His research focuses on the early programming of health and disease, as well as on the prevention of gestational diabetes (GDM), type 2 diabetes and related metabolic outcomes by lifestyle interventions. In Finland he is in charge of the Helsinki Birth Cohort Study, a unique birth cohort study with a follow-up of over 20,000 individuals from birth until the age of over 80 years. Furthermore, he has been involved in the gestational diabetes prevention study RADIEL, in which a lifestyle intervention was shown to successfully reduce GDM and the Finnish Diabetes Prevention Study (DPS) – the first randomised study to show that lifestyle intervention is effective in the prevention of type 2 diabetes.