The epidemic of diabetes is spreading quickly to the poor and the deprived. Nutrition during fetal life influences the future risk for diabetes; and both under- and overnutrition contribute and coexist in rapid-transition countries. Nutrient imbalance seems particularly important; for example, low maternal vitamin B(12) status coupled with high folate predicted higher adiposity and insulin resistance in Indian children, suggesting a role for 1-C (methyl) group donors in fetal programming. Maternal hyperglycemia worsens the situation. Improving the early-life environment may be more cost-effective for preventing diabetes than controlling lifestyle factors alone in later life.