Oxidative stress parameters in type I, type II and insulin-treated type 2 diabetes mellitus; insulin treatment efficiency.

BACKGROUND: Our aim was to evaluate oxidative stress parameters on three groups of diabetic patients, insulin-dependent diabetes mellitus (IDDM), non-insulin-dependent diabetes mellitus (NIDDM), and insulin-treated type 2 diabetes mellitus (ITDM2), with similar HbA1c value and to determine if insulin's impact on these parameters was the same for IDDM and ITDM2.
METHODS: This study has been conducted on 18 IDDM, 55 NIDDM, 27 ITDM2, compared to 12 healthy subjects. Plasmatic concentrations of thiobarbituric acid reactive substances (TBARS), fatty acids, total antioxidant status (TAS), alpha-tocopherol, and erythrocyte reduced glutathione (GSH) were measured as well as enzymatic activities of superoxide dismutase (SOD), and glutathione peroxidase/reductase.
RESULTS: Diabetic patients have significant increase of SOD activity, of TBARS concentration (concomitant with low levels of unsaturated fatty acids) and significant decrease of GSH and alpha-tocopherol. NIDDM have significantly lower levels of GSH and higher levels of TBARS compared to IDDM. ITDM2 values are intermediate between IDDM and NIDDM but are far from reaching those of IDDM.
CONCLUSION: Diabetic patients undergo an important oxidative stress that is nearly corrected for IDDM, but only partially improved for ITDM2, although length of insulin treatment and HbA1c values are similar, suggesting metabolic differences between the two types of diabetes.