Effect of Vitamin D supplement on the risks of Cardiovascular disease in patients with type 2 diabetes in the Kurdistan Region of Iraq

 

Hasan Qader Sofihussein¹, Abdulqader Azeez Al-Naqshabandi², Hawri Fatih Sami³,

Mudhafar Mohamed M. Saeed⁴*

¹Polytechnic University of Sulaimani, Technical Institute of Sulaimani, Department of Pharmacy,

Sulaimani, Kudistan Region, Iraq.

²Hawler Medical University, College of pharmacy, Hawler, Kudistan Region, Iraq.

³Cihan University, College of Science, Hawler, Kudistan Region, Iraq.

⁴Polytechnic University of Sulaimani, Technical Institute of Sulaimani, Department of Pharmacy,

Sulaimani, Kudistan Region, Iraq.

 

ABSTRACT:

Bachground: Hypovitaminosis D has been observed in all ethnicities and age groups worldwide. Beyond its role in bone metabolism and calcium homeostasis, there is abundant evidence showing that there is a link between vitamin D and major pathological conditions such as cancer, type II diabetes mellitus, autoimmune disease, and various inflammatory disorders. Decreasing risks of these diseases involve the supplementation of vitamin D₃ on daily doses at its normal level. This research focused on the role of vitamin D₃ supplement on the level of glycated hemoglobin and hs-CRP and its impact on reducing risks of cardiovascular disease in type-2 diabetic vitamin D deficient patients.  Methods:The study sample consisted of 91 patients (17 males and 74 females). For a period of 14 weeks, they received daily supplementation with 5000 IU added to their other treatment regimens. Before and after supplementation with vitamin D₃, data on the patients’ anthropometric characteristics were collected and analyzed. Body mass index was measured. Afterwards, fasting venous blood samples were taken from the patients for investigation of, HbA1c, FBS, lipid profile, fasting serum insulin (mU/L), amylin (pg/ml), C-peptide (ng/ml), TNF-a,IL6, and hs-CRP. TG/HDL-c, and the homeostasis model of assessments of insulin resistance (HOMA-IR) were calculated. Results:The current study was carried out on 91 patients withtype-2 diabetes. Fourteen weeks of supplementation with vitamin D resulted in sharp amelioration in vitamin D level which in turn led to a significant decrease in the level of HbA1c, fasting blood glucose, IL-6, TNF-α, hs-CRP, waist circumference (WC), BMI, TG and TG/HDL-c ratio. While, a non-significant drop in HOMA-IR, Total cholesterol, and LDL-c. It also resulted in significant improvement in the level of fasting insulin, C-peptide, and HDL-c, and non-significant improvement in amylin. Conclusion: Vitamin D supplementation significantly decreased percentage of glycated hemoglobin as well as the level of hs-CRP, which in turn results in reducing cardiovascular disease risks in type-2 diabetic vitamin D deficient patients.

 

 

INTRODUCTION:

Despite current preventive and therapeutic strategies, cardiovascular diseases are still among the leading causes of death globally^[1,2].

 

Despite current preventive and therapeutic strategies, cardiovascular diseases are still among the leading causes of death globally^[1,2].

Beside the traditionaland most perceived risk factor for cardiovascular disease and MI development, new risk factors are rising with potential important restorative ramifications. Among them, hypovitaminosis D has been the focal point of ongoing interest.

 

There are two noteworthy forms of vitamin D: vitamin D₂ which is synthesized from ergosterol found in plants and fungi, and vitamin D₃ which is obtained from aliments or through the transformation of 7-dehydrocholesterol in the skin^[3,4]. It should be noted that the cutaneous synthesis of vitamin D₃ from sunlight exposure is the primary source of vitamin D in humans. Vitamin D₃  undergoes hydroxylation inside the liver to 25 (OH) vitamin D₃ which is its principal circulating form within the blood, and then in the kidneys the hydroxyl form of the vitamin undergoes another hydroxylation  to 1,25 di (OH) vitamin D₃ which is the most potent form of the vitamin. The 1, 25 di (OH) vitamin D₃ reaches the nucleus wherein, with the aid of binding to its receptors, it regulates the transcription and characteristic of more than 200 genes^[5,6].

 

It is well known that vitamin D deficiency, or insufficiency, is highly prevalent in the general population^[7]. Traditionally, vitamin D plays a key role in bone metabolism and regulates calcium homeostasis.  However, it has been found that the vitamin is closely associated with increasing the major cardiovascular risk factors such as diabetes, hypertension, and chronic kidney disease. Following the detection of nuclear vitamin D receptor (VDR) in many cells including vascular endothelial cells, endothelium, and cardiomyocytes, several mechanisms have been proposed for the possible link between hypovitaminosis D and cardiac disease^[8]. Interestingly, it was shown that vitamin D supplementation in heart failure patients is associated with improved survival^[9]. Deficiency of vitamin D was shown to be common in patients with MI, and preliminary studies indicated a possible association with their short- and long-term prognosis^[10,11].

 

There are few studies which discussed the influence of vitamin D levels on the risks of cardiovascular diseases in type-2 diabetic Kurdish patients. Thus, the present study was designed to examine the effects of vitamin D supplementation on the risk markers for cardiovascular diseases in type-2 diabetic patients with deficiency of vitamin D.

 

MATERIAL AND METHODS:

Following the relevant guidelines, the present study was approved by the Ethical Committee of Hawler Medical University. Moreover, informed written consent to participate in the study was obtained from each patient. In addition, they were given the right to quit the study whenever they wanted to. The study was conducted in the Endocrinology Center of Sulaimani, the Kurdistan Region of Iraq in cooperation with the Department of Clinical Analysis of the College of Pharmacy, Hawler Medical University located in Erbil, the Kurdistan Region of Iraq from 1^st December, 2017 to 1^stJune, 2018. The eligible patients were recruited based on the study’s inclusion criteria which were both genders, age of equal to or over 40 years, andhavingtype-2 diabetes with vitamin D deficiency. The exclusion criteria were renal disease, hepatic disease, terminal illnesses coronary artery disease, pregnant and breastfeeding women, mal-nutrition, and patients with serum C-reactive protein (CRP) of equal to or more than 6 mg/L.

 

The patients who had referred to the Endocrinology Center of Sulaimani, the Kurdistan Region of Iraq were selected as the study sample. Located in the north of Iraq, Sulaimani Governorate is a mountainous region characterized by cold weather in the winter and limited exposure to sun light. The patients were individually examined by the researchers and an endocrinologist.  The study sample consisted of 87 patients (15 males and 72 females) who met the abovementioned inclusion and exclusion criteria. For a period of 14 weeks, they received daily supplementation with 5000 IU added to their other treatment regimens. The participants were required to contact the researchers as soon as they noticed a reaction to the supplements.

 

Before and after supplementation with vitamin D₃, data on the patients’ anthropometric characteristics including weight (kg), height (m), and waist circumference (cm) were collected and analyzed.

 

Body mass index was measured by utilizing Quetelet equation (weight (kg) divided by squared height (m). Afterwards, venous blood samples of 12-hour overnight fasting were taken from the patients. The samples were then divided into two portions. Portion one was put in EDTA(which is a test tube for determining the percentage of glycosylated hemoglobin (HbA1c).Portion two was placed in a non-coagulant test tube where the sera were separated by centrifugation of 3000 rpm for 15 minutes. Those separated sera were then kept at -20ºC for consequent measurements within 2 weeks after the sampling. Moreover, lipid profile (mg/dl) including triglyceride (TG), total cholesterol (TC), low-density lipoprotein-cholesterol (LDL-c), high-density lipoprotein-cholesterol (HDL-c), and fasting serum glucose (FSG) were measured spectrophotometrically through enzymatic reaction. By calculating the Log of TG/HDL-c, the atherogenicity was specified. Fasting serum insulin (mU/L), amylin (pg/ml), C-peptide (ng/ml), TNF-a, IL6, and hs-CRP were specified by employing the technology of enzyme-linked immunosorbent assay (ELISA). The following formula was used to determine the homeostasis model of assessments of insulin resistance (HOMA-IR).

HOMA-IR=

Fasting serum glucose (mg/dl)×Fasting serum insulin (mU/L)/405

 

Statistical analysis:

The results were expressed as numbers, percentages, and means±SD. To analyze the collected data, independent samples t-test, paired sample student's t-test, Chi-square test, and simple (rho) correlation test were utilized. In all tests, a level of p≤0.05 was considered as statistically significant. For this purpose, Excel 2007 and SPSS version 20 were used.

 

RESULTS:

The current study was carried out on 91 patients withtype-2 diabetes. Their mean age was about 50 years. The number of the females were 4 times more than the males. Except for 2 participants, they were all married. Moreover, a small portion of the participants were smokers, half of them had hypertension, and about 61% of them resided rural areas (See Table 1).

Table 1.Features of the patients

The results are expressed as number (percentage) and mean ± SD

 

 

Fourteen weeks of supplementation withvitamin D resulted in sharp amelioration in vitamin D level which in turn led to a significant decreasein HbA1c and fasting blood glucose, and a non-significant drop inHOMA-IR. It also resulted in significant improvement in production of fasting insulin and C-peptide, and non-significant improvement inamylin (See Table 2).     

 

 

Table 2. Assessment of glycemic status and related biomarkers

The results are expressed as mean ± SD. P-value represents the level of significant difference between pre-and post-treatment using two tailed paired student's (t) test. HOMA-IR: Homeostatic model assessment for insulin resistance

 

Table 3. Assessment of inflammatory markers and related biomarkers

The results are expressed as mean ± SD. P-value represents the level of significant difference between pre-and post-treatment through two tailed paired student's (t) test.

 

Table 4. Anthropometric measurements and fasting lipid profile data

The results are expressed as mean ± SD. P-value represents the level of significant difference between pre-and post-treatment using two tailed paired student's (t) test.

 

In addition, supplementation with 5000 IU/day vitamin D for 14 weeks led to significant decrease in the chronic low-grade inflammatory markers(tumor necrosis factor-α,interleukin-6, and high sensitivity C-reactive protein) (See Table 3).

 

Fourteen weeks of supplementation with vitamin D resulted in significant drop in waist circumference (WC) and body mass index (BMI) were significantly decreased after 14 weeks supplementation as well as triglycerides and Triglyceride to high density lipoprotein ratio, yet, HDL significantly increased.  Total cholesterol and LDL decreased after supplementation non-significantly (See Table 4).  

 

DISCUSSION:

Our daily requirement for vitamin D can be met through exposure to sunlight and consumption of food rich vitamin D^[12]. Low serum level of 25(OH) vitamin D is shown to be associated with insulin resistance^[13,14].  Vitamin D deficiency has been linked to cardiovascular disease, infection, and even cancer^[15]. Rise in serum cholesterol is associated with increase in cardiovascular diseases^[16]. Studies have also demonstrated that 25(OH) vitamin D deficiency is a novel CV risk factor, predicting both CV events and mortality^[17]. All of the participants in this study were type-2 diabetic patients with vitamin D deficiency. This study was aimed at evaluating the effects of vitamin D₃ supplement on a number of valuable risk factors for cardiovascular disease such as glycemic status, biomarkers of inflammation, lipid concentration, and obesity index in type-2 diabetic patients.  In addition, vitamin D₃ played a potential role in decreasing the risk of cardiovascular diseases by reducing   HbA1c, hs-CRP, and the TG/HDL-C (an index for cardiovascular disease). Vitamin D₃ supplementation results in lowering level of HbA1c by 1.5%, and according to the United Kingdom Prospective for Diabetes Studies  (UKPDS), 0.9% decline of HbA1c results in trimming the risks for myocardial infarction by14%^[18]. As the relative cardiovascular risk categories for average hs-CRP levels are low risk<1.0 mg/liter, moderate risk=1.0–3.0 mg/liter, and high risk=3.0–10.0 mg/liter^[19], vitamin D₃ supplementation dwindled the mean level of hs-CRP from high risk (3.04±1.68) to moderate risk (2.53±1.42). Furthermore, the findings of the current study revealed a potential role of vitamin D₃ supplementation in glycemic indices; it resulted in a significant decrease in the level of  fasting blood glucose and HOMA-IR, which may be though the effects of vitamin D on the secretory function of the beta cells of pancreas which led to increased circulatory concentration of  amylin, c-peptide remarkably, and insulin non-significantly. These results are in agreement with recent studies conducted by Razzaghi et al.,^[20] and Talaei et al.,^[21]. It has been shown that 1-year vitamin D supplementation with 420 IU/day increased serum vitamin D concentration that concomitantly provided advantageous effects on fasting glucose level and insulin resistance^[22]. Also, it has been indicated that 50,000 IU vitamin D intake every two weeks for 12weeks improved markers of insulin resistance in women at risk of pre-eclampsia^[23].

 

In the present study, the effect of vitamin D₃ supplementation on inflammatory markers (i.e. IL6, TNF-α, and hs-CRP) was assessed. It was observed that vitamin D supplement significantly reduced hs-CRP, IL6 and TNF-alpha in type-2 diabetic patients with vitamin D deficiency. This finding is consistent with other previously conducted studies^[21,24-28]. Similarly, Sharifi et al.^[29], administered vitamin D₃ doses of 50,000 IU every 14 days for 4months to patients with liver disease and found a reduction in the hs-CRP level. A total dose of 60,000 IU /month vitamin D for 3months led to significant improvement hs-CRP levelin rheumatoid arthritis patients with persisting disease activity and vitamin D deficiency. In addition, a 3-month treatment with 2000 IU/day vitamin D in Crohn's disease significantly decreased hs-CRP level^[30]. The results of the current study are in line with these findings. They also demonstrated the anti-inflammatory effects of vitamin D₃ supplementation in patients with T2DM.

 

Regarding the effects of vitamin D on lipid profiles, several experimental and clinical studies previously demonstrated that vitamin D₃ supplementation have decreasing effects on serum lipid. The results of the present study indicated significant increase in serum HDLc and decrease in triglycerides, while there was non-significant decrease in total cholesterol and LDLc. These findings are in agreement with those of the study carried out by Razzaghi et al.^[20].  Supplementation with 4000 IU/day vitamin D₃ in postmenopausal women with type-2 diabetes mellitus for 6 months resulted in a significant decrease in serum triglyceride level without affecting the level of other lipid profiles^[31]. No significant change was observed in circulating levels of triglyceride and LDL- and HDL-cholesterol in patients with type-2 diabetes mellitus following supplementation with 16,000 IU of vitamin D₃ orally once a week for 8 weeks^[32]. This finding is in contrast with those of the present study, which may be due to the amount of vitamin D dose.

 

It has been demonstrated that an elevated ratio of triglycerides (TG) to high-density lipoprotein cholesterol (HDL-C) is a risk factor forcoronary artery disease in patients with type-2 diabetes mellitus (T2DM) and is also found to be associated with cardiovascular events (CVEs) in the general population^[33]. In the present study, vitamin D₃ supplementation was found to lead to a significant dropin the value of TC to HDL-C ratio, which in turnreducedthe risks for cardiovascular disease.

 

In a study carried out by Wang et al.,^[34], the dose range of vitamin D₃ was 300-3300 IU, and it was observed that vitamin D₃ supplementation had no statistically significant effects on TC,HDL-C, and TG.  Moreover, few mechanisms could explain the effect of vitamin D on decreasing concentration of lipids and lipoproteins. Vitamin D intake might increase calcium absorption, which in turn would result in increasing fat absorption^[35]. In addition, by improving insulin sensitivity, vitamin D might mediate its potential benefit for lipid profile^[36].

 

CONCLUSION:

Vitamin D supplementation significantly decreased percentage of glycated hemoglobin as well as the level of hs-CRP, which in turn results in reducing cardiovascular disease risks in type-2 diabetic vitamin D deficient patients.

 

CONFLICT OF INTEREST:

The authors declare no conflict of interest.

 

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Accepted on 29.01.2020           © RJPT All right reserved

Research J. Pharm. and Tech 2020; 13(9):4125-4129.