A comparison of post-prandial changes in flow-mediated dilatation in patients with type 2 diabetes with and without macroalbuminuria.

During the post-prandial period there is a decrease in systemic vascular resistance. This study compared meal-induced changes in flow-mediated dilatation (FMD) in patients with Type 2 diabetes with and without evidence of diabetic nephropathy as defined by the presence of macroalbuminuria. The effects on FMD of other factors such as smoking history, antihypertensive treatment and insulin use were also examined. Twelve patients with macroalbuminuria (>300 mg albumin/day) and 12 age- and sex-matched patients with normoalbuminuria (<50 mg albumin/day) participated in the study. Following a 12-hr overnight fast, forearm basal and reactive hyperaemic blood flow was assessed by venous occlusion plethysmography before and 2-hr after ingestion of a meal (2750 kJ) consisting of 56% fat, 26% carbohydrate and 16% protein. Plasma lipid and glycaemic indices were measured at the same times. The combined and grouped data was analysed using paired t tests and correlation and regression analyses. The meal resulted in significant increases in plasma glucose and triglyceride concentrations. While the meal resulted in a similar increase in basal blood flow rate in both patient groups, post-meal reactive hyperaemic flow increased significantly (p=0.04) in normoalbuminuric patients (mean individual increase: 33%) but remained unchanged in patients with macroalbuminuria (mean individual increase: 4%). The use of antihypertensive agents and insulin was also associated with an attenuated post-prandial hyperaemic response. In summary, our study demonstrated that the degree of renal impairment in patients with Type 2 diabetes may influence vasoactivity following a meal. Patients with evidence of diabetic nephropathy had a decreased post-prandial hyperaemic response, a result that indicated a reduced vasodilator reserve. The mechanism of this reduction in vasodilatation of peripheral vessels during the post-prandial period is probably multi-factorial. These changes in vasoactivity have the potential to combine with other cardiovascular risk factors to enhance the development of atheroma.