A study of 468 men born in Hertfordshire between 1920 and 1930 found that reduced fetal and infant growth was strongly associated with impaired glucose tolerance and non-insulin dependent diabetes (NIDDM) in adulthood. Men with lower birth weights and weights at 1 year had higher rates of impaired glucose tolerance and NIDDM. Plasma glucose and insulin concentrations were lower in men with higher birth weights and weights at 1 year. Plasma 32-33 split proinsulin concentrations were also lower in men with higher weights at 1 year, suggesting β-cell dysfunction. Blood pressure was inversely related to birth weight and strongly related to plasma glucose and 32-33 split proinsulin concentrations. The study suggests that reduced early growth is linked to high blood pressure, which may explain the association between hypertension and impaired glucose tolerance. The findings indicate that reduced growth in early life is strongly linked with impaired glucose tolerance and NIDDM, and with raised plasma concentrations of 32-33 split proinsulin, interpreted as a sign of β-cell dysfunction. The study also suggests that poor nutrition during critical periods of fetal life and infancy may lead to impaired development of β-cell function, which could contribute to the development of diabetes. The study supports the hypothesis that environmental factors, rather than genetic ones, may be responsible for the observed associations. The study was funded by several organizations, including the MRC, the Dunhill Medical Trust, and Lilly Research Laboratories.A study of 468 men born in Hertfordshire between 1920 and 1930 found that reduced fetal and infant growth was strongly associated with impaired glucose tolerance and non-insulin dependent diabetes (NIDDM) in adulthood. Men with lower birth weights and weights at 1 year had higher rates of impaired glucose tolerance and NIDDM. Plasma glucose and insulin concentrations were lower in men with higher birth weights and weights at 1 year. Plasma 32-33 split proinsulin concentrations were also lower in men with higher weights at 1 year, suggesting β-cell dysfunction. Blood pressure was inversely related to birth weight and strongly related to plasma glucose and 32-33 split proinsulin concentrations. The study suggests that reduced early growth is linked to high blood pressure, which may explain the association between hypertension and impaired glucose tolerance. The findings indicate that reduced growth in early life is strongly linked with impaired glucose tolerance and NIDDM, and with raised plasma concentrations of 32-33 split proinsulin, interpreted as a sign of β-cell dysfunction. The study also suggests that poor nutrition during critical periods of fetal life and infancy may lead to impaired development of β-cell function, which could contribute to the development of diabetes. The study supports the hypothesis that environmental factors, rather than genetic ones, may be responsible for the observed associations. The study was funded by several organizations, including the MRC, the Dunhill Medical Trust, and Lilly Research Laboratories.