Total Radical-Trapping Antioxidant Parameter in NIDDM Patients

Antonio Ceriello; Nadia Bortolotti; Edmondo Falleti; Claudio Taboga; Laura Tonutti; Adriana Crescentini; Enrico Motz; Sebastiano Lizzio; Assunta Russo; Ettore Bartoli

doi:10.2337/diacare.20.2.194

Original Articles

Total Radical-Trapping Antioxidant Parameter in NIDDM Patients

Antonio Ceriello, MD,
Nadia Bortolotti, PHD,
Edmondo Falleti, PHD,
Claudio Taboga, MD,
Laura Tonutti, MD,
Adriana Crescentini,
Enrico Motz, MD,
Sebastiano Lizzio, MD,
Assunta Russo, MD and
Ettore Bartoli, MD

Department of Medicine and Pathology, Clinical and Experimental, University of Udine, Chair of Internal Medicine, Udine General Hospital Udine, Italy
Chair of Clinical Pathology, Udine General Hospital Udine, Italy
Diabetology Unit, Udine General Hospital Udine, Italy

Address correspondence and reprint requests to Antonio Ceriello, MD, Chair of Internal Medicine, University of Udine, Pie S. Maria della Misericordia, 33100 Udine, Italy.

Diabetes Care 1997 Feb; 20(2): 194-197. https://doi.org/10.2337/diacare.20.2.194

Abstract

OBJECTIVE The existence of an oxidative stress in diabetes is still debated. This is largely due to the lack of good tools to assay the level of oxidative stress. The use of total radical-trapping antioxidant parameter (TRAP) has recently been proposed to explore the antioxidant property of a plasma sample. TRAP may be either directly measured by a fluorescence-based method (TRAPm) or calculated (TRAPc) by a mathematical formula, taking into account the serum levels of four natural antioxidants: protein-bound SH (thiol) groups, uric acid, vitamin E, and vitamin C. The difference between TRAPm and TRAPc is due to antioxidants, which are still unidentified, and to the possible synergism among the antioxidants.

RESEARCH DESIGN AND METHODS In this study, we evaluated malondialdehyde (MDA), TRAPm, TRAPc, protein-bound SH groups, uric acid, vitamin E, and vitamin C in 40 NIDDM patients and 40 matched normal control subjects.

RESULTS TRAPm and TRAPc were significantly lower in diabetic patients. A good correlation between TRAPm and TRAPc was found in both NIDDM patients (r = 0.68, P < 0.0001) and control subjects (r = 0.74, P < 0.0001). Protein-bound SH groups and uric acid were significantly lower in diabetic subjects, while MDA and vitamin E level were significantly higher. After correction for serum triglycerides (MDA) and cholesterol (vitamin E), MDA lost significance, while vitamin E did not. Vitamin C was not different in the two groups.

CONCLUSIONS These data show decreased TRAP levels in NIDDM patients, suggesting the existence of lower antioxidant defenses in diabetes. The decrease appears to be due to various antioxidants, some of them not yet clearly defined. TRAP may represent a more reliable estimation of serum antioxidant capacity than the measurement of each known antioxidants. The correlation found between TRAPm and TRAPc values suggests that TRAPc, easier to measure than TRAPm, might be adequately reliable for routine assessment of oxidative stress in diabetic patients.