INTRODUCTION

The management of type 2 diabetes mellitus (T2DM) has evolved considerably over recent decades. Earlier therapeutic strategies focused primarily on glycemic control, and glycated hemoglobin (HbA1c) served as the central treatment target. This approach was supported by landmark trials showing that improved glycemic control reduced the risk of microvascular complications [1–3]. More recently, however, large cardiovascular and renal outcome trials have shown that some glucose-lowering therapies provide benefits beyond glycemic reduction [4–9]. Contemporary management therefore increasingly addresses the prevention of cardiovascular and renal complications in parallel with effective glycemic control.

In response to this changing evidence base, major professional organizations have revised their clinical practice guidelines. The American Diabetes Association (ADA) publishes annually updated Standards of Care, and its pharmacological treatment recommendations are largely based on the consensus framework developed jointly with the European Association for the Study of Diabetes (EASD) since 2018 [10–12]. The National Institute for Health and Care Excellence (NICE) provides a structured approach designed for implementation within a publicly funded healthcare system [13], whereas the Japan Diabetes Society emphasizes pathophysiology-based treatment tailored to East Asian populations [14,15]. Thus, although these guidelines rely on broadly overlapping evidence, they differ substantially in their conceptual frameworks and therapeutic algorithms.

Differences in population characteristics, healthcare systems, and clinical priorities shape how evidence is translated into national recommendations. As a result, major guidelines have developed distinct approaches to pharmacological treatment. The Korean Diabetes Association (KDA) guideline reflects this context-specific translation of evidence by retaining a glycemia-centered treatment structure while increasingly incorporating cardiovascular and renal risk considerations relevant to Korean patients [16,17].

In this review, we examine the conceptual features of contemporary diabetes guidelines and situate the KDA framework within this broader landscape. We focus on key similarities and differences across guidelines and discuss their implications for clinical decision-making.

STRUCTURAL OVERVIEW OF CONTEMPORARY T2DM GUIDELINES

ADA standards of care and the ADA/EASD consensus framework

The ADA recommendations provide a widely used framework for T2DM management and are largely grounded in the ADA/EASD consensus reports introduced in 2018 and updated in 2022 [10,11]. These reports established a person-centered, comorbidity-driven model in which cardiovascular and renal risk reduction is incorporated directly into pharmacological decision-making. A key strength of the ADA framework is its capacity to incorporate high-quality contemporary clinical trial evidence rapidly through annual updates to the Standards of Care [12]. This update cycle allows emerging data to be reflected promptly, particularly evidence on the cardiorenal benefits of sodium-glucose cotransporter 2 (SGLT2) inhibitors and glucagon-like peptide 1 receptor agonists (GLP-1 RAs). Accordingly, treatment selection is guided not only by glycemic status but also by the presence of atherosclerotic cardiovascular disease (ASCVD), heart failure, chronic kidney disease, and obesity. The 2024–2026 ADA Standards of Care further reinforce this shift by moving away from a universal metformin-first strategy and toward individualized therapy [12,18,19]. For patients with established cardiorenal disease, SGLT2 inhibitors or GLP-1 RAs may be appropriate initial therapies independent of metformin use, although metformin remains the preferred initial medication for most patients with T2DM. The ADA framework also emphasizes person-centered care in real-world clinical settings by explicitly incorporating patient preferences, treatment burden, cost, and social determinants of health. Through this combination of evidence integration and contextual flexibility, the ADA Standards of Care have become a foundational reference for diabetes guidelines worldwide.

National Institute for Health and Care Excellence guideline

The NICE guidelines provide a structured framework for T2DM management within the United Kingdom’s National Health Service. Historically, NICE has emphasized clarity, feasibility, and cost-effectiveness through a stepwise approach that begins with metformin. The February 2026 update marks a major change in this framework [13]. The updated NICE guideline recommends dual therapy with modified-release metformin and an SGLT2 inhibitor as first-line treatment for all patients, including those without comorbidities, and triple therapy, including subcutaneous semaglutide, for patients with ASCVD. This structured approach is implemented through seven treatment pathways organized around key clinical profiles: absence of comorbidities, obesity, chronic kidney disease, early-onset T2DM, heart failure, ASCVD, and frailty. These pathways allow treatment to be tailored to dominant risk factors while preserving a unified algorithmic structure. The guideline also prioritizes modified-release metformin because of its improved tolerability, which may support adherence, addresses disparities in SGLT2 inhibitor uptake, and continues to incorporate formal cost-effectiveness analyses into therapeutic recommendations.

Japan Diabetes Society guideline

The JDS guidelines use a distinct approach that emphasizes pathophysiology-driven, glycemia-centered management [14,15]. Rather than prioritizing drug selection primarily according to cardiovascular outcomes, the JDS framework bases therapeutic decisions on underlying metabolic abnormalities, including insulin secretory capacity, insulin resistance, obesity, and hypoglycemia risk. This approach reflects the clinical characteristics of East Asian populations, among whom β-cell dysfunction is a dominant feature even in relatively nonobese individuals. Accordingly, a broad range of pharmacological agents may be selected according to individual patient profiles, without imposing a rigid hierarchy of drug classes. Recent updates have increasingly incorporated evidence supporting the cardiovascular and renal benefits of newer agents, including GLP-1 RAs and dual incretin therapies such as tirzepatide. However, these agents are incorporated into a flexible, pathophysiology-based framework rather than a strictly comorbidity-driven algorithm. In this respect, the JDS guidelines retain a distinctive balance between traditional glycemic control principles and evolving outcome-based evidence, while also reflecting Japanese clinical evidence and healthcare system characteristics.

Korean Diabetes Association guideline

The KDA guideline provides a pragmatic model that connects glycemia-centered management with contemporary cardiorenal evidence. Although the KDA guidelines were traditionally organized around glycemic control [20,21], they have progressively incorporated comorbidity-driven treatment considerations [16,22,23]. In the 2025 revision, metformin is no longer mandated as universal first-line therapy, allowing initial treatment to be individualized through early combination therapy or injectable regimens when clinically indicated [16]. At the same time, SGLT2 inhibitors and GLP-1 RAs are actively recommended for patients with ASCVD, heart failure, or chronic kidney disease, reflecting alignment with global evidence. The KDA guideline also identifies cerebrovascular disease as a distinct therapeutic consideration, particularly in patients with prior ischemic stroke or transient ischemic attack. This emphasis may reflect both the relatively high burden of stroke in East Asian populations [24] and evidence from cardiovascular outcome trials suggesting stroke-related benefits with selected agents, such as GLP-1 RAs [8,9] and thiazolidinediones [25,26]. In addition, the guideline permits flexible use of combination therapies, including oral quadruple regimens [27] and GLP-1 RA-based injectable approaches. These features reflect adaptation to real-world clinical practice in Korea, where treatment intensity, adherence, and healthcare access patterns may differ from those in Western settings. Overall, the KDA guidelines retain a glycemia-centered structure while rapidly incorporating emerging evidence and allowing flexible, context-sensitive treatment for Korean patients. Table 1 summarizes the pharmacotherapy decision pathways across contemporary guidelines.

COMPARATIVE CONCEPTUAL DIFFERENCES ACROSS CONTEMPORARY DIABETES GUIDELINES

Contemporary diabetes guidelines increasingly draw on a common evidence base emphasizing cardiovascular and renal risk reduction [4–9], but they differ substantially in how this evidence is organized and implemented. The ADA applies a person-centered, risk-based framework that prioritizes SGLT2 inhibitors and GLP-1 RAs for patients with cardiorenal disease while preserving flexibility in treatment sequencing and intensification [10–12,18,19]. In contrast, the NICE guideline uses the most structured and protocol-driven approach, with early combination therapy recommended through predefined pathways linked to major clinical profiles [13]. The JDS guideline takes a different approach by emphasizing pathophysiology-based treatment selection, in which therapeutic decisions are guided primarily by insulin secretory capacity, insulin resistance, obesity, and metabolic phenotype rather than by fixed comorbidity-driven algorithms [14,15].

The guidelines also differ in how they operationalize glycemic management and treatment intensification. The ADA emphasizes individualized escalation based on glycemic status and comorbidity profile [10–12], whereas NICE maintains structured stepwise intensification pathways that distinguish glycemic treatment goals from organ-protective goals [13]. The JDS framework places greater emphasis on metabolic and pathophysiological characteristics than on predefined treatment sequences [14,15]. Taken together, these frameworks show that contemporary diabetes guidelines balance cardiovascular risk reduction, glycemic control, treatment structure, and pathophysiology in different ways.

POSITIONING THE KDA FRAMEWORK: INTEGRATION OF GLYCEMIA, COMORBIDITY, AND DISEASE TRAJECTORY

The KDA guideline algorithm incorporates glycemic management strategies, comorbidity-based treatment, and insulin initiation approaches for hypercatabolic states or islet failure within a single treatment framework [16]. However, several of these concepts are not presented as detailed formal recommendation statements in the guideline itself. The accompanying KDA consensus statement elaborates on these areas through more explicit operational recommendations and also addresses pathophysiology-based treatment selection, which is not covered extensively in the guideline document [17].

Conceptually, the KDA framework can be understood as a pragmatic hybrid model that integrates glycemia-centered management with contemporary cardiorenal risk reduction strategies (Fig. 1) [16,17]. Like other major guidelines, the KDA incorporates SGLT2 inhibitors and GLP-1 RAs for patients with ASCVD, heart failure, or chronic kidney disease [16]. However, these comorbidity-based considerations are integrated into a predominantly glycemia-centered treatment structure rather than replacing conventional glycemic algorithms. The KDA framework also extends comorbidity-oriented treatment considerations to cerebrovascular disease, thereby broadening organ-specific risk assessment within its glycemia-centered therapeutic structure.

With respect to implementation, the KDA framework emphasizes early and flexible combination therapy, including both oral and injectable regimens. This approach allows broader and earlier multidrug intensification to address therapeutic inertia in real-world practice [16,17]. GLP-1 RAs are preferentially considered before insulin when appropriate, whereas insulin initiation is recommended in hypercatabolic states or islet failure regardless of HbA1c level [16,17]. The framework also incorporates treatment deintensification after metabolic stabilization, enabling therapy to be adjusted dynamically according to disease trajectory and clinical status [17]. These features position the KDA framework as an integrative, practice-oriented model that balances glycemic control, comorbidity management, and therapeutic flexibility (Fig. 2).

CONCLUSION: IMPLICATIONS FOR CONTEMPORARY DIABETES CARE

Contemporary diabetes guidelines share an increasingly convergent evidence base centered on cardiovascular and renal risk reduction, yet they differ substantially in how this evidence is translated into clinical practice. These differences reflect distinct emphases on comorbidity, glycemic control, and pathophysiology and are reflected in diverse treatment frameworks across regions. Within this landscape, the KDA guidelines serve as a pragmatic bridging model that retains a predominantly glycemia-centered structure while incorporating comorbidity-based treatment considerations and flexibility for real-world application. The accompanying consensus statement further extends this approach by addressing disease severity, pathophysiological heterogeneity, and dynamic treatment pathways, including intensification and deintensification strategies. Together, these perspectives underscore the need for diabetes care frameworks that supplement fixed treatment algorithms with adaptable, pathophysiology-informed approaches capable of addressing the growing complexity and heterogeneity of contemporary clinical practice.

Article information

CONFLICTS OF INTEREST

The authors declare that they have no financial conflicts of interest relevant to this article. Several authors participated in the development of the Korean Diabetes Association clinical practice guidelines and the accompanying consensus statement discussed in this review. The interpretations and opinions expressed in this article are those of the authors and do not necessarily represent the official positions of the Korean Diabetes Association.

ACKNOWLEDGMENTS

The authors acknowledge the members of the KDA Clinical Practice Guidelines Committee for their valuable contributions to the development of the KDA guidelines and for their insightful discussions, which informed this work. Artificial intelligence–assisted tools were used solely for English-language editing and grammatical refinement, and the authors take full responsibility for the content and interpretation of the manuscript.

Fig. 1

Integrated treatment framework for type 2 diabetes: the Korean Diabetes Association (KDA) approach incorporating glycemia, comorbidity, and disease trajectory. This figure illustrates the integrated treatment framework proposed by the KDA. The framework combines glycemia-centered management, comorbidity-driven organ protection, and disease trajectory–based decision-making. Treatment is adjusted dynamically through stepwise intensification, including early combination therapy and timely insulin initiation in hypercatabolic states or islet failure, followed by deintensification after metabolic stabilization and β-cell recovery when appropriate. ASCVD, atherosclerotic cardiovascular disease; HF, heart failure; CKD, chronic kidney disease; SGLT2i, sodium-glucose cotransporter 2 inhibitor; GLP-1 RA, glucagon-like peptide 1 receptor agonist; GIP, glucose-dependent insulinotropic polypeptide; TZD, thiazolidinedione.

Fig. 2

Positioning the Korean Diabetes Association (KDA) within contemporary diabetes treatment frameworks. This figure shows the relative positioning of major contemporary diabetes treatment frameworks according to their emphasis on glycemia-centered management, cardiorenal risk reduction, treatment structure, and pathophysiology- or person-centered decision-making. Within this comparison, the KDA framework is positioned as a pragmatic bridging model that retains a predominantly glycemia-centered structure while incorporating cardiorenal risk considerations and flexible implementation strategies. JDS, Japan Diabetes Society; ADA, American Diabetes Association; NICE, National Institute for Health and Care Excellence; NHS, National Health Service.

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