|Year : 2013 | Volume
| Issue : 1 | Page : 31-35
Serum homocysteine in type 2 diabetes with cardiovascular complications
Nandinibala Kangabam1, Prabita Devi Oinam1, Joshita Lourembam1, Davina Hijam1, Premchand Singh2, Maisnam Amuba Singh1
1 Department of Biochemistry, Regional Institute of Medical Sciences, Imphal, Manipur, India
2 Department of Medicine, Regional Institute of Medical Sciences, Imphal, Manipur, India
|Date of Web Publication||17-Aug-2013|
Maisnam Amuba Singh
Department of Biochemistry, Regional Institute of Medical Sciences, Imphal, Manipur - 795 004
Source of Support: None, Conflict of Interest: None
Objectives: To determine the association between plasma homocysteine concentration and metabolic parameters in type 2 diabetes mellitus with and without cardiovascular complications. Materials and Methods: Cases of sixty type 2 diabetes mellitus patient (thirty with cardiovascular complications and another thirty without cardiovascular complications) were randomly selected from patients attending Diabetes Clinic and Medical wards, RIMS, Imphal. Another thirty age and sex-matched normal volunteers were taken as control. Serum homocysteine was estimated by ELISA. F-test (ANOVA) and correlation technique were used to analyze the data sets. Results: The serum homocysteine levels of type 2 diabetes mellitus patients both with and without cardiovascular complications were found to be significantly higher (P < 0.001) than the control subjects with 27.20 ± 6.02 μmol/l and 18.03 ± 4.61 μmol/l compared to 9.36 ± 1.70 μmol/l in the controls. Homocysteine is positively correlated with total cholesterol (r = 0.121, P < 0.05) and negatively correlated with HDL level (r= −0.166, P < 0.05). A positive correlation is found between the serum homocysteine level and blood pressure. Conclusions: Homocysteine and dyslipidaemia increases the cardiovascular risk significantly in type 2 diabetes mellitus. Homocysteine may be estimated as a prognostic indicator to assess the risk of developing cardiovascular complications.
Keywords: Dyslipidemia, Homocysteine, Type 2 diabetes mellitus
|How to cite this article:|
Kangabam N, Oinam PD, Lourembam J, Hijam D, Singh P, Singh MA. Serum homocysteine in type 2 diabetes with cardiovascular complications. J Med Soc 2013;27:31-5
|How to cite this URL:|
Kangabam N, Oinam PD, Lourembam J, Hijam D, Singh P, Singh MA. Serum homocysteine in type 2 diabetes with cardiovascular complications. J Med Soc [serial online] 2013 [cited 2020 Oct 29];27:31-5. Available from: https://www.jmedsoc.org/text.asp?2013/27/1/31/116631
| Introduction|| |
Diabetes mellitus (DM) is a syndrome characterized by chronic hyperglycemia and disturbances of carbohydrate, fat, and protein metabolism associated with absolute or relative deficiencies in insulin secretion and/or insulin action.  Type 1 DM patients have absolute insulin deficiency and are prone to ketosis under basal conditions and depend on exogenous insulin for life. Type 2 DM, on the other hand, is due to relative deficiency of insulin as a result of impaired secretion of insulin as well as insulin resistance.  Cardiovascular disease (CVD) is a major cause of morbidity and mortality, and, in India, in the past 5 decades, its rate among urban population has risen rapidly. Dyslipidemia is the most important predictive factor for coronary artery disease. 
As obesity, hypertension, and dyslipidemia, which are known to be frequently associated with type 2 DM, are insufficient in explaining the increase in risk, researchers are focusing on investigating new risk factors. Homocysteine (Hcy) is a sulphur containing amino acid in the body, which is produced by conversion of methionine. The normal value ranges from 5-15 μmol/L.  Recently, mild elevations of plasma Hcy have been identified as an independent risk factor for early atherosclerotic vascular disease and thromboembolic disease.  High circulating Hcy concentrations may increase the risk of CVDs when present with other cardiovascular risk factors like hypercholesterolemia and diabetes.  The study is, therefore, aimed to investigate serum levels of Hcy in subjects with type 2 DM and to assess the correlation between hyper-homocysteinemia and the duration of diabetes, lipid parameters, and cardiovascular complications among diabetic patients.
| Materials and Methods|| |
The study was conducted in the Department of Biochemistry in collaboration with the Department of Medicine, Regional Institute of Medical Sciences (RIMS), Imphal, Manipur. It was a cross-sectional study conducted during a period from October 2009 to April 2011. The study was approved by the Institutional Ethics Committee.
All participants were selected randomly from those who visited Diabetes Clinic, RIMS, Hospital. After careful clinical examination and confirmed diagnosis by a diabetologist, 60 patients presenting with type 2 DM were included in the study. These diabetic patients were divided into 2 subgroups: Group 1 (n = 30), type 2 DM with cardiovascular complications; Group 2 (n = 30) type 2 DM without complications. A total of 30 apparently healthy individuals with no symptoms suggestive of DM were taken as control subjects.
Exclusion criteria for both groups were individuals with pregnancy or having severe renal or hepatic impairment, congestive heart failure, cancer or thyroid disease, or taking lipid-lowering drugs or group B vitamins supplement.
The diagnosis of DM was based on WHO criteria, i.e. a fasting plasma glucose of ≥ 126 mg/dl (7.0 mmol/L) after minimum 12-h fast, with symptoms of diabetes and 2 h of postprandial glucose level of ≥ 200 mg/dl (11.1 mmol/L) after 75 g oral glucose load. Participants suffering from diabetes were included in the study irrespective of their glycemic status. Diagnosis of cardiovascular complications was based on history, clinical findings, and findings from serial tracings of 12 lead ECG.
Fasting sample was used for estimation of all parameters except for postprandial glucose estimation. About 7 ml of venous blood was drawn from antecubital vein and 6 ml was collected in plain vial and 1 ml in EDTA vial for estimation of glycosylated hemoglobin.
Serum Hcy estimation was done by enzyme-linked immunosorbant assay (ELISA) method using axis-Hcy enzyme immunoassay (EIA) kit from Axis-Shield Diagnostic, UK. Fasting and postprandial blood sugar was estimated quantitatively by glucose oxidase (GOD) technique. Serum lipid parameters (triglycerides [TG], total cholesterol, and HDL cholesterol) were estimated by enzymatic method using reagents procured from Anamol Laboratories Pvt., Maharashtra, India. Serum low-density lipoprotein (LDL) cholesterol was calculated by the formula of Friedwald et al. 
HbA 1c was estimated by Fast Ion Exchange Resin Separation method as described by Goldstein et al.  using commercially available reagent kit from HUMAN (Wiesbaden, Germany).
The data was analyzed using SPSS package version 16. P < 0.05 was considered statistically significant.
| Results|| |
[Table 1] deals with the distribution of the number of study subjects along with percentage over the three groups considered according to their socio-demographic and behavioral factors.
It is evident from [Table 2] that the mean age of the control group was 55 years, which was youngest, followed by diabetic group (57 years) and the oldest subjects (64 years) were in the group who had diabetes with cardiovascular complications. The average duration of diabetes was 7 years in patients of diabetes without complications and 11 years with cardiovascular complications. The fasting blood glucose level for control was 93.28 mg/dl, whereas it was 112.46 mg/dl for the diabetic without complication group and 151.33 mg/dl for diabetic with complication group. The mean glycosylated hemoglobin among the control group was 5.58 ± 0.85%, among the diabetic group was 7.08 ± 2.01%, and among the complication group was 8.24 ± 2.40%. The highest serum total cholesterol (TC) was found in type 2 diabetes with cardiovascular complication (229.17 ± 16.03) and lowest in the control group (174.28 ± 15.70). Similarly, a significant increasing trend was seen for TG and very low density lipoprotein (VLDL) among the control, diabetes with and without complication groups (P < 0.001). On the contrary, a reverse finding was observed in the cases of HDL. The mean Hcy levels in control and diabetic groups were 9.36 ± 1.70 μmol/L and 18.03 ± 4.61 μmol/L. The highest value was found in diabetes with cardiovascular complication (27.20 ± 6.02 μmol/L). A statistically significant difference was detected between diabetes patients and controls regarding the mean Hcy level, being significantly higher in patients of type 2 diabetes with cardiovascular complications (P < 0.001).
No significant correlations were found between serum Hcy and parameters considered in both controls and type 2 diabetes patients. However, serum Hcy level was significantly correlated positively with LDL (r = 0.452; P < 0.05) and negatively with HDL cholesterol (r = 0.451; P < 0.05) in patients of type 2 diabetes with cardiovascular complications [Table 3].
|Table 3: Group - wise correlation between serum total homocysteine level and index of glycemic control, age, duration of diabetes, blood pressure, blood sugar, and serum lipid profile levels|
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| Discussion|| |
In the present study, 76.7% of type 2 diabetes patients with cardiovascular complications were males and 23.3% were females. Thus, higher prevalence of DM was seen in males. This is consistent with the findings of Ho et al.,  who reported the occurrence of DM more in males (0.95%) than in females (0.20%). The mean (± SD) fasting blood sugar level in type 2 diabetes with cardiovascular complications was 151.33 ± 52.59 mg/dl, whereas it was 112.46 ± 26.81 mg/dl in diabetics without complications and 93.28 ± 7.82 mg/dl in controls as shown in [Table 2]. These differences were statistically significant (P < 0.001) and consistent with the reports given by Verma et al. and Akinloye et al. 
The mean ± SD HbA 1c was 5.58 ± 0.85% in control, 7.08 ± 2.01% in diabetes patients, and 8.24 ± 2.4% in type 2 diabetes with complications, and the differences were statistically significant. This was similar with the observations made by Gabbay et al.,  who noted that glycosylated hemoglobin concentration was elevated as much as two-fold in diabetes and decreased with improvement of glycemic control. Higher glucose concentrations and increased glycosylated hemoglobin might accelerate atherosclerotic processes through several plausible mechanisms such as oxidative stress and protein glycation of vessel walls.
In this study, there was significantly (P < 0.001) higher level of total Hcy in diabetic patients with and without cardiovascular complications as compared to the control subjects. This finding was consistent with the findings of Soinio et al.  and Coppola et al.,  thus indicating that hyperhomocysteinemia is an independent risk factor of CVD incidence in type 2 diabetic patients.
Durand et al.  showed that plasma Hcy levels increase linearly up to the age of 60-65 years, but rises much faster thereafter, increasing by approximately 10% or 1 μmoL/L per decade and has concluded that the age dependent increase may be attributed to deterioration of renal function.
Serum TG levels show an increasing trend from control to diabetic subjects. This finding was in agreement with Taylor et al.,  who reported an increase in serum TG concentrations in type 2 DM.
Several studies suggest that elevated plasma Hcy level has both atherogenic and thrombogenic effects. Hyperhomocysteinemia causes endothelial dysfunction by increasing oxidant stress and decreases the release of nitric oxide, impairing vasodilation. Excess of Hcy stimulates smooth muscle cell proliferation and collagen synthesis promoting intima-media thickening. Hyperhomocysteinemia is also considered to have thrombogenic activity by increasing platelet aggregation and causing abnormalities in the coagulation system. High plasma Hcy level is also shown to be associated with increased lipid peroxidation. ,,
An alternative route of Hcy metabolism in hyperhomocysteinemia is the formation of Hcy-thiolactone, which then reacts with LDL to form LDL-Hcy-thiolactone aggregates. These are taken up by macrophages and are subsequently incorporated into foam cells in early atherosclerotic plaques. Within these plaques, Hcy-thiolactone acylates proteins and modifies oxidative processes of the vessels, thereby promoting atherothrombosis. 
In our study, the association between elevated plasma Hcy level and increased rate of coronary heart disease events was statistically significant even in those diabetes patients without myocardial infarction at baseline. This suggests that plasma Hcy level is involved not only in the progression of advanced coronary heart disease but also in the earlier phases of atherogenesis. Thus, our study shows strong association of hyperhomocysteinemia and dyslipidemia in patients of type 2 diabetes with cardiovascular complications.
| Conclusion|| |
The results of this study confirm the hypothesis that hyperhomocysteinemia is a risk factor for endothelial dysfunction and vascular diseases such as atherosclerosis and occlusive vascular disorders. However, further studies are required to determine whether genetic, nutritional deficiencies, or diseases related to Hcy metabolism account for hyperhomocysteinemia observed in patients of type 2 DM with and without cardiovascular complications. Effective assessment of the role of lipid fractions and glycemic control in coronary heart disease will be more useful if the sample size is large.
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[Table 1], [Table 2], [Table 3]