Type 2 diabetes in Norway 2009-2021: Have declining incidence rates continued?

Aims/hypothesis To investigate updated trends in the incidence and prevalence of diagnosed type 2 diabetes in Norway by age, sex, country of birth and education. Methods A nationwide cohort study using registries on primary and specialist healthcare, dispensed drugs, and demographic factors in Norway. We analysed incidence trends 2009-2021 using Poisson regression and JoinPoint. Results During 2009-2021, 195 935 incident type 2 diabetes cases were identified. After a decline in incidence 2009-2014, the incidence was largely stable over time, with a suggestive upward trend 2019-2021. The overall incidence rates were 651 per 100 000 person-years in 2009 and 530 per 100 000 in 2021. There were 165 432 prevalent cases of type 2 diabetes in 2009 (5.5% of the population), consistently increasing throughout the study period to a peak at 259 017 (7.5%) in 2021. The time trends were largely consistent across age, sex, country of birth and education. Inhabitants with lower education and born in Asia or Africa had substantially higher incidence and prevalence than those with higher education and born in Norway or other continents, respectively. Conclusions/interpretation The previously described decline in incidence of diagnosed type 2 diabetes during 2009-2014 was not sustained, and prevalence continued to increase throughout 2009-2021.