One of the best results from the cross-sectional study has been the exposition of incidence rates.  As shown on this slide that incidence rates of IDDM varied widely.  The lowest rate was reported from Korea, and the highest from Finland.  These differences are as much as 40 fold between the two countries.  Based on this cross-sectional study, we immediately noticed that both genetic and environmental conditions should be regarded as risk factors for IDDM.  In these cross-sectional studies, we also note that IDDM incidence is lower in Asia, moderate in North America, and higher in Scandinavian countries.