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The Use of Continuous Glucose Monitoring System in the Home Health Setting

SANCHEZ, IRIS APRN-BC, ADM

Home Healthcare Nurse: The Journal for the Home Care and Hospice Professional: May 2010 - Volume 28 - Issue 5 - p 291–295
doi: 10.1097/NHH.0b013e3181dbf063
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Address for correspondence: P.O. Box 244, San Juan, TX 78589; isanchez@palmvalleyhealthcare.com.

The author has disclosed that she has no financial relationships related to this article.

For 18 additional continuing nursing education articles on diabetes, go to nursingcenter.com/ce

Figure

Figure

DIABETES MELLITUS, a metabolic disorder characterized by hyperglycemia, results from either a defect in insulin secretion, insulin action, or both. Diabetes mellitus can be classified into four major categories based on the cause. Type 1 diabetes mellitus accounts for approximately 5% to 10% and type 2 diabetes for 90% to 95% of all diabetes cases (American Diabetes Association [ADA], 2009).

According to the CDC, diabetes and its associated complications cost the United States $174 billion in direct and indirect costs in 2007 (2008). An estimated 24 million people in the United States have diabetes, and the number is expected to double by the year 2050. A person with diabetes spends $11,744 annually on healthcare cost compared with $5,095 for a person without diabetes (CDC).

The management of diabetes mellitus involves a multidisciplinary team approach across the spectrum of care. Multiple modalities are often employed for diagnosing, treating, and managing hyperglycemia, hypoglycemia, and the complications associated with diabetes. New technologies have emerged to assist healthcare providers in the management. The following case study illustrates the benefits and barriers of continuous glucose monitoring system use.

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Case Study

Mrs. C was a patient with type 2 diabetes who would check her blood sugars no more than once a day at varying times. Her glycated hemoglobin (A1C), a measure of average glucose for the past 3 months (Fonseca et al., 2009), was 10.9%. The current American Diabetes Association (ADA, 2009) guidelines for A1C are 7% or less if the patient is not experiencing recurrent hypoglycemia. An A1C of 10.9% correlates with an average blood glucose of 269 mg/dL (Table 1) (ADA). The patient was on three oral hypoglycemic agents and needed to initiate insulin in addition to her oral agents to decrease the A1C. She refused stating her blood glucose was within the accepted range and that she had a fear of hypoglycemia with insulin. Her fasting and random fingerstick capillary blood glucose results ranged from 140 to 180 mg/dL and 190 to 220 mg/dL, respectively. A systematic review did not arrive at a consensus on frequency or timing of self-monitoring of blood glucose (SMBG) in patients with type 2 diabetes (Welschen et al., 2005). The patient was instructed to continue performing SMBG fasting and 2 hours postprandial but the home health nurse soon reported the patient was not monitoring blood glucose as instructed.

Table 1

Table 1

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Continuous Glucose Monitoring

Continuous glucose monitoring (CGM) provides information regarding the direction, magnitude, duration, frequency, causes of excursions in blood sugars, and helps identify periods of hypo- and hyperglycemia (Klonoff, 2005).

Current technology has been able to produce wireless sensors maintained in place from 3 to 7 days depending on the manufacturers' FDA indications. A small catheter is inserted into the subcutaneous tissue using a small needle similar to the ones used for insulin injections. The process is similar to inserting an intravenous catheter where the needle is used to pierce the skin, the sheath is threaded into place, and the needle is then removed and disposed. The patient is required to calibrate, using a comparison between a fingerstick capillary SMBG and interstitial CGM reading three times a day. Calibration is required to ensure that there are no discrepancies between the interstitial blood glucose and fingerstick capillary blood glucose because there is a physiologic lag between the two values (Messer et al., 2009). The ideal times to perform fingerstick glucose for calibration purposes are while fasting or 3 hours postprandially to avoid times when blood glucose is most likely to be rising or falling (Klonoff, 2005). The sensor is continuously measuring interstitial glucose levels. Depending on the manufacturer, glucose levels are measured every 1 to 10 minutes for the duration the sensor is in place (Harman-Boehm, 2008). Once the sensor is removed, interstitial blood glucose readings are electronically downloaded into a computer. Results can be displayed in charts or graphs.

Currently, three companies have developed and distribute continuous glucose monitoring systems (CGMS) (Diabetes Monitor, 2009). Two current methods for using CGMS are available. One method is a blinded CGM used as a diagnostic tool to show interstitial blood glucose readings retrospectively. Using the method does not allow the patient to react to an interstitial blood glucose result and thus give a more accurate picture of a patient's daily glucose level. In contrast, a real-time (RT) CGMS displays interstitial blood glucose readings, which can be used at any point in time to proactively respond to abnormal blood glucose levels especially for those patients using insulin.

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Benefits of CGM

A fingerstick capillary glucose reading provides a snapshot of one point in time. Excursions and trends are difficult to ascertain. CGM provides the ability to provide a "continuous movie" of interstitial glucose readings, which can have an impact on how a patient views glycemic control. Patients with A1C at target levels but with high postprandial blood glucose are often surprised to view the correlative effects of medication administration timing, meals, activity, and exercise.

Results from the Juvenile Diabetes Research Foundation Continuous Glucose Monitoring Study Group demonstrated improved glycemic control in adults with type 1 diabetes who used CGM (Beck, 2009; Tamborlane et al., 2008). The use of RT-CGM in patients with type 2 diabetes demonstrated a reduction in A1C, modification in diet, exercise habits, and glycemic control when compared with patients who only performed SMBG (Yoo et al., 2008). Advantages and disadvantages of CGM are presented in Table 2, and clinical indications are listed in Table 3 (Klonoff, 2005).

Table 2

Table 2

Table 3

Table 3

Medicare, Medicaid, and most private insurance companies reimburse physicians, nurse practitioners, and physician assistants for the insertion of CGM, the interpretation of the results, and evaluation and management. Home health agencies are not reimbursed for these services, but diabetes management education is a covered service.

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CGM: A Case Study

CGM was placed on Mrs. C for 72 hours in an attempt to demonstrate how her diabetes was uncontrolled and help her make a decision to start insulin.

Figure 1 shows interstitial glucose readings within range during the fasting hours but quickly rising after breakfast. On 2 days, she had decreases in blood glucose close to supper time but a rise after late afternoon began to decrease throughout the night. One day, her fingerstick capillary blood glucose increased to greater than 400 mg/dL; the sensor cannot record interstitial blood glucose above 400 mg/dL. The home health nurse was called out to administer rapid-acting insulin causing a sharp decrease in glucose levels, which persisted throughout the night.

Figure 1

Figure 1

Showing the erratic glucose excursions to the patient helped her comprehend the importance of diet, exercise, and medication. She finally agreed to initiate a long-acting insulin analog along with her oral medications. Additionally, she received diabetes self-management education by a certified diabetes educator, which included dietary modifications, weight loss instruction, and activity.

After 6 months of treatment with insulin, oral hypoglycemic agents, and diet modification, the patient's A1C was 7.2% and she reported fasting fingerstick capillary blood glucose levels less than 130 mg/dL and postprandial fingerstick capillary blood glucose levels less than 150 mg/dL, which were verified on her glucometer. Her physician decided to repeat another CGM (Figure 2).

Figure 2

Figure 2

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Lessons Learned

  1. The patient and the nurse must be familiar with the device. The patient must check a minimum of three fingerstick capillary blood glucoses to ensure the device is calibrated.
  2. Older adults with diabetes are less technologically inclined than younger individuals (Allen et al., 2009). Learning methods need to be individualized.
  3. A teaching guide was developed to ensure consistency in educating home health patients in whom CGM was initiated by a primary care provider (Table 4).
  4. Nurses need to be trained to troubleshoot calibration errors along with other alerts.
  5. CGM is not a home health covered service. However, diabetes education is a covered service. CGM can be a valuable marketing tool.
Table 4

Table 4

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REFERENCES

Allen, N. A., Fain, J. A., Braun, B., & Chipkin, S. R. (2009). Continuous glucose monitoring in non-insulin-using individuals with type 2 diabetes: Acceptability, feasibility, and teaching opportunities. Diabetes Technology & Therapeutics, 11(3), 151–158.
American Diabetes Association. (2009). Standards of medical care in diabetes 2009. Diabetes Care, 32(Suppl.1)
Beck, R. W. (2009). The effect of continuous glucose monitoring in well-controlled type 1 diabetes. Diabetes Care, 32(8), 1378–1383.
, from Center for Disease Control and Prevention. Department of Health and Human Services (2008). Preventing chronic diseases: Investing wisely in health. Retrieved October 19, 2008
    from Diabetes Monitor (2009). Diabetes Monitor—Continuous glucose monitoring. Retrieved.
    Fonseca, V., Inzucchi, S. E., & Ferrannini, E. (2009). Redefining the diagnosis of diabetes using glycated hemoglobin. Diabetes Care, 32(7), 1344–1345.
    Harman-Boehm, I. (2008). Continuous glucose monitoring in type 2 diabetes. Diabetes Research and Clinical Practice, 825, S118-S121.
    Klonoff, D. C. (2005). Continuous glucose monitoring. Diabetes Care, 28(5), 1231–1239.
    Messer, L., Ruedy, K., Xing, D., Coffey, J., Englert, K., Caswell, K., et al. (2009). Educating families on real time continuous glucose monitoring: The DirecNet navigator pilot study experience. The Diabetes Educator, 35(1), 124–135.
    Tamborlane, W. V., Beck, R. W., Bode, B. W., Buckingham, B., Chase, H. P., Clemons, R., et al. (2008). Continuous glucose monitoring and intensive treatment of type 1 diabetes. New England Journal of Medicine, 359(14), 1464–1476.
    Welschen, L. M., Bloemendal, E., Nijpels, G., Dekker, J. M., Heine, R. J., Stalman, W. A., et al. (2005). Self-monitoring of blood glucose in patients with type 2 diabetes who are not using insulin: A systematic review. Diabetes Care, 28, 1510–1517.
    Yoo, H. J., An, H. G., Park, S. Y., Ryu, O. H., Kim, H. Y., Seo, J. A., et al. (2008). Use of a real time continuous glucose monitoring system as a motivational device for poorly controlled type 2 diabetes. Diabetes Research and Clinical Practice, 2008(82), 73–79.
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