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Death Rate and Blood Glucose Management

Is extreme blood glucose control increasing or decreasing mortality rate in hospitalized patients?

Diabetes mellitus has been connected with poor clinical outcome after cardiac surgery, wound infections, ischemic events, neurological and renal complications and mortality rate. Maintaining a blood glucose level of less than 180 mg/dl will minimize symptoms of hyperglycemia and hypoglycemia without poorly upsetting patient-oriented outcome. Hospitalized patients do not benefit from tight blood glucose control (BGC). Over the last decade, the incidence of diabetes mellitus has increased markedly in developed countries. 90% of those without diabetes mellitus had problems with their blood glucose homeostasis as a result of various surgical stresses like insulin resistance and a pancreatic β-cell function. Sulfonylureas should be withheld to avoid hypoglycemia. Thiazolidinedione should also be avoided if a patient has cardiovascular conditions. Metformin should be temporarily stopped in patients with renal problems and if insulin is to be used, then a long-acting should be combined to a short-acting insulin before meals so that it gives a better approximates of normal physiology. Previous studies have found that the infusion of glucose, insulin, and potassium does not improve mortality in patients with acute myocardial infarction.

The purpose of this study is to investigate whether extreme glucose control has any effect on mortality rates in hospitalized patients. Patients’ data were obtained from a hospital and it was comprised of 5 sections, including anesthetist, surgeon, intensive care unit, and high-dependency unit and ward nurses. Personal identifiers were removed to make the data set anonymous. Patients were then classified as having good, moderate, or poor glucose control if the highest recorded blood glucose level was <200 mg/dl, between 200 and 250 mg/dl or >250 mg/dl respectively. Diabetic patients were started on sliding scale insulin infusion soon after surgery to maintain blood glucose levels between 90 and 144 mg/dl according to protocol. Infusion was continued for the first 24 hours before patients were switched to their baseline medications. Blood sugar level was checked every 6 hours. Nondiabetic patients’ blood glucose measurement >144 mg/dl or consecutive blood glucose of >126 mg/dl were noted. X2 or Fisher’s exact test or the Kruskal-Wallis test were the statistical analysis used. Confidence interval and exact P values were presented throughout and Bonferroni- corrected probability value for overall 5% statistical significance.

Of the 9,064 patients that had cardiac surgery, 8,727 of them had their postoperative blood glucose level available. 7,457 had good BG, 905 had moderate and 365 had poor value in the first 60 hours after surgery. Moderate and poor had advanced NYHA class, and a history of congestive heart failure, hypertension, arrhythmia, renal failure and an ejection fraction <50% P≤ 0.004. Of the 3,962, the total patients who required inotropic support after surgery 3263 were good, 482 moderate and 217 had poor BGC (P<0.001). Hospital mortality was 2.3% with a P <0.001. Intensive care unit and total postoperative stay also were significantly longer in the poor BGC group (P<0.001). After controlling for confounding factors associated with in-hospital death and diabetic status, inadequate BGC was found to be an independent predictor of in-hospital death P<0.001. Mortality risk connected with poor BGC was greater than with moderate control (OR, 2.32; 95% CI, 1.28 to 4.20; P=0.005) and was greater than the difference between moderate and good BGC control (OR, 1.68; 95% CI, 1.25 to 2.25; P=0.001). Other predictors of an in-hospital death identified were age > 65 years, female gender, advanced NYHA class, renal failure, arrhythmias, ejection fraction < 50%, presence of left main stem disease and aortic procedures. Inadequate BGC in nondiabetic patients had an independent predictor of pulmonary, renal and gastrointestinal complications P<0.001. 50% of patients with poor and moderate BGC were not previously identified as having diabetes.

In conclusion, insulin infusion protocol was not effective in maintaining tight blood glucose control in all patients regardless of their diabetes status. Insulin infusion protocol has therefore been extended to 48 hours after surgery to all patients regardless of their diabetes status and have adopted a stricter attitude toward initiating insulin infusion. We now aim to keep blood glucose levels between 79.2 and 109.8 mg/dl in critically ill patients in intensive care. The weakness of this study is that it was retrospective and the data collection was not blinded, which could have caused some bias.

Practice Pearls:

  • Derangement of glucose metabolism after surgery is not specific to patients with DM.
  • More than 50% of patients developing moderate to poor BGC after cardiac surgery were not previously identified as having diabetes.
  • Moderate to poor BGC is an independent predictor of in-hospital mortality and is strongly associated with morbidity in patients not known to have diabetes.

References:

Management of Diabetes and Hyperglycemia in Hospitalized Patients; Leonor Corsino, MD, MHS, FACE, Ketan Dhatariya, and Guillermo Umpierrez.; October 4, 2014.

ADA July 2016 Statistics About Diabetes, Overall Numbers, Diabetes and Prediabetes

Furnary AP, Gao G, et al. “Continuous insulin infusion reduces mortality in patients with diabetes undergoing coronary artery bypass grafting”. J Thorac Cardiovasc Surg. 2003; 125: 1007-1021.

Lazar HL, Chipkin SR et al. “Tight glycemic control in diabetic coronary artery bypass graft patients improves perioperative outcomes and decreases recurrent ischemic events.” Circulation. 2004; 109: 1497-1502