en تخصصي Special پژوهشي Research <div style="clear:both;"></div>Epidemiology is the study and analysis of distribution and determinants of health-related conditions or events including diseases, and the practice of this study to the control of diseases and other health problems (<a href="#_ENREF_1" title="Belbasis, 2018 #3">1</a>). One of the basic issues in epidemiology and the beginning of a research project is conducting a suitable design for our study (<a href="#_ENREF_2" title="Checkoway, 2007 #4">2</a>). The aim of this study is to brief explanation the classification of different types of epidemiological studies according to diabetes disease.<br> The researcher should design his/her own study design based on his/her research question, available resources, time and budget. Figure 1 shows the classification of epidemiological studies (Figure 1) (<a href="#_ENREF_3" title="Rothman, 1998 #1">3</a>,<a href="#_ENREF_4" title="Bailey, 1994 #2">4</a>)<br> &nbsp; Epidemiological study 58 62 http://ijdo.ssu.ac.ir/browse.php?a_code=A-10-30-272&slc_lang=en&sid=1 Maryam Askari 0000-0002-8422-8293 Yes Diabetes Research Center, Shahid Sadoughi University of Medical Sciences, Yazd, Iran Hassan ali Mahmoudi Kohani 0000-0002-3073-2822 No Diabetes Research Center, Shahid Sadoughi University of Medical Sciences, Yazd, Iran Nasim Namiranian 0000-0002-5133-6204 No Diabetes Research Center, Shahid Sadoughi University of Medical Sciences, Yazd, Iran