Fluctuating hyperglycaemia increases oxidative stress response in lean rats compared to sustained hyperglycaemia despite lower glycaemic exposure.

OBJECTIVE: To compare the effect of fluctuating glucose with sustained hyperglycaemia on systemic oxidative stress during 72 h of glucose infusion. METHODS: Catheterised male Sprague-Dawley rats were given either a continuous high (CHG), low (CLG) or pulsatile (FLU) infusion of glucose or saline (VEH) for 72 h. Plasma ascorbate oxidation ratio (AOR) and malondialdehyde (MDA) were used as biomarkers of oxidative stress and damage. RESULTS: The FLU group showed significant increases in both plasma AOR and MDA at 48 and 72 h (p < 0.05 all cases), whereas the CHG group, despite being infused with three times the amount of glucose, only showed increased MDA levels at 72 h time point (p < 0.05). CONCLUSION: Our data suggests that fluctuating glucose levels lead to oxidative stress similar to that of sustained hyperglycaemia despite a much lower total glycaemic exposure. Thus, our data supports the notion that fluctuating glucose may be relatively more deleterious than sustained hyperglycaemia.