Underreporting of diabetes mellitus as the cause of death in Bauru, State of São Paulo, Brazil over 40 years: a documental study.

Objective: To evaluate, characterize and search for trends in the underreporting of diabetes mellitus (DM) as the cause of death in Bauru, São Paulo, Brazil, over 40 years. Subjects and methods: This was a documental study. Clinical and mortality data were collected from individuals known to have type 1 (DM1) and type 2 diabetes mellitus (DM2), residing in Bauru, State of São Paulo, followed at a local endocrinology clinic from 1982 to 2021, who deceased during this period. Results: A significant underreporting of DM as the cause of death (64.41%) was found, mostly associated with male gender (OR = 1.59 [95% CI: 1.18; 2.15]; p < 0.01), DM2 (OR = 2.64 [95% CI: 1.32; 5.26]; p < 0.01), dying in the first decade of the study (OR = 4.07 [95% CI: 1.54; 10.71]; p < 0.001) and shorter DM duration (OR = 1.02 [95% CI: 1.01; 1.04]; p < 0.01). Age, type of treatment, body mass index, marital status and ethnicity, did not show a significant association with DM underreporting. There was a decreasing trend in DM1 underreporting (Decade Percentual Change = -7.10 [95% CI: -11.35; -3.40]), but a stationary trend for DM and DM2. The main primary cause of death was cardiovascular-related complications. Conclusion: The underreporting of DM as the cause of death was very frequently found, and was associated with male gender, decade of death, shorter DM duration and DM2. If our data could be applied to the whole country, DM would possibly emerge as a more prominent cause of death in Brazil. Future studies in other cities and geographic regions are warranted to confirm our findings.