LONDON—The health impact of diet and physical activity may play a part in the marked ethnic differences in type 2 diabetes and cardiovascular disease in the UK according to research reported at the London School of Hygiene & Tropical Medicine. In the Pemberton Lecture at the 2012 Meeting of the Society for Social Medicine Professor Peter Whincup of St George’s London University also said that social class has a big effect on health — but not in the same way in all ethnic groups. He explained to Peter Goodwin why the study of ethnicity and health is needed to help reduce inequalities such as a six-fold difference in the incidence of diabetes between communities in the same city.