Diabetes and pregnancy: The need for standardized terminology

The intersection of diabetes and pregnancy poses significant challenges for clinicians and researchers alike. Despite decades of investigation into maternal–fetal medicine, a persistent obstacle remains: the lack of standardized terminology when describing hyperglycemia in pregnancy. This deficiency not only contributes to clinical uncertainty but also hampers the comparability of research findings across different regions and healthcare settings. Several factors have contributed to this lack of consensus, including the evolving understanding of pregnancy-related metabolic changes, variability in population risk profiles, and differing resource availability across healthcare systems. In this editorial, we advocate for the establishment of a unified lexicon that clearly distinguishes between pregestational diabetes, diabetes in pregnancy, early gestational diabetes, and late gestational diabetes. Achieving consensus would require multidisciplinary collaboration, endorsement by international organizations, and alignment with emerging evidence—critical steps toward improving both diagnosis and management globally.

One of the primary issues in current practice is the marked variability not only in diagnostic strategies and thresholds endorsed by different medical organizations, but also in the terminology used to define hyperglycemia in pregnancy. For decades, the oral glucose tolerance test (OGTT) has served as the cornerstone for diagnosing gestational diabetes mellitus (GDM). However, controversies persist regarding which parameters should be applied and at what gestational age the diagnosis should be made. Variations in the use of the 75 g or 100 g OGTT, the implementation of preliminary screening tests such as the O'Sullivan Test, and differing thresholds across guidelines reflect this inconsistency. For instance, the IADPSG 2010 recommendation of a fasting glucose threshold of 92 mg/dL for early GDM diagnosis has been questioned, as emerging data from trials like TOBOGM suggest the need for more evidence-based, context-specific criteria. ¹ Notably, the IADPSG itself later acknowledged that applying this fasting glucose cutoff in early pregnancy may not be justified by current evidence. ²

Alternative diagnostic tools, such as fasting plasma glucose and hemoglobin A1c (HbA1c), are also employed inconsistently. ³ While these measures offer potential value under certain conditions, their limitations—particularly during early pregnancy—highlight the broader challenge. HbA1c levels, in particular, can be affected by altered red blood cell turnover, iron deficiency, and hemoglobinopathies such as thalassemia, which are prevalent in certain populations. Collectively, these diagnostic inconsistencies reinforce the urgent need for a harmonized terminology framework, which would serve as a foundation for subsequent refinement of diagnostic strategies and thresholds.

These diagnostic inconsistencies are further compounded by the lack of standardized terminology for classifying diabetes in pregnancy. Multiple terms—such as “pregestational diabetes,” “diabetes in pregnancy, or overt diabetes in pregnacy,” “early gestational diabetes,” and “late gestational diabetes”—are often used interchangeably or without clear differentiation. ⁴ For example, while some guidelines restrict the term “gestational diabetes mellitus” to diagnoses made between 24 and 28 weeks, others extend its definition to include cases detected before 24 weeks or even after 28 weeks. ⁵ Such discrepancies not only cause confusion among clinicians but also hinder effective communication in research publications and international collaborations. A unified terminology would provide clarity, allowing practitioners and investigators to speak the same language when addressing screening protocols, diagnostic thresholds, and treatment strategies.

Adopting standardized terminology has several potential benefits. First, it would streamline clinical practice by reducing diagnostic ambiguity. When healthcare providers agree on definitions and criteria, they can more accurately identify and manage patients, leading to earlier intervention and potentially improved maternal and fetal outcomes. Second, a unified lexicon would facilitate the design and interpretation of clinical research. Studies could be more readily compared and synthesized in meta-analyses if researchers use the same definitions for gestational diabetes subtypes. This consistency is particularly important in light of emerging evidence suggesting that early identification and treatment of gestational diabetes—especially in high-risk populations—can reduce the incidence of adverse neonatal outcomes. ⁶

It is also important to acknowledge the evolving landscape of research in this field. The recent focus on early gestational diabetes has been driven by evidence suggesting that recognizing and addressing glucose abnormalities before 20 weeks may mitigate neonatal complications. Future research should continue to refine both the terminology and conceptual framework of early GDM, as a clear definition will be essential to guide diagnosis, research strategies, and clinical interventions worldwide. ⁷

Beyond clinical implications, standardized terminology is essential for developing public health policies and guidelines. Professional organizations such as the American Diabetes Association, the World Health Organization, and regional entities like the Canadian Diabetes Association have all provided diagnostic criteria that differ in significant ways.^8,9 A consensus on terminology would empower these organizations to issue more coherent recommendations, ultimately enhancing global efforts to address the rising prevalence of diabetes during pregnancy. In fact, data from recent meta-analyses and large-scale studies highlight the global impact of hyperglycemia during pregnancy, indicating that up to 16–20% of live births involve mothers with some form of gestational hyperglycemia. ¹⁰ Such figures highlight the urgency of harmonizing diagnostic criteria to better capture and address this public health challenge.

In conclusion, the current state of diabetes management in pregnancy is hindered by inconsistent terminology and variable diagnostic protocols. By establishing a unified framework that clearly differentiates between pregestational diabetes, diabetes in pregnancy, early gestational diabetes, and late gestational diabetes, the medical community can take a significant step toward resolving these challenges. A standardized terminology would not only reduce clinical confusion but also provide a solid foundation for future research, enabling studies that more accurately assess the pathophysiological differences and long-term outcomes associated with each category of diabetes in pregnancy.