Objective: Previous studies have suggested that the e4 allele of apolipoprotein E (apo E) relates to the endothelium-dependent arterial dilation in men with type 2 diabetes. This study attempted to assess whether apo e4 allele is associated with endothelial dysfunction in women with type 2 diabetes.
Research design and methods: We selected 144 Chinese Han female type 2 diabetic patients without clinically detectable angiopathy. Polymerase chain reaction/ASO probes were used to determine their mouthwash DNA apo E genotypes, and high-resolution ultrasound was used to measure brachial artery diameter at rest, after reactive hyperemia (with increased flow causing endothelium-dependent dilation) and after sublingual glyceryltrinitrate (GTN, an endothelium-independent dilator).
Results: The flow-mediated arterial dilation among the subjects with e4/3 or e4/4 was 3.56+/-0.23%, which was significantly lower than that in subjects with e2/2 or e3/2 (3.97+/-0.36%) (p=0.000). The baseline vessel size, GTN-induced dilation and baseline blood flows were not significantly different among different apo E genotypes. On univariate analysis, reduced flow-mediated arterial dilation was significantly related to total cholesterol, LDL, Lp(a), high blood pressure, older age, family history of premature vascular disease, larger vessel size, duration of diabetes and e4 allele (p<0.05). By multiple stepwise regression analysis, reduced flow-mediated arterial dilation was associated with older age, large vessel size, duration of diabetes, positive family history, LDL, Lp(a) and e4 allele (p<0.01).
Conclusion: The apo e4 allele is associated with impairment of endothelium-dependent arterial dilation in the relatively early stage of female type 2 diabetes.