The effect of aspirin and vitamins C and E on HbA1c assays

BackgroundAspirin (ASA) and vitamins C and E may inhibit non-enzymatic glycation in vivo and may also interfere with HbA1c assays, masking true results. We investigated the effect of usual doses of ASA, vitamin C and E on HbA1c levels in a group of non-diabetic volunteers.MethodsA randomized clinical trial was performed with 28 healthy non-diabetic individuals. Subjects were allocated to take ASA 200 mg/day, vitamin C 1 g/day, vitamin E 400 mg/day, or to a control group, for a period of 4 months. Blood samples were collected at baseline and at monthly intervals for HbA1c analysis by HPLC Variant II (BioRad), HPLC L-9100 (Merck – Hitachi) and Tina Quant® HbA1c II immunoassay (Roche).ResultsHbA1c levels of the control, vitamin C and E groups did not change throughout the study, independently of the method used. HbA1c measured by Hitachi L-9100 HPLC increased significantly (P = 0.033) at 4 months after ASA intake, although this increase was of only 0.17%. Conclusions: Treatment with vitamins C and E in pharmacological doses does not have any impact on HbA1c measurements in non-diabetic patients with the three methods employed. ASA induces a modest, not clinically relevant, increase in HbA1c levels with one of the methods.