Hyperhomocysteinemia and impaired vasomotor function in type 2 diabetes mellitus.
BACKGROUND
Hyperhomocysteinemia has been shown to adversely affect vascular function. The aim of this study was to determine whether hyperhomocysteinemia was independently associated with changes in endothelium-dependent and -independent vasomotor functions in patients with type 2 diabetes mellitus.


METHODS
Fasting homocysteine (tHcy) was measured in 123 patients with type 2 diabetes and in 61 nondiabetic controls. Endothelium-dependent and -independent vasodilation was measured using high-resolution vascular ultrasound.


RESULTS
Plasma tHcy concentration was increased in the diabetic patients (11.1 +/- 3.7 micromol L(-1) vs. 9.8 +/- 2.9, P < 0.05). The prevalence of hyperhomocysteinemia (defined as tHcy > 15 micromol L(-1)) was higher in the diabetic patients (P < 0.05). Within group comparisons showed that both the abnormalities in endothelium-dependent and -independent vasodilation were significantly more severe in diabetic patients with tHcy 10-15 (P < 0.05) and tHcy > 15 micromol L(-1) (P < 0.05) than in those patients with tHcy < 10 micromol L(-1). When compared with nondiabetic controls matched for tHcy levels, impairment of endothelium-dependent and -independent vasodilation were already evident, even in patients with normal tHcy levels (P < 0.01). Despite significant univariate relationships between tHcy and endothelium-dependent (r = -0.24, P < 0.01) and -independent vasodilation (r = -0.33, P < 0.01) in patients with diabetes, only the relationship between tHcy and endothelium-independent vasodilation remained significant after adjusting for other cardiovascular risk factors in multiple regression analysis.


CONCLUSIONS
Impairment of endothelium-dependent and -independent vasodilation was already present in diabetic patients with normal tHcy levels, and these abnormalities became more severe with increasing tHcy levels. Only the association between tHcy and endothelium-independent vasodilation was free of other cardiovascular risk factors.
Tan
K C B
KC
Department of Medicine, University of Hong Kong, Hong Kong. kcbtan@hkucc.hku.hk
O
Karmin
K
Chow
W-S
WS
Ai
V H G
VH
Siow
Y L
YL
Lam
K S L
KS
D000328:Adult; D001916:Brachial Artery / Q000000981:diagnostic imaging; D003924:Diabetes Mellitus, Type 2 / Q000097:blood / Q000150:complications / Q000503:physiopathology*; D004730:Endothelium, Vascular / Q000000981:diagnostic imaging / Q000502:physiology*; D005260:Female; D006710:Homocysteine / Q000097:blood; D006801:Humans; D020138:Hyperhomocysteinemia / Q000097:blood / Q000150:complications* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D014463:Ultrasonography; D014664:Vasodilation / Q000502:physiology*
D006710:Homocysteine