Serum calcineurin activity in relation to oxidative stress and glycemic control in type II diabetes mellitus

Objectives: In view of the well-recognized prevalence of oxidative stress in diabetes mellitus and the susceptibility of calcineurin (Ca2+-calmodulin dependent protein phosphatase 2 B) to free radicals, calcineurin was assayed in the sera of type II diabetic patients. Design and methods: Serum contents of thiobarbituric acid reactive substances, calcineurin and calmodulin, as well as activities of calcineurin and superoxide dismutase were measured in 81 diabetic patients and compared with age-matched controls. Results: Oxidative stress in diabetic subjects was evidenced by increased thiobarbituric acid reactive substances, decreased superoxide dismutase activity concomitant with decreased calcineurin activity in sera. The observed decrease in calcineurin activity had a reciprocal correlation with fasting blood sugar, thiobarbituric acid reactive substances, and glycosylated hemoglobin. Conclusion: The inverse correlation observed between serum calcineurin activity and glycosylated hemoglobin levels suggests that an assay of serum calcineurin activity may be useful in simultaneous assessment of oxidative stress and glycemic control in type II diabetes mellitus.