|Year : 2020 | Volume
| Issue : 4 | Page : 373-379
Vitamin D levels in patients with metabolic syndrome
Attia Mahdy Attia E.L Shamy1, Eglal M Kenawy1, Ashraf M Al-Kabeer1, Mona M Abdelmeguid2
1 Department of Internal Medicine, Faculty of Medicine, Al-Azhar University, Assiut, Egypt
2 Department of Clinical Pathology, Faculty of Medicine, Al-Azhar University, Assiut, Egypt
|Date of Submission||12-Oct-2019|
|Date of Decision||18-Mar-2020|
|Date of Acceptance||13-Aug-2020|
|Date of Web Publication||29-Dec-2020|
Eglal M Kenawy
Department of Internal Medicine, Al-Azhar University Hospital, Assiut, 71511
Source of Support: None, Conflict of Interest: None
Background Metabolic syndrome (MS) is characterized by several cardiovascular risk factors, such as insulin resistance, impaired glucose tolerance, diabetes mellitus, obesity, abdominal fat accumulation, dyslipidemia, and hypertension.
Objective To find an association between plasma 25-cholecalciferol (vitamin D) level and the MS.
Patients and methods A case–control study was conducted on 48 patients with MS who were compared with 48 age-matched and sex-matched healthy individuals (without MS).
Results Although there was a significant increase in all parameters of MS in patient group over the control group, there was no statistically significant difference between them in vitamin D levels (P≥0.090). In both studied groups, there was no statistically significant correlation between vitamin D level and BMI (P≥0.299), waist circumference (P≥0.208), blood pressure (systolic P≥0.257 and diastolic P≥0.081), fasting blood sugar (P≥0.227), and serum triglycerides (P≥0.438). We found an inverse correlation between vitamin D and high-density lipoprotein-cholesterol (P≤0.001) in both groups. Only patients with MS showed an inverse correlation between vitamin D and lipid accumulation product (P≤0.001).
Conclusion Although vitamin D level is not correlated with all MS parameters; it is negatively correlated with high-density lipoprotein-cholesterol and lipid accumulation product, which is considered an accurate index for MS.
Keywords: diabetes mellitus, metabolic syndrome, vitamin D
|How to cite this article:|
Shamy AE, Kenawy EM, Al-Kabeer AM, Abdelmeguid MM. Vitamin D levels in patients with metabolic syndrome. Al-Azhar Assiut Med J 2020;18:373-9
|How to cite this URL:|
Shamy AE, Kenawy EM, Al-Kabeer AM, Abdelmeguid MM. Vitamin D levels in patients with metabolic syndrome. Al-Azhar Assiut Med J [serial online] 2020 [cited 2021 May 8];18:373-9. Available from: http://www.azmj.eg.net/text.asp?2020/18/4/373/305210
| Introduction|| |
Vitamin D mainly regulates calcium and phosphate metabolism. Vitamin D deficiency had been linked to many diseases like carcinomas, autoimmune diseases, infections, and respiratory and cardiac diseases . Moreover, previous studies found a relation between vitamin D deficiency and the development of type 1 and 2 diabetes mellitus (DM) . Furthermore, vitamin D deficiency seems to have a higher frequency in type 2 diabetic patients compared with the nondiabetic population . However, other studies did not find that vitamin D supplementation can favor an improvement in glucose homeostasis parameters .
Metabolic syndrome (MS) is a metabolic disorder characterized by several cardiovascular risk factors, such as insulin resistance, impaired glucose tolerance, DM, obesity, abdominal fat accumulation, dyslipidemia, and hypertension .
The prevalence of MS was increased worldwide and the leading causes may be owing to sedentary lifestyle; unhealthy nutrition, leading to gaining weight; and advanced age .
The term vitamin D is used for both vitamin D2 (ergocalciferol), which is vegetative, and vitamin D3 (cholecalciferol), which can be synthesized endogenously from subcutaneous tissue with ultraviolet lights . Whatsoever, a previous study found that vitamin D may improve insulin resistance in peripheral tissues such as muscles, liver, and adipose tissue , and other studies reported a high prevalence of vitamin D deficiency in patients with type 1 DM .
Many previous studies have reported the association between Vitamin D and MS and impaired insulin secretion, whereas others have not confirmed this observation ,.
| Aim|| |
This work aimed to find an association between plasma 25-cholicalciferol (vitamin D) level and the MS.
| Patients and methods|| |
A case–control study was conducted on 48 patients with MS (according to guidelines used by The National Institute of Health) attending the outpatient clinic of Al-Azhar University Hospital (Assiut branch), who were compared with 48 age-matched and sex-matched individuals without MS. This study wes approved by the Ethical Committee of Al-Azhar Faculty of Medicine, Assiut. Patients without underlying diseases except for meeting the criteria of MS were selected from the outpatient clinics. Subsequently, a written consent had been obtained from all the participants. All patients and controls were subjected to the following:
- Full history taking and thorough clinical examination. Blood pressure was measured twice in the sitting position at intervals of 1–2 min, and the mean value of the two measurements was taken.
- Abdominal ultrasonography.
- Laboratory investigations:
- Fasting blood glucose (FBG), serum triglyceride (TG), serum high-density lipoprotein (HDL), and serum level of vitamin D [25(OH)D], which was measured by human 25-dihydroxy vitamin D ELISA kit industries by SunRed Company (Shanghai, China).
For the diagnosis of MS, patients must have three or more of the following criteria according to International Diabetes Federation (IDF) :
- Large waist circumference (WC): 35 inches or more for women and 40 inches or more for men.
- High TG level: 150 mg/dl or more.
- Reduced high-density lipoprotein-cholesterol (HDL-c): less than 40 mg/dl for men and less than 50 mg\dl for women.
- Increased blood pressure: 130/85 mmHg or higher.
- Elevated fasting blood sugar: 100 mg/dl or higher.
Lipid accumulation product (LAP) was calculated according to the following formulas :
Patients aged above 18 years, who fulfilled at least three or more criteria of MS according to the aforementioned IDF criteria, were included.
Exclusion criteria by history, clinical examination, and some laboratory data
- Patients with an impaired general condition, cirrhosis, nephrotic syndrome, hypopituitarism, adrenal tumors, hypothyroidism, alcoholism, pacemakers, platinum in any part of the body, decompensated heart failure and conditions that might affect anthropometric measurements (pregnancy, orthopedic problems, etc.) had been excluded from the study.
- Patients with type 1 diabetes were excluded as well.
Recorded data were analyzed using the statistical package for social sciences, version 20.0 (SPSS Inc., Chicago, Illinois, USA). Quantitative data were expressed as mean±SD. Qualitative data were expressed as frequency and percentage.
The following tests were done:
- Independent samples t test of significance was used when comparing between two means.
- χ2 test of significance was used to compare proportions between qualitative parameters.
- Pearson’s correlation coefficient (r) test was used to assess the degree of association between two sets of variables.
- The confidence interval was set to 95%, and the margin of error accepted was set to 5%. So, the P value was considered significant as follows:
- P value
- P value less than 0.05 was considered significant.
- P value less than 0.001 was considered as highly significant.
- P value more than 0.05 was considered insignificant.
| Results|| |
In our study, we found a statistically significant increase in BMI (P≤0.001), WC (P≤0.001), and blood pressure [systolic (P≤0.001) and diastolic (P≤0.001)] in patients with MS more than individuals without MS ([Table 1]). Moreover, there was a significant increase in the serum levels of FBG (P≤0.005), LAP (P≤0.027), and TG (P≤0.001) and a significant decrease in HDL (P≤0.001) level in patients with MS more than individuals without MS ([Table 2]). No significant difference in the vitamin D level (P≥0.090) between the two studied groups was found ([Table 3] and [Table 4]). Finally, a significant and inverse correlation between vitamin D level and both HDL (P≤0.001) and LAP (P≤0.013) in patients with MS was found ([Table 5]) ([Figure 1] and [Figure 2]). There was an inverse correlation between vitamin D and HDL (P≤0.001) in individuals without MS ([Table 6]). Moreover, the correlation between vitamin D and other clinical and some laboratory data such as age, weight, height, BMI, WC, systolic blood pressure, diastolic blood pressure, FBG, TG, alanine aminotransferase, and aspartate aminotransferase were statically insignificant (P>0.05) ([Table 5] and [Table 6]).
|Table 1 Comparison between patients with metabolic syndrome (48) and individuals without metabolic syndrome (48) according to clinical and radiological data|
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|Table 2 Comparison between patients with metabolic syndrome and individuals without metabolic syndrome according to laboratory data|
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|Table 4 Comparison between vitamin D level in patient with and without bright liver|
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|Table 5 Correlation between vitamin D and all parameters in patients with metabolic syndrome (N=48)|
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|Figure 1 Correlation between serum vitamin D level and serum high-density lipoprotein level in 48 patients with metabolic syndrome.|
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|Figure 2 Correlation between serum vitamin D level and lipid accumulating product (LAP) level in 48 patient with metabolic syndrome.|
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|Table 6 Correlation between vitamin D and all parameters in individuals without metabolic syndrome (N=48)|
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| Discussion|| |
Vitamin D may play a protective role on beta cells of pancreas through regulating inflammatory cytokine, and it helps in the promotion of pro-insulin to insulin using calcium-dependent endopeptidases through increasing calcium amount as mediated by vitamin D receptors in the cytosol of the pancreatic beta cells .
In our study, we found a statistically insignificant difference in the vitamin D level between patients with MS and apparently healthy in individuals without MS. This result was similar to a study done by Rudvan et al.  on 191 patients with MS, which found no statistically significant difference in vitamin D levels between patients with MS and control.
In contrary to our results, the study done by Diaz  obtained a significant low vitamin D level in patients with MS than others who did not have the criteria of MS. However, a statistically inverse correlation between vitamin D level with HDL and LAP had been found in our studied patients with MS. Bardini et al.  found an inverse and significant relation between vitamin D level and LAP, which is in agreement with our results. Moreover, Rudvan et al.  had detected a paradoxical and statistically significant relation between vitamin D level and HDL, with no detectable significant relation with TGs. However, Glueck and Jetty  in 2016 found a significant and inverse relation between vitamin D level and TGs level and a positive and significant relation between vitamin D level and HDL.
Insulin resistance was associated with developing type 2 DM and dyslipidemia and increased cardiovascular risk. The relationships between vitamin D deficiency and insulin resistance and MS development have been studied. Although previous studies reported some conflicting results, most of them confirmed the relationship between vitamin D deficiency and insulin resistance and dyslipidemia development .
The National Health and Nutrition Examination Survey (NHANES) study in 2008 assessed the relationship between vitamin D and insulin resistance and DM, by comparing groups of different ethnicities such as non-Hispanic whites, non-Hispanic blacks, and Mexican-Americans. They found high levels of vitamin D in non-Hispanic whites, moderate levels in Mexican-Americans, and low levels in non-Hispanic blacks. Additionally, a significant and inverse relationship was found between vitamin D levels and insulin resistance and DM in non-Hispanic whites and Mexican-Americans .
In addition, Alkhatatbeh and Abdul‑Razzak  found a significant inverse association between serum 25-hydroxyvitamin D and HbA1c and FBG in adult patients with DM. On the contrary, a study had been done by Rudvan et al.  demonstrated that the group with insulin resistance had statistically significantly higher levels of vitamin D compared with those without insulin resistance. Whatsoever, we did not find any significant relation between the low level of vitamin D and IF or DM. The unexpectedly insignificant relationship between vitamin D levels and the presence IF or DM can be explained by the fact of vitamin D deficiency was nearly same in patients with MS (41.7%) and control (50%), as well as the different ethnicity of our patients, which differs from other studies. Moreover, most of the studied patients in the studies by Alkhatatbeh and Abdul‑Razzak . and Rudvan et al.  were females, so the presence of other independent variables like gynecological conditions (polycystic ovarian syndrome or endometriosis), menopausal status, and timing of the menstrual cycle may have affected the insulin resistance indices.
Liu et al.  had published a study that examined the role of vitamin D in blood pressure and endothelial functions and had demonstrated that high level of blood pressure was associated with low vitamin D levels. In the current study, we found no association between vitamin D level and blood pressure, being similar to the studies by Caro et al.  and Jorde and Grimnes . This result might be explained by other risk factors of hypertension such as smoking, stressful life, and high-salt diet, which is common in Egypt.
Regarding WC, which is a cornerstone in the diagnosis of MS, a study was done by Fariborz et al.  obtained no significant correlation between vitamin D level and WC, which is in agreement with our study. Another study done by Kavaric and Vojnosanit  demonstrated a significant and inverse relation between vitamin D level and WC. Thus, this field needs more future studies on a large number of patients to make this correlation, if it exists, clearer and more reasonable.
| Conclusion|| |
In this study, although vitamin D is not correlated with each component of the MS, it was found to positively correlate with LAP which is a calculated parameter from both WC and TGs level. Both are components of the MS. Vitamin D also negatively correlated with HDL-c, which also is a component of the MS.
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Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2]
[Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6]