Possible link between glycated hemoglobin and lipid peroxidation in hyperthyroidism

Background: Glycated hemoglobin (HbA(1C)) levels are enhanced by elevated glucose concentrations. Glycation of hemoglobin is also modulated by lipid peroxides, ascorbic acid and reduced glutathione (GSH). We determined the strength of the relationships among these variables in a group of hyperthyroid patients. Methods: Twenty-two untreated hyperthyroid patients and 17 healthy controls were recruited for the study. Whole blood GSH, HbA(1C), plasma lipid peroxides, ascorbic acid and fasting glucose were analyzed in both the groups. Direct and partial correlation analysis was performed to explore the possible relationships between these variables. Results: In hyperthyroid patients, HbA(1C) and lipid peroxides levels were found to be significantly increased than the controls. Ascorbic acid and GSH were decreased significantly in the test group when compared with the healthy control group. With partial correlation analysis, fasting glucose and lipid peroxides were found to have a significant positive correlation with HbA(1C). Ascorbic acid and GSH showed no significant association with HbA(1C) levels. Conclusion: These data suggest that HbA(1C) levels are closely associated with fasting glucose and lipid peroxides in hyperthyroid patients. Therefore, serum lipid peroxides level should be kept in mind while interpreting HbA(1C) as a long-term glycemic index in hyperthyroid cases. (C) 2004 Elsevier B.V All rights reserved.