Introduction: The Dutch Institute for Healthcare Improvement (CBO) and the Association of Physicians in Internal Medicine (NIV) have revised their guideline on diabetes and pregnancy. One chapter deals with the question of whether it is useful to screen for diabetes in pregnancy. The complications of gestational diabetes, the effect of treatment on the complications and the effectiveness of screening tests are discussed by way of answer to the question. Effects on mother and child: Gestational diabetes is a risk factor for macrosomia, which can lead to shoulder dystocia, fractures and brachial plexus injuries. In rare cases perinatal mortality may occur. Effect of treatment: Systematic reviews are not conclusive about the effectiveness of treatment in reducing perinatal morbidity and mortality. A large randomised controlled trial showed a reduced relative risk of perinatal mortality, shoulder dystocia, humerus fracture and brachial plexus injury. Which screenings tests should be used? Screening tests are only moderately sensitive and specific. The fasting glucose test and 50 g glucose challenge test have the best combination of sensitivity and specificity. The reliability of the diagnostic 75g or 100g glucose tolerance test is limited. Is screening for gestational diabetes useful? Screening in the second half of pregnancy is not recommended in view of the limitations of the available screening tests. A diagnostic glucose tolerance test should be performed when gestational diabetes is suspected based on signs and symptoms. Greater awareness is indicated in women with risk factors for gestational diabetes. Women particularly at risk are those of South Asian, Hindustani, Afro-Surinamese, Turkish and Moroccan background. The risk also increases with advancing age, increasing weight and with a family history of diabetes. Screening at the beginning of pregnancy may be considered for existing, undiagnosed diabetes using a fasting plasma glucose test. This method is similar to the detection of diabetes outside pregnancy. This is described in the guideline on diabetes of the Dutch Association of General Practitioners.