Abnormal Retinal Vascular Reactivity in Individuals with Impaired Glucose Tolerance: A Preliminary Study

Abstract

PURPOSE. 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). METHODS.Sixty age-and sex-matched white European adults (30 with IGT and 30 with normal glucose tolerance [NGT]) were recruited for the study. Fasting plasma glucose, lipids, and 24-hour blood pressure (BP) were measured in all subjects. Systemic vascular and endothelial function was assessed by using carotid-artery intimal media thickness (cIMT) and flowmediated dilation (FMD). Retinal vascular reactivity was assessed by the dynamic retinal vessel analyzer. Additionally, blood glutathione (reduced glutathione [GSH], glutathione disulfide [GSSG], and total glutathione [tGSH]) and plasma von Willebrand (vWF) factor levels were also measured.RESULTS. Individuals with IGT demonstrated higher BP values (P < 0.001), fasting triglyceride (TG) levels and TG:high-density lipoprotein (HDL) ratios (P < 0.001) than NGT subjects. Furthermore, total:HDL-cholesterol (HDL-C) ratios and Framingham scores were raised (P ¼ 0.010 and P < 0.001, respectively). Blood glutathione levels (GSH, GSSG, and tGSH) were lower (P < 0.001, P ¼ 0.039, and P < 0.001, respectively) while plasma vWF was increased (P ¼ 0.014) in IGT subjects compared to controls. IGT individuals also demonstrated higher IMT in right and left carotid arteries (P ¼ 0.017 and P ¼ 0.005, respectively) alongside larger brachial artery diameter (P ¼ 0.015) and lower FMD percentage (P ¼ 0.026) and glyceryl trinitrate-induced dilation (P ¼ 0.012) than healthy controls. At the retinal arterial level, the IGT subjects showed higher baseline diameter fluctuations (BDFs) (P ¼ 0.026), longer reaction time (RT) (P ¼ 0.032), and reduced baseline-corrected flicker response (bFR) (P ¼ 0.045). In IGT subjects, retinal BDF correlated with total:HDL (P ¼ 0.003) and HDL-C (P ¼ 0.004). Arterial RT also correlated with FMD (P ¼ 0.017) in IGT but not NGT subjects.CONCLUSIONS. 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 cardiovascular diseases. Multifactorial preventive interventions to decrease vascular risk in these individuals should be considered. (Invest Ophthalmol Vis Sci. 2012;53:5102-5108)

Ageing effect on flicker‐induced diameter changes in retinal microvessels of healthy individuals

“…In previous studies, we have already documented that individuals with various levels of cardiovascular risk exhibit abnormal retinal and venous responses to flicker-induced provocation (Mroczkowska et al 2012(Mroczkowska et al , 2013Patel et al 2012;Qin et al 2014). In the present study, in a sample with low CVD risk, decreases in the postflicker constrictory phase of retinal veins were apparent in the middle-aged and older individuals only.…”

“…) and impaired glucose tolerance (Patel et al. ). Therefore, it is possible to use the assessment of retinal microvascular function as an early marker for vascular and endothelial dysfunction.…”

“…assessment is that it provides integrated and dynamic data analysis that is specific to each individual. In addition, its output has proven to be modified not only by overt disease but also in the presence of more subtle risk factors for CVD (Pemp et al 2009;Reimann et al 2009;Kotliar et al 2011) including ethnicity (Patel et al 2011) and impaired glucose tolerance (Patel et al 2012). Therefore, it is possible to use the assessment of retinal microvascular function as an early marker for vascular and endothelial dysfunction.…”

The clinical implications of recent studies on the structure and function of the retinal microvasculature in diabetes

“…Several studies reported that the flicker light-induced vasodilation is reduced in individuals with diabetes [72][73][74][75][76] and those with impaired glucose tolerance [77], and is further impaired with increasing severity of diabetic retinopathy [72,73]. It has been suggested that endothelial dysfunction may underlie this reduced response in diabetes.…”

Retinal vascular function in asymptomatic individuals with a positive family history of cardiovascular disease

“…), altered lipid and oxidative stress marker levels (Seshadri et al. ,b) and impaired glucose tolerance (Patel et al …”