biostudies-literatureUnknown12(4)Hong JS<h4>Objectives</h4>The lower risk of death in overweight or obese patients, compared with normal-weight individuals, has caused confusion for patients with diabetes and healthcare providers. This study investigated the relationship between body mass index (BMI) and mortality in patients with type 2 diabetes.<h4>Design</h4>A retrospective cohort study.<h4>Setting</h4>We established a national population database by merging the Korea National Health Insurance (KNHI) claims database, the National Health Check-ups Database and the KNHI Qualification Database of South Korea.<h4>Participants</h4>A total of 53 988 patients who were newly diagnosed with type 2 diabetes (E11 in International Classification of Diseases, 10th Edition) in 2007, had available BMI data, lacked a history of any serious cBMJ opene048784https://www.ebi.ac.uk/biostudies/studies/S-EPMC8977808biostudies-literatureBody mass index and all-cause mortality in patients with newly diagnosed type 2 diabetes mellitus in South Korea: a retrospective cohort study.PMC8977808Hong JSKang HCfalseBody mass index and all-cause mortality in patients with newly diagnosed type 2 diabetes mellitus in South Korea: a retrospective cohort study.<h4>Objectives</h4>The lower risk of death in overweight or obese patients, compared with normal-weight individuals, has caused confusion for patients with diabetes and healthcare providers. This study investigated the relationship between body mass index (BMI) and mortality in patients with type 2 diabetes.<h4>Design</h4>A retrospective cohort study.<h4>Setting</h4>We established a national population database by merging the Korea National Health Insurance (KNHI) claims database, the National Health Check-ups Database and the KNHI Qualification Database of South Korea.<h4>Participants</h4>A total of 53 988 patients who were newly diagnosed with type 2 diabetes (E11 in International Classification of Diseases, 10th Edition) in 2007, had available BMI data, lacked a history of any serious c2022-01-01T00:00:00Z2022 Apr2025-04-04T19:41:05.223Z2025-04-04T19:41:05.223ZS-EPMC89778083536550710.1136/bmjopen-2021-048784