Disputation

Paz Lopez-Doriga Ruiz

MD Paz Lopez-Doriga Ruiz at Institute of Clinical Medicine defended the thesis “Influenza, Immunization and Diabetes - the DiaFlu study” for the degree of PhD (Philosophiae Doctor). Principal supervisor was Department Director Hanne L. Gulseth, Norwegian Institute of Public Health.

Summary of the research

DiaFlu is a register-based influenza study to investigate relationships between the pandemic influenza infection in 2009-2010, the pandemic influenza vaccination and diabetes.

The aims of this thesis were to study if the pandemic influenza infection and vaccination were associated with a subsequent increased risk of developing type 1 diabetes, we also tested whether people with type 2 diabetes had higher risk of hospitalization with pandemic influenza during 2009-2010, and higher subsequent mortality, compared to people without type 2 diabetes. We used data collected to monitor occurrence of type 2 diabetes in Norway from 2009 to 2014.

We linked individual-level data from several national registers (the Norwegian Patients Registry, the primary care dataset, the Norwegian prescription database, the Norwegian Immunisation Registry, the Norwegian Surveillance System for Communicable Diseases, Statistics Norway and Norwegian Cause of Death Registry).

The results from the DiaFlu study have shown a concrete use of central health registers for research and health monitoring. The pandemic influenza vaccination was not associated with increased risk of type 1 diabetes at 4 years follow-up. Respiratory infections, such as influenza infection, may influence the pathology of type 1 diabetes. We found a two-fold excess of incident diabetes in the subgroups with laboratory confirmed pandemic influenza A H1N1 or pandemic influenza diagnosed in specialist health care. The prevalence of type 2 diabetes in Norway continues to rise from 2009 -2014. During the same period, we observed a declining incidence of type 2 diabetes. The relative mortality hazard in hospitalized vs non hospitalized was lower in individuals with type 2 diabetes compared to those without.