Till Örebro universitet

Background and aims: Non-western immigrants to Europe are at high risk for type 2 diabetes (T2D). In this nationwide study including incident cases of T2D, the aim was to compare mortality in first- and second generation immigrants with native Swedes.

Materials and methods: Patients living in Sweden diagnosed with a new-onset pharmacologically treated T2D between 2006 to 2012 were identified through the Swedish Prescription Drug Register. Patients were followed until December 31, 2016 for all-cause mortality (ACM) and until December 31, 2012 for cause-specific mortality (CSM). Analyses were adjusted for age at diagnosis, sex, year of diagnosis, socioeconomy, education, treatment and region. Comparisons were assessed using coxregression analysis.

Results: In total, 169 300 individuals (129 533 (76.3%) native Swedes; 31 988 (18.9%) first-generation immigrants, and 7 799 (4.8%) second-generation immigrants with either one or both parents born outside Sweden) were diagnosed with T2D between 2006 and 2012 and fulfilled inclusion criteria. First-generation immigrants had lower ACM rate [hazard ratio (HR): 0.85, 95% CI 0.82 to 0.89] compared with native Swedes. The mortality was particularly low in persons born in the Middle East [0.45,0.40 to 0.51], Asia [0.56, 0.46 to 0.68], and Africa [0.88. 0.82 to 0.95]. Mortality rates decreased with older age at migration and shorter stay in Sweden, with the lowest rate in those originating from the Middle East living in Sweden <25 years [0.40, 0.34 to 0.46]. First-generation immigrants born in the Middle East (0.43; 0.30-0.62), and Asia (0.38; 0.19- 0.77) had lower cardiovascular disease related mortality rates compared with native Swedes. Middle Eastern immigrants further displayed lower cancer related mortality rate (0.59, 0.42 to 0.84) compared with native Swedes. Second generation immigrants displayed similar survival rates as native Swedes.

Conclusion: Our data indicate that in T2D patients, exposure to the Swedish environment seems to have a larger impact on mortality risk than region of origin. This study indicates protecting mechanisms on mortality related to the non-western environment.