Coenzyme Q10 improves endothelial dysfunction of the brachial artery in Type II diabetes mellitus

Abstract

In Type II (non-insulin-dependent) diabetes mellitus the pathogenesis of vascular disease, its most common complication, remains unclear [1]. Endothelial dysfunction reflects the disordered physiology of several endothelium-derived vasoactive factors, in particular nitric oxide [2]. Endothelial dysfunction occurs commonly in diabetes and is an early feature of vasculopathy [3,4]. Increased oxidative stress due to the effects of hyperglycaemia and its sequelae is a recognized feature of diabetes [5]. It might cause endothelial dysfunction through the inactivation and Abstract Aim/hypothesis. We assessed whether dietary supplementation with coenzyme Q 10 improves endothelial function of the brachial artery in patients with Type II (non-insulin-dependent) diabetes mellitus and dyslipidaemia. Methods. A total of 40 patients with Type II diabetes and dyslipidaemia were randomized to receive 200 mg of coenzyme Q 10 or placebo orally for 12 weeks. Endothelium-dependent and independent function of the brachial artery was measured as flowmediated dilatation and glyceryl-trinitrate-mediated dilatation, respectively. A computerized system was used to quantitate vessel diameter changes before and after intervention. Arterial function was compared with 18 non-diabetic subjects. Oxidative stress was assessed by measuring plasma F 2 -isoprostane concentrations, and plasma antioxidant status by oxygen radical absorbance capacity. Results. The diabetic patients had impaired flow-mediated dilation [3.8 % (SEM 0.5) vs 6.4 % (SEM 1.0), p = 0.016], but preserved glyceryl-trinitrate-mediated dilation, of the brachial artery compared with non-diabetic subjects. Flow-mediated dilation of the brachial artery increased by 1.6 % (SEM 0.3) with coenzyme Q 10 and decreased by ±0.4 % (SEM 0.5) with placebo (p = 0.005); there were no group differences in the changes in pre-stimulatory arterial diameter, post-ischaemic hyperaemia or glyceryl-trinitrate-mediated dilation response. Coenzyme Q 10 treatment resulted in a threefold increase in plasma coenzyme Q 10 (p < 0.001) but did not alter plasma F 2 -isoprostanes, oxygen radical absorbance capacity, lipid concentrations, glycaemic control or blood pressure. Conclusion/interpretation. Coenzyme Q 10 supplementation improves endothelial function of conduit arteries of the peripheral circulation in dyslipidaemic patients with Type II diabetes. The mechanism could involve increased endothelial release and/or activity of nitric oxide due to improvement in vascular oxidative stress, an effect that might not be reflected by changes in plasma F 2 -isoprostane concentrations. [Diabetologia (2002) 45: 420±426]

Hemodynamic Effects of Fenofibrate and Coenzyme Q10 in Type 2 Diabetic Subjects With Left Ventricular Diastolic Dysfunction

“…These doses and this duration of therapy were equivalent to those employed in previous clinical studies of these compounds (7,8,11). Participants underwent two echocardiograms at baseline and two at treatment end, with pre-and postintervention data taken as the mean value at each time point.…”

“…CoQ supplementation could improve LVDD by increasing myocardial energy production and decreasing oxidative stress, actions complementary to fenofibrate. CoQ improves endothelial function in type 2 diabetes (8), with modest beneficial effects on BP (9) and left ventricular (LV) systolic function (10).…”

Coenzyme Q10 in the treatment of hypertension: a meta-analysis of the clinical trials

“…15,17 In patients with diabetes or dyslipidemia, we have shown that CoQ 10 improves endothelial function and lowers blood pressure. 30 Investigators of hypertensive patients treated with CoQ 10 observed decreased peripheral resistance accompanying lowered blood pressure and unchanged cardiac output. 15,17 It should be noted however that in normal animals or humans, CoQ 10 has no direct vasodilating or hypotensive effect.…”

Biological correlates of day-to-day variation in flow-mediated dilation in individuals with Type 2 diabetes: a study of test?retest reliability

“…However, dietary [4] and pharmacological [5] interventions significantly improve endothelial function, even in this high-risk group. One non-invasive technique for assessing endothelial health uses ultrasound to examine the magnitude of the increase in diameter in the brachial artery after an increase in blood flow [6,7], a phenomenon called flow-mediated dilation (FMD) [8].…”