Endocrine Abstracts

Background: Many in vitro studies have suggested that oxidative stress induced by hyperglycemic condition has pivotal role for pathogenesis of vascular complications in diabetics. This study intended to evaluate oxidative stress and antioxidant potential in patients with type 2 diabetes mellitus (DM), and to clarify the relation between oxidative stress and metabolic derangements including chronic hyperglycemia.

Materials and methods: We measured the levels of derivatives of reactive oxidative metabolites (ROM) and biological antioxidant potential (BAP) in 59 patients with type 2 DM and 10 healthy controls. Values for ROM and BAP were assessed using Free Radical Analytical System 4 (FRAS4; H&D srl, Parma, Italy). The adjusted BAP/ROM ratio was calculated by dividing the BAP/ROM ratio by 7.510, which was the average value obtained from healthy Japanese adults, and thus the data were standardized to a level 1.00.

Results: ROM levels in patients with type 2 DM increased significantly compared with those in controls (370±69 vs. 299±23 CARR U, respectively; p < 0.01). There were no differences in BAP levels between the two groups. On the other hand, adjusted BAP/ROM ratios were significantly decreased in patients with type 2 DM compared with those in controls (0.84±0.20 vs. 0.98±0.17 μM/CARR U, p< 0.05). It was found that ROM levels positively correlated with HbA1c, plasma glucose, and waist size, and adjusted BAP/ROM ratios negatively correlated with HbA1c, plasma glucose, waist size, and serum triglycerides. Stepwise multiple regression analysis indicated that HbA1c and waist size were independent factors contributing to the elevated ROM levels. The ROM level in type 2 DM patients complicated with metabolic syndrome was significantly 10% higher than that in DM patients without metabolic syndrome (p<0.05). Treatment with either glimepiride(n=10), miglitol (n=5)or vildagliptin(n=13) for 3 months improved HbA1c level from 11.1% to 7.4%, 6.8% to 6.4%, 7.6% to 6.9% and reduced ROM levels significantly by 13%*, 4%*, 7%*(from 330±46 to 290±45, from 337±66 to 322±61, from 289±40 to 269±49 CARR U, *P<0.05), respectively.

Conclusions: These results clearly demonstrate that glycemic control and visceral obesity are independently associated with an increasing oxidative stress in patients with type 2 DM.

Declaration of interest: The authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project.

Funding: This research did not receive any specific grant from any funding agency in the public, commercial or not-for-profit sector.