Aspirin resistance associated with HbA1c and obesity in diabetic patients

Diabetes is known to be a prothrombotic state. Since serotonin uptake plays a role in both platelet activation and depression, we undertook to examine a hypothesis that aspirin resistance (AR) may be associated with both HbA1c and depressive symptoms and to assess other potential determinants of AR in diabetic patients.

A whole-blood desktop platelet function analyzer (PFA-100) with an epinephrine agonist was used to assess AR among patients with type 2 diabetes. AR was defined as PFA closure times <192 s. Depression symptoms were assessed with the Physicians Health Questionnaire. Patients being treated for type 2 diabetes (N=48) who took aspirin within the past 24 h constituted the study sample. Associations with AR were assessed with the use of the Mann-Whitney test and Fisher's Exact Test as well as with logistic regression models.

AR was observed in 11 patients (23%) and was not significantly associated with age, sex, or race. AR was significantly associated with HbA1c > or = 8% (P=.002) and obesity (BMI> or = 30 kg/m(2); P=.01) and borderline associated with having > or = 1 depressive symptom (P=.07). Results were similar after multivariable adjustment in logistic regression models. No statistically significant associations of AR with age, sex, race, plasma glucose, blood pressure, cholesterol, or smoking were observed.

These data suggest that AR may be of special concern for diabetic patients with poor glucose control and obesity. Whether the PFA-100 or any other practical measure of AR can be used in clinical practice to identify added cardiovascular disease risk and to inform platelet inhibition therapy needs further study.