Non-diabetics can have more complications from surgery than diabetics

Diabetics can have fewer complications from surgery than non-diabetics who have perioperative hyperglycemia. But non-diabetics without hyperglycemia have the lowest risk for events. A study examining the glucose levels of both diabetics and non-diabetics prior to surgery helps explain the paradox of why many non-diabetics fare worse when it comes to surgical complications. Findings were published in JAMA. “The idea of a patient with no history of diabetes does not guarantee no perioperative hyperglycemia. Many non-diabetic patients will never have sugars checked despite the stress of surgery and this response is often missed,” said Dr. Judy Chen, an assistant professor of surgery at the University of Washington. Read: Is whey the way to go with diabetes? Stress hyperglycemia in non-diabetics and could be due to various reasons such as medication side effects, or inflammation related to surgery, she said. Hyperglycemia (blood glucose level is more than 140 mg/dL) was found in some studies to occur in nearly 40% of surgical patients perioperatively, the study said. Common complications include surgical site infection, myocardial infarction, and death. About 15% of surgical patients have diabetes. In these patients detecting and treating perioperative hyperglycemia a is routine which lowers the risk of adverse postoperative outcomes. But perioperative hyperglycemia is common among surgical patients who do not have diabetes. Paradoxically, several studies show that at similar levels of hyperglycemia, patients without diabetes have up to a 50% greater risk of complications compared to those with diabetes. One explanation is that many patients are unaware that they have diabetes which could be why perioperative hyperglycemia occurs. Also testing for diabetes status is not routine before surgery at most centres. However, the University of Washington Medical Center conducts universal blood glucose level testing and routine treatment of hyperglycemia for most surgical patients regardless of their diabetes status. The prospective cohort study included consecutive patients undergoing general, vascular, and gynecologic operations with a planned admission at the centre between January 2013 and October 2016. Glucose testing was conducted on the day of surgery, then repeated intraoperatively at 60- to 90-minute intervals, and in the morning on post-operative days one and two. An insulin infusion was given to patients who became hyperglycemic. Glucose elevation was rated in each patient as being mild, moderate or severe, and the researchers followed an algorithm for administering insulin which varied depending on the severity of the hyperglycemia. During the study period, a total of 5,868 patients underwent surgery. Of this, 4,899 patients did not have diabetes and 969 patients had diabetes. Of patients without diabetes, 23.8% (1,165 patients) had a preoperative glycated hemoglobin A1c (HbA 1c) test within 90 days. And of these, 78.7% (917) proved to not have diabetes, while 153 (13.1%) were in intermediate range with an HbA1c of 6% to 6.5%; and the remaining 95 (8.2%) had HbA 1c levels greater than 6.5%. Perioperatively, hyperglycemia occurred in 57% of the overall cohort – occurring in 2,484 of the patients with no diabetes and 882 of the patients with diabetes. As for complications, 32 (12.4%) overall experienced complications with this happening in 594 (12%) of the patients without diabetes and 138 (14%) patients with diabetes. Of all the patients, 513 (9.6%) experienced a serious complication and occurred in 423 (8.6%) of patients without diabetes and 90 (9.2%) of patients with diabetes. But the story took on interesting nuances when hyperglycemia was taken into account. “At each level of hyperglycemia, the proportion of patients without diabetes who experienced any complication was higher than that among patients with diabetes…(and) Patients without diabetes also experienced higher rates of serious complications at similar levels of hyperglycemia (as the diabetics),” the study said. The study also showed that treating the hyperglycemia with insulin had a positive benefit in the non-diabetics. “Lower proportions of complications and serious complications were observed when comparing patients without diabetes who received insulin in response to hyperglycemia with those who did not and had hyperglycemia,” said the study. Overall, hyperglycemia within 24 hours was common and seen in nearly 6 of 10 of the surgical cohorts and in almost half of patients without diabetes. At both moderate and severe levels of hyperglycemia, patients with no history of diabetes were at a higher risk of experiencing a postoperative complication than patients who did have diabetes. The main message for doctors is that “surgery itself is enough to warrant checking blood sugar once in the operating room, especially in surgeries that are longer than 60 minutes and patients are expected to be admitted. Any insulin administered in perioperative hyperglycemia show some protective effect to reducing adverse events, thus improving patient care and outcomes,” said Dr. Chen. “We have long understood that glucose values rise after surgery due to stress hormones like cortisol and adrenaline increasing. We have also understood that higher glucose values post operatively increase the risk of surgical site infections,” said Dr. Ilana Halperin, an assistant professor of medicine at the University of Toronto and a Diabetes Canada Clinical Practice Guideline author. She was not part of the study. While the study adds to the body of knowledge about surgical risks and glycemia levels it suggests that patients with no known history of diabetes may have a further increased risk of developing complications, irrespective of the use of insulin or glucose levels. However, a limitation is that it shows an association rather than a causal relationship. “We don’t know if more aggressive treatment is needed in these patients with stress hyperglycemia post operatively,” she said. “Stress hyperglycemia can resolve rapidly and so any additional treatments with long-acting insulin need to be closely monitored as the glucose normalizes post operatively the patients may develop hypoglycemia,” she said. More research needs to be done to help resolve these issues, determine the biologic mechanisms, and determine the appropriate treatment protocols to reduce postoperative complications without causing hypoglycemia.

Non-diabetics can have more complications from surgery than diabetics

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