Plasma homocysteine concentrations and insulin sensitivity in hypertensivesubjects

Hyperhomocysteinemia is associated with several cardiovascular disease risk factors including endothelial dysfunction and abnormalities of clotting fu nctions, which are also common features of insulin resistance syndrome obse rved in hypertensive patients. Recent study has shown that acute hyperinsul inemia can lower plasma homocysteine concentrations in nondiabetic but not in type 2 diabetic individuals, indicating that insulin may regulate homocy steine metabolism. To investigate the relationships between plasma homocyst eine concentration and insulin sensitivity, we studied 90 Chinese hypertens ive patients and a group of control subjects (n = 86) matched for age, gend er, and body mass index. Fasting plasma homocysteine levels, plasma lipopro tein concentrations, plasma glucose, and insulin responses to oral glucose tolerance tests (OGTT) were determined. The results showed that fasting pla sma homocysteine concentrations were significantly higher in subjects with hypertension than in those with normotension (mean +/- SEM, 8.1 +/- 0.6 v 6 .8 +/- 0.2 mu mol/L; P < .05). Fasting plasma homocysteine levels correlate d significantly with insulin secretion in response to OGTT even after adjus tment for body mass index (P < .05) in hypertensive patients but not in nor motensive individuals. However, fasting plasma homocysteine concentrations showed no correlations with steady-state plasma glucose concentration, a me asurement of insulin sensitivity, during an insulin suppression test in gro ups of hypertensive (n = 42) and normotensive (n = 37) subjects. When the s teady-state plasma glucose concentrations were divided into three tertiles, fasting plasma homocysteine concentrations showed no difference across the se three groups in either hypertensive patients (8.6 +/- 0.5 v 7.2 +/- 0.5 v 8.4 +/- 0.6 mu mol/L; P = .148) or normotensive subjects (6.3 +/- 0.4 v 8 .0 +/- 0.8 v 7.0 +/- 0.8 mu mol/L; P = .199). in conclusion, hypertensive C hinese subjects had higher fasting plasma homocysteine concentrations and a higher degree of insulin resistance when compared to a group of age-, gend er-, and body mass index-matched normotensive individuals. pasting plasma h omocysteine levels were associated with insulin response to OGTT in hyperte nsives but not in normotensives. No correlation tvas observed between the d egree of insulin resistance and plasma homocysteine levels in either the hy pertensive or the normotensive group. The role of insulin in homocysteine m etabolism deserves further investigation. (C) 2000 American Journal of Hype rtension, Ltd.