Oxidative stress status in patients with diabetes mellitus: relationship to diet.

OBJECTIVE: To investigate the relationship between dietary intakes and in vivo oxidative stress (OS) status in diabetic patients.

DESIGN: Case-control study.

SETTING: Outpatient-Clinic and Laboratory Endocrinology, University Antwerp.

SUBJECTS AND METHODS: A total of 30 patients (24 type 1 diabetes mellitus (T1DM)/6 type 2 diabetes mellitus (T2DM) were asked to complete a 2 weekdays+1 weekend day food consumption questionnaire during the week preceding their yearly diabetes control consultation, when samples were collected for the assay of oxidative stress (OS) (blood levels of antioxidants, peroxides, malondialdehyde (MDA) and minerals). Blood samples were also collected from 25 age- and sex-matched healthy controls.

RESULTS: Diabetic patients had lower glutathione (5.80+/-1.15 vs 6.75+/-1.03 micromol/g Hb in the controls, P=0.002) and higher MDA (0.687+/-0.212 vs 0.545+/-0.101 micromol/l, P=0.002). Although the group average intakes were within the Belgian RDA, intakes of fat >35% energy, fibre <15 g/1000 kcal, fruit <2 portions and vitamin E <10 mg/day were seen in more than 20 patients. Blood antioxidants did not correlate with intakes of energy, fat, protein or fibres or of their respective antioxidant. Vitamins A and E correlated with serum lipids (r=0.58, P <0.0005 between serum alpha-tocopherol and cholesterol). Blood peroxide levels were only related to intakes of saturated fat and cholesterol (P<0.05). In diabetic subjects but not in controls (P<0.05) MDA was related to glutathione and uric acid.

CONCLUSIONS: In diabetic patients, blood levels of antioxidants are not related to their dietary intakes but to serum lipids. Levels of oxidative damage products are only related to intakes of saturated fats and cholesterol and to levels of endogenous antioxidants.