Background Women with hypertensive disorders in pregnancy are at an increased risk of cardiovascular disease and type 2 diabetes later in life. Offspring born from these hypertensive pregnancies have increased levels of cardiovascular risk factors; whether they are at an increased risk of type 2 diabetes is not known. Objective The objective of the investigation was to study the risk of type 2 diabetes in the adult offspring exposed to maternal preeclampsia or gestational hypertension in utero. Study Design We studied 5335 members of the Helsinki Birth Cohort Study, who were born between 1934 and 1944 and who lived in Finland in 1995 when the National Medication Purchase Register was initiated. We ascertained gestational hypertension and preeclampsia according to modern criteria by using maternal and birth records. We defined type 2 diabetes through purchases of antidiabetic medication recorded in the comprehensive National Medication Purchase Register, excluding the 31 subjects who had purchased only insulin. We used Cox regression to assess hazard ratios for type 2 diabetes. Results A total of 590 men (21.6%) and 433 women (16.9%) had purchased medication for diabetes. The hazard ratio for type 2 diabetes for offspring exposed to any maternal hypertension in pregnancy was 1.13 (95% confidence interval, 1.00–1.29; n = 1780). For maternal gestational hypertension, it was 1.15 (95% confidence interval, 1.00–1.33; n = 1336) and for preeclampsia 0.98 (95% confidence interval, 0.71–1.34; n = 231). For type 2 diabetes with first medication purchase before 62 years, the corresponding hazard ratios were 1.25 (95% confidence interval, 1.04–1.51); 1.28 (95% confidence interval, 1.05–1.58), and 1.18 (95% confidence interval, 0.75–1.84). The hazard ratios were similar when adjusted for birthweight SD score for gestation, length of gestation, maternal body mass index in late pregnancy, height, age, and parity and for childhood or adult socioeconomic position. An increased risk of type 2 diabetes was also associated with low birthweight SD score, independent of the association with gestational hypertension. Conclusion Offspring exposed to maternal gestational hypertension in utero have an increased risk of type 2 diabetes in late adult life. This finding underlines the role of the whole spectrum of hypertensive disorders of pregnancy as risk factors of offspring disease throughout life. It also reinforces previous suggestions that adult health care providers should incorporate birth histories when evaluating an individual’s risk to develop type 2 diabetes.