BACKGROUND: This study investigated the prevalence of diabetes mellitus (DM) and impaired fasting glucose, as well as their management and comorbidities among older Korean adults. METHODS: Data from 269,447 individuals aged 65 years and older from the Korean National Health Insurance Service between 2000 and 2019 were analyzed to evaluate trends in DM prevalence, healthcare utilization, mortality, and complications. RESULTS: Among 269,447 individuals, 18.6% (n=50,159/269,447) were diagnosed with DM and 27.0% (n=72,670/269,447) had impaired fasting glucose. The DM group had the highest body mass index, waist circumference, and prevalence of current smokers (P<
0.001) but not the highest hypertension prevalence. From 2010 to 2019, the prevalence of DM and impaired fasting glucose increased from 15.5% to 21.9% and from 26.0% to 30.6%, respectively. Cancer-related mortality in DM was 1.15 times higher than in those with normal glucose tolerance (P<
0.001), and cardiovascular disease-related mortality was 1.32 times higher (P<
0.001)
all mortalities were higher in female participants. Myocardial infarction (hazard ratio [HR], 1.34
P<
0.001), stroke (HR, 1.24
P<
0.001), and heart failure (HR, 1.13
P<
0.001) were significantly higher in those with DM. CONCLUSION: This is the first study to investigate the prevalence of DM and related complications in older individuals based on longterm representative data in Korea. These results highlight the necessity for targeted interventions to enhance management and outcomes in this population.