WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT• Large clinical trials show that chronic use of GLP-1 agonists cause a fall in blood pressure independent of weight loss. Animal studies have shown acute haemodynamic and vasodilator effects of these drugs. The exact mechanism of the blood pressure drop and acute cardiovascular effects has not been studied in humans. WHAT THIS STUDY ADDS• This study shows that exenatide also has acute haemodynamic effects in humans. This study demonstrates direct vascular effects and potentially direct cardiac effects. This will enable future studies to look at GLP-1 agonists as aids in the treatment of cardiovascular disease in type 2 diabetes. AIMSIn clinical studies of glucagon-like peptide-1 (GLP-1) agonists used in the management of patients with type 2 diabetes, there is often a small accompanying fall in blood pressure. The mechanism underlying this effect is not known, although exenatide, a GLP-1 mimetic, has acute regional vasodilator properties in rats. We have therefore studied the haemodynamic effects of exenatide in healthy male volunteers. METHODSWe compared the effects of a single 10 mg subcutaneous injection of exenatide with placebo in a double-blind, randomized, crossover study. For 2 h after dosing, haemodynamic measurements were made using a Finometer, venous occlusion plethysmography and Doppler ultrasound. The urine sodium : creatinine excretion ratio was determined. RESULTSAt the end of the study when exenatide was compared with placebo, heart rate had risen by a mean of 8.2 (95% CI 4.2, 12.2, P < 0.01) beats min, cardiac output by a mean of 1.2 (95% CI 0.42, 20.3, P < 0.05) l min -1 and total peripheral resistance had fallen by 120 (95% CI -8, -233, P < 0.05) dyn s cm .There were no differences in blood pressure. The urinary sodium : creatinine ratio was increased by mean 12.4 (95% CI 4.6, 20.2, P < 0.05) mmol mmol -1 when exenatide was compared with placebo. CONCLUSIONSExenatide has significant haemodynamic effects in healthy volunteers. The results of this study are consistent with exenatide having both vasodilator and natriuretic properties. The vascular changes may contribute to the hypotensive effect of exenatide when used chronically in patients with diabetes.

Data from epidemiological and in vitro studies suggest that orange juice (OJ) may have a positive impact on lipid metabolism. However, there have been reports in the media claiming detrimental consequences of 100% juice consumption, including weight-gain and adverse effects on insulin sensitivity and blood lipid profile. The effect of daily OJ consumption was assessed using a randomised, placebo-controlled, single-blinded, parallel group design. Thirty-six overweight, but otherwise healthy men (40-60 years; 27-35 kg m(-2)) with elevated fasting serum cholesterol (5-7 mmol l(-1)), were recruited from the general UK population. None were using nutritional strategies or medication to lower their cholesterol, nor were regular consumers of citrus products. Assessment of BMI, HOMA-IR, and circulating lipid (total cholesterol, low-density lipoprotein, high-density lipoprotein, non-esterified fatty acids, triacylglycerol, apolipoprotein-A1 and apolipoprotein-B) concentrations, was made when fasted before (V1) and after a 12-week intervention (V2), during which participants consumed 250 ml per d of OJ or an energy and sugars-matched orange-flavoured drink (control). The two groups were matched at V1 with respect to all parameters described above. Although triacylglycerol concentration was similar between the groups at both visits, a trend for the change in this variable to differ between groups was observed (P = 0.060), with those in control exhibiting a significant increase in triacylglycerol at V2, compared with V1. In OJ, those with the highest initial triacylglycerol concentration showed the greatest reduction at V2 (R(2) = 0.579; P < 0.001), whereas there was no correlation between these variables in controls (R(2) = 0.023; P = 0.548). Twelve weeks consumption of 250 ml per d of OJ did not adversely affect insulin sensitivity, circulating lipids or body weight.