significantly higher — by 46.2 % (p = 0.004), and insulin sensitivity was by 27.5 % lower (p = 0.027). The functional activity of β-cells did not change statistically significantly between all groups, regardless of the vitamin D status. An inverse correlation was established between the concentrations of vitamin D and glycated hemoglobin, HOMA-2-IR, C-peptide and S%. Among the parameters of lipid metabolism in the vitamin D deficiency group, a statistically significantly higher level of triglycerides and very low density lipoproteins was found. In the correlation and regression analysis, insulin resistance parameters, glycemic control indices, lipid profiles and metformin intake were independently associated with vitamin D deficiency. Conclusions. Vitamin D deficiency in patients with type 2 diabetes mellitus is associated with more pronounced insulin resistance, obesity and inadequate glycemic control compared to the optimal level or its insufficiency.

Keywords

• vitamin d
• type 2 diabetes mellitus
• insulin resistance
• β-cell function
• obesity