Association Between Short-term Air Pollutions,uncomfortable Temperatures And Type 2 Diabetes Outpatient Visits In Chongqing Main Urban Areas:A Hospital-based Study

BackgroundType 2 diabetes（T2DM）,a common chronic metabolic disease,is generating an increasing disease burden.Studies have found that air pollutions and uncomfortable temperatures affect the risk of T2DM.At present,most relevant studies were carried out in Europe and the United States,and less attention was paid to Asian patients.At the same time,researchers mostly focused on the effects of long-term exposure and ignored short-term exposure.Objectives1.Describe the characteristics of temporal changes and distribution of daily outpatient visits for T2DM from two large hospitals,air pollutants and meteorological factors in Chongqing main areas during 2014 to 2019;2.To evaluate the association and lag effects between short-term exposure to particulate matter with an aerodynamic diameter equal to or less than 10μm(PM₁₀),particulate matter with an aerodynamic diameter equal to or less than 2.5μm(PM_2.5),sulfur dioxide（SO₂）,nitrogen dioxide（NO₂）,carbon monoxide（CO）,ozone（O₃）and T2DM outpatient visits in Chongqing and explore the differences in the effects among people with different gender,age,and treatment season.3.To evaluate the association and lag effects between uncomfortable temperatures and outpatient visits of T2DM in Chongqing and explore the differences in the effects among people with different gender and age.Methods1.Descriptive statistics,trend analysis of changes and Spearman correlation analysis were conducted on daily T2DM outpatient visits from two large hospitals in Chongqing,air pollutants and meteorological data during 2014-2019.2.The generalized additive model（GAM）was used to assess the associations between short-term exposure to air pollutants and T2DM outpatient visits in Chongqing.Subgroup analysis of age,gender and visit season was conducted to clarify the susceptibility to atmospheric pollutants.3.QAIC（Quasi-AIC）of the akaike information criterion（AIC）was used to select the best high temperature（extreme high temperature,heatwave）and low temperature（extreme low temperature,cold spell）.The cross-basis functions of indicators were included into the distribution lag non-linear model（DLNM）to assess the exposure-response relationship between the uncomfortable temperatures and T2DM outpatient visits,and identify sensitive groups using stratified analysis.Results1.A total of 544,705 T2DM outpatient visits in Chongqing from 2014 to 2019 were included in this study.The number of middle-aged outpatients（35-64）was 285,515,the number of elderly outpatients（≥65）was 259,190,accounting for 52.42%and 47.58%of the total number,respectively.Middle-aged patients were significantly more numerous than the elderly.The number of male outpatients was 292,895,and the number of female outpatients was 251,810,accounting for 53.77%and 46.23%of the total number,respectively.Male patients were significantly more numerous than female.As for the seasonal distribution,there were 272,242 outpatients visiting the hospital in the cool seasons（October-March）and272,463 outpatients in the warm seasons（April-September）,accounting for 49.98%and50.02%of the total number of patients,respectively.2.During the study period,PM₁₀,PM_2.5,SO₂,and CO levels showed a decreasing trend,NO₂ showed an increase followed by a decrease,and O₃ showed an increasing trend.The concentrations of PM₁₀,PM_2.5,SO₂,NO₂ and CO were low in summer and high in winter.The concentration of O₃ was high in summer and low in winter.The three temperature factors（maximum temperature,average temperature,minimum temperature）and wind speed all showed a trend of high in summer and low in winter.Relative humidity showed a trend of low in summer and high in winter.3.Short-term exposure to NO₂was associated with increased outpatient visits for T2DM at lag0-2 and lag01-05.Among them,the strongest correlation was the in lag 0,for each 10μg/m³ increase in NO₂,the corresponding percentage change in outpatient visits was 1.78%（95%confidence interval（CI）:0.92%,2.65%）.Short-term exposure to O₃ was significantly negatively correlated with T2DM outpatient visits at lag0-2 and lag01-07,and the effect was strongest at lag02.For each 10μg/m³ increase in the 8 hours maximum concentration of O₃,the corresponding percentage change in T2DM outpatient visits was-0.90%（95%CI:-1.30%,-0.50%）.As subgroup results,the effects did not differ by age and gender.However,in different visiting seasons,the correlations of NO₂ and O₃ in the cool seasons were stronger than in the warm seasons.4.Among the effects of high temperatures,extreme high temperatures were significantly negatively associated with T2DM outpatient visits at lag0-2 and significantly positively associated at lag5-7.The most significant association was found at lag0 with a relative risk（RR）of 0.92（95%CI:0.89,0.95）.Heatwaves were significantly negatively associated with T2DM outpatient visits at lag0-3 and positively associated at lag5-7,with a maximum RR of 0.90（95%CI:0.88,0.92）at lag0.Among the effects of low temperatures,extreme low temperatures were significantly negatively associated with T2DM outpatient visits only at lag0-1,with a maximum RR=0.94（95%CI:0.90,0.98）at lag0.Cold spells were negatively associated with T2DM outpatient visits at lag2-7,with a maximum RR=0.94（95%CI:0.92,0.96）at lag4.In age-and gender-stratified analysis,only the negative associations of extreme high temperatures and heatwaves had significant age differences,and the associations were stronger in the elderly.Conclusions1.Short-term exposure to NO₂ was significant positively associated with daily T2DM outpatient visits,and O₃ was significantly negative,and both were lagged and cumulative.Both NO₂ and O₃ effects were stronger in the cool season.2.High temperature indicators（extreme high temperatures,heatwaves）were significantly negatively associated with T2DM outpatient visits in the early lag period and significantly positively associated in the late lag period.Low temperature indicators were both significantly negatively associated with T2DM outpatient visits,but the effect of extreme low temperatures were statistically significant in the early lag period and the effect of cold spells were statistically significant in the mid-lag phase.Only the negative associations of extreme high temperatures and heatwaves were more significant in the elderly.