Age-Dependent Changes of Serum Oxygen Radical Scavenger Capacity and Haemoglobin Glycosylation in Non-Insulin-Dependent Diabetic Patients

• Published in: Gerontology (Basel) 2001-03, Vol.47 (2), p.88-92
• Main Authors: Pieri, C., Testa, R., Marra, M., Bonfigli, A.R., Manfrini, S., Testa, I.
• Format: Article
• Language: English
• Subjects: Adult; Age Factors; Aged; Aged, 80 and over; Biological and medical sciences; Body Mass Index; Clinical Section; Diabetes Mellitus, Type 2 - blood; Diabetes. Impaired glucose tolerance; Endocrine pancreas. Apud cells (diseases); Endocrinopathies; Etiopathogenesis. Screening. Investigations. Target tissue resistance; Female; Free Radical Scavengers - blood; Glycated Hemoglobin A - metabolism; Glycosylation; Hemoglobins - metabolism; Humans; Male; Medical sciences; Middle Aged; Oxygen - analysis; Oxygen - blood; Regression Analysis
• ISSN: 0304-324X; 1423-0003
• DOI: 10.1159/000052779

Background: Contradictory results have been reported in the literature concerning the correlation between glycosylated haemoglobin (HbA1c) and peroxidation level in serum of diabetic patients. Objective: To evaluate this correlation in type 2 diabetic patients by comparing the level of HbA1c with the oxygen radical absorbance capacity (ORAC OH ) of serum. Methods: One hundred and five type 2 diabetic patients were enroled for the study. After having obtained informed consent, venous blood samples were drawn after overnight fast at the time of routine diabetic check-ups. The blood was collected in plain and EDTA (1 mg/ml) tubes. Glycosylated haemoglobin (HbA1c) was determined by cation-exchange chromatography (HPLC), and spectrophotometric detection (Diamat Analyzer, BioRad). Serum was used for biochemical determinations performed by standard laboratory procedures and for ORAC OH analysis. This last parameter was determined measuring the loss of β-phycoerytrin fluorescence due to oxidation by hydroxyl radicals generated by Cu 2+ and H 2 O 2 , in the presence and absence of serum. Seventy-eight control age-matched subjects were obtained from the personnel staff of our Research Department and old healthy subjects, selected on the basis of Senieur Protocol, were relatives of the above mentioned personnel. Results: When the population of diabetic patients was taken as a whole, a decrease of ORAC OH has been observed compared to the controls. Moreover, negative correlations were found comparing ORAC OH either with HbA1c (r = –0.213; p = 0.029) and with the age of patients (r = –0.27; p = 0.005). To better understand the effect of age, the data were re-examined dividing the diabetics into two populations, i.e. under and over 65 years of age. An age-dependent decrease of ORAC OH and an increase in HbA1c levels has been observed comparing these two populations; however, the correlation between the two parameters remained statistically significant only in the oldest group (r = –0.31; p = 0.026). Conclusions: Present data point to an involvement of oxidative stress in the glycation of haemoglobin especially in old diabetic patients, and provide support for the potential use of an antioxidant therapy in these patients, irrespective of their glycaemic control.