His research interests include the epidemiology and prevention of non-communicable diseases such as diabetes, cardiovascular disease (CVD), cancer and dementia. He has contributed many landmark scientific research projects. He started his research career with the North Karelia Project in Finland, the first community-based prevention programme for CVD. He initiated the Finnish Diabetes Prevention Study (DPS) that demonstrated a 58% reduction in incidence type 2 diabetes with lifestyle intervention. This finding was later confirmed by similar trials from many countries. He has contributed to over 1900 scientific publications. His h-index is 229. He has received many prestigious scientific awards, f. ex. ESC Geoffrey Rose Award.