Renata Ortiz Pedrini

Lack of interference of aspirin in HbA1c measured by ion-exchange HPLC in type 2 diabetic patients: a randomized, double-blind, placebo-controlled study.

Remarkable clinical trials, like the Diabetes Control and Complications Trial (DCCT) and United Kingdom Prospective Diabetes Study (UKPDS), have established that HbA1c is the cornerstone to predict the development of chronic vascular complications in diabetic subjects [1,2]. The American Diabetes Association (ADA) recommends HbA1c measurements at least twice a year, with target levels b7% [3]. However, it should be taken into account that many factors can influence the results, such as the analytical interference of some drugs, like aspirin (acetylsalicylic acid) [4–6]. This is an important issue, because low-dose aspirin is recommended for both primary and secondary cardiovascular disease prevention in diabetic patients [3]. Some in vitro and in vivo studies have suggested a potential interference of aspirin in HbA1c assays, especially in those that rely on the change of charge, like ion-exchange HPLC and electrophoresis [6–8]. Aspirin induces an acetylation of hemoglobin, giving it a negative charge and consequently increasing HbA1c levels in chromatographic assays [9]. There are no randomized clinical trials analyzing the possible effects of the antiplatelet agent on HbA1c values measured by ionexchange HPLC assay in diabetic patients. Therefore, the aim of this study was to evaluate the influence of low-dose aspirin on HbA1c levels measured by this method in type 2 diabetic patients. In this randomized, crossover, double-blind, placebocontrolled study, 14 type 2 DM patients received aspirin (300 mg/d) or an identical placebo for 8 weeks, with a 6week washout period. All patients signed a written informed consent approved by the Ethics Committee of the Hospital. The sample size calculation disclosed that a minimum of 12 patients was needed to detect an absolute change in HbA1c N0.5% (α=0.05 and β=0.20). The patients entered a run-in phase of 8 weeks, to stabilize metabolic control. All patients, except for 2 who received only insulin, used metformin, either alone or in combination