Recent research in Europe and the USA has shown that adults who had a low birthweight or who were thin at birth with a low ponderal index (birthweight/length3) tend to be insulin resistant and have an increased risk of developing Type 2 diabetes mellitus. Low birthweight and Type 2 diabetes are common in India. We have studied glucose and insulin metabolism in 506 men and women (aged 39-60 years) born in a hospital in Mysore, South India, which kept detailed obstetric records from 1934. The prevalence of Type 2 diabetes was 15%. In contrast to Western populations, higher rates were found in men and women who were short at birth (p = 0.07) and had a high ponderal index (p = 0.05). Their mothers tended to be heavier than average during pregnancy (p = 0.004). Higher ponderal index at birth was also associated with a lower 30 minute insulin increment (p = 0.009), a marker of reduced beta cell function. We speculate that the rise in Type 2 diabetes in Indian urban populations may have been triggered by mild obesity in mothers, leading to glucose intolerance during pregnancy, macrosomic changes in the fetus, and insulin deficiency in adult life.