['We compared the association between smoking habits and later occurrence of type 2 diabetes on the one hand and between smoking and diabetes with autoimmunity on the other hand.', 'We used data from a prospective study of 11-year cumulative incidence of diabetes in the Nord-Trøndelag Health Survey.', 'Confirming previous reports, heavy smoking (>/=20 cigarettes per day) carried an increased relative risk (RR) of type 2 diabetes (n=738, RR=1.64, 95% CI: 1.12-2.39). In contrast, smoking reduced the risk of latent autoimmune diabetes in adults (LADA) and of traditional type 1 diabetes (LADA n= 81, RR=0.25, 95% CI: 0.11-0.60; type 1 diabetes, n=18, RR=0.17, 95% CI: 0.04-0.73).'] Is smoking associated with an increased risk of type 2 diabetes but a decreased risk of autoimmune diabetes in adults : an 11-year follow-up of incidence of diabetes in the Nord-Trøndelag study?