Comparison of cardiovascular autonomic function and biomarkers between vitamin D insufficient and deficient people with newly diagnosed type 2 diabetes mellitus.

Abstract

Introduction: Vitamin D is a neuroactive hormone having influence on several biological functions. Cardiovascular autonomic dysfunctions as well as inflammation and oxidative stress are evident in newly diagnosed type 2 diabetes mellitus (T2DM). Vitamin D deficiency has been associated with the development and progression of cardiovascular autonomic dysfunctions in T2DM. Vitamin D insufficiency is prevalent in T2DM. However, the autonomic function status and biomarkers in vitamin D deficient and vitamin D insufficient newly diagnosed T2DM subjects are not clear. Therefore, the present study aimed to compare the cardiovascular autonomic function and biomarkers between vitamin D insufficient and vitamin D deficient people with newly diagnosed T2DM.

Methods: Newly diagnosed 47 T2DM subjects (mean age 38 ± 4.2 years) were recruited based on American Diabetes Association criteria. They were divided into vitamin D deficient (<20 ng/ml; n = 30) and vitamin D insufficient group (20-30 ng/ml, n = 17) according to Endocrinology Society guidelines. Heart rate variability (HRV), baroreflex sensitivity (BRS) and conventional autonomic function tests, 25 (OH) D, oxidative stress parameters and inflammatory markers were measured.

Results: Compared to the vitamin D insufficient group, the vitamin D deficient group showed significantly decreased 25 (OH) D (P < 0.001), BRS (P = .004), high frequency (normalised units) (P < .001), total power (P = .048), adiponectin (P = .050); and significantly increased low frequency (normalised units) (P = .036) and low frequency: high frequency ratio (P = .038), malondialdehyde (P < .001), interleukin-6 (P = .009), fibroblast growth factor-21 (P = .043), and redox ratio (P = .005).

Conclusion: The present study found the vitamin D deficient group had a reduced parasympathetic and higher sympathetic tone along with greater oxidative stress and inflammation compared to the vitamin D insufficient group in newly diagnosed T2DM subjects.