Study On The Relationship Between Homocysteine And Type 2 Diabetes & Its Complications

Hyperhomocysteinemia has emerged as an important and independent risk factorfor cardiovascular diseases. The purpose of this study is to assess the relationshipbetween tHcy, MTHFR gene polymorphism and diabetes and its complications.Methods:To measure the plasma tHcy concentration and folate level in 84 healthyindividuals and 266 2TDM subjects (classified into four groups, i.e. NDC, DN,DR and DC) by rHPLC and radioimmunoassay, respectively and detect theMTHFR 677CT and MTHFR1298AC gene polymorphism by PCR-RFLP tocompare tHcy, folate, MTHFR677CT and MTHFR1298AC genotype distributionand allele frequencies among groups.Results:1. All the chromatograms show that the peaks are well separated. When the sample is reduced with NaHB4 and eluted with phosphate, the lower limit of detection is 1.0μmol/L ,the intra-assay is 4.48%, the inter-assay is 4.20%, and recovery is 98.62?5.05%;2. Patients with diabetic complications have higher tHcy levels than control andnon-diabetes complications subjects(DN14.335 0.491 μmol/L, DR14.197+ 7.504μmol/L, DC18.921 ?.710μmol/L vs CON9.870?.249μmol/L, NDC 10.004+4.728μmol/L)(P<0.001)), and have lower folate levels;3. Patients in DN, DR and DC groups with HHcy are more than those in CON andNDC groups (35.9%, 43.2%* 65.2%vsl.2% 17.4%, P<0.01);4. For the MTHFR677CT mutation, the genotype frequencies for the DMC groupsare higher than those for CON and NCD groups(28.1%, 22.7%, 35.9% vs 14.3%, 18.5% and 45.3%, 40.9%, 51.5% vs 29.2%, 32.1%)(P<0.001); Themutation is associated with higher plasma tHcy levels (17.80100.059μmol/L, 5.575?.132μmol/L vs 8.692?.956μmol/L) (P<0.05) and lower folate concentration;5. There are no significant differences hi MTHFR1298AC genotype distributionand allele frequencies in five groups, neither are tHcy and folate levels between mutant and wide type(P>0.05);6. When two genotypes are combined to analyse, the tHcy levels are significantlyincreased for mutant state (P<0.01). There appears no subjects with 677TT/ 1298AC and 677TT/1298CC genotype in this study;7. The factors correlated with plasma tHcy level are plasma folate concentration,MTHFR677CT genotype and age by multivariate stepwise regression analysis(R=0.718, R2=0.516, P=0.000);8. A logistic regression analysis demonstrates that tHcy is an independent predictor of DM, DR and DC with odds ratios (95%CI) of 1.109(1.019-1.207) (P=0.017), 1.201(1.051-1.372) (P=0.007), 1.678(1.342-2.099) (P=0.000). Conclution:The determination of plasma tHcy by rHPLC is precise and repeatable, and the method is applicable to routine quantitative analysis of tHcy hi clinical and research laboratory. The folate level in plasma and MTHFR genotype are the parameters of the stronger association with tHcy. HHcy is the dangerous factor to DN, DR and DC. It is significant to reduce the incidence of diabetes complications if earlier prevention and correction of HHcy can be done. The supplement of folate is expected to reach it.