en تخصصي Special پژوهشي Research <span style="font-size:11pt"><span style="text-justify:inter-ideograph"><span style="line-height:normal"><span sans-serif="" style="font-family:Calibri,"><b><span style="font-size:12.0pt"><span new="" roman="" style="font-family:" times=""><span style="color:black">Objective:</span></span></span></b><b> </b><span style="font-size:10.5pt"><span new="" roman="" style="font-family:" times="">The role of environmental factors in the development of type1 diabetes mellitus (T1D) is inconclusive. This study aimed to investigate the associations between selected environmental factors and T1D.</span></span></span></span></span></span><br> <span style="font-size:11pt"><span style="text-justify:inter-ideograph"><span style="line-height:normal"><span sans-serif="" style="font-family:Calibri,"><b><span style="font-size:12.0pt"><span new="" roman="" style="font-family:" times=""><span style="color:black">Materials and Methods</span></span></span></b><b><span style="font-size:12.0pt"><span new="" roman="" style="font-family:" times=""><span style="color:black">:</span></span></span></b> <span style="font-size:10.5pt"><span new="" roman="" style="font-family:" times="">This group matched case-control study included diabetic and healthy subjects younger than 19 years old in 2017. Cases were diabetic subjects diagnosed before the age of 19 years and controls were healthy subjects with similar distributions of age, sex, and place of living. Information including demographic characteristics, birth season, duration of breastfeeding and major psychological stressors was obtained by a parent-administered questionnaire. Data were analyzed using SPSS version 16 and T-test and chi-square test. Statistical significance was defined as <i>P</i>< 0.05.<b><i></i></b></span></span></span></span></span></span><br> <span style="font-size:11pt"><span style="text-justify:inter-ideograph"><span style="line-height:normal"><span sans-serif="" style="font-family:Calibri,"><b><span lang="EN" style="font-size:12.0pt"><span new="" roman="" style="font-family:" times="">Results:</span></span></b> <span lang="EN" style="font-size:10.5pt"><span new="" roman="" style="font-family:" times="">The mean age of cases was 12.5 (&plusmn;5.2) years and 13 (&plusmn;6.7) in controls </span></span><span style="font-size:10.5pt"><span new="" roman="" style="font-family:" times="">(</span></span><i><span style="font-size:10.5pt"><span new="" roman="" style="font-family:" times="">P</span></span></i><span style="font-size:10.5pt"><span new="" roman="" style="font-family:" times="">: 0.55). Compared to controls, children with T1D had a higher chance of having a major psychological stressor in the family before the onset of diabetes (</span></span><i><span style="font-size:10.5pt"><span new="" roman="" style="font-family:" times="">P</span></span></i><span style="font-size:10.5pt"><span new="" roman="" style="font-family:" times="">: 0.0001) with odds ratio (OR) 3.3, higher neonatal jaundice (</span></span><i><span style="font-size:10.5pt"><span new="" roman="" style="font-family:" times="">P</span></span></i><span style="font-size:10.5pt"><span new="" roman="" style="font-family:" times="">: 0.01, OR: 2.25), infection leading to hospitalization within the first year of life (</span></span><i><span style="font-size:10.5pt"><span new="" roman="" style="font-family:" times="">P</span></span></i><span style="font-size:10.5pt"><span new="" roman="" style="font-family:" times="">: 0.007, OR: 6.46), and lower family income (</span></span><i><span style="font-size:10.5pt"><span new="" roman="" style="font-family:" times="">P</span></span></i><span style="font-size:10.5pt"><span new="" roman="" style="font-family:" times="">: 0.018). </span></span><span lang="EN" style="font-size:10.5pt"><span new="" roman="" style="font-family:" times="">Duration of breastfeeding was shorter inT1D group </span></span><span style="font-size:10.5pt"><span new="" roman="" style="font-family:" times="">(</span></span><i><span style="font-size:10.5pt"><span new="" roman="" style="font-family:" times="">P</span></span></i><span style="font-size:10.5pt"><span new="" roman="" style="font-family:" times="">: 0.018, OR: 3.46) and they had started cereals one month earlier (</span></span><i><span style="font-size:10.5pt"><span new="" roman="" style="font-family:" times="">P</span></span></i><span style="font-size:10.5pt"><span new="" roman="" style="font-family:" times="">: 0.015).</span></span></span></span></span></span><br> <b><span style="font-size:12.0pt"><span style="line-height:115%"><span new="" roman="" style="font-family:" times=""><span style="color:black">Conclusion</span></span></span></span></b><b><span style="font-size:12.0pt"><span style="line-height:115%"><span new="" roman="" style="font-family:" times=""><span style="color:black">:</span></span></span></span></b> <span style="font-size:10.5pt"><span style="line-height:115%"><span new="" roman="" style="font-family:" times="">Certain environmental factors including major psychological stressors, neonatal jaundice, infection leading to hospitalization with</span></span></span><span lang="EN" style="font-size:10.5pt"><span style="line-height:115%"><span new="" roman="" style="font-family:" times="">in first year of birth</span></span></span><span style="font-size:10.5pt"><span style="line-height:115%"><span new="" roman="" style="font-family:" times=""> and </span></span></span><span lang="EN" style="font-size:10.5pt"><span style="line-height:115%"><span new="" roman="" style="font-family:" times="">shorter duration of breastfeeding </span></span></span><span style="font-size:10.5pt"><span style="line-height:115%"><span new="" roman="" style="font-family:" times="">were associated with the development of T1D</span></span></span><span lang="EN" style="font-size:10.5pt"><span style="line-height:115%"><span new="" roman="" style="font-family:" times="">.</span></span></span> Environmental factors, Diabetes Mellitus, Type 1 152 158 http://ijdo.ssu.ac.ir/browse.php?a_code=A-10-30-353&slc_lang=en&sid=1 Zahra Razavi 0000-0001-5318-9087 Yes Professor, Department of Pediatrics, Hamadan University of Medical Sciences, Hamadan, Iran. Hammed Sadri 0000-0002-5225-9351 No M.D., Hamadan University of Medical Sciences, Hamadan, Iran.