en Health Health Original Article Original Article <span style="font-size:14px;"><span style="font-family:Times New Roman;"><span style="line-height:14pt"><b><i><span style="color:blue">Background</span></i></b><i><span style="color:blue">:</span></i> Diabetes, a currently threatening disease, has severe consequences for individuals&rsquo; health conditions. The present study aimed to investigate the factors affecting the changes in the longitudinal outcome of blood sugar using a three-level analysis with the presence of missing data in diabetic patients.</span><br> <span style="line-height:14pt"><b><i><span style="color:blue">Methods:</span></i></b> A total of 526 diabetic patients were followed longitudinally selected from the annual data collected from the rural population monitored by Tonekabon health centers in the North of Iran during 2018-2019 from the Iranian Integrated Health System (SIB) database. In analyzing this longitudinal data, the three-level model (level 1: observation (time), level 2: subject, level 3: health center) was carried out with multiple imputations of possible missing values in longitudinal data.</span><br> <span style="line-height:14pt"><b><i><span style="color:blue">Results:</span></i></b> Results of fitting the three-level model indicated that every unit of change in the body mass index (BMI) significantly increased the fasting blood sugar by an average of 0.5 mg/dl (p=0.024). The impact of level 1 (observations) was insignificant in the three-level model. Still, the random effect of level 3 (healthcare centers) showed a highly significant measure for health centers (14.62, p<0.001).</span><br> <span style="line-height:14pt"><b><i><span style="color:blue">Conclusion</span></i></b><i><span style="color:blue">:</span></i> The BMI reduction, the healthcare centers&#39; socioeconomic status, and the health services provided have potential effects in controlling diabetes. </span></span></span><br> &nbsp; Blood sugar change, Diabetic patients, Body mass index, Health care centers, Three-level model, Missing data, FCS imputation algorithm, Longitudinal data 615 622 http://caspjim.com/browse.php?a_code=A-10-133-8&slc_lang=en&sid=1 Tahereh Rohani tahereh.rohani@yahoo.com 100319475328460049930 100319475328460049930 No Student Research Committee, Babol University of Medical Sciences, Babol, Iran Karimollah Hajian-Tilaki drhajian@yahoo.com 100319475328460049931 100319475328460049931 Yes Dept of Biostatistics and Epidemiology, School of Public Health, Babol University of Medical Sciences, Babol, Iran Mahmoud Hajiahmadi hajiahmadi@yahoo.com 100319475328460049932 100319475328460049932 No Dept of Biostatistics and Epidemiology, School of Public Health, Babol University of Medical Sciences, Babol, Iran Behzad Heidari heidaribeh@yahoo.com 100319475328460049933 100319475328460049933 No Dept of Internal Medicine, Ayatollah Rohani hospital, Babol University of Medical Sciences, Babol, Iran. Natali Rahimi Rahimabadi natali.rahimi@gmail.com 100319475328460049934 100319475328460049934 No Tonekabon Health Center, Mazandaran University of Medical Sciences, Tonekabon, Iran. Zahra Geraili geraili.stat@gmail.com 100319475328460049935 100319475328460049935 No Student Research Committee, Babol University of Medical Sciences, Babol, Iran