Assessment of associations between ischaemic attacks in patients with type 2 diabetes mellitus and air concentrations of particulate matter <2.5 μm

OBJECTIVE To investigate the relationship between air concentrations of fine particulate matter <2.5 µm in diameter (PM2.5) and ischaemic attacks in high-risk elderly patients (aged ≥60 years). METHODS This retrospective data analysis study extracted clinical data from an electronic medical chart system and environmental air quality data from the Ministry of the Environment Atmospheric Environmental Regional Observation System. Patients were stratified into four groups according to whether or not they had type 2 diabetes mellitus (T2DM) and/or an ischaemic attack (i.e. cerebral infarctions and myocardial infarctions) during the 2-year study period. Analysis of the combined clinical and environmental data produced the odds ratio for the likelihood of experiencing an ischaemic attack. RESULTS Clinical data were collected from 94 647 patients. On days when the air temperature was ≥25℃ and PM2.5 concentration was ≥20µg/m(3), an ischaemic attack was more likely to occur in the T2DM group than in the group without T2DM. An ischaemic attack was more likely to occur 2 days after an increase in the PM2.5 concentration compared with the same day as and 3-6 days after the increase. CONCLUSION The results of this study confirmed an association between PM2.5 and ischaemic attacks in high-risk patients.