Determinants of Hyperhomocysteinemia in Type 2 Diabetic Subjects

Abstract

Hyperhomocysteinemia is a recently recognized risk factor for cardiovascular disease that is independent of major risk factors such as diabetes, hypertension, hypercholesterolemia, and smoking. Although the mechanisms by which homocysteine promotes atherothrombosis are unknown, the epidemiological evidence for the ssociation of hyperhomocysteinemia with atherothrombotic disease is strong (Deland, Refsum, Brattstrom, 1992; Boushey et al, 1995; Welch, Loscalzo, 1998). Recent retrospective and prospective studies, it is now widely accepted that increased total plasma homocysteine is a risk factor for cardiovascular disease. Impaired enzyme function as a result of genetic mutation or deficiency of the essential B vitamins folic acid B 12 and B6 can lead to hyperhomocysteinemia. Several evidence suggests that it may play a role m atherothrombotic disease. Gradually increased homocysteine causes dysfunction of vascular endothelium. It was an observational study with a case-control design. Two Groups of subject were included in this study. I 08 subjects were diabetic without CVDs in Group I and IO 1 subjects were selected diabetic with CVDs in group II. A total of 209 subjects included in this study and its association with clinical, socio-economical and biochemical risk factors. Purposively and their economical, and clinical characteristics were noted in a pre­designed case record form. Nutritional intake was assessed by food frequency questionnaire (24 hr dietary recall) method. Each subject went through OGTT following appropriate preparation and OM was diagnosed as per WHO Study Group Criteria. Blood glucose was measured by glucose oxidase method (Randox, UK) using a semi auto analyzer (300 MICROLAB). Lipids were measured by enzymatic methods using the same analyzer in the lab of Rajshahi Diabetic center. Plasma homocysteine concentration was measured by fluorescence Polarization Immunoassay (FPIA) technology (Abbott Laboratories, USA). Significance of differences will be analyzed by Student's t- test, as appropriate. Pearson's correlation and multivariate regression, as appropriate, were used to analyze the association between the other variables. Two Groups were age (yrs, M±SD) - matched and 55.4% male subjects were in Group II. BMI (kg/m2, M±SD); systolic blood pressure (mm of Hz) and diastolic blood pressure (mm of Hz) were significantly higher in Group II [(29±4.7); (130.5±12.9) and (88.4±8.6)] as compare to Group I [(24.1±3.8); (120.7±13) and (82.7±8)]; (p=0.013; p<0.001 and p=0.007) respectively. Fasting serum glucose level (mmol/1, M±SD) were significantly higher in Group II compared to Group I (18.5±6.01 vs 11.2±4.2; P<0.001). Serum glucose at 2 h after 75 g glucose administration were found to be (18.3±5.9) in Group I and (17.7±5.7) in Group II; (p=0.477). There was no significant difference in the two Groups. Sernm total cholesterol (mg/di, M±SD) were significantly higher in Group II compared to Group I (226±47 vs 207±34.2; P<0.001). Serum triglyceride (gm/di, M±SD) were significantly higher in Group II compared to Group I (218±85.5 vs 172±67.3; P<0.001). Serum HDL levels also significantly higher in Group I (47±8.1) as compare to Group II (39.8±10); (p=0.004). Serum homocysteine (µmol/L,, M±SD) were also significantly higher then compare to Group I (7.6±1.5) and Group II (14.5±5.8); (p<0.001). 37.6% subjects were in Group II their homocysteine level was below cut off value (<12 µmol/L) and 62.4% subjects were above cut off value of homocysteine level. BMI (kg/m2, M±SD); systolic blood pressure (mm of Hz) and diastolic blood pressure (mm of Hz) were significantly higher in Group II [(29±4.7); (130.5±12.9) and (88.4±8.6)] as compare to Group I [(24.1±3.8); (120.7±13) and (82.7±8)]; (p=0.013; p<0.001 and p=0.007) respectively. Fasting serum glucose level (mmol/1, M±SD) were significantly higher in Group II compared to Group I (18.5±6.01 vs 11.2±4.2; P<0.001). Serum glucose at 2 h after 75 g glucose administration were found to be (18.3±5.9) in Group I and (17.7±5.7) in Group II; (p=0.477). There was no significant difference in the two Groups. Sernm total cholesterol (mg/di, M±SD) were significantly higher in Group II compared to Group I (226±47 vs 207±34.2; P<0.001). Serum triglyceride (gm/di, M±SD) were significantly higher in Group II compared to Group I (218±85.5 vs 172±67.3; P<0.001). Serum HDL levels also significantly higher in Group I (47±8.1) as compare to Group II (39.8±10); (p=0.004). Serum homocysteine (µmol/L,, M±SD) were also significantly higher then compare to Group I (7.6±1.5) and Group II (14.5±5.8); (p<0.001). 37.6% subjects were in Group II their homocysteine level was below cut off value (<12 µmol/L) and 62.4% subjects were above cut off value of homocysteine level. The daily mean intake of dietary folate (mg/day, M±SD) in the study subjects as follows: as Group I (7.7±1.8) and Group II (1.8±0.93) respectively (p<0.001 ). Daily vitamin B6 as follows: as Group I (1.6±0.38) and Group II (1.0±0.61) respectively (p<0.001). And daily vitamin B12 as follows: as Group I (277±74.1) and Group II (119.1±29.8) respectively (p<0.001). There was significant difference in dietary intake folate, vitamins B6 and B12 in between the two Groups. On the coefficient correlation of homocysteine with other variables. From the data, a highly positive correlation of homocysteine was found with BMI, duration of OM, habit of exercise fasting blood glucose level and serum triglyceride (r=0.468, p= 0.050; t=0.392, p<0.001; r=0.181,p=0.009; r=0.332, p<0.001 and r=0.146; p=0.035) andnegative correlation was found between dietary folate, vitamin B6 and B 12 (r=- 0.563,p<0.001;1=-0.379 ,p<0.00 l and r=-0.484) respectively (p<0.001) among the Group II. On further analysis by multiple linear regressions Hyperhomocystenemia was found to have significant negative association only with dietary folate and vitamin B6 (ð€€•=-0.408; p<0.001 and ð€€–=-0.128; p=0.053) when the effects of Age, BMI and groups were adjusted. From the above discussion it may be concluded that, Hyperhomocysteneimia is a important risk factor of cardiovascular disease in Bangladeshi diabetic population. Dietary deficiency of folate and vit B6 are the major determinants of hyperhomocystienemia in type 2 diabetic subjects.