AIM:The aim of the study was to test the hypothesis of an association between low birth weight (LBW), abnormal glucose metabolism and heredity. METHODS:Common subjects were identified as newborns in a local birth register and as adult participants in the Västerbotten Intervention Programme (n=7796). Outcome measures such as impaired fasting glucose (IFG) and impaired glucose tolerance (IGT) were investigated in relation to LBW, family history of diabetes, and sex. RESULTS:Fasting plasma glucose and two-hour plasma glucose were elevated among women with LBW in relation to normal birth weight (NBW). Men and women with NBW had increased risks of IFG and IGT if there was a hereditary background of diabetes mellitus. LBW and hereditary background of diabetes mellitus interacted on the risk of IFG and IGT in women. CONCLUSIONS:Hereditary background of diabetes and LBW increase the risk of abnormal glucose metabolism such as IFG and IGT in early middle age. LBW and hereditary background of diabetes have a synergy effect on the risk of IFG and IGT in women.