Effects of an oral glucose challenge on free radicals/antioxidants balance in an older population with type II diabetes

J Gerontol A Biol Sci Med Sci. 1999 Nov;54(11):M541-5. doi: 10.1093/gerona/54.11.m541.


Background: Our goal was to assess the effect of chronic vs acute hyperglycemia on free radicals (FR)/antioxidants balance in serum and leukocytes in an older (>65 years old) population with type II diabetes mellitus (DM).

Methods: Case-control study comparing older male patients with type II DM with normal controls. FRs and antioxidants were measured at baseline and 120 min after an oral 100-g glucose load.

Results: Baseline measurements showed an increased level of oxidized glutathione (GSSG) (p = .01) in the serum of diabetic subjects. Similar findings were observed at the intracellular level in the same group for GSSG (p = .0004), total glutathione (GSH + GSSG) (p = .0001) (GSH is reduced glutathione), decreased GSH/GSSG ratio (p = .0001), and ascorbic acid (p = .008). Monocytes from diabetic subjects produced larger amounts of nitric oxide (NO) in vitro (p = .03). After the oral glucose challenge, between-group comparisons demonstrated similar findings at the intracellular level for increased oxidized glutathione (p = .0004), GSH + GSSG (p = .0001), decreased GSH/GSSG (p = .0001), ascorbic acid (p = .02), and increased NO (p = .02) for the diabetic subjects. Within-group comparisons showed a significant drop of ascorbic acid in the control and the diabetic groups (p < .01), an increased level of GSSG in the diabetic group (p < .01), a decreased GSH/GSSG ratio (p < .05), and decreased production of NO by monocytes after in vitro stimulation in the control group (p < .05).

Conclusions: Our results suggest that type II diabetes in an older population is associated with increased basal oxidative stress. Hyperglycemic challenge is associated with an accentuation of this phenomenon as measured in the leukocytes.

MeSH terms

  • Administration, Oral
  • Aged
  • Antioxidants / metabolism*
  • Ascorbic Acid / metabolism
  • Case-Control Studies
  • Diabetes Mellitus, Type 2 / metabolism*
  • Free Radicals
  • Glucose / pharmacology*
  • Glutathione / metabolism
  • Glutathione Disulfide / metabolism
  • Humans
  • Male
  • Nitric Oxide / metabolism


  • Antioxidants
  • Free Radicals
  • Nitric Oxide
  • Glutathione
  • Glucose
  • Ascorbic Acid
  • Glutathione Disulfide