Association between altitude and death from COVID-19 in subjects with diabetes mellitus during the first wave: cross sectional study of the National Death Index

Background. In high Andean areas, there is greater insulin sensitivity which may be a protective factor against complications in subjects with diabetes mellitus.  Objective: Determine the association between altitude of residence and death from COVID-19 in deaths with diabetes mellitus in Peru during the first wave.. Methods: We carried out a cross-sectional analysis of deaths registered in the National Death System of Peru (SINADEF in Spanish). We selected Peruvians with diabetes mellitus identified by presenting the diagnosis in any of the six boxes on the certificate. The dependent variable was death from COVID-19 as the basic cause of death, located in last place among causes A, B, C and D according to the Pan American Health Organization. The independent variable was the altitude of residence, categorized as less than 1 500 m a.s.l, 1 500 to 2 499 m  a.s.l. and greater than 2 500 m a.sl. Through a multilevel analysis by geographic region and using a Poisson regression, we obtained the risk ratios of death from COVID-19 according to the altitude of residence. We adjusted by individual and contextual variables. Results: We included 16 406 deaths with diabetes mellitus between March-December 2020. 34.3% died from Covid19 and 9.7% came from areas above 2 500 m. The proportion of deaths from COVID-19 of those with residence altitude above 2 500 m  was 20% lower compared to residents below 1 500 m (RR: 0.80; 95% CI: 0.70 – 0.91; p<0.001), adjusted for individual and socioeconomic factors. Its influence is also shown as the altitude changes every 100, 250, 500 and 1000 m a.s.l., through multilevel analysis. Conclusion: A higher altitude of residence is associated with a lower proportion of deaths from COVID-19 in people with diabetes mellitus during the first wave in Peru. The study contribute to expanding knowledge of the effects of altitude with respect to mortality in people with diabetes mellitus in a context of a highly contagious and virulent infectious disease. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement The author(s) received no specific funding for this work. ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: We use publicly accessible data from the website of the Ministry of Health of Peru. No records contained individually identifying data. The research protocol was reviewed and approved by the Institutional ethics and Research Committee of the Universidad Científica del Sur under code N°49-CIEI-CIENTIFICA-2021. I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes All relevant data are within the manuscript and its Supporting Information files.