Type 1 diabetes risk up in first 180 days after influenza diagnosis

Influenza may trigger an increase in the likelihood of developing type 1 diabetes, a new Japan study has found.

“These results, which must be confirmed in other populations, suggest that influenza may be a causal factor for new-onset type 1 diabetes. The molecular mechanisms underlying the potential aetiological relationship between influenza and type 1 diabetes should be elucidated,” the researchers said.

The population-based retrospective cohort study included 10,400 patients with new-onset type 1 diabetes, whose data were drawn from the National Database of Health Insurance Claims and Specific Health Check-ups. Type 1 diabetes incidence rates were compared between the time period of 180 days after an influenza diagnosis vs other time period.

A total of 441 patients developed type 1 diabetes within 180 days of an influenza diagnosis, with a rate of 2.4 cases per day. Outside of this time span, another 1,755 participants had new-onset diabetes, corresponding to a rate of 1.9 cases per day.

Statistical analysis showed that the risk of developing type 1 diabetes was 30-percent higher during the 180-day period after being diagnosed with influenza (risk ratio [RR], 1.30, 95 percent confidence interval [CI], 1.15–1.46; p<0.001).

The principal findings were robust to sensitivity analyses. Notably, the researchers found no elevations in the risk of type 1 diabetes 180 days before influenza diagnosis and from day 181–360 after. The link between influenza and diabetes risk also remained across most age groups and was unaffected by any type of anti-influenza drugs.