a slightly increasing trendp < 0.001
In the younger group with T1D aged 14–17 years, the proportion of smokers was 6.4% in 2016 and 8.3% in 2023 after adjusting for sex, migration background, diabetes duration and taking repeated measurements into account, with a slightly increasing trend (relative increase: 2.86%, CI 1.21–4.55 per year, p < 0.001).