The impact of diabetes mellitus on perioperative anesthetic management. Challenges and strategies for optimized care

 

 

Nº de DOI: 10.34896/RSI.2026.85.40.001

 

 

AUTHORS

1. Nathaly Yessenia Tituana Ordóñez. General Practitioner. Attached to Private Clinics of Ecuador. Graduate of the Catholic University of Cuenca. (Zaruma-Ecuador). https://orcid.org/0009-0001-2840-3923
2. Celia Belén Ortega Almendariz. General Practitioner. Attached to Private Clinics of Ecuador. Graduate of the University of Cuenca. (Quito-Ecuador). https://orcid.org/0009-0008-3547-5029
3. Luis David Vinueza Lobato. General Practitioner. Attached to Private Clinics of Ecuador. Graduate of the Catholic University of Cuenca. (Azogues-Ecuador). https://orcid.org/0009-0003-4843-1723
4. María Magdalena Toro Andrade. General Practitioner and Master’s Degree in Health Management. Attached to the Julius Doefpner General Hospital. Graduate of the Particular Technical University of Loja. (⁠Zamora-Ecuador). https://orcid.org/0009-0007-0080-5393
5. Jeniffer Alina Murillo Caicedo. General Practitioner. Attached to Private Clinics of Ecuador. Graduate of the University of Guayaquil. (Guayaquil-Ecuador). https://orcid.org/0009-0007-3167-0604

 

ABSTRACT

In summary, perioperative success depends less on achieving strict normoglycemia and more on minimizing glycemic variability and anticipating the multi-organ effects of the disease. By focusing perioperatively on a proactive model of metabolic prehabilitation and intraoperative stabilization, anesthesiologists can attenuate the risks of the diabetic surgical patient.

KEY WORDS

Diabetes mellitus, including perioperative care, anesthesia, glycemic control and postoperative complications.

RESUMEN

En resumen, el éxito perioperatorio depende menos de alcanzar una normoglucemia estricta y más de minimizar la variabilidad glucémica y anticipar los efectos multiorgánicos de la enfermedad. Al centrarse perioperatoriamente en un modelo proactivo de prehabilitación metabólica y estabilización intraoperatoria, los anestesiólogos pueden atenuar los riesgos en pacientes quirúrgicos diabéticos.

PALABRAS CLAVE

Diabetes mellitus, cuidado perioperatorio, anestesia, control glucémico, complicaciones postoperatorias.

INTRODUCTION

Diabetes mellitus (DM) presents a significant and growing problem in perioperative medicine, as patients suffering from this metabolic illness experience a disproportionately higher burden of postoperative complications, such as surgical site infections, delayed wound healing, and cardiovascular events. This systematic review investigates the implications of DM on anesthetic management with particular emphasis on the interactions between chronic hyperglycemia, acute metabolic stress, and end-organ dysfunction. This review discusses the evidence of pathophysiological challenges posed by diabetic autonomic neuropathy, microvascular fragility, and an exaggerated neuroendocrine stress response to surgery. Next, we discuss preoperative optimization strategies, including the more nuanced management of new pharmacological agents such as the sodium-glucose cotransporter-2 (SGLT2) inhibitors and modifications to ERAS protocols for the diabetic patient.

OBJECTIVE

The objective of this systematic review is to analyze the complex impact of Diabetes Mellitus on perioperative anesthetic management.

METHODOLOGY

Literature Search Strategy and Database Selection:

To produce a comprehensive review of the current literature, a systematic search was conducted through several electronic databases, including PubMed, MEDLINE, EMBASE and Cochrane Central Register of Controlled Trials. The search strategy included the use of a combination of Medical Subject Headings (MeSH) terms and keywords about Diabetes Mellitus, including Perioperative Care, Anesthesia, Glycemic Control, and Postoperative Complications. The search was limited to English studies with an emphasis on high-quality studies published in the last ten years, although studies were included that form the foundations of literature if high-quality studies were not available. In addition, clinical practice guidelines from leading organizations, including the American Diabetes Association (ADA), Enhanced Recovery After Surgery (ERAS) Society and numerous national anesthesiology societies were searched manually to add to the review of current standards of care⁴.

Inclusion and Exclusion Criteria for Study Selection:

Studies were included if they met the following criteria: (a) they included adult patients with Type 1 or Type 2 DM undergoing elective or emergency surgery, (b) the studies were about perioperative anesthetic management, including preoperative assessment, intraoperative monitoring, or early postoperative care, and (c) studies reported clinical outcomes, including glycemic stability, organ injury and/or surgical outcomes. Randomized controlled trials (RCTs), systematic reviews and meta-analyses were prioritized. Exclusion criteria included a study primarily focused on pediatric patients, focused solely on non-surgical management for diabetes, and case reports that were either unique to the individual or not broadly applicable. Abstracts from major international congresses, including Albanian Congress of Trauma and Emergency Surgery (ACTES), were screened for emerging trends and preliminary findings related to diabetic care in trauma patients⁵.

Data Extraction and Quality Assessment Framework:

A standardized form was used for data extraction to ensure thorough and comprehensive evaluation of the studies that included descriptors of study design, demographics of patients, surgical procedure types, anesthetic techniques, glycemic target, and outcomes of interest. Studies were quality-assessed using established frameworks, randomized-controlled trials (RCTs) were assessed for risk of bias using the Cochrane tool, while observational studies were assessed using the Newcastle-Ottawa Scale. For clinical guidelines, the AGREE II tool was utilized to assess the rigor of recommendations cited⁶. This methodological structure allowed for synthesis of disparate data points into a coherent narrative to describe the current state of perioperative care for diabetic patients.

RESULTS

The worldwide prevalence of diabetes mellitus is now at pandemic levels, presenting a considerable burden on healthcare systems across the globe. As the number of individuals living with DM rises, the number of DM patients presenting for surgical procedures continues to increase. Patients with diabetes not only are more likely to experience surgery in their lifetime, but they also have considerably higher rates of perioperative morbidity and mortality when compared with non-diabetes patients¹. The presence of DM adds a layer of complexity to anesthetic management that is unrelated to simply regulating blood glucose levels. DM represents an entire system physiological state characterized by compromised vasculature, altered immune function, and altered autonomic regulation, all of which create challenges associated with the metabolic stress of surgery.

Within the perioperative milieu, the anesthesiologist is the metabolic controller, managing the “tightrope” of the harms of hyperglycemia while dealing with the immediate complications of hypoglycemia. Surgery and anesthesia induce a powerful neuroendocrine response, characterized by the release of counter-regulatory hormones, such as cortisol, catecholamines, and growth hormone, and in the diabetic population, this often results in significant insulin resistance and metabolic volatility that outpaces conventional insulin plans. In addition, the chronic complications of diabetes (e.g., diabetic autonomic neuropathy (DAN) or stiff joint syndrome), create real technical or hemodynamic challenges at induction or maintenance of anesthesia.

Despite advances in surgical techniques and anesthetic agents, ensuring the safety of the diabetic patient is inconsistently managed across clinical settings. Previous management strategies have typically been focused on targeting specific glucose levels, however, the evidence is now pointing toward the importance of stability and prevention of rapid glucose fluctuations². The development of new classes of glucose-lowering agents, particularly the SGLT2 inhibitors, also create unique risks such as euglycemic ketoacidosis, modifying preoperative fasting and medication considerations³.

This systematic review seeks to provide a thorough assessment of the burdens associated with anesthetic management of patients with diabetes. It will review the pathophysiological processes associated with perioperative risk and evaluate the standard and emerging methods of preoperative optimization and risk stratification. By bringing together information from recent clinical trials and consensus guidelines, this review aims to provide a summary of and approach to optimized, evidence-based practice while being sensitive to the specific needs of this high-risk patient population.

Pathophysiological Challenges in the Diabetic Surgical Patient:

Macrovascular and Microvascular Complications:

The sustained state of hyperglycemia in DM causes widespread vascular damage, leading to significant impairment of the patient’s physiologic reserve in the setting of surgery. Macrovascular complications, such as coronary artery disease (CAD) and peripheral vascular disease, are extremely common and often more severe in the diabetic patient population. Diabetic patients are at increased risk for acute coronary syndrome (ACS) during the perioperative period, frequently presenting with atypical or «silent» ischemia due to concomitant neuropathy, highlighting the need for a very high index of suspicion, with careful monitoring of biomarkers of cardiac injury and ECG changes even in the absence of definitive chest pain^7.

At the microvascular level, the thickening of capillary basement membranes and endothelial dysfunction leads to impaired perfusion and impaired tissue delivery of oxygen. This microvascular fragility creates a «hypoxic niche» at the wound site despite adequate systemic oxygen saturation, and tissue hypoxia is a primary driver of delayed wound healing and increased risk of surgical site infections (SSIs). Additionally, the kidney damage related to microvascular disease puts the diabetic patient at risk for perioperative development of acute kidney injury (AKI) when exposed to nephrotoxic agents or to periods of hypotension⁸. The combined macro- and microvascular disease leaves the diabetic cardiovascular system with no «vascular plasticity» ability to adapt to the significant fluid shifts and hemodynamic changes that will occur during a surgical procedure.

Diabetic Autonomic Neuropathy and Hemodynamic Instability:

Diabetic autonomic neuropathy (DAN) is perhaps the most insidious challenge for the anesthesiologist. DAN affects both sympathetic and parasympathetic systems and leads to a loss of normal cardiovascular compensatory mechanisms. One of the most important manifestations is the blunting of the heart rate response to stress and loss of compensatory vasoconstriction in the induction of anesthesia, resulting in profound and refractory hypotension after the induction of anesthesia which directly impacts perfusion of vital organs⁹.

DAN is also associated with gastric paresis, which is the inability to normally empty the gastric contents even after a fasting period, putting patients at risk for pulmonary aspiration during airway management and sometimes resulting in specialized anesthetic management approaches like rapid sequence induction (RSI) in symptomatic patients¹⁰. Furthermore, DAN complicates the evaluation of hemodynamic data, for instance, if the patient is not tachycardic in response to hypovolemia or pain, the clinician may think the patient is less physiologically distressed than they actually are. Thus, managing the diabetic patient with DAN requires an aggressive approach to fluid resuscitation and the careful use of vasopressors to maintain hemodynamic stability.

Metabolic Disturbances and Altered Immune Function:

The surgical process initiates a neuroendocrine «storm,» signified by rising cortisol and catecholamine levels, which provoke gluconeogenesis and glycogenolysis while causing peripheral insulin resistance. In diabetic patients, the stress-induced hyperglycemia is added onto a pre-existing state of metabolic instability, producing rapid and extreme fluctuations in blood glucose levels. Studies have shown that glycemic variability—the «swing» between high and low glucose—is worse for the vascular endothelium than steady moderate hyperglycemia due to the increased oxidative stress and inflammatory cytokine release¹.

This metabolic derangement is amplified by the impaired immune response associated with DM. Hyperglycemia impairs neutrophil function, specifically chemotaxis and phagocytosis, both of which correlate to an increased risk of infection. Furthermore, the «sweet» environment of hyperglycemia in the blood serves as a substrate for bacteria to grow, increasing a fit patient’s risk of postoperative sepsis. The anesthesiologist must realize that the metabolic stress response can cause a once well-controlled diabetic to enter a state of metabolic crisis, necessitating frequent monitoring and aggressive yet cautious titration of insulin to avoid both severe hyperglycemia and the lurking threat of hypoglycemia while under anesthesia².

Preoperative Assessment and Risk Optimization:

Evaluation of End Organ Damage and Glycemic Control:

The preoperative assessment of the diabetic patient must be more than a cursory review of blood glucose logs. It includes a thorough assessment of end organ damage to ascertain the patient’s physiological resilience. Glycated hemoglobin (HbA1c) is an especially important value, not only as a marker of long-term glycemic control but as an ‘proxy’ for the degree of chronic oxidative stress endured by the patient’s system. There is some debate regarding the exact HbA1c, that would justify postponing elective surgery, however, levels above 8.0-8.5% are certainly associated with appreciably worse outcomes³. Again, the aim should be optimization rather than simply «clearing.»

The evaluation must include looking for «hidden» complications. For instance, the «prayer sign» or stiff joint syndrome, due to glycosylation of collagen in the cervical spine and temporomandibular joints may indicate a potentially challenging intubation¹¹. Renal function should be assessed via the estimated glomerular filtration rate (eGFR), and not serum creatinine alone, as patients with diabetes often have reduced renal reserve, even with a «normal» creatinine⁸. Lastly, a complete cardiovascular assessment, including specific evaluation for silent ischemia and orthostatic hypotension (a marker of DAN), is paramount to an anesthetic plan that is tailored to the specific risk profile of the patient.

Preoperative Pharmacological Management and Fasting Protocol:

Over the past few years, approaches to managing diabetes management in the preoperative period have shifted from a one-size-fits-all to a more tailored approach. The «hold all orders» seen in the past are being shifted to a more nuanced understanding of maintaining metabolic homeostasis. For example, it is frequently recommended that patients take a lesser dose of long-acting basal insulin (60-80%) the night before or the day of surgery to prevent diabetic keto acidosis during fasting¹. Patients should be advised to hold multi-dose oral hypoglycemic agents on the day of surgery, with particular attention paid to those on SGLT2 inhibitors.

The advent of SGLT2 inhibitors (e.g., canagliflozin, empagliflozin) has introduced risk for euglycemic diabetic keto acidosis (DKA), a life-threatening condition characterized by the patient developing metabolic acidosis despite relatively normal blood glucose levels. Current guidelines recommend holding SGLT2 inhibitors for 3-4 days prior to major surgery to allow complete drug clearance³. With regards to fasting, the discussions on carbohydrate loading in an ERAS protocol will be particularly relevant for patients with diabetes. Clear carbohydrate drinks to be ingested 2 hours prior to surgery may be beneficial in reducing insulin resistance in healthy patients. However, if a diabetic is ingested them prior to surgery, it may exacerbate their hyperglycemic state or, if the patient has gastroparesis, increase their risk of aspiration. Therefore, ERAS protocols may need to be «diabetic-tailored,» preferably utilizing small volumes of carbohydrate solutions, and monitoring gastric emptying with surgical stewardship⁶.

Patient Stratification and Risk Assessment Models:

Effective perioperative management must involve the use of validated tools that aid in stratifying patient risk and the management process based on the greatest level of clinical evidence. The ASA Physical Status Classification is still the primary tool for assessing patient risk level, however, it lacks the specificity for diabetics, including those who may have nutritional deficiencies. More specific models, such as the American College of Surgeons (ACS) National Surgical Quality Improvement Program (NSQIP) Surgical Risk Calculator, assist with assessing risk by predicting the likelihood of complications, including surgical site infection (SSI), acute kidney injury (AKI) and myocardial infarction (MI). Risk assessment tools incorporate diabetes status as part of their co-morbid or coagulopathy risk⁶.

Risk stratification should involve identification of patients who may benefit from metabolic «prehabilitation» – a multiweek process that includes the optimization of nutritional status, glycemic control and activity level before elective surgery. Early identification of the «high-risk» diabetic patient along the preoperative patient journey will allow for an intensive management approach to commence (e.g., transitioning from oral agents to insulin-based therapy and involving a multi-disciplinary team such as endocrinology or diabetic nurse specialist)¹². The surgical team will be able to move away from a one-shoe-fits-all perioperative plan process based on these prediction tools utilized in stratification. Rather the surgical artisanal can develop a personalized perioperative plan that meets the diabetes-specific vulnerability of the patients identified.

Intraoperative Anesthetic Management and Monitoring:

General and Regional Anesthesia Techniques Comparison:

The selection of the anesthetic technique is a critical factor in influencing the metabolic response to surgery. While general anesthesia (GA) allows for the necessary depth and immobility of the patient, the use of GA does little to dampen the afferent signals that initiate the neuroendocrine stress response. Conversely, regional anesthesia (RA), particularly neuraxial techniques such as spinal or epidural anesthesia, can effectively interrupt those signals at its source. Regional anesthesia prevents the surgical stimulus from reaching the central nervous system, thus preventing the concomitant release of cortisol and catecholamines which has an overall stabilizing effect on glycemic control when compared to GA alone⁴.

Regional anesthesia carries additional advantages for all patients, especially diabetic patients, in addition to preventing or minimizing opioid use and the subsequent delay in gastric emptying in a population already prone to gastroparesis. In addition, the use of peripheral nerve blocks for extremity surgery provides excellent postoperative analgesia without unwanted resident or side effects to significantly interfere with metabolic management. Dialing in the intraoperative anesthetic technique is ultimately a decision for the anesthesia provider, and neuraxial techniques should be used with caution in patients with significant DAN, as the combination of the sympathetic block of the neuraxial anesthesia with the obesity and baseline autonomic dysfunction in the patient makes the hemodynamic responsibilities unpredictable, and prone to a more severe hypotensation. The decision between GA and RA, therefore, must be individualized and often reaches a “combined” anesthetic approach that allows for integrating the advantages of both anesthetic approaches while minimizing disadvantages².

Glucose Monitoring and Insulin Delivery Intra-op:

The intraoperative management of glycemia requires the transition from achieving «normal» to achieving «stability.» Early studies noted that tight glycemic control (80 to 110mg/dL) might lead to improved outcomes following surgery. However, more recent large studies confirmed that tight glycemic control significantly increased outcomes of severe hypoglycemia, which itself could be fatal or lead to permanent neurological damage. As a result, the most recent consensus has favored a moderate blood glucose value (140-180 mg/dL), which provided some «safety margin» against hypoglycemia while generally remaining below the renal threshold for glucose (~180 mg/dL), and avoiding osmotic diuresis and loss of fluids¹.

The frequency of blood glucose monitoring is important to note, especially during longer operative procedures or when executing an insulin infusion via the intravenous route. In patients who are sedated or in anesthesia, the classic adrenergic symptoms of hypoglycemia—such as tachycardia, trembling, and perspiration—may be obscured due to the effect of anesthetic drugs or beta blockers. Due to this, checks of blood glucose should occur frequently (every 1-2 hours). The use of continuous glucose monitoring (CGM) systems in the OR is a topic of ongoing investigation. Although they may have some potential for providing real-time trends and limiting variability, their accuracy with rapid hemodynamic changes or hypothermia is unknown at this time¹¹. Intravenous (IV) infusions are preferred for insulin delivery since the onset is rapid and the half-life is short, allowing for precise titration, as dictated by the changing situation in the surgical field.

Fluid Therapy and Electrolyte Homeostasis:

Managing fluids for diabetic patients can be a challenging balancing act. The chronic hyperglycemia status often lends itself to a state of chronic dehydration due to osmotic diuresis, but because of the presence of diabetic cardiomyopathy or diastolic dysfunction, the patient is also at risk for fluid overload. Goal-directed fluid therapy GDFT), with the use of various dynamic parameters including stroke volume variation or pulse pressure variation, is particularly useful in this population in order to ensure adequate volume delivery of impacted organs without producing pulmonary edema⁸.

Equally, electrolyte homeostasis is critical. Insulin therapy moves potassium into the intracellular compartment, therefore, monitoring for hypokalemia is imperative in patients whose potassium may be already depleted due to pre-operative fasting or use of diuretics. Alternatively, diabetic patients with underlying renal dysfunction may have functional hyperkalemia. In addition, the possibility of metabolic acidosis, whether from DKA or lactic acidosis from hypoperfusion, needs to be continually assessed via arterial blood gas analysis. The intravenous fluid selected plays a role as well. While most fluid IV fluids may be used, balanced salt solutions are generally preferred over normal saline to avoid the risk of hyperchloremic metabolic acidosis, as the clinician attempts to interpret the patient’s acid-base status⁴.

Postoperative Management and Preventing Complications:

Postoperative glycemic targets and transition to home regimen:

The first few hours the patient is awake postoperative is a time of high metabolic variability as the effects of anesthetic agents dissipate and the surgical stress response peaks. Target glycemic range of 140-180mg/dL should remain the priority in this phase. As the patient progresses from IV insulin to their own regimen, a «bridging therapy» may be warranted, completing overlapping the IV infusion with the first dose of subcutaneous basal insulin administered to avoid rebound hyperglycemia from sudden removal of IV insulin¹.

Resuming oral calories is a critical milestone. In patients affected by gastroparesis, this transition will need to occur slowly to monitor for nausea or vomiting from early oral intake which can lead to electrolyte imbalances and poor glucose control. When the patient eventually resumes oral caloric intake, the timing to restart oral hypoglycemic agents will be critical, particularly metformin and SGLT2 inhibitors. These agents should only be started once renal function is stable and the patient is reliably eating regularly to reduce the risk of lactic acidosis and DKA, respectively³.

Managing Surgical Site Infections and Wound Healing:

Diabetes considerably heightens the risk of surgical site infections (SSIs) and wound dehiscence due to multiple causes contributing to healing delays, thus increasing both patient morbidity and healthcare costs. Factors that affect healing processes including collagen synthesis, reduced wound tensile strength, and the previously noted dysfunction of neutrophil activity are all involved in this impaired healing. The most effective method to reduce the risk of SSI is to maintain stable perioperative glucose levels. In addition to this, other relatively trivial considerations such as appropriate oxygenation and normothermia are also important.

The anesthesiologist supports the healing process through hemodynamic stability in order to ensure adequate tissue perfusion, as well as the oxygen supplementation as appropriate. In higher risk diabetic patients, more aggressive surveillance of the surgical site and prophylactic approaches like negative pressure wound therapy or special dressings may be appropriate. Educational interventions that start preoperatively and extend into the postoperative period can aide in empowering patients to monitor for early signs of infection and the importance of tight glycemic control in the healing period⁶.

Enhanced Recovery After Surgery (ERAS) protocols in diabetic patients:

The goal of enhanced recovery after surgery (ERAS) protocols is to lower the surgical stress response and promote healing through a series of evidence-based approaches, i.e., the ERAS process is aimed at promoting recovery from surgery. While ERAS protocols are effective in the general population, such protocols need to be approached with caution and adjusted for the diabetic patient. Early ambulation and not routinely using nasogastric tubes and drains are two key aspects that are useful for diabetic patients since they allow for a more rapid return of bowel function, and minimizes the thromboembolic risk from surgery¹³.

Nevertheless, the ERAS concepts/care pathways including «carbohydrate loading» and «early oral intake» must be approached with caution. As previously mentioned, the risk of gastroparesis and unpredictable hyperglycemia can be reasons for more conservative approaches to oral rehydration in the diabetic patient. Dexamethasone is another common component of ERAS protocols as a prophylaxis for postoperative nausea and vomiting (PONV). Dexamethasone can result in significant hyperglycemia for diabetes, and this must be weighed against the benefit of decreasing the PONV and the diabetic metabolic risk. Anesthesiologists may consider using a lower dose of dexamethasone, or consider using an alternate agent. Ultimately, a «diabetic specific» ERAS pathway – one that considers metabolic stability regardless of traditional recovery benchmarks – needs to be developed and studied in order to facilitate care pathways for diabetic patients⁴.

DISCUSSION

The synthesis of the aforementioned literature will serve to illustrate that the perioperative management of a diabetic patient is not simply addressing a laboratory value, but rather a complex, systemic metabolic disorder. The common theme, which emerged from reviewing the literature, was the acknowledgment of «stability over normality»¹⁴. Although theoretically ideal, the goal of normal glucose levels creates the risk of hypoglycemia, which is devastating as an anesthetized or sedated patient often do not display clinical symptoms.

The clinical impact of this literature review defines a transition from the current approach of glycemic management to a more proactive patient-centered approach. Preoperatively, measure end-organ reserve in lieu of «clearing» the patient based on an HbA1c level. Intraoperatively, the choice of anesthetic technique and fluid therapy should be considered an intervention in terms of metabolic stress response, instead of simply a route of administration. Postoperatively, the focus should be on transferring care so metabolic improvements made in the operating room do not get lost in recovery¹⁵.

Finally, the data support the need for teams of professionals. The anesthesiologist has transitioned to a perioperative physician who must manage care in coordination with surgeons, endocrinologists, and nurses to implement evidence-based practice protocol like ERAS¹⁶. By viewing the patient with diabetes through the framework of physiological resilience and metabolic plasticity, the clinician will be better positioned to anticipate complications and plan interventions that are appropriate based on the individual’s specific risk profile.

In spite of the growing body of evidence describing glucose management and the literature reviewed about the importance of glucose management, there are still barriers to implementing standardized perioperative care for patients with diabetes. One of the primary barriers is lack of high-level consensus on universal glycemia targets. Diversity among professional societies often produced differing recommendations, which contributes to institutional heterogeneity¹⁴. Increased variation in professional recommendations creates uncertainty for providers and inconsistency in care for patients transitioning from department to department.

Institutional barriers are also significant. Establishing far-reaching protocols, such as ERAS or intensive insulin infusion protocols, requires substantial resources, such as training for staff, ability to monitor closely, and collegial culture of care¹⁵. In many locations, high surgical turnover may benefit more than thorough metabolic optimization. More importantly, the increasing complexity of the diabetic population, often involving elderly patients with multiple morbidities and polypharmacy, complicates the creation of «standard» protocols.

Lastly, patient-related factors, such as their health literacy and ability to follow preoperative instructions, can obstruct our pursuit of successful optimization. An example of this is manifest as the mismanagement of newer agents, such as SGLT2 inhibitors, in the days leading to surgery that lead to life-threatening complications that no intraoperative protocol can manage. Overcoming these barriers will depend on more robust education of providers, better streamlined institutional workflows, and increased patient engagement throughout the perioperative period.

Although we have made considerable strides in understanding the diabetic surgical patient, we do note several limitations in the current evidence base. Most of the data avail to us has come from observational studies or small clinical trials that we may not be able to apply broadly across surgical specialties or patients. For example, although the benefits of tight glycemic control are clear in the context of cardiac surgery, it is less clear that those benefits translate to minor ambulatory surgical procedures¹⁵.

We need large, multiplace, randomized controlled trials (RCTs) to help define the glycemic range most appropriate in the context of glycemia and surgical considerations. More specifically, studies to show whether or not «personalized targets» based on chronic glucose levels represented by the HbA1c would yield better outcomes than general targets, is important. Finally, research on the utility of modern and novel technology in perioperative periods, such as closed-loop insulin delivery systems («artificial pancreas») or non-invasive continuous glucose monitors in the perioperative setting will have to be subject of vigorous investigation.

Future studies should also investigate the long-term effects of perioperative metabolic management on longer outcomes than the short term 30-day post-operative time period. For instance, the long-term effects of glycemic variability on long-term cognition, cardiovascular health, and quality of life, are still unknown. With the increasing prevalence of diabetes on a global scale, refining our perioperative strategies in high quality will us determine what is best for this vulnerable population of patients to be safe and return to their premorbid baseline.

CONCLUSIONS

1. Diabetes mellitus remains one of the greatest challenges in contemporary anesthetic practice and requires a complex, multimodal approach to perioperative care. This systematic review has demonstrated that the effects of diabetes reach far beyond mere hyperglycemia, and include profound alterations in autonomic function, vascular integrity, and immune response. The foundation of optimized care lays in the minimization of glycemic variability, the reduction of the surgical stress response by providing individualized anesthetic considerations, and the provision of combination care through multidisciplinary protocols, such as ERAS.
2. Fundamental strategies for success encompass a comprehensive preoperative risk classification, vigilant intraoperative monitoring and, albeit conservatively, active postoperative management. Tight euglycemia is often unsafe and impractical, but we can agree that a stable blood glucose range of 140 to 180 mg/dL represents a reasonable compromise in risk reduction. Also, one should not forget the role of nutrition and fluid homeostasis in promoting successful wound healing and minimizing systemic complication.
3. In the future, as we look toward integrating new technologies and standardizing evidence-based practices, application of these practices will still need to be balanced with clinical judgment when treating the individual patient. With careful attention and application of physiologic and metabolic principles of the diabetic patient, the surgery team will improve outcomes, lower complication burden, and expedite recovery for this increasing population.

 

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