Effect of glucose variability on pathways associated with glucotoxicity in diabetes: Evaluation of a novel in vitro experimental approach.
OBJECTIVE
Glycaemic variability (GV) has been hypothesized to increase the risk of diabetes complications; however, results of clinical studies are contradictory. The effect of GV on cell phenotypes has been investigated in vitro showing that GV may have more deleterious effect on cells that high glucose itself. However, methodology used to study GV in vitro differs significantly between studies and does not reflect in vivo situation. Therefore we aimed to establish clinically relevant an in vitro experimental approach for the study of GV that reflects intra-day glucose fluctuations of subjects with type 1 diabetes mellitus (T1DM) and of healthy subjects and to test how low and high GV affect expression of genes that protects cells from hyperglycaemia-induced damage.


METHODS
Human umbilical vein endothelial cells (HUVEC) were cultured 24h in medium with different glucose profiles: high GV, low GV and GV of healthy subjects-profiles created according to CGM of T1DM patients and healthy subjects. These profiles were compared to commonly used 5.5 and 25mmol/l glucose concentrations. Gene expression was determined using quantitative PCR.


RESULTS
Our results showed general down-regulation of enzymes that are involved in the protection against hyperglycaemia-induced intracellular changes in both low and high GV compared to normal glycaemia similarly to the decrease induced by continuous hyperglycaemia. Gene expressions did not differ between high and low GV.


CONCLUSIONS
Our data indicate that GV may have similar or even greater effect than continuous hyperglycaemia on the expression of several genes relevant to pathogenesis of diabetes microvascular complications.
Department of Pathophysiology, Faculty of Medicine, Masaryk University, Brno, Czech Republic.
Katarína
K
Kuricová
Department of Pathophysiology, Faculty of Medicine, Masaryk University, Brno, Czech Republic.
Lukáš
L
Pácal
3rd Department of Internal Medicine, 1st Faculty of Medicine, Charles University, Prague, Czech Republic.
Jan
J
Šoupal
3rd Department of Internal Medicine, 1st Faculty of Medicine, Charles University, Prague, Czech Republic. Electronic address: mpra@lf1.cuni.cz.
Martin
M
Prázný
Department of Pathophysiology, Faculty of Medicine, Masaryk University, Brno, Czech Republic.
Kateřina
K
Kaňková
D017209:Apoptosis / Q000187:drug effects; D015415:Biomarkers / Q000378:metabolism*; D001786:Blood Glucose / Q000378:metabolism; D016022:Case-Control Studies; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D003922:Diabetes Mellitus, Type 1 / Q000150:complications* / Q000188:drug therapy / Q000503:physiopathology; D020869:Gene Expression Profiling; D005947:Glucose / Q000009:adverse effects*; D061307:Human Umbilical Vein Endothelial Cells / Q000187:drug effects* / Q000378:metabolism; D006801:Humans; D006943:Hyperglycemia / Q000209:etiology* / Q000473:pathology; D007003:Hypoglycemia / Q000209:etiology* / Q000473:pathology; D066298:In Vitro Techniques; D020411:Oligonucleotide Array Sequence Analysis; D012333:RNA, Messenger / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction
D015415:Biomarkers; D001786:Blood Glucose; D012333:RNA, Messenger; D005947:Glucose
Continuous glucose monitoring; Diabetes complications; Glycaemic variability; Hyperglycaemia; Hypoglycaemia; Pentose phosphate pathway