in the care of patients with diabetes regarding necessary information to deliver appropriate insulin therapy, reduce insulin errors, and provide quality care.
There is a misconception that the most important aspect of education is the content of the education. Although content is crucial, data suggest that attention to the preferred style of learning of the health-care providers can greatly increase retention and understanding of the insulin safety principles.21 Flexibility of the education style and format may pay great dividends in patient education as well.
The education should be first targeted at the areas of highest frequency of errors, such as choosing the appropriate types, dosing, and route of insulin therapy; administering the insulin safely and accurately; and timely and accurate monitoring of the glucose levels. Other targets should include the development of the health-care provider’s understanding of how insulin therapy affects the patient’s clinical outcomes and how the clinical status of the patient in turn affects the decisions for their insulin therapy.
Scope of Education of Hospital Staff
All staff involved in the care of the patient with diabetes require education and training in the tasks needed to safely use insulin therapy. Too often, the as-needed (or per diem nurse, PRN) nursing staff and the evening or night shifts receive little training and education. A common cause of inpatient hypoglycemia is when insulin is given before a meal, but the patient is then transported to another part of the hospital and unable to eat the planned meal, resulting in hypoglycemia. Ideally, the hospital will have a comprehensive, in-depth resource and training available for the entire hospital staff, but this is a labor-intensive project, which so far has been done by only a few.16,22 The use of diabetes teams throughout the hospital is a useful tool,15,16 as is the development of preferred areas for more complex glycemic control. The use of online resources, especially for education modules or for reference, is also useful.
Glucose Monitoring
In the hospital setting, glucose monitoring is sometimes done by the central hospital laboratory, but the majority of the glucose monitoring is done with the use of point-of-care (POC) glucose monitors. A few centers are using POC blood-gas analyzers to measure glucose in critical care units, and a small but slowly growing number of centers are using continuous glucose monitoring systems (CGMS) in specific settings.23–25 At present, most inpatient centers rely heavily on POC glucose monitors for the vast majority of their glucose measurements, in large part because of the ease of use and timeliness. It should be remembered, however, that the central hospital laboratory method is highly accurate and relatively free of interfering substances, and should always be used when a POC glucose level needs confirmation or when the accuracy of the POC meter is in question.
From a systems perspective (see Figure 4.1), several key aspects of POC glucose monitoring should be evaluated constantly:
1. The choice of a POC glucose monitoring system;
2. The frequency of validation of the glucose strips and the monitors;
3. The robustness of the staff education programs and proficiency testing; and
4. The degree to which glucometrics are used to improve in-hospital glycemic control and to reduce errors in insulin therapy.
Figure 4.1—Systems perspective for medical errors.
These systemic issues are key because a significantly inaccurate glucose level may lead to relatively large insulin dosing errors. Additionally, the vulnerability of the particular POC glucose meter may make it unsafe in selected circumstances, and no POC glucose meter should be used without a clear understanding of its limitations and when it is unsafe to use that meter to monitor glucose levels.
Glucose Monitoring Errors
When insulin is to be administered, the glucose level at that time point is important data needed to select the correct dose and the optimal route of administration, and an important safety check to avoid iatrogenic hypoglycemia. Other factors that should be considered to avoid hypoglycemia include the clinical context of the patient and the factors that can be expected to influence insulin resistance of the patient and the expected effect of the dose of insulin. The patient’s vulnerability to hypoglycemia also needs to be considered. For example, an 80-year-old patient with chronic renal failure and hypoglycemic unawareness will be extremely vulnerable to fasting hypoglycemia.26 This patient requires careful and conservative insulin dosing and frequent glucose monitoring. To do otherwise would be an error. Likewise, if a patient receives intravenous (IV) insulin, but the frequency of glucose monitoring is every 6 h, the infrequent monitoring is an error, because the change in glucose levels after IV insulin can be rapid. In this case, the probability of harm increases greatly when the glucose measurements are too far apart.
Often the health-care team uncritically assumes that the monitoring method is accurate. In 2009, the U.S. Food and Drug Administration (FDA) reported the death of 13 patients with diabetes on peritoneal dialysis who were being monitored with a widely used glucose meter that followed a glucose dehydrogenase method, using a pyrrolo-quinoline quinone (PQQ) coenzyme to measure glucose concentrations. This method is less sensitive to ambient oxygen levels and some other interfering substances and will falsely measure maltose as glucose. Because patients who receive icodextrin in their peritoneal infusate will slowly metabolize the icodextrin to maltose, this process can lead to high maltose levels in the patient’s blood up to 2 weeks after the last peritoneal dialysate. In each of the cases reported by the FDA, the health-care providers used a POC glucose meter of the PQQ type, resulting in an erroneously measured and markedly elevated POC glucose, which was used to order inappropriately large doses of insulin and resulted in severe hypoglycemia, coma, seizures, and ultimately death. Despite the 2009 FDA report, however, a recently published report indicates patients in some hospitals and outpatient centers are still using meters of this type with patients who either are or recently have been on peritoneal dialysis with similar lethal outcomes.
The FDA, in response to strong concerns presented by multiple organizations and individuals, most recently tightened the standards for accuracy of POC glucose meters being used in the hospital setting. The new standards recommended by the FDA are expected to be implemented by the end of 2015, and state that 99% of the glucose values must be within ±10% of the glucose levels ≥70 mg/L and within ±7% of values <70 mg/dL. Also, 100% of the values must be within ±20% of the glucose levels ≥70mg/dL or within ±15% of those values <70mg/L. The latter standard is crucial, as other authors have shown the potential for severe errors in clinical decision making when the result obtained by the POC glucose meter is so far from the true value of glucose so as to be misleading.27
Recently Scott et al.28 pointed out the weaknesses of the POC meters in use, especially in the operating room29 and in intensive care settings. Variations in hematocrit, blood pH, oxygen saturation, fever, dehydration, or ketosis all had varying and sometimes significant effects on the results obtained with a POC glucose meter,30 and in critical care, most POC glucose meters were clearly inferior in accuracy to the results obtained by intra-arterial samples tested for glucose levels on POC blood-gas analyzers. Arterial samples are used in preference to fingerstick glucose samples in patients who have circulatory compromise, and the capillary values of glucose may diverge significantly from the arterial values when acidosis or circulatory collapse alters the capillary blood flow.
Errors in monitoring may be due to sampling errors when the site from which the blood sample is obtained does not accurately represent the true blood glucose value. In the operating room, severe hypoglycemia has resulted when the anesthesiologist did not realize the arterial line that they were sampling from was being flushed with 5% glucose solution.31 As a result, insulin
