[The importance of oxidative stress in pathogenesis of type 1 diabetes--determination of catalase activity in lymphocytes of diabetic patients].

INTRODUCTION: Type 1 diabetes is a protoype of disease with an intensive oxidative stress. The oxidative stress means disturbing dynamic balance between prooxidants and antioxidants, either due to the increased production of the oxygen free radicals or the decreased antioxidant activity. The antioxidative enzyme catalase diminishes free radical hydrogen-peroxyde, which can be very toxic to pancreatic cells.

MATERIAL AND METHODS: Our study included 40 children with type 1 diabetes. We analysed the activity of enzyme catalase in lymphocytes in different phases of disease: at the beginning of diabetes, in remission period and in the later chronic course.

RESULTS: There is a significant increase in the catalase activity during all phases of disease (p<0.00001) compared with the control group. The highest catalase activity occurs in the early course of disease (p<0.05) followed by a linear decrease and the lowest activity in chronic course. If metabolic control gets worse, the catalase activity gets higher with statistic significance at p<0.05. A higher residual beta cells secretion is associated with a lower catalase activity. Therefore, the catalase activity is in direct corelation with GHbA1 (r=0.895), and inverse correlation with C-peptide (r=-0.945).

DISCUSSION AND CONCLUSION: A significant increase in the catalase activity in all phases of type 1 diabetes indirectly confirms the importance of the oxidative stress in pathogenesis of disease. The activation of catalase is probably the secundary phenomenon. The fact that the catalase activity reaches its highest values at the beginning of diabetes could implicate the predictive value of catalase determination.