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Blood Glucose Monitoring in Paediatric Patients


that the target BG range is between 70 and 180 mg/dl and that patient-generated BG values outside that range will be treated according to rules suggested by the healthcare provider. Zone A (upper and lower) data pairs represent patient-generated values within 20 % of the reference values and/or <70 mg/dl when the reference is <70 mg/dl. Points in zone A are categorised as clinically accurate because they could lead to accurate treatment decisions. Zone C (upper and lower) data pairs represent possible ‘overcorrection errors’, as patient-generated values in these zones might trigger treatment responses that could result in BG values outside the target range. Zone D (upper and lower) values are failure to treat errors because the patient-generated values are within the target range when the reference value is either low (<70 mg/dl) or high (>240 mg/dl). Zone E values are errors where the patient-generated values are either high (>180 mg/dl) when the reference is low (<70 mg/dl) or low (<70 mg/dl) when the reference is high (>240 mg/dl). Patient self-treatment based on these errors could result in serious hypoglycaemia or hyperglycaemia. Zone B data pairs are those where the patient-generated value deviates from the reference by >20 %, but may not result in clinically significant treatment errors. They are designated clinically acceptable.


EGA has been used by most manufacturers of SBGM devices to demonstrate the clinical accuracy of their meters and, together with statistical analyses, were reported to the FDA as part of pre-marketing proposals.4


results from a variety of SBGM devices were presented.6


In the original presentation of the EGA, In no case


was the clinically accurate/acceptable (zones A + B) percentage <94 %. Therefore, with more than 20 years of data, it could reasonably be assumed that the clinical accuracy of SBGM systems analysed using either EGA or CEG is sufficient to permit patients to make appropriate treatment decisions. However, it should be emphasised that this is a level of accuracy deemed acceptable for patients who are self-managing their diabetes. SBGM devices may not be sufficiently accurate for use in other situations, such as titrating insulin doses in acutely ill patients in an intensive care unit (ICU) setting or for diagnosing diabetes.9


The FDA held a public meeting in March 2010 on ‘Blood Glucose Meters’ and invited members of academia, business and patients with diabetes support groups to discuss their experiences with SBGM accuracy and make suggestions for changing accuracy standards. A synopsis of the meeting concluded that while there are two types of standards for reporting accuracy – regulatory and clinical – they are not always in agreement. The FDA was challenged to decide on an acceptable percentage of data pairs that should fall into each of the five zones of the EGA. In other words, clinical accuracy standards need to be strengthened if SBGM devices are to be used to monitor BG levels in situations more critical than routine outpatient settings. Optimal BG target ranges and accuracy required for different clinical situations, such as hospital or ICU use or tight glycaemic control, needs to be identified and reagent strips need to be labelled to reflect both their analytical and clinical performance.


There are other important sources of error in obtaining a BG reading from a SBGM device that do not relate to the performance of the meter. Such errors might be the result of insufficient cleansing of the fingertip, inappropriate squeezing to obtain a drop of blood, failure to match calibration codes to strips and incorrect displays (mmol instead of mg/dl), to name a few.


EUROPEAN ENDOCRINOLOGY


Figure 1: Error Grid Analysis 400


C 300 E A


200 B D 100 B


D


C 0 0 100 200 300 Reference blood glucose (mg/dl) Table 1: Uses of Self-blood Glucose Monitoring


Daily management decisions Intensive therapy


Prevention of severe hypoglycaemia Reduction of glycated haemoglobin


Management of illness/prevention of diabetic ketoacidosis


Uses of Self-blood Glucose Monitoring Devices As stated earlier, SBGM was designed for patient use in day-to-day and hour-to-hour clinical decision-making. To paediatricians and parents for whom SBGM has always been a part of routine clinical diabetes management, the vast improvement in glycaemic monitoring afforded by these devices is often overlooked. SBGM replaced urine glucose tests, which were difficult to obtain, especially when the patient was outside of the home, wearing diapers, or ill. At best, urine testing reflects previous glycaemia rather than immediate glucose levels. Thus the information provided by SBGM and the ease with which the results are obtained have made it possible to manage diabetes in a variety of outpatient situations (see Table 1). Patients, including children and their parents, have successfully used these systems to achieve a level of intensive glucose control sufficient to demonstrate the relationship between glycaemia and the risk of long-term microvascular complications in the DCCT.2


Parents have used the systems to monitor


overnight BG levels to prevent serious nocturnal hypoglycaemia and during illness to prevent diabetic ketoacidosis. Indeed, it has been shown that the frequency of SBGM testing is related to both lower


HbA1c levels and to the occurrence of acute complications such as ketoacidosis and/or hypoglycaemia.10


Along with multiple daily insulin


Athletes and their coaches use SBGM data to individualise treatment scenarios to prevent hypoglycaemia and/or hyperglycaemia and thus expand the opportunities available for physical activity.


23


Nurses, other school personnel and care providers use the systems to assist the child with treatment decisions and keep him/her safe throughout the school day or while apart from their parents.13


injection therapy, SBGM has revolutionised the way in which children with diabetes are monitored and treated within school systems and in day care centres.11,12


400


E


Blood glucose estimate (mg/dl)


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