Behavioral skills in self-monitoring of blood glucose: relationship to accuracy

Non-compliance with lens care and maintenance in diabetic contact lens wearers

We hypothesize that diabetic contact lens wearers may represent a special group displaying higher levels of compliance with their lens care regimens as a result of learned behaviour relating to maintenance of their diabetic condition. To test this hypothesis, a prospective, single centre, controlled, masked study was performed whereby 29 diabetic contact lens patients and 29 non-diabetic control subjects were issued with disposable hydrogel contact lenses and a multipurpose lens care regimen. All participants were given identical instruction on lens care and maintenance. Compliance levels were assessed at a 12-month aftercare appointment by demonstration and questionnaire. Twenty-four different aspects of compliance were scored, 12 by observation and 12 by questionnaire report, of which only two showed a significant difference between the diabetic and control groups. Although the combined population of contact lens wearers was generally compliant, there were examples of non-compliance in both groups. Neither the duration of diabetes nor the degree of metabolic control appeared to have a significant effect on compliance. The results suggest that eye care practitioners cannot assume that diabetic patients will be more compliant with contact lens care and maintenance than non-diabetic patients.

Blood glucose monitoring skills in children with Type I diabetes

While blood glucose monitoring has become increasingly important in diabetes care, studies have yet to address the accuracy of youngsters' performance of blood glucose testing with current reflectance meters. The present study examined testing skills and predictors of accurate testing skills in a sample of 7-14-year-old children attending a summer camp for youth with diabetes (n=266). A 15-item behavior observational skill test was used to assess accuracy of blood glucose monitoring skills with reflectance meters. Accurate performance of individual skills ranged between 14.6% and 99.6% for the sample. However, a number of children made critical errors (errors that were likely to lead to inaccurate blood glucose testing results). When duration of diabetes and metabolic control were controlled, female gender, older age, experience with a particular meter, and absence of hypoglycemia at the time of testing were positively associated with accurate skill performance. Findings suggest that younger children, children using a new blood glucose testing meter, and children suspected of having hypoglycemia should be supervised and observed when testing. Although all young children should be supervised when blood glucose testing, boys may need closer supervision until an older age than girls. This study underscores the need for health care providers to periodically observe children's blood glucose monitoring techniques to assure accurate testing habits and to correct problematic testing behaviors.

Assessment of blood glucose self-monitoring skills in a camp for diabetic children: the effects of individualized feedback counselling

We report a study of the accuracy and precision of blood glucose self-monitoring by children and adolescents attending a diabetic summer camp, and of the efficacy of feed-back counselling aimed at correcting identified problems. Of 96 eligible campers, 71 were enrolled. Of those, 41 were found to test with random error > 20% or systemic error > 10% and were randomized into control (n = 19) and intervention (n = 20) groups. Intervention consisted of one or two 15- to 30-min individualized sessions that involved testing under supervision, corrections of errors, and discussion of the importance of correct testing. Group sessions were also given on the same aspects. Re-testing at the end of camp revealed only marginal changes in the results for either group. Evaluation during counselling indicated that most problems were not due to lack of knowledge of the skills involved. We concluded that poor blood glucose monitoring by children and adolescents results most frequently from poor attitude rather than lack of skill.

Identifying technique errors. Self-monitoring of blood glucose in the home setting

1. Twenty-two study participants aged 65 and older were observed performing self-monitoring of blood glucose (SMBG) in their homes 3 to 4 weeks after initial meter instruction to identify elderly patients' technique errors in SMBG. Periodic evaluation of the elders' SMBG is vital for ongoing accurate results. 2. Overall, the elderly patients were able to perform the blood glucose test correctly. However, performing the quality control checks proved more difficult. The three most frequent errors included failure to check control solution expiration dates (86%), not shaking the vials of control solution (82%), and not verifying glucose control solution results (68%). 3. Further studies using larger samples and various populations are needed to further assess and document SMBG by the elderly patient. As the numbers of elders using SMBG increase, so does the need for research to promote the most appropriate and cost-effective education and evaluation of this self-care.

Capillary and venous blood glucose measurements using a direct glucose-sensing meter

The aim of the study was to evaluate the precision and accuracy of the ExacTech home blood glucose meter when used with either capillary or venous blood and to compare this with a reference whole blood glucose assay. Non-fasting glucose measurements were used since a validation study showed no capillary-venous differences between fasting and post-prandial states. In a cross-sectional study, blood was taken from 182 patients and measured in duplicate on three batches of strips. Altogether we analysed 1089 readings. The regression of the data from capillary blood samples (meter vs reference method) had a correlation coefficient, of 0.93, and a mean bias of 0.2 mmol l-1. The corrected 90% confidence interval was +/- 1.5 mmol l-1 overall, and +/- 0.9 mmol l-1 for readings under 7.0 mmol l-1. Regression of the data from venous blood samples (meter vs reference method) had a correlation coefficient of 0.93 and a slope of x 1.1. The corrected 90% confidence interval was +/- 1.7 mmol l-1. Thus venous blood may be used even though the meter is calibrated for capillary samples but the value must be corrected by dividing by 1.1. Error-grid analysis showed that day-to-day clinical decisions could be made on the basis of ExacTech readings, although a diagnosis of borderline diabetes may not be possible.

A prospective evaluation of glucose reagent teststrips in the prehospital setting

Reagent teststrip determination of blood glucose has been shown to be accurate for hospital and home testing and is commonly used in prehospital care despite the lack of studies in this arena. This prospective, multicenter study examines the ability of glucose reagent teststrips to detect hypoglycemia when used under field conditions compared with simultaneously drawn control samples for laboratory glucose determination. Also examined was the accuracy of the teststrips in the laboratory glucose range less than or equal to 200 mg/dL. One hundred eighty-one pairs of data were analyzed. Hypoglycemia was defined as laboratory glucose less than or equal to 60 mg/dL. The teststrips correctly identified 31 of 33 patients in this range (sensitivity = 94%), and 125 of 148 patients without hypoglycemia (specificity = 85%). The two false negative readings were 70 and 90 mg/dL. Reagent teststrips were within +/- 40 mg/dL of the laboratory value in 70% of cases. The correlation coefficient (Spearman r) between teststrip and laboratory glucose in the range less than or equal to 200 mg/dL was .80. Using teststrip readings of 90 mg/dL or less as a measure of hypoglycemia yields 100% sensitivity with a specificity of 57%. We conclude glucose reagent teststrips are a useful adjunct for use in the prehospital setting and may be valuable for the detection of hypoglycemia.

Data source automation: new technology for the management of patient-generated test results

Self-monitoring of blood glucose is widely accepted by patients today, but its usefulness to clinicians has been seriously limited by our inability to interpret the patient-generated data. It is difficult or impossible to make optimal use of hand-kept diaries, no matter how compulsively kept. Patterns elude us, summaries are inaccurate, and large blocks of data are almost entirely ignored. To remedy these problems, data source automation--the automatic recording of data at their site of origin--is being applied to diabetes. Meters will measure blood glucose and memorize the result, date, and time of day. One system even allows the patient to record insulin dosage, exercise, and diet. The advantage of these systems lies in their potential for data management. Recognition of patterns of blood glucose concentration, easy longitudinal comparison of data, and aggregation of large data bases are all facilitated by computerized manipulation of the stored data. In-hospital use of glucose meters can have better documented quality control. It is possible to communicate data to physicians by telephone modem. Effective use of these systems, though, requires convenient software; and their acceptance in actual clinical practice must be demonstrated. But data management capabilities, as they are refined and brought into common use, could significantly improve diabetic management.

A new, improved test system for rapid measurement of blood glucose

Several models of blood glucose meters are available to diabetic patients. They all require several steps for their operation, which increases the potential for user error. A new meter (One Touch TM System, Lifescan Inc., a Johnson & Johnson Company, Mountain View, CA) was designed to minimise the operational steps and therefore increase reliability. This system was compared for precision, accuracy and clinical safety to the Yellow Spring Instrument (YSI) Model 23A Glucose Analyser (Yellow Springs, OH) in 20 diabetic subjects. Good precision was demonstrated by the coefficient of variation (CV%) in 20 tests performed by each subject on a single heparinised specimen of their own venous blood. The CV was 4.5% (range 1.8-10.4). Accuracy was determined by the regression of the mean of the glucose results corrected for glycolysis compared to the mean YSI result. The regression line had a slope of 1.02, a Y intercept at -4.21 mg/dl, a correlation coefficient (r) of 0.999 (P less than 0.001) and a root mean square % (RMS) error of 4.385. Clinical safety was demonstrated by error grid analysis in which 399 of 400 tests fell in the clinically safe range, and reading error analysis in which two of 400 tests fell more than 25% from the reference method. It is concluded that the One Touch system has good accuracy when compared with the YSI method, is easier to use than the presently available meters, and is a useful addition to the management of diabetes in patients who perform self-monitoring of blood glucose.

Impact of blood glucose monitoring on diabetic control: obstacles and interventions

Despite frequent use in the management of diabetes mellitus, self-monitoring of blood glucose (SMBG) is not achieving its potential therapeutic impact. Among the behavioral factors which may interfere with the improvement of diabetic control through SMBG are noncompliance and inadequate utilization of obtained blood glucose data. This paper reviews the research concerning these issues, including estimates of the prevalence and clinical significance of each of these limiting factors and an evaluation of assessment and intervention strategies which have been investigated. The methodological problems encountered in attempts to demonstrate that SMBG behaviors affect diabetic control are discussed. Although the existing research literature provides very weak evidence linking SMBG behaviors and diabetic control, the author asserts that it is premature to conclude that such relationships cannot be established and maintained.

Self-monitoring of blood glucose by adolescents with diabetes: technical skills and utilization of data

Two studies of adolescent patients were conducted to determine their technical skills and utilization of data obtained by self-monitoring of blood glucose (SMBG). In Study 1, direct observations of 58 adolescents revealed an overall SMBG technical accuracy score of 82%. Most frequent errors were not cleaning fingers (45%), not placing blood on strips correctly (21%), and wiping strip at wrong time (14%). Technical performance was inversely correlated with blood glucose concentration, but was unrelated to other variables. In Study 2, a questionnaire was used to determine SMBG practices among 64 adolescents. Although the majority of patients reported doing daily SMBG, most did not record results in logbooks every time or utilize such data for self-management. No significant relationships were found between SMBG behaviors and other variables. We conclude that periodic evaluation and retraining are required for maintenance of SMBG skills and that methods to enhance utilization of SMBG data be developed for this patient population.

A proficiency score for assessing the reliability of self blood glucose monitoring

The reliability of self blood glucose analysis was studied in 83 insulin-treated diabetic patients. Reliability was assessed by laboratory analysis of capillary blood samples collected simultaneously on filter paper. Patient and laboratory results were compared using a scoring system which produces an easily understood Proficiency Score. The score was designed to highlight unreliable performance in measuring glucose concentrations in the euglycaemic as well as hypo- and hyperglycaemic ranges. Only 17% of patients achieved acceptable Proficiency Scores by maintaining adequate performance on five occasions.

The accuracy of blood glucose testing by children

While studies have evaluated the accuracy of adult patients and health personnel in reading various glucose oxidase impregnated strips to estimate blood glucose, there are no studies exclusively evaluating the accuracy of children with diabetes reading their own strips as compared to a staff member, and meter to meter variability in reading these strips. We evaluated the accuracy of reading chemstrip bG by children at a summer camp. The children's visual readings of their own strips were compared to the visual reading of a single staff member. A total of 356 Chemstrip bG's were visually read by diabetic children and a single trained staff member at a summer camp for diabetics. The strips were then analyzed by two Accu-Chek bG meters. Intermachine variability was found to be negligible over the entire bG range. For the purposes of this study, we define accurate visual readings as those within +/- 15 percent of the meter reading of a given strip. At low bG values (40-79 mg/dl), accuracy by children and staff is low, with underestimating occurring in 39 percent of staff readings and 57 percent of children's readings. At intermediate bG values (120-239 mg/dl) readings are more accurate, especially when read by the staff, with misreadings occurring in only 16-19 percent of the strips. At high bG values (240-399 mg/dl), accuracy by children is decreased, with underestimation 500 percent more often than staff. We conclude that children are less accurate at reading Chemstrip bG than a trained staff member (51% versus 33% misreading), especially at the upper and lower ranges of bG values when visual readings are least accurate, and the need for therapeutic intervention is the greatest.

Home blood glucose monitoring: keystone for modern diabetes care

Home monitoring of capillary blood glucose concentrations has changed diabetes care, giving physicians and patients a way to adjust their therapy and achieve better diabetic control. The practical strategies and equipment for home diabetic monitoring are discussed, including the changing role of urine testing and how inexpensive machines may enhance the value of blood glucose monitoring.