Foreword

Last year we celebrated the 100th anniversary of the discovery of insulin, arguably one of the greatest breakthroughs in medical history. As we reflect on this milestone, we are pleased to introduce this Special Issue of Obstetrics & Gynecology focusing on Diabetes in Pregnancy. The articles included were carefully selected from more than 100 submissions. They highlight not only the progress we have made in our field, but also the challenges that remain, reminding us that the work that was started a century ago is far from complete. In the preinsulin era, achieving pregnancy in the context of diabetes mellitus was uncommon, and maternal and perinatal mortality approximated 50%.1 Scientific progress has changed that landscape dramatically, and, with careful prepregnancy and prenatal care, we now regularly observe a positive outcome for mother and child. However, with this progress, we have encountered new challenges. Once a rarity, diabetes has become the most prevalent metabolic disorder of pregnancy, with approximately one in six live births affected, and a majority of patients have gestational or type 2 diabetes.2 In this issue, large observational studies and meta-analyses illustrate the unacceptable rates of major adverse outcomes that persist in this population, including more than threefold increased odds of stillbirth and perinatal mortality among individuals with pre-existing diabetes.3 Effective prenatal care can reduce diabetes-related complications, but it has been challenging to get this care to those who need it most.4 Carter and colleagues (see page 621) report on the effectiveness of group prenatal care, an approach that may be particularly beneficial and increase access in resource-limited environments.5 Liu et al (see page 670) demonstrate an association between neighborhood deprivation in early pregnancy and development of gestational diabetes, providing what we hope will be further incentive for health care organizations to consider community interventions to mitigate this risk.6 For decades, pregnant and lactating women were excluded from clinical studies. This exclusion resulted in evidence-based care for diabetes in pregnancy falling behind nonpregnancy diabetes care, with expert opinion reigning as gold standard during gestation. More recently, we have seen a much-needed investment in pregnancy research and thus an increase in well-designed studies, particularly in the area of diabetes technology. In this issue, Durnwald and colleagues (see page 684) examine continuous glucose monitoring (CGM) data ascertained from more than 700 pregnant people without preexisting diabetes.7 They identified distinct differences in early pregnancy glycemia among individuals who experienced specific adverse outcomes compared with those who did not experience those outcomes, laying the groundwork for using this technology to proactively identify and ultimately manage those at greatest risk. In an observational study of pregnant people with type 2 diabetes, Battarbee et al (see page 649) report that CGM compared with intermittent glucose monitoring was associated with less neonatal morbidity and fewer preterm births.8 These articles are complemented by state-of-the-art reviews summarizing the evidence for CGM, which provide practical approaches to its integration in our clinical practice. The work presented in this issue also makes us acutely aware that our approaches to clinical care should be measured, and just as more insulin is not always better, more technology is not always better. A randomized controlled trial by Feldman and colleagues (see page 707) demonstrates that alternate-day blood glucose monitoring was as effective as daily testing in people with gestational diabetes,9 and Savitsky and colleagues (see page 715) report that universal fetal echocardiogram is not cost effective in individuals with well-controlled diabetes in the first trimester of pregnancy.10 These studies encourage us to assess the downstream quality of life and financial consequences of doing more, reserving “more” for interventions proven to achieve better outcomes. We are extremely grateful to those who provided their time and expertise by serving as peer reviewers, people with and without diabetes who were willing to enroll in these studies to inform our care with evidence, and the commitment of the investigators who continue to move this work forward.