Perioperative Glycemic Management for Patients with and without Diabetes

People with diabetes are at an increased risk for worse postoperative outcomes, compared to people without diabetes. Notably, up to one in 10 people who undergo surgery have unrecognized diabetes and an additional 10% may have postoperative hyperglycemia without meeting the criteria for a diagnosis of diabetes. Management of postoperative hyperglycemia has been demonstrated to reduce the incidence of poor outcomes, but evidence demonstrates that postoperative hyperglycemia remains a quality gap for surgical patients. In this review, we will outline the evidence for preoperative screening for postoperative hyperglycemic risk, review the evidence for perioperative glycemic management, and examine the barriers to these best practices. RÉSUMÉ Les personnes atteintes de diabète courent un risque accru de voir leurs résultats postopératoires moins bons que ceux des personne non atteinte de diabète. En particulier, près d’une personne sur dix qui subit une intervention chirurgicale présente un diabète non diagnostiqué et dix pour cent supplémentaires peuvent présenter une hyperglycémie postopératoire sans pour autant répondre aux critères de diagnostic du diabète. Il a été démontré que le traitement de l’hyperglycémie postopératoire réduit l’incidence des mauvais résultats, mais les données probantes montrent que l’hyperglycémie postopératoire demeure une lacune chez les patients opérés. Dans cette revue, nous présentons les données probantes relatives au dépistage préopératoire du risque d’hyperglycémie postopératoire, nous passons en revue les données probantes relatives à la gestion de la glycémie périopératoire et nous examinons les obstacles à ces meilleures pratiques. Postoperative Hyperglycemia Is a Modifiable Risk Factor for Worse Postoperative Outcomes Diabetes affects 20–30% of the surgical patients.1 People with diabetes who undergo surgery have worse outcomes than people without diabetes, including increased postoperative infection risk,2,3 30-day readmission rates,4 length of stay,5 and mortality.6,7 Recent evidence suggests that these poor outcomes are more strongly associated with intraoperative and postoperative hyperglycemia rather than a preoperative diagnosis of diabetes.6,8 This is especially important, as unrecognized diabetes may account for an additional 4–10% of surgical patients8,9 and approximately 10% of people without diabetes will have postoperative hyperglycemia.8,10–14 These patients may be less likely to have postoperative hyperglycemia recognized C a n a d i a n J o u r n a l o f G e n e r a l I n t e r n a l M e d i c i n e V o l u m e 1 6 , I s s u e 1 , 2 0 2 1 17 Ruzycki e t a l . CJGIM_4_WKBK.indd 17 3/19/21 5:36 PM and appropriately treated, and subsequently may suffer more adverse outcomes than people with recognized diabetes.8 The association between intraoperative hyperglycemia and poor patient outcomes is less clear15,16; however, the management of intraoperative hyperglycemia is the responsibility of the anesthesiologist and, therefore, preand postoperative diabetes management will be the focus of this review. Evidence-based glucose management strategies have demonstrated improved glycemic control, reduced length of stay, and reduced incidence of hypoglycemia.17,18 Observational studies have found that maintaining blood glucose in-target is associated with lower 30-day readmission rates and shorter length of stay in medical and surgical patients.19 In gynecologic oncology patients, preand post-intervention studies have shown that perioperative glycemic management pathways that are multidisciplinary, comprehensive, and adhere to best practices for glycemic management reduce the incidence of surgical site infections.20,21 The RABBIT-2 study was a landmark randomized controlled trial that found that basal bolus insulin therapy (BBIT) to maintain in-target glucose for postoperative patients significantly reduced postoperative complications, compared to subcutaneous sliding-scale insulin regimens.22 Recommendations for Perioperative Glycemic Management for Patients with and without Diabetes Preoperative measurement of hemoglobin A1C There is a considerable variation in perioperative glycemic management recommendations in major society guidelines (Table 1). Unlike guidelines from Australia, Great Britain, and Ireland that recommend delaying surgery for patients with elevated hemoglobin A1C, Diabetes Canada, the American Society of Anesthesiologists, and the American Diabetes Association do not make recommendations on preoperative hemoglobin A1C measurement or targets for elective surgeries. This is supported by the current evidence that intraoperative and immediate postoperative hyperglycemia is more strongly associated with poor outcomes than preoperative glycemic control.6,8,29 However, preoperative hemoglobin A1C measurement can identify patients with unrecognized diabetes and patients without diabetes at risk of postoperative hyperglycemia.8,9,29 In addition, preoperative hemoglobin A1C measurement can help guide postoperative glycemic management; patients with elevated hemoglobin A1C will be more likely to require and benefit from insulin than patients with in-target hemoglobin A1C.8 As such, it is reasonable to measure hemoglobin A1C in all people with diabetes and those who are at-risk of diabetes within 3 months of a scheduled surgery (Box 1). Preoperative noninsulin medication management Similarly, major society guidelines provide differing recommendations for perioperative management of noninsulin medications (Table 2). Diabetes Canada does not make recommendations for holding, continuing, or dose reducing medications for diabetes in the perioperative period. In contrast, guidelines from the Association of Anaesthetists of Great Britain and Ireland, and the American Society of Anesthesiologists make recommendations for each class of diabetes medications. Table 1. Comparison of major society guideline recommendations for perioperative glycemic management for patients with and without