Purpose: The purpose of this study is to evaluate the prevalence and possible clinical predictors of preeclampsia present in early pregnancy among women with type 1 diabetes. Methods: A systematic search of PubMed was conducted in April 2017. Inclusion criteria were largely unselected cohort, including at least 100 women with type 1 diabetes, dealing with either the prevalence of preeclampsia or possible clinical predictors of preeclampsia identified in early pregnancy. Results: Based on 11,518 pregnancies in 11 articles, the prevalence of preeclampsia in women with type 1 diabetes was 17%, five to six times more than in the background population. In early pregnancy, the following clinical predictors were associated with increased prevalence of preeclampsia: diabetic nephropathy (OR 3.7–23.5), microalbuminuria (OR 3.8–11.7), diabetic retinopathy (OR 1.9–2.9) and pre-existing hypertension (OR 3.8–17.1) as well as high blood pressure within the normotensive range. HbA1C, body mass index and nulliparity were positively associated with preeclampsia, but not consistently. Conclusion: The prevalence of preeclampsia in women with type 1 diabetes was 17%. In early pregnancy pre-existing hypertension and high blood pressure within the normotensive range as well as presence of microangiopathy were predictors of preeclampsia. Poor glycaemic control, obesity and nulliparity probably also contribute to the increased risk.