Abnormal retinal vascular reactivity in individuals with impaired glucose tolerance:a preliminary study

To investigate the relationship between vascular function parameters measured at the retinal and systemic level and known markers for cardiovascular risk in patients with impaired glucose tolerance (IGT). Sixty age- and gender- matched White-European adults (30 IGT and 30 normal glucose tolerance -NGT) were recruited for the study. Fasting plasma glucose, lipids and 24-hour blood pressure (BP) was measured in all subjects. Systemic vascular and endothelial function was assessed using carotid-artery intimal media thickness (cIMT) and flow mediated dilation (FMD). Retinal vascular reactivity was assessed by the Dynamic Retinal Vessel Analyser (DVA). Additionally, blood glutathione (GSH, GSSG and tGSH) and plasma von-Willebrand (vWF) factor levels were also measured. Individuals with IGT demonstrated higher BP values (p<0.001), fasting TG and TG:HDL ratios (p<0.001) than NGT subjects. Furthermore, Total:HDL-C ratios and Framingham scores were raised (p=0.010 and p<0.001 respectively). Blood glutathione levels (GSH, GSSG and tGSH) were lower (p<0.001, p=0.039 and p<0.001 respectively) while plasma vWF was increased (p=0.014) in IGT subjects compared to controls. IGT individuals also demonstrated higher IMT in right and left carotid arteries (p=0.017 and p=0.005, respectively) alongside larger brachial artery diameter (p=0.015), lower FMD% (p=0.026) and GTN induced dilation (GID) (p=0.012) than healthy controls. At the retinal arterial level, the IGT subjects showed higher baseline fluctuations (BDF) (p=0.026), longer reaction time (RT) (p=0.032) and reduced baseline-corrected flicker response (bFR) (p=0.045). In IGT subjects retinal BDF correlated with and Total:HDL (p= 0.003) and HDL-C (p= 0.004). Arterial RT also correlated with FMD (p=0.017) in IGT but not NGT subjects. In IGT individuals there is a relationship between macro- and microvascular function, as well as a direct correlation between the observed retinal microcirculatory changes and established plasma markers for CVD. Multifactorial preventive interventions to decrease vascular risk in these individuals should be considered.

Overweight status is associated with extensive signs of microvascular dysfunction and cardiovascular risk

The aim of this present study was to investigate if overweight individuals exhibit signs of vascular dysfunction associated with a high risk for cardiovascular disease (CVD). One hundred lean and 100 overweight participants were recruited for the present study. Retinal microvascular function was assessed using the Dynamic Retinal Vessel Analyser (DVA), and systemic macrovascular function by means of flow-mediated dilation (FMD). Investigations also included body composition, carotid intimal-media thickness (c-IMT), ambulatory blood pressure monitoring (BP), fasting plasma glucose, triglycerides (TG), cholesterol levels (HDL-C and LDL-C), and plasma von Willebrand factor (vWF). Overweight individuals presented with higher right and left c-IMT (p = 0.005 and p = 0.002, respectively), average 24-h BP values (all p <0.001), plasma glucose (p = 0.008), TG (p = 0.003), TG: HDL-C ratio (p = 0.010), and vWF levels (p = 0.004). Moreover, overweight individuals showed lower retinal arterial microvascular dilation (p = 0.039) and baseline-corrected flicker (bFR) responses (p = 0.022), as well as, prolonged dilation reaction time (RT, p = 0.047). These observations emphasise the importance of vascular screening and consideration of preventive interventions to decrease vascular risk in all individuals with adiposity above normal range.