Aim: To compare the consumption of the cow milk proteins A1 and B β-casein among children and adolescents in Iceland and Scandinavia (Norway, Denmark, Sweden and Finland) as this might explain the lower incidence of type 1 diabetes (per 100,000/year, 0–14 years) in Iceland. Methods: The consumption of A1 β-casein in each country among 2- and 11- to 14-year-old children was calculated from results on food intake and on cow milk protein concentration. The consumption values were then compared and evaluated against the incidence of type 1 diabetes. Results: There was a significant difference between the consumption of A1 (p = 0.034) as well as the sum of A1 and B (p = 0.021) β-casein in Iceland and Scandinavia for 2-year-old children. In the same age group, consumption of A1 β-casein correlated with the incidence of type 1 diabetes in the countries (r = 0.9; p = 0.037). No significant difference in consumption of A1 or the sum of A1 and B β-casein was found for 11- to 14-year-old adolescents. Conclusion: This study supports that lower consumption of A1 β-casein might be related to the lower incidence of type 1 diabetes in Iceland than in Scandinavia. Additionally it indicates that consumption in young childhood might be of more importance for the development of the disease incidence than consumption in adolescence.