Relationship Between Vitamin D Level And Heart Rate Variability In Type 2 Diabetes

[Background]Type 2 diabetes mellitus(T2DM)is a chronic metabolic disease,which is mainly caused by islet beta cell dysfunction and insulin resistance.Chronic persistent hyperglycemia can cause various complications,including damage of heart,brain and kidney caused by macrovascular and microvascular damage,and diabetic autonomic neuropathy caused by autonomic nerve damage.Diabetic Cardiac Autonomic Neuropathy(DCAN)is one of the complications of diabetic autonomic neuropathy which is often overlooked.DCAN is caused by chronic hyperglycemia-related cardiac macrovascular and microvascular disease which can lead to myocardial ischemia,hypoxia and cardiac blood supply disorders,resulting in autonomic nervous system lesions that innervate the heart.Its main clinical manifestations include coronary artery dysfunction,orthostatic hypotension,painless myocardial infarction,etc.Heart Rate Variability(HRV)represents the balance between sympathetic and parasympathetic nerves of the cardiac autonomic nervous system.HRV,as a non-invasive and quantitative analysis method is mainly used to analyse the changes of cardiac cycle differences.The main clinical monitoring indicators include:CD Standard Deviation of Normal-to-Normal intervals(SDNN);?Low Frequency(LF);?High Frequency(HF);?Ratio of Low Frequency to High Frequency(LF/HF);?Heart Rate(HR).The above main monitoring indicators have been widely used in clinical practice and provide a method for evaluating cardiac autonomic neuropathy.Being one of the main causes of diabetes-related deaths DCAN is usually occult in onset with rapid or slow progression.Therefore,early prevention and treatment of DCAN is of great importance.Vitamin D participates in the metabolism of calcium and phosphorus.In recent years,its role in lung cancer,immunity,cardiovascular and cerebrovascular diseases has attracted much attention.There are several forms of vitamin D metabolites in blood.25-hydroxyvitamin D is the most abundant form in circulation,which can reflect the nutritional status of vitamin D in the body.The level of serum 25(OH)D is often monitored to evaluate the content of vitamin D in the body.Vitamin D exerts its vascular effect by regulating the renin-angiotensin system,and deficiency of it is related to the mortality of related cardiovascular diseases.At present,there are few studies on the relationship between vitamin D and cardiac autonomic neuropathy.The purpose of this study is to observe the relationship between vitamin D level and heart rate variability in patients with T2DM,and to provide theoretical basis for the early prevention and treatment of cardiac autonomic neuropathy.[Objective]1.To compare the general characteristics of 25(OH)D deficiency group,25-hydroxyvitamin D insufficiency group and 25(OH)D adequacy group in patients with T2DM.2.To compare the characteristics of heart rate variability(HRV)and other indices in s 25(OH)D deficiency group,25-hydroxyvitamin D insufficiency group and 25(OH)D adequacy group of patients with T2DM and analyze their correlation.3.The independent influencing factors of heart rate variability in patients with T2DM were analyzed by generalized linear regression model.[Methods]279 patients with T2DM who were hospitalized in the Department of Endocrinology of the Second Hospital of Shandong University from January 2018 to May 2019 were collected.According to the classification criteria of serum 25(OH)D level,the patients were divided into 25(OH)D deficiency group(n=99),25(OH)D insufficiency group(n=86)and serum 25(OH)D adequacy group(n=94).The general clinical indicators of patients,including gender,age,body mass index,waist circumference,history of hypertension,history of heart disease and so on were recorded.The heart rate variability indicators of patients,including related indicators such as SDNN,LF,HF,LF/HF,HR were measured blood samples were collected to detect hematological indicators,including liver function,blood sugar,blood lipid,creatinine,uric acid,glycated hemoglobin,biochemical ions and other related indicators.SPSS 22.0 was used for data statistical analysis.The analysis methods included univariate analysis,correlation analysis and generalized linear regression analysis.The significance level was set at P<0.05.[Results]1.There were no significant differences in gender,age,body mass index,waist circumference,systolic blood pressure,diastolic blood pressure,course of diabetes,history of hypertension and history of heart disease among the three groups(P>0.05).2.Single factor analysis among the three groups indicated that there were significant differences in triglyceride,low density lipoprotein cholesterol,total cholesterol,high density lipoprotein cholesterol,HR,LF,HF,LF/HF and SDNN(P<0.05).The levels of triglyceride and total cholesterol in 25(OH)D deficiency group were significantly higher than those in 25(OH)D adequacy group(P<0.05).HR in serum 25(OH)D deficiency group was significantly higher than that in 25(OH)D insufficiency group(P<0.05);LF,LF/HF and LDL-cholesterol in 25(OH)D deficiency group were significantly higher than those in 25(OH)D insufficiency group and 25(OH)D adequacy group(P<0.05);HF and SDNN in 25(OH)D deficiency group were significantly lower than those in 25(OH)D insufficiency group(P<0.05).HDL cholesterol in 25(OH)D deficiency group was significantly lower than that in serum 25(OH)D adequacy group(P<0.05).The correlation analysis showed that high density lipoprotein cholesterol,HF,SDNN were positively correlated with serum 25(OH)D levels(rs>0,P<0.05),while triglyceride,total cholesterol,low density lipoprotein cholesterol,LF,LF/HF were negatively correlated with serum 25(OH)D levels(rs<0,P<0.05).3.The analysis of generalized linear regression model indicated that serum 25(OH)D level was an independent influencing factor of heart rate variability in patients with T2DM(P=0.026).[Conclusion]1.T2DM patients with serum 25(OH)D deficiency are at high risk for cardiac autonomic neuropathy.2.Serum 25(OH)D levels were correlated with triglyceride,low density lipoprotein cholesterol,total cholesterol,high density lipoprotein cholesterol,LF,HF,LF/HF and SDNN levels.Serum 25(OH)D levels were positively correlated with high density lipoprotein cholesterol,HF and SDNN levels,and negatively correlated with triglyceride,total cholesterol,low density lipoprotein cholesterol,LF and LF/HF levels.3.Serum 25(OH)D level is an independent influencing factor of heart rate variability in patients with T2DM.