Anesthetic Considerations for Patients with Diabetes

Diabetes mellitus is a chronic disease characterized by a decrease in insulin production (type 1) or impaired utilization of insulin as a result of peripheral insulin resistance (type 2) causing hyperglycemia (1). According to the WHO, roughly 180 million people in the world suffer from diabetes and this number is likely to double by 2030. The reason for this dramatic increase in diabetes is thought to be the aging of the population, increased prevalence of obesity, sedentary lifestyle, and dietary changes (1). The increasing prevalence of diabetes in the general population has many implications for the anesthesiologist. Complications, particularly associated with poor glycemic control, can affect multiple organ systems and jeopardize the safety of any planned anesthetic. It is essential that anesthesiologists and sedation providers have in-depth knowledge of the pathophysiology of diabetes mellitus and the comorbid conditions that commonly accompany it. Anesthesiologists and sedation providers must also understand certain surgical and anesthetic considerations when planning an effective and safe anesthetic for diabetic patients (2). 

As previously mentioned, it is important for the anesthesiologist to have a good understanding of the pathophysiology of diabetes. Type 1 diabetics completely lack insulin secretion, making them prone to lipolysis, proteolysis and ketogenesis. These processes are inhibited by minimal levels of insulin secretion and are rare in type 2 diabetics unless there is an additional stress such as sepsis or dehydration. However, both groups are subject to the effects of hyperglycemia (3). Diabetics are at increased risk of myocardial ischemia, cerebrovascular infarction and renal ischemia because of their increased incidence of coronary artery disease, arterial atheroma, and renal parenchymal disease. Increased mortality is found in all diabetics undergoing surgery and type 1 diabetics are particularly at risk of postoperative complications. Increased wound complications are associated with diabetes and anastomotic healing is severely impaired when glycemic control is poor (3).  

A good preoperative assessment is essential to determine the physiological status of the patient. Patients should be assessed for signs of cardiovascular disease – including an assessment of exercise tolerance, neuropathy – peripheral and autonomic, and musculoskeletal issues (4). Diabetics with stiff joint syndrome (due to glycosylation) often have limited mobility of the upper cervical spine and are more likely to have a poor view on direct laryngoscopy and they may therefore present difficulties with tracheal intubation (4). Additionally, reviewing the medication history of diabetic patients is an important part of the preoperative assessment. Poorly controlled diabetes is associated with worsening organ damage. For instance, long-term uncontrolled hyperglycemia is an important risk factor for development of end-stage renal disease. Angiotensin-converting enzyme (ACE) inhibitors are commonly prescribed for the prevention of renal complications in diabetic patients; however, patients with a creatinine concentration >3.0 mg dl−1 or creatinine clearance of <30 ml min−1 should probably not receive ACE inhibitors because of an increased risk for deterioration of renal function (3).  

The main concern for the anesthesiologist in the perioperative management of diabetic patients is maintaining glycemic control (3). Anesthetic techniques, particularly the use of spinal, epidural, splanchnic or other regional blockade, may modulate the secretion of the catabolic hormones and any residual insulin secretion. The perioperative increase in circulating glucose, epinephrine and cortisol concentrations found in non‐diabetic patients exposed to surgical stress under general anesthesia is blocked by the use of epidural anesthesia (3). High‐dose opiate anesthetic techniques produce hemodynamic, hormonal, and metabolic stability in diabetic patients. These techniques effectively block the entire sympathetic nervous system and the hypothalamic–pituitary axis, probably by a direct effect on the hypothalamus and higher centers (3). Abolition of the catabolic hormonal response to surgery will, therefore, abolish the hyperglycemia seen in normal patients and may be of benefit in the diabetic patient. Volatile anesthetics, such as halothane and isoflurane, inhibit the insulin response to glucose in a reversible and dose‐dependent manner and may also be used. Benzodiazepines decrease the secretion of ACTH, and thus the production of cortisol, when used in high doses during surgery.  They reduce sympathetic stimulation but, paradoxically, stimulate growth hormone secretion and result in a decrease in the glycemic response to surgery. These effects are minimal when midazolam, for instance is given in usual sedative doses, but may be relevant if the drug is given by continuous IV infusion to patients in intensive care (3).  

After surgery in diabetics patients, intravenous insulin (if used) should be continued for at least two hours after the first meal. Nausea and vomiting should be prevented if possible and should be treated vigorously to re‐establish normal dietary intake as soon as possible after surgery. Good analgesia is important, as adequate pain relief decreases catabolic hormone secretion. Non‐steroidal anti‐inflammatory drugs can be used for analgesia but they should be used with caution as many diabetics have pre‐existing renal dysfunction (4).  

References 

1. K. Candiotti, S. Sharma, R. Shankar, Obesity, obstructive sleep apnoea, and diabetes mellitus: anaesthetic implications, BJA: British Journal of Anaesthesia, Volume 103, Issue suppl_1, December 2009, Pages i23–i30, https://doi.org/10.1093/bja/aep294 

1. Cornelius, Bryant W. “Patients With Type 2 Diabetes: Anesthetic Management in the Ambulatory Setting. Part 1: Pathophysiology and Associated Disease States.” Anesthesia progress vol. 63,4 (2016): 208-215. doi:10.2344/0003-3006-63.4.208 

1. G. R. McAnulty, H. J. Robertshaw, G. M. Hall, Anaesthetic management of patients with diabetes mellitus, BJA: British Journal of Anaesthesia, Volume 85, Issue 1, 1 July 2000, Pages 80–90, https://doi.org/10.1093/bja/85.1.80 

1. Robertshaw, H.J. and Hall, G.M. (2006), Diabetes mellitus: anaesthetic management. Anaesthesia, 61: 1187-1190. doi:10.1111/j.1365-2044.2006.04834.x