In the 1950s and 1960s, the Seven Countries Study looked at the dietary patterns of people living in the Mediterranean region, and the term Mediterranean diet was coined for the first time. Traditional diets were considered to be largely responsible for the good health of people living in Greece and southern Italy. There is no single Mediterranean diet; 20 countries, each with its own socio-cultural and economic circumstances, have a coastline in the Mediterranean basin. However, in broad terms, the diet consists of vegetables, fruit and legumes, nuts, cereals and whole grains, olive oil, moderate consumption of fish and poultry, relatively low consumption of red meat and moderate consumption of wine. The authors of this article recently reviewed of all the available studies that have assessed the effect of a Mediterranean diet on people with diabetes, as well as on diabetes prevention and metabolic and cardiovascular outcomes. Here they summarize their findings and look at some of the reasons that might explain any effect.