Association Between Diabetes Prevalence and Mortality from Gastrointestinal Cancers in Türkiye: A Longitudinal Ecological Study

Background/Objectives: This study aimed to analyze the effect of diabetes prevalence on mortality levels from gastrointestinal cancers. Methods: The study utilized mortality data for Türkiye from the World Health Organization (WHO) Mortality Database, covering deaths from stomach, colon and rectum, liver, and pancreas cancers, as well as diabetes prevalence data, between 2009 and 2023. Health expenditure and life expectancy data from the World Bank were used as control variables. Results: Diabetes prevalence was significantly correlated with colon and rectum cancer mortality (r = 0.929; p < 0.01), pancreas cancer mortality (r = 0.978; p < 0.01), life expectancy (r = 0.941; p < 0.01), and health expenditure (r = −0.635; p < 0.01). Correlations of diabetes prevalence with esophagus, stomach, and liver cancer mortality were statistically insignificant (p > 0.05). According to generalized linear model analysis results, there was an effect of diabetes prevalence on colon and rectum cancer mortality (B = 383.108; p < 0.01) and pancreas cancer mortality (B = 330.415; p < 0.01). Effects of diabetes prevalence on esophagus, stomach, and liver cancer mortality were statistically insignificant (p > 0.05). Conclusions: Diabetes prevalence was significantly associated with mortality levels for colon and rectal cancer and pancreatic cancer; however, it did not have a significant effect on mortality levels for esophageal, gastric, and liver cancers. Although there is a close relationship between diabetes and the digestive system, a similar relationship between cancer mortality levels of digestive system organs and diabetes is not valid for every organ. We believe that the effect of diabetes on gastrointestinal cancers has a tissue- or organ-specific mechanism of action rather than a digestive mechanism.