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. 2025 Apr 25;18:698–704. doi: 10.1016/j.ibneur.2025.04.010

The impact of perioperative hyperglycemia on postoperative cognitive function: A comprehensive review

Jiale Song a,b, Shuqin Li a,b, Heng Zhao c, Qian Hao b, Hongyuan Sui b, Hongmei Zhou b,⁎, Jian Lu b,⁎
PMCID: PMC12434691  PMID: 40959536

Abstract

Hyperglycemia, commonly triggered by the physiological stress of surgery, is exacerbated by counter-regulatory hormonal responses and can lead to significant complications including Postoperative Cognitive Dysfunction (POCD) and delirium. These conditions not only extend hospitalization and increase healthcare costs but also negatively impact long-term patient well-being. This review addresses multiple objectives by conducting a comprehensive literature review that synthesizes existing research across various surgical disciplines to assess the impact of hyperglycemia on cognitive outcomes. This involves integrating findings from both observational studies and clinical trials to offer a nuanced perspective on the current knowledge landscape. Secondly, it identifies significant gaps in research, including inconsistencies in outcomes and methodological shortcomings. Highlighting these gaps emphasizes the need for a more standardized approach to understanding hyperglycemia's cognitive effects post-surgery. Lastly, the review proposes future research directions, advocating for innovative research methodologies and clinical interventions aimed at mitigating the cognitive impairments associated with perioperative hyperglycemia. By providing an exhaustive examination of these aspects, the review seeks to enhance scholarly discourse and inform clinical practice, ultimately aiming to refine perioperative care protocols. This will protect cognitive functions and improve overall patient outcomes, bridging the gap between theoretical research and practical application, thereby setting the stage for advancements that could transform perioperative management standards.

Keywords: Hyperglycemia, Cognitive dysfunction, Glucose metabolism, Surgery, Perioperative hyperglycemia

Introduction

The meticulous management of glucose levels is a critical component of perioperative care, influencing a wide array of patient outcomes across diverse surgical interventions (Shanks et al., 2018). The perioperative period, characterized by significant physiological stress, necessitates a delicate balance of multiple systems to ensure optimal patient recovery and minimal morbidity. Within this complex milieu, the regulation of blood glucose emerges as a pivotal concern, with normoglycemia representing an ideal often challenged by the stress-induced hyperglycemic responses inherent to surgical procedures. The ramifications of such glucose fluctuations are profound, affecting everything from wound healing to infection rates (Järvelä et al., 2018), and more subtly, the cognitive outcomes that dictate the quality and efficacy of postoperative recovery (Hermanides et al., 2018).Perioperative hyperglycemia refers to the abnormal increase in blood glucose levels before, during, or postoperative period. At present, there is no exact standard for the range of perioperative hyperglycemia, but there are requirements for the glycemic control level in different stages of the perioperative period. According to the World Health Organization (WHO) standard preoperative hyperglycemia was fasting glucose of 126 mg/dL (7.0 mmol/L) or HbA1c 6.5 %; intraoperative hyperglycemia definition: blood glucose> 180 mg/dL (10.0 mmol / L); postoperative hyperglycemia defined as blood glucose duration> 140180 mg/dL (7.810.0 mmol / L).

Notably, the development of cognitive impairments, including Postoperative Cognitive Dysfunction (POCD) and delirium,stands out among the adverse effects linked to perioperative hyperglycemia (Hermanides et al., 2018, Windmann et al., 2019). These cognitive issues not only extend hospitalization durations but also escalate healthcare costs and adversely affect patients' long-term well-being. The critical examination of hyperglycemia's role in precipitating cognitive impairments is not a mere academic endeavor; it is a clinical necessity. By delineating the relationship between elevated glucose levels and post-surgical cognitive outcomes, healthcare professionals are better positioned to adapt perioperative management strategies. Consequently, this ensures the preservation of cognitive function, enhances patient recovery, and mitigates the broader impacts on healthcare systems (Greco et al., 2016).

This review endeavors to meticulously delineate the complex interrelationships between perioperative hyperglycemia and its cognitive ramifications. Our objectives are manifold and are structured to provide a comprehensive analysis of the current state of knowledge, identify existing research gaps, and propose directions for future investigative efforts.

First, we undertake a comprehensive literature review to synthesize the existing body of research examining the correlation between perioperative hyperglycemia and subsequent cognitive outcomes. This review spans a diverse array of surgical disciplines, incorporating findings from both observational studies and rigorous clinical trials. The goal of this synthesis is not merely to aggregate existing knowledge, but to critically evaluate how hyperglycemia influences cognitive health across different surgical contexts, providing a nuanced understanding of the scope and limitations of current research.

Second, we aim to identify and articulate the current limitations within the field. This involves a thorough critique of discrepancies in research outcomes, methodological challenges, and notable deficiencies in the robustness of available data. By highlighting these gaps, this review seeks to underscore the complexities and subtleties involved in fully comprehending the myriad ways in which hyperglycemia can impact cognitive health postoperatively. This segment is critical, as it not only sheds light on the need for more refined research methodologies but also on the urgent need for a standardized approach in studying these effects.

Third, we propose potential pathways for future research, aiming to address the gaps identified. This section of the review advocates for the exploration of innovative research methodologies and interventions that could potentially ameliorate the cognitive detriments associated with perioperative hyperglycemia. Emphasis is placed on elucidating the underlying biological mechanisms at play and on the development of clinical interventions that can effectively manage glucose levels to optimize cognitive outcomes post-surgery.

In providing a detailed exposition of these objectives, this review aspires to enhance the academic discourse surrounding perioperative glucose management. More crucially, it aims to influence clinical practice by informing the refinement of perioperative care protocols. The ultimate goal is to safeguard cognitive function and improve overall patient outcomes in the postoperative milieu. This scholarly endeavor not only bridges the gap between theoretical research and practical application but also sets the stage for future advancements that could transform patient care standards in perioperative management.

Physiology of glucose metabolism

Glucose, a pivotal source of energy for the body’s cells, is meticulously regulated within a narrow physiological range to ensure optimal cellular function and metabolic homeostasis. The regulation of glucose levels is primarily orchestrated by the hormones insulin and glucagon, which are secreted by the pancreas. Insulin, released in response to elevated blood glucose levels, such as after a meal, facilitates the uptake of glucose by cells, especially in muscle and adipose tissues, and promotes the storage of glucose as glycogen in the liver. Conversely, glucagon is secreted when blood glucose levels fall, stimulating glycogenolysis (the breakdown of glycogen to glucose) in the liver and gluconeogenesis (the synthesis of glucose from non-carbohydrate sources), thereby elevating blood glucose levels. This harmonious interplay between insulin and glucagon ensures the maintenance of blood glucose levels within a tight physiological range, crucial for the functioning of the brain and other glucose-dependent tissues.

Hyperglycemia occurs when blood glucose levels exceed the normal range. It can manifest in two primary contexts: chronic hyperglycemia, often associated with diabetes mellitus, where there is insufficient insulin production or action; and acute hyperglycemia, which can arise transiently due to stress, illness, or, notably, during the perioperative period. In the context of surgery, hyperglycemia is frequently observed due to a combination of factors including the physiological stress response to surgery, which elevates counter-regulatory hormones such as cortisol, catecholamines, glucagon, and growth hormone (Duwayri and Jordan, 2020). These hormones antagonize insulin action, leading to decreased glucose uptake by peripheral tissues and increased hepatic glucose production. Moreover, the administration of certain medications during surgery, such as corticosteroids, and intravenous glucose solutions can contribute to elevated glucose levels. In patients with existing diabetes, the stress of surgery can exacerbate hyperglycemia due to their underlying impaired glucose regulation (Greco et al., 2024). Hyperglycemia in the perioperative setting, if not adequately managed, can impede wound healing, increase the risk of infection, and affect overall recovery, including the potential exacerbation of cognitive impairments.

Fig. 1.

Fig. 1

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The mechanism of blood glucose regulation. The regulation of glucose levels is primarily orchestrated by the hormones insulin and glucagon. This harmonious interplay between insulin and glucagon ensures the maintenance of blood glucose levels.

Fig. 2.

Fig. 2

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Mechanisms of hyperglycemia induced by anesthesia and surgery. The surgical stress response activates the hypothalamic-pituitary-adrenal axis and the sympathetic nervous system, culminating in the increased secretion of counter-regulatory hormones such as cortisol, catecholamines, glucagon, and growth hormone. These hormones lead to pronounced hyperglycemia in different ways. For another, the inflammatory response triggered by surgery exacerbates insulin resistance, which leads to hyperglycemia.

Fig. 3.

Fig. 3

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The mechanism of cognitive decline caused by hyperglycemia. The detrimental impact of hyperglycemia on cognitive functions is mediated through several pathways that ultimately lead to neuronal damage and cognitive decline, mainly including BBB impairment, mitochondrial, oxidative stress, AGEs-RAGE pathway abnormal activation.

Fig. 4.

Fig. 4

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The key point of perioperative blood glucose management. Blood glucose levels are maintained between 140 and 180 mg/dL. By assessing HbA1c levels, the perioperative diabetes management plan was adjusted accordingly. Avoiding the risk of hypoglycemia.

Surgery results in hyperglycemia

Surgical interventions, irrespective of their nature and complexity, invariably elicit a profound physiological stress response in patients, leading to significant metabolic alterations, one of the most notable being the development of hyperglycemia. This perioperative hyperglycemia is not merely a transient biochemical anomaly but a multifactorial phenomenon with substantive implications for patient outcomes. The underpinning mechanisms that contribute to the elevation of blood glucose levels during and after surgical procedures are both diverse and interrelated, encompassing hormonal, inflammatory, and insulin resistance pathways, alongside iatrogenic factors.

At the core of the surgical stress response is the activation of the hypothalamic-pituitary-adrenal axis and the sympathetic nervous system, culminating in the increased secretion of counter-regulatory hormones such as cortisol, catecholamines, glucagon, and growth hormone. These hormones not only facilitate gluconeogenesis and glycogenolysis, elevating plasma glucose levels, but also induce a state of insulin resistance, markedly reducing peripheral glucose uptake. This complex hormonal cascade ensures the provision of adequate glucose to vital organs, particularly the brain, during times of acute stress. However, in the perioperative context, this well-intentioned physiological response can overshoot, leading to pronounced hyperglycemia (Peacock, 2019).

Concomitant with hormonal alterations, surgery initiates an inflammatory response characterized by the release of cytokines, such as tumor necrosis factor-alpha (TNF-α) and interleukins, which further exacerbate insulin resistance and disrupt glucose homeostasis. These inflammatory mediators impair insulin signaling pathways, diminishing glucose transport into cells, and thereby contribute to the persistence of hyperglycemia (Dong et al., 2021).

Moreover, the perioperative management practices, including the administration of corticosteroids for inflammation and intravenous glucose solutions for nutritional support, can inadvertently elevate blood glucose levels. Such iatrogenic contributions necessitate meticulous attention to glucose monitoring and management strategies during the perioperative period.

Patients with preexisting conditions such as diabetes mellitus are especially vulnerable to the exacerbation of hyperglycemia under surgical stress (Dungan et al., 2009, Akiboye and Rayman, 2017). In these individuals, the baseline impairment in glucose regulation intersects with surgery-induced metabolic disturbances, amplifying the risk of severe hyperglycemia and its associated complications (Chmieliauskaite et al., 2023, Kulikov et al., 2022, Ekström et al., 2023). Understanding the multifaceted origins and consequences of surgery-induced hyperglycemia underscores the importance of integrated care approaches (Knaak et al., 2019). These approaches should encompass vigilant monitoring, judicious use of glucose-elevating medications, and the application of evidence-based glucose management protocols. Such strategies are paramount not only for optimizing surgical outcomes but also for safeguarding against the long-term sequelae of perioperative hyperglycemia, including cognitive impairments, thus enhancing overall patient recovery and quality of life (Sreedharan et al., 2023).

It is worth mentioning that blood glucose monitoring is the basis of blood glucose management.Vigilant blood glucose monitoring, also known as intensive blood glucose monitoring, refers to a high-frequency and demanding comprehensive blood glucose monitoring method. It usually refers to measuring blood glucose multiple times throughout the day, such as measuring fasting blood glucose in the morning, measuring postprandial blood glucose 1–2 hours after each meal, before bed blood glucose, and even measuring blood glucose at 2–3 in the morning. In the perioperative period, in addition to the traditional finger stick blood glucose measurement using a blood glucose meter, continuous blood glucose monitoring (CGM) technology can also be used. CGM can continuously record the interstitial fluid glucose concentration, providing a more continuous and detailed blood glucose change curve, which can detect blood glucose trends and hidden hypoglycemic or hyperglycemic states. The above monitoring methods help doctors better understand the blood glucose level of patients during the perioperative period, so as to adjust treatment measures in time, and ultimately achieve the goal of reducing the occurrence of intraoperative hyperglycemia.

Hyperglycemia and cognitive function

The detrimental impact of hyperglycemia on cognitive functions is mediated through several interconnected pathways that ultimately lead to neuronal damage and cognitive decline. One key mechanism involves the exacerbation of oxidative stress, where elevated glucose levels lead to an overproduction of reactive oxygen species (ROS). These ROS can damage cellular components, including lipids, proteins, and nucleic acids, leading to neuronal injury and impaired cognitive functions (González et al., 2023).

Another pathway involves the advanced glycation end products (AGEs). Hyperglycemia accelerates the formation of AGEs, which can cross-link with proteins and alter their function. These AGEs interact with their receptors (RAGE) on neuronal cells, triggering inflammatory responses and further oxidative stress, contributing to neurodegeneration and cognitive deficits (Pal and Bhadada, 2023).

Hyperglycemia also disrupts cerebral blood flow and impairs the blood-brain barrier (BBB) integrity. The resulting endothelial dysfunction can lead to decreased nutrient and oxygen supply to the brain and increased permeability of potentially neurotoxic substances into the brain parenchyma, further affecting cognitive function (Wei et al., 2023).

Furthermore, hyperglycemia-induced metabolic disturbances can lead to mitochondrial dysfunction and impaired energy metabolism within brain cells, compromising neuronal viability and function. This is particularly detrimental to brain regions that are critical for cognitive processes, such as the hippocampus and prefrontal cortex (Sifuentes-Franco et al., 2017).

Evidence from non-perioperative settings

Evidence from both diabetic and non-diabetic populations in non-perioperative settings underscores the negative impact of hyperglycemia on cognitive performance (Lin et al., 2023). In individuals with diabetes, chronic hyperglycemia has been associated with an increased risk of developing cognitive impairments, including a greater likelihood of dementia. Studies have shown correlations between elevated HbA1c levels (a marker of long-term glucose control) and reduced performance in cognitive tests, particularly those assessing memory, executive function, and processing speed (Maan et al., 2021, Wei et al., 2022, Valenza et al., 2020).

In non-diabetic populations, episodes of acute hyperglycemia have also been linked to cognitive dysfunction. Research indicates that even in the absence of diabetes, fluctuations in blood glucose levels can affect cognitive abilities, with higher glucose levels associated with poorer performance in cognitive tasks. Such findings suggest that the brain's cognitive functions are sensitive to glucose regulation, even in individuals without a history of diabetes (Park et al., 2024).

These observations from non-perioperative settings provide valuable context for understanding the potential cognitive risks associated with perioperative hyperglycemia. They highlight the critical need for effective glucose management strategies not only for individuals with diabetes but also for the broader surgical population to mitigate the risk of postoperative cognitive complications.

Perioperative hyperglycemia and cognitive impairment

The cognitive outcomes associated with perioperative hyperglycemia can vary significantly depending on whether the hyperglycemia is acute or chronic. Acute perioperative hyperglycemia, often a transient response to surgical stress, can lead to immediate but temporary alterations in cognitive functions. These alterations are typically reversible with the normalization of blood glucose levels. However, even transient episodes of hyperglycemia during surgery can exacerbate brain metabolic stress, especially in patients with limited cerebral metabolic reserve.

In contrast, chronic hyperglycemia, commonly seen in patients with uncontrolled diabetes, is associated with long-term structural and functional changes in the brain. These changes include the accumulation of advanced glycation end products (AGEs), increased oxidative stress, and microvascular damage, contributing to a higher risk and earlier onset of cognitive decline and dementia. The brain regions most affected are those critical for memory and executive function, thus impacting cognitive domains most relevant to daily functioning (Moreira et al., 2013).

Hyperglycemia plays a significant role in the development and severity of POCD, a condition characterized by cognitive impairment following surgery. The mechanisms by which hyperglycemia exacerbates POCD likely involve a combination of the pathways described earlier, including oxidative stress, inflammation, and vascular dysfunction, leading to neuronal damage and cognitive deficits. Furthermore, hyperglycemia may potentiate the effects of anesthesia and surgical stress on the brain, increasing the vulnerability of neuronal tissues and exacerbating the cognitive impacts of surgery (Thiele et al., 2021).

Studies have demonstrated that patients experiencing hyperglycemia during or after surgery are at an increased risk for POCD (Hermanides et al., 2018). This association underscores the importance of maintaining optimal glucose control in the perioperative period to mitigate the risk of cognitive impairments.

Influence on other perioperative complications

Hyperglycemia in the perioperative setting can also contribute to a range of complications that, while not directly related to cognitive function, can indirectly influence cognitive outcomes. For instance, hyperglycemia is a well-known risk factor for surgical site infections, which can prolong hospital stays, increase the use of systemic antibiotics, and lead to additional stress and inflammation, all of which can negatively impact cognitive recovery (Thiele et al., 2021).

Moreover, hyperglycemia can exacerbate cardiovascular complications, including myocardial infarction and stroke, during the perioperative period. These events can have direct neurological consequences, further impairing cognitive function (Mapanga and Essop, 2016; Rawlings et al., 2019). Additionally, the management of these complications often requires interventions and medications that can themselves affect cognitive status, highlighting the complex interplay between hyperglycemia and cognitive outcomes following surgery (Puskas et al., 2007).

In summary, both acute and chronic perioperative hyperglycemia significantly contribute to the risk and severity of cognitive impairments, including POCD. The indirect effects of hyperglycemia-related complications further underscore the critical need for vigilant glucose monitoring and management in surgical patients to protect cognitive health and overall recovery.

Glucose management in perioperative care

The management of perioperative glucose levels is guided by a blend of clinical evidence and consensus recommendations, aiming to minimize the risk of hyperglycemia-related complications while avoiding hypoglycemia. Current guidelines generally advocate for maintaining blood glucose levels within a target range, often between 140 and 180 mg/dL for most patients undergoing surgery (Morin et al., 2023). This range is considered to strike a balance between reducing the risks associated with hyperglycemia and avoiding the acute dangers of hypoglycemia, especially in the critical care setting (American Diabetes Association, 2019).

For patients with known diabetes, these guidelines emphasize the importance of evaluating preoperative glycemic control, typically assessed through HbA1c levels, and adjusting perioperative diabetes management plans accordingly (Halperin et al., 2022). Insulin therapy, both through basal-bolus regimens and intravenous insulin infusions, is the cornerstone of managing perioperative hyperglycemia, especially in critically ill patients and those with type І diabetes (Partridge et al., 2016). The use of continuous glucose monitoring systems is also becoming more prevalent, offering real-time insights into glucose trends and enhancing the precision of glucose management.

Achieving optimal glucose control in the perioperative period presents numerous challenges. Variability in individual responses to surgery and anesthesia, differences in pre-existing glycemic control, and the dynamic nature of the perioperative metabolic state all contribute to the difficulty of maintaining glucose levels within the desired range (Morin et al., 2023). Additionally, the risk of hypoglycemia, particularly in insulin-treated patients, represents a significant concern, given its potential for acute neurological harm (Xie et al., 2018).

Controversies persist regarding the ideal target glucose range for perioperative patients. While tighter glucose control (e.g., targeting levels closer to the normal range of 80–110 mg/dL) has been suggested to improve outcomes in some surgical populations, such as cardiac surgery patients, it may increase the risk of hypoglycemia (van den Boom et al., 2018). Conversely, more liberal glucose targets may minimize the risk of hypoglycemia but could potentially leave patients exposed to the adverse effects of mild to moderate hyperglycemia. These controversies are compounded by the variability in recommendations across different professional organizations and the evolving nature of the evidence base (Morin et al., 2023, Membership of the Working Party et al., 2015, Thompson et al., 2016).

The management of perioperative glucose levels is further complicated by logistical issues, such as the need for frequent glucose monitoring and adjustments to insulin dosing. In the context of the broader hospital environment, where resources and staffing may be limited, implementing intensive glucose management protocols can be challenging.

In conclusion, the management of perioperative glucose levels is a critical component of surgical care, necessitating a careful balance between minimizing the risks of hyperglycemia and avoiding hypoglycemia. Despite existing guidelines, the optimal approach to glucose control in the perioperative setting remains a subject of ongoing debate and investigation, highlighting the need for individualized care plans and continuous monitoring to achieve the best possible outcomes for surgical patients (Duggan and Chen, 2019).

Future directions in research and practice

While considerable progress has been made in understanding the relationship between hyperglycemia and cognitive impairment in the perioperative setting, significant gaps in knowledge remain. One critical area requiring further investigation is the precise mechanisms by which perioperative hyperglycemia exacerbates cognitive decline, including the roles of inflammation, oxidative stress, and vascular changes (Gupta et al., 2022). Additionally, the impact of acute versus chronic hyperglycemia on postoperative cognitive outcomes, especially in non-diabetic patients, is not fully understood and warrants deeper exploration.

There is also a need for longitudinal studies to ascertain the long-term cognitive trajectories of patients experiencing perioperative hyperglycemia. Such research could elucidate whether temporary spikes in glucose levels have lasting cognitive consequences (Rolandsson et al., 2024, Sakusic et al., 2018, Zhou et al., 2024). Moreover, the differential effects of hyperglycemia on various domains of cognition (e.g., memory, executive function, attention) and how these relate to specific surgical procedures and patient populations are areas ripe for exploration.

Future research should also focus on developing and validating interventions to better manage perioperative glucose levels and prevent cognitive impairment. This includes pharmacological approaches, such as optimizing insulin therapy regimens or exploring the use of non-insulin glucose-lowering agents in the perioperative context. Non-pharmacological interventions, including dietary management, exercise programs, and stress reduction techniques before and after surgery (Galindo et al., 2022), may also play a role in mitigating hyperglycemia and its cognitive sequelae.

The potential for personalized medicine approaches, which tailor glucose management strategies based on individual patient characteristics (e.g., genetic factors, pre-existing conditions, type of surgery), is another exciting area for research. Such approaches could enhance the efficacy of interventions by accounting for the variability in patients' responses to surgery and glucose-lowering treatments (Duggan et al., 2016).

Technological advancements in glucose monitoring and management hold promise for improving perioperative care. Continuous glucose monitoring (CGM) systems, which provide real-time glucose readings and trend data, are becoming increasingly sophisticated and user-friendly. These devices could enable more precise glucose control in the perioperative setting by allowing for timely adjustments to insulin therapy and other interventions (Ajjan, 2017).

Artificial pancreas systems, which combine CGM with automated insulin delivery devices, represent a cutting-edge development in glucose management. While currently used primarily in the management of type І diabetes, the potential application of these systems in the perioperative setting, particularly for patients at high risk of hyperglycemia and its complications, is an area of interest (Namikawa et al., 2016).

Furthermore, the integration of glucose monitoring technologies with electronic health records and decision-support systems could enhance the coordination of care and adherence to evidence-based guidelines for perioperative glucose management (Reddy and Oliver, 2024).

In summary, addressing the gaps in our understanding of hyperglycemia's impact on cognitive function in the perioperative setting, exploring novel interventions for glucose control, and leveraging technological advances in glucose monitoring are crucial steps toward optimizing patient outcomes. These efforts will require multidisciplinary collaboration and innovation in both research and clinical practice.

Summary and conclusion

This review has elucidated the multifaceted relationship between perioperative hyperglycemia and cognitive impairment, highlighting the complex mechanisms through which elevated glucose levels can impact cognitive functions, including oxidative stress, inflammation, and vascular dysfunction (Gupta et al., 2022). The evidence from both diabetic and non-diabetic populations underscores the detrimental effects of hyperglycemia on cognitive outcomes, with acute perioperative hyperglycemia exacerbating POCD and potentially leading to long-term cognitive decline (Kurnaz et al., 2017).

The current guidelines for managing perioperative glucose levels aim to balance the risks associated with hyperglycemia and hypoglycemia. However, achieving optimal glucose control in the surgical setting presents significant challenges, including the variability in individual responses and the logistical difficulties of implementing intensive glucose monitoring and management protocols. Despite these challenges, the imperative to address hyperglycemia in the perioperative period is clear, given its association with not only cognitive impairment but also other complications that can indirectly affect cognitive recovery and overall patient outcomes.

For perioperative care, this review suggests several practical implications, including the need for vigilant glucose monitoring, especially in patients at high risk of hyperglycemia and cognitive complications. The adoption of continuous glucose monitoring technologies and the exploration of personalized medicine approaches may offer avenues for more precise and effective management of perioperative glucose levels. Furthermore, interdisciplinary collaboration is essential in developing comprehensive care plans that address the multifactorial nature of perioperative hyperglycemia and cognitive impairment.

Future research should aim to fill the gaps in our understanding of the mechanisms linking hyperglycemia to cognitive impairment in the surgical context and to identify the most effective interventions for preventing and managing these complications. Longitudinal studies exploring the long-term cognitive trajectories of patients experiencing perioperative hyperglycemia are particularly needed, as are clinical trials testing novel pharmacological and non-pharmacological interventions. Additionally, the potential of new technologies for improving glucose control and patient outcomes in the perioperative setting warrants further investigation.

This article contains many practical implications, including determining the scope of perioperative glucose control, emphasizing the importance of perioperative glucose monitoring and glucose management, facing the difficulties encountered in perioperative glucose management and providing the direction for solving this difficulties in the future. Differences in individual responses to surgery and anesthesia, uneven levels of preoperative blood glucose control, and constantly changing perioperative metabolic status all make it difficult to maintain blood glucose in the ideal range. At present, the target of blood glucose control is controversial, and different professional organizations vary. This article suggests that blood glucose should be controlled at 140–180 mg/dL in combination with multiple aspects. Although strict blood glucose control is beneficial for some surgical patients, it will increase the risk of hypoglycemia; although a relatively relaxed target can reduce the occurrence of hypoglycemia, it may bear the harm of mild to moderate hyperglycemia. This paper proposes to use the advantages of continuous glucose monitoring system and artificial pancreas system by combining glucose monitoring technology with electronic health record and decision support system to improve the level of perioperative blood glucose management.

In conclusion, perioperative hyperglycemia represents a significant risk factor for cognitive impairment and other adverse outcomes following surgery. Addressing this challenge requires a concerted effort from clinicians, researchers, and healthcare systems to implement evidence-based practices for glucose management and to continue exploring innovative approaches to care. By prioritizing the management of perioperative hyperglycemia, it is possible to enhance cognitive recovery, improve overall patient outcomes, and reduce the burden on healthcare resources.

Contributions from authors

JS and SL did the literature search, prepared the figures, and drafted the paper. HZ, QH and HS assisted in revising the manuscript. HZ and JL developed this paper's primary content and figures and completed the manuscript.

CRediT authorship contribution statement

Song Jiale: Writing – review & editing, Writing – original draft. Lu Jian: Writing – review & editing. Zhou Hongmei: Supervision. Sui Hongyuan: Supervision. Hao Qian: Supervision. Zhao Heng: Supervision. Li Shuqin: Writing – review & editing.

Ethics approval

Ethical issues (including plagiarism, data fabrication, double publi cation) have been completely observed by the authors.

Funding statement

This work was supported by Medical and Health Science and Technology project of Zhejiang Province (2024KY1683).

Abbreviations

POCD, postoperative cognitive dysfunction; TNF-α, tumor necrosis factor-alpha; ROS, reactive oxygen species; AGEs, advanced glycation end products; RAGE, receptors on advanced glycation end products; BBB, blood-brain barrier; CGM, continuous glucose monitoring

Disclosure statement

The authors have no conflicts of interest to declare.

Conflicts of Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Contributor Information

Hongmei Zhou, Email: drhongmeizhou@163.com.

Jian Lu, Email: ljp200681@163.com.

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