Inhalation of ultrafine carbon particles alters heart rate and heart rate variability in people with type 2 diabetes

Background: diabetes may confer an increased risk for the cardiovascular health effects of particulate air pollution,but few human clinical studies of air pollution have included people with diabetes. ultrafine particles (ufp,≤100 nm in diameter) have been hypothesized to be an important component of particulate air pollution with regard to cardiovascular health effects. methods: 17 never-smoker subjects 30-60 years of age,with stable type 2 diabetes but otherwise healthy,inhaled either filtered air (0-10 particles/cm3) or elemental carbon ufp (~107 particles/cm3,~50 ug/m3,count median diameter 32 nm) by mouthpiece,for 2 hours at rest,in a double-blind,randomized,crossover study design. a digital 12-lead electrocardiogram (ecg) was recorded continuously for 48 hours,beginning 1 hour prior to exposure. results: analysis of 5-minute segments of the ecg during quiet rest showed reduced high-frequency heart rate variability with ufp relative to air exposure (p = 0.014),paralleled by non-significant reductions in time-domain heart rate variability parameters. in the analysis of longer durations of the ecg,we found that ufp exposure increased the heart rate relative to air exposure. during the 21- to 45-hour interval after exposure,the average heart rate increased approximately 8 beats per minute with ufp,compared to 5 beats per minute with air (p = 0.045). there were no ufp effects on cardiac rhythm or repolarization. conclusions: inhalation of elemental carbon ultrafine particles alters heart rate and heart rate variability in people with type 2 diabetes. our findings suggest that effects may occur and persist hours after a single 2-hour exposure. © 2014 vora et al.; licensee biomed central ltd.