Swine flu may double risk for type 1 diabetes

Norwegians aged 30 years or younger infected with the H1N1 influenza virus during the pandemic were twice as likely to develop type 1 diabetes vs. the general population, according to findings presented at the European Association for the Study of Diabetes Annual Meeting.

“Our findings support a suggested role of respiratory infections in the etiology of type 1 diabetes,” Paz Lopez-Doriga Ruiz, a PhD student in the department of endocrinology at Oslo University Hospital in Norway, told Endocrine Today. “Influenza virus could be a contributing factor to the development of clinical diabetes, due to stress and inflammation in predisposed individuals.”

The 2009 pandemic of H1N1, also known as swine influenza, has previously been associated with the development of autoimmune diseases, Ruiz and colleagues wrote in a poster presenting the findings. In a register-based study, Ruiz and colleagues assessed whether a diagnosis of pandemic influenza was associated with a higher subsequent risk for type 1 diabetes.

Researchers analysed prospective national health registries of the Norwegian population aged 30 years or younger (n = 2.28 million) between June 2009, when a wave of pandemic influenza H1N1 spread across Norway, and June 2014, linking the registry data with patient-level information. Pandemic influenza was defined as influenza diagnosis during the pandemic outbreak in Norway or laboratory-confirmed influenza A (H1N1). Results were adjusted for birth year, sex, place of birth, education and pandemic influenza vaccination.

During the pandemic, 76,173 individuals were diagnosed with pandemic influenza (3%); 2,376 individuals were diagnosed with type 1 diabetes during follow-up. Those who reported influenza-like illness during the pandemic were 18% more likely to subsequently be diagnosed with type 1 diabetes than those who did not have influenza (HR = 1.19; 95% CI, 0.97-1.46). Researchers observed a stronger association in children, who had a 25% increased risk for developing the disease after a H1N1 diagnosis (95% CI, 0.97-1.61).

Results also showed that Norwegians with laboratory-confirmed H1N1 influenza, or who were hospitalised with an influenza diagnosis during the pandemic season, had a doubled risk for later developing type 1 diabetes vs. the general Norwegian population (HR = 2.26; 95% CI, 1.51-3.38).

“This extends the viral hypothesis, and further supports a suggested role of respiratory infections in the etiology of type 1 diabetes,” the researchers wrote. – by Regina Schaffer

Reference:

Ruiz PLD, et al. Abstract 363. Presented at: European Association for the Study of Diabetes Annual Meeting; Sept. 11-15, 2017; Lisbon, Portugal.

Disclosure: Ruiz reports no relevant financial disclosures.