Monitoring Glucose Levels and HbA1c
The HbA1c is an important tool to incorporate into the inpatient evaluation. It is now accepted as a diagnostic test for diabetes, and values can supplement patient clinical history in determining the effectiveness of pre-hospitalization treatment regimens. The test can help to identify some of the 25 percent of patients with diabetes mellitus (DM) that had previously been undiagnosed and recognition of DM while inpatient may reduce their risk of readmission.1,17 Since it is relatively easy and inexpensive, it has become an “opt out” test on many order sets, is recommended in some guidelines and testing it on all patients with hyperglycemia without a value documented within the last 60 days is a required component for Joint Commission Certification in Advanced Inpatient Diabetes Care.13
Guidelines recommend that all patients have blood glucose testing upon admission and those with a BG value >140mg/dL have ongoing testing for at least 24-48 h.13 POC glucose meters are currently the method most widely used for monitoring glucose because of the rapid turnaround and need to make timely adjustments to therapy. However, there are a wide number of potential issues (shock, hypoxia, dehydration, extremes in hematocrit, elevated bilirubin and triglycerides) impacting the accuracy.18,19 Additionally, issues with some monitors and lack of Food and Drug Administration (FDA) approval for critical care or hospital use have also been raised.20,21 Outside of these analytical issues, pre-analytical issues with site selection and interface with results for the correct patient being available to caregivers are important influencers on the quality of care being provided. Incorporating meter quality control and the processes for testing and recording values are important components for multidisciplinary committees to consider. Procedures aligned with The Joint Commission (TJC) must be established to assure ongoing quality control of the monitors, process of patient testing and recording the results. Additionally, with such threats to valid POC test results, clinical condition should guide treatment with the use of confirmatory venous samples when in question. Hospitalized patients require frequent testing due to the fluctuations and many variables influencing blood glucose. Testing is generally recommended to be performed before meals and at bedtime in patients who are eating or receiving bolus tube feeds13 although recent studies have called into question the value of the bedtime value.22 In patients who are NPO or receiving continuous enteral or parenteral nutrition, glucose monitoring is performed every four to six hours depending on whether short-acting or rapid-acting analog insulin is used. For patients on intravenous insulin, the ADA and AACE recommend hourly blood glucose monitoring except for patients with stable blood glucose within the target range, for whom monitoring can be performed up to every two hours.
In 2001, van den Berghe published results demonstrating significant improvements in mortality in surgical ICU patients treated with IV insulin therapy targeted at normalizing blood glucose.23 Following this, numerous specialty organizations published recommendations targeting “very tight” glycemic control and many hospitals implemented infusion protocols to normalize blood glucose values in their critically ill patients.24,25 However, subsequent trials had mixed results and finally NICE SUGAR ultimately demonstrated increased mortality and hypoglycemia with “very tight”/normalized blood glucose versus moderate control.26, 27 Revised guidelines now recommend that insulin therapy be initiated if the blood glucose is >180 mg/dL and then maintained between 140 and 180 mg/dL in critically ill patients. Glucose targets somewhat lower than these may be appropriate in selected patients although strong evidence is lacking. The Society of Critical Care Medicine guidelines continue to recommend a target of 100-150 mg/dL but emphasize avoiding hypoglycemia.28 For these purposes, critical illness generally refers to patients requiring invasive mechanical ventilation, those requiring pressor support and patients with multisystem organ failure.
For post-operative cardiovascular surgery, The Joint Commission’s Surgical Care Improvement Project (SCIP) updates from January 2014 set targets of blood glucose levels in the 18-24 hour window after anesthesia end time of <180mg/dL; but these SCIP glycemic metrics are currently on hold as of early 2015 with new metrics still to be determined at the time of this publication.29
With very few prospective, RCT data for establishing specific guidelines in non-critically ill patients, the ADA/AACE recommendations in 2009 are based on clinical experience and judgment.13
Hypoglycemia has associated risks demonstrated in various studies, and strategies are necessary to avoid it. Studies have used variable definitions for hypoglycemia but the ADA has defined hypoglycemia as a blood glucose level <70 mg/dL and severe hypoglycemia as <40 mg/dL.30
Inpatient hyperglycemia is best managed with insulin only. Insulin works reliably, and doses can be rapidly adjusted depending on changes in glucose levels and food intake. Oral agents should be discontinued during acute illness in most circumstances.13 Most are associated with some risks and are limited in their ability to be rapidly adjusted to achieve goals.31, 32
- are NPO on no nutritional replacement
- are on new or tapering steroids
- hypoglycemic risk factors including but not limited to end-stage liver or kidney disease, -
elderly patients or those with an unknown drug overdose
The general recommendations for dosing subcutaneous insulin are derived from published studies and current ADA/AACE and Endocrine Society guidelines. They generally involve:
Following resolution of their indication for insulin infusion, patients will need to be transitioned to subcutaneous insulin. Patients with type 1 DM, on insulin prior to admission to the hospital and those requiring insulin infusion rates more than two units/hour, will need to be transitioned to basal/bolus insulin regimens. The average infusion rate over the preceding six to eight hours is then multiplied by 24 to determine the predicted requirement for the next day. Given that patients are likely to be continuing to improve and have reduced insulin requirements, that daily estimate is further reduced to 60-80 percent. This value can be used as the total daily requirement if they were receiving significant nutritional support in the ICU (TPN or tube feeds) or the basal amount with nutritional layered over time as oral intake increases.35-40
Preparation for transition to the outpatient setting is an important goal of inpatient diabetes management and begins with the hospital admission. The HbA1C is an important laboratory test that should be ordered in nondiabetic hyperglycemic patients and diabetic patients who have not had a recent test. An HbA1c value >6.5% is diagnostic of diabetes, 5.7-6.4% is “pre-diabetes” and one over 9 percent has been recommended by some to indicate the need for newly aggressive treatment strategies.41 Modification of the outpatient regimen should be done with careful planning and assessment of patient and facility-specific resources as well as with communication with the outpatient provider.42 There are several published algorithms for diabetes treatment that can be used to guide such decisions but it is most important to factor in individual patient needs.47 All patients with diabetes should receive teaching in diabetes self-management education focused on survival skills.13
Communication to the outpatient provider regarding the education provided, relevant lab values including the HbA1c and medication changes is essential for patient safety and a requirement of The Joint Commission’s Inpatient Diabetes Disease Certification.
1 Centers for Disease Control and Prevention 2014 National diabetes fact sheet: national estimates and general information on diabetes and prediabetes in the United States. Atlanta: U.S. Department of Health and Human Services. Available at http://www.cdc.gov/diabetes/pubs/statsreport14/national-diabetes-report-web.pdf Accessed on May 20, 2015.
2 Umpierrez GE, Isaacs SD, Bazargan N, You X, Thaler LM, Kitabchi AE. Hyperglycemia: an independent marker of in-hospital mortality in patients with undiagnosed diabetes. J Clin Endocrinol Metab. 2002 Mar; 87:978–982.
3Fraze T, Jiang HJ, Burgess J. Hospital stays for patients with diabetes, 2008. AHRQ Healthcare Cost and Utilization Project. Statistical Brief #93. August 2010. Available from http://www.hcup-us.ahrq. gov/reports/statbriefs/sb93.pdf. Accessed May 15, 2015.
4Newton CA, Young S. Financial implications of glycemic control: results of an inpatient diabetes management program. Endocr Pract. 2006;12(Suppl 3).43–48
5 Center for Medicare and Medicaid Services Hospital-Acquired Condition (HAC) Reduction Program. Available at http://www.cms.gov/Medicare/Medicare-Fee-for-Service-Payment/AcuteInpatientPPS/ HAC-Reduction-Program.html. Accessed May 2015.
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