長期罹患糖尿病的患者最後併發動脈硬化合併症的結果會導致心血管及腦血管疾病。過去研究証實糖尿病患者血液中的同半胱氨酸(homocysteine; Hcy)濃度較正常個體高，這些增高的同半胱氨酸可能會造成動脈內皮損傷並促使血液凝集而促進動脈硬化。血液中同半胱氨酸濃度增加可視為急性心肌梗塞、腦血管疾病與動靜脈栓塞血管病灶的獨立危險因子。再甲基化代謝路徑的主要酵素methyltetrahydrofolate reductase (MTHFR)缺乏會導致同半胱氨酸濃度增高。MTHFR基因位於人類第一對染色體之短p臂的36.3位置上(1p36.3)，而且已知有許多單核酸多型性(single nucleotide polymorphisms; SNPs)會影響MTHFR酵素基因的功能。這些單核酸多型性的對偶基因本身與同半胱氨酸在第二型糖尿病患併發動脈硬化之間的關係仍然不是非常清楚。本篇研究主題是探討第二型糖尿病患者血液中同半胱氨酸濃度和其代謝酵素MTHFR C677T和A1298C基因多型性的關連性，同時也檢測上述基因型與冠狀動脈其它危險因子之間的相關性。本研究共採集56位T2DM患者和62位正常對照組的周邊血液，再利用聚合連鎖反應與限制分析MTHFR C677T和A1298C 基因的多型性。結果發現糖尿病病患併發動脈硬化的過程中，MTHFR A1298C或C677T的基因型可能與糖尿病的成因無關，但C677T的基因多型性與糖尿病病人的膽固醇、同半胱氨酸和收縮壓的臨床生化檢驗值有關。
The cardiovascular and cerebral vascular diseases complication found in patients with long diabetic mellitus duration can result in arteriosclerosis. Recent studies proved that circulatory homocysteine levels in patients with diabetes mellitus are higher than that in normal individuals, and the increased homocysteine may promote atherosclerosis by damaging the inner lining of arteries and promoting blood clots. In addition, increased blood homocysteine is an independent risk factor for several vasculopathies including arteriosclerosis, acute myocardial infraction, cerebrovascular diseases, arterial and venous thrombosis. Methyltetrahydrofolate reductase (MTHFR) deficiency of remethylation pathways are associated with elevated homocysteine concentrations. The MTHFR gene has been mapped to chromosome 1p36.3 and many single nucleotide polymorphisms (SNPs) that could affect its function have been detected within this gene. The allele frequencies of these SNPs and the role of homocysteine in the development of atherosclerosis in diabetic patients are still uncler. The aim of this study was to determine the relationship between blood total homocysteine (tHcy) levels and the C677T and A1298C polymorphisms of the MTHFR gene in patients with type 2 diabetes mellius﹐as well as to determine the relationship between the MTHFR polymorphisms with other coronary risk factors. Peripheral blood samples were collected and genomic DNA was extracted from 56 T2DM patients and 62 healthy control study subjects. MTHFR C677T and A1298C polymorphisms were analyzed by PCR and RFLP analysis. Our results demonstrated that though the C677T and A1298C polymorphisms of the MTHFR gene were not associated with type 2 diabetes mellius,C677T polymorphisms were associated with circulatory levels of cholesterol,honocysteine and diastolic pressure.
