LAUSR

Abstract Some clinical studies reported that glucose variability increased the risk of developing diabetes-related late complications more than constant hyperglycemia, while others claimed that the evidence was not strong enough to support such a conclusion. A few in vitro studies investigated the effect of constantly high or variable glucose levels (VGLs) on endothelial cells (EC). The first aim of this work was to review these studies and demonstrate that most of them support the notion that viability and other metabolic parameters of EC deteriorate faster in cell cultures with VGLs than in cultures with stable normal or high glucose concentration. The second aim was to verify whether the effect of glucose concentration is the same regardless of other culture conditions such as the substrate on which the cells are grown. We cultured Human Umbilical Vein Endothelial Cells (HUVECs) for 7 or 14 days in constant (5 mM or 20 mM) or variable (switching between 5 mM and 20 mM once a day) glucose concentration in culture plates, which were either not-covered with any additional substrate or were covered with fibronectin or gelatin. We assessed the cell viability using a propidium iodide test. The ANOVA revealed that HUVECs viability was affected not only by glucose concentration and duration of the cell culturing but also by the type of substrate and interactions of these three factors. In conclusion, the effect of glucose level on EC viability should not be analyzed in isolation from other culture conditions that may amplify or attenuate this effect.