Maternal obesity in early pregnancy is an important risk factor for gestational diabetes mellitus (GDM) [1]. Epidemiological studies show that both conditions are prevalent and at an increasing rate worldwide, and they are associated with increased fetomaternal complications. They carry lifelong consequences for both the mother and her offspring, and thus place heavy demands on health care resources [1–3]. Authors of a meta-analysis concluded that GDM was increased twofold in women with mild obesity, fourfold in women with moderate obesity, and eightfold in women with severe obesity [1], as compared with women with a normal body mass index (BMI). There is little consensus internationally about the diagnosis and subsequent management of GDM, which results in wide variations in obstetric care in countries throughout the world [4,5]. Whereas much of the debate around GDM is focused on the screening tests used and the diagnostic criteria involved, until recently little attention has been given to the importance of preanalytical glucose sample handling and the subsequent effect this has on diagnostic accuracy [6]. This has the potential to revolutionize our approach to GDM in the future.