Multicenter evaluation of the reliability of five blood glucose monitoring systems

As part of a tender AP-HP Paris Hospitals, an assessment of the reliability record of five blood glucose monitoring systems (BGMSs) (Optium Xceed (Abbott), Contour TS (Bayer), One Touch Ultra (Lifescan), Stat Strip Xpress (Nova) and Accu Check (Roche) and an evaluation of their sensitivity to changes in hematocrit were conducted in 4 hospitals of Paris. In terms of inaccuracy, all BGMSs have submitted CV repetability under the limits of acceptability. One BGMS (Lifescan) presented a CV of reproducibility outside limit of acceptability (13.1%). The inaccuracy was measured by a comparison method on multiparameter analyser relative to the hexokinase method for two sites, the glucose oxidase for the two others. The coefficients of correlation varied from 0.8405 to 0.9303. However, according to both defined acceptability criteria (absolute value difference between the result acquired on analyzer and those determined with the BGMS), the percentage of results outside acceptability was above 20% for two BGMSs (Abbott and Lifescan). Similarly, a net effect of changes in hematocrit was observed on the results of those two BGMSs. BGMS Nova was the most reliable, because of the correction device for hematocrit and blank substractions owed to interferences. In terms of expertise, BGMSs Nova and Roche have been selected with the best analytical performance and practicability satisfactory. In the future, accreditation with standard NF/EN 22870 requested for point of care testing, will require a close collaboration between biologists and clinicians to establish a system of strict quality control to detect deviations of these BGMSs.     

Programme d'assurance qualité des analyseurs de glycémie capillaire au lit du patient : une revue de la littérature et une expérience de sept ans

A new paradigm which has to be faced by the biologist is the quality control far from the laboratory. An international literature review about « point-of-care-testing » clearly shows a lack of capillary blood glucose meters evaluation methods during their daily practice by patients and especially by nurses in hospital.Method. – Used for more than 7 years, is based on the standardization of all the meters from the hospital, and then, the regular comparison of patients'capillary results with fluoric plasma glycemia measured by the laboratory reference method. The efficace and simple management of results, thanks to the laboratory computer system, combined to a regular “remind” to services, allows a stimulating feedback for nurses'adhesion in this quality program.Results. – This experience shows that the laboratory can reach a quality assurance program (QAP), based on an efficient quality control, which validates more than the meter itself, the technical use by nurses. We propose first, the evaluation of electrodes Optium H, used with the devices Optium (Medisense), and then, the QAP sensitivity in ordinary usefulness.Conclusion. – This program, easy to put in application, in all hospital structures and sizes, reassuring for nurses'staff, is through a medical approach a good help in diabetic patients'education.     

Performance of glucose dehydrogenase (GDH) based and glucose oxidase (GOX) based blood glucose meter systems at moderately high altitude

OBJECTIVE: Self-monitoring of blood glucose (SMBG) is a fairly efficient method of preventing hypoglycaemia in diabetic patients. Blood glucose meters (BGMs) are influenced by factors such as altitude, temperature, blood oxygen concentration, low atmospheric pressure or humidity. In this study we aimed at evaluating the performance of glucose dehydrogenase (GDH) or glucose oxidase (GOX) based glucometers at moderately high altitude. METHOD: A total of 286 female or male patients, most of whom had type 2 diabetes, were included in this study. The simultaneous readings made by two different glucometers were compared with the readings made at the reference laboratory. RESULTS: Blood glucose levels measured by a GDH based glucometer at moderately high altitude were significantly (p=0.007) higher compared to those measured at the reference laboratory. Although blood glucose levels measured by a GOX based glucometer were lower compared to those measured at the reference laboratory, the difference was not significant (p=0.54). The difference between GOX and GDH readings with regard to blood glucose levels was also significant (p=0.001). Blood glucometers were influenced by moderately high altitude. CONCLUSION: The use of a GOX based glucometer at moderately high altitude may be useful in detecting hypoglycaemia at these conditions, since significantly higher blood glucose levels were measured with a GDH based glucometer compared to reference readings.     

A hospital-wide blind control program for bedside glucose meters

We have instituted hospital-wide proficiency testing of nursing personnel who operate glucose-monitoring instruments. Whole blood samples with known glucose levels were distributed to all nursing units for analysis on a biweekly basis. Measurements obtained by nurses on glucose meters were compared with one another and with true glucose levels to identify discrepant performance and institute corrective action. After 10 months of operation, we found that the nursing units using glucose meters daily showed mean absolute variation from true glucose of 12.7% (range, 10.0% to 17.7%), whereas intermittent users showed mean absolute variation of 15.3% (range, 10.7% to 24.0%). Of 552 total paired determinations, 199 (36.9%) differed from true glucose by greater than 15%. This program was successful in establishing uniform quality control procedures among nonlaboratory personnel who had no previous experience in laboratory measurements.     

Diagnostic equipment outside the laboratory.

A questionnaire was circulated to clinical biochemistry laboratories in the North West Thames region of the United Kingdom requesting information on extralaboratory equipment. Data on the types and numbers of instruments in use, their relationship with the laboratory, and quality assurance procedures were obtained. Laboratories were prepared to maintain equipment over which they had no responsibility for purchase, training of users, or use. The quality assurance of these instruments gave even greater cause for concern. Although internal quality control procedures were performed on many of the instruments, laboratories were involved in only a minority of these procedures. Quality control procedures and training of users were undertaken on site in less than 50% of blood gas analysers and bilirubin meters and in less than 25% of glucose meters. External quality assessment procedures were non-existent for all of the instruments in use with the exception of glucose stick meters in two laboratories.     

Performance of glucose dehydrogenase (GDH) based and glucose oxidase (GOX) based blood glucose meter systems at moderately high altitude

Objective: Self-monitoring of blood glucose (SMBG) is a fairly efficient method of preventing hypoglycaemia in diabetic patients. Blood glucose meters (BGMs) are influenced by factors such as altitude, temperature, blood oxygen concentration, low atmospheric pressure or humidity. In this study we aimed at evaluating the performance of glucose dehydrogenase (GDH) or glucose oxidase (GOX) based glucometers at moderately high altitude.

Method: A total of 286 female or male patients, most of whom had type 2 diabetes, were included in this study. The simultaneous readings made by two different glucometers were compared with the readings made at the reference laboratory.

Results: Blood glucose levels measured by a GDH based glucometer at moderately high altitude were significantly (p = 0.007) higher compared to those measured at the reference laboratory. Although blood glucose levels measured by a GOX based glucometer were lower compared to those measured at the reference laboratory, the difference was not significant (p = 0.54). The difference between GOX and GDH readings with regard to blood glucose levels was also significant (p = 0.001). Blood glucometers were influenced by moderately high altitude.

Conclusion: The use of a GOX based glucometer at moderately high altitude may be useful in detecting hypoglycaemia at these conditions, since significantly higher blood glucose levels were measured with a GDH based glucometer compared to reference readings.     

For the careful use of handheld and portable whole blood glucose meters

Accurate and frequent glucose measurement is an essential requirement for tight glucose control. Many varieties of handheld and portable blood glucose meters, such as self-monitoring-of-blood-glucose (SMBG) and point-of-care testing (POCT) devices, are widely used for a real-time measurement of whole blood glucose outside the laboratory unit. Obviously, SMBG device has been developed for the home-based use of diabetic patients to achieve better management. In the hospital-based setting, some of SMBG devices have been shown to be inaccurate in the glucose measurement due to a number of factors. Fetal errors were also reported. Thus, the use of SMBG device is restricted in the hospital-based settings. Compared with SMBG device, POCT device for the glucose measurement is thought to be superior in its performance. SMBG device, therefore, is now replacing with POCT one in the hospital-based settings. Although medical doctors or nurses frequently treat POCT device, it will be hoped that clinical laboratory stuffs positively support them for the quality of the equipment, the quality of the use, and the quality of the pre analytical conditions. From these viewpoints, we discussed here about the careful use of these handheld and portable whole blood glucose meters.     

Experience of a quality assessment scheme for non-laboratory glucose meters.

In late 1989 a quality assessment scheme was introduced for glucose meters at 12 non-laboratory sites in a unit of management. The overall monthly imprecision of the meters varied from 3.4% to 17.1%, the highest coefficients of variation being recorded for glucose concentrations outside the range 3-20 mmol/l. In the same period 37% of results fell outside +/- 10% of laboratory set target limits; 13% fell outside +/- 20% of these limits. Participants have been advised of the unreliability of results outside the range 3-20 mmol/l. The main benefit of the scheme has been the improved confidence of users in the results obtained.     

麦邦数据远程传输型血糖仪临床测量准确性的评价研究

目的 评价麦邦数据远程传输型血糖仪监测院外糖尿病患者血糖水平的准确性,为麦邦数据远程传输型血糖仪的临床使用提供数据参考。方法 应用等效性临床试验研究设计,按照纳入排除标准选取广州市天河区已诊断为糖尿病的患者,共计210例,采用麦邦数据远程传输型血糖仪和我院内分泌科所使用的美国雅培辅理善越佳型血糖仪,分别测量受试者指端血的血糖浓度,并与静脉血生化血糖值进行比较,分别计算两种血糖仪的测量结果与生化仪血糖值的相关系数和测量偏倚。上述的血糖检测控制在20 min内全部完成。结果 两种便携式血糖仪与全自动生化仪所测结果的相关系数分别为r=0.98、0.97,相关性均较好,且呈线性相关;两种血糖仪与生化仪测量值差值95%的置信区间均在标准等效区间（-0.83,0.83）mmol/L内,均满足临床等效性要求;麦邦数据远程传输型血糖仪95.28%的数据在临床可接受范围内,高于国家标准的要求,而雅培辅理善越佳型血糖仪低于此标准;各组检测结果之间差异虽无统计学意义（P＞0.05）,但两种血糖仪检测的结果均高于生化仪检测的结果。结论 通过等效性分析,麦邦数据远程传输型血糖仪可以用于临床血糖监测及个人血糖检测,但不能取代实验室血糖检测结果作为临床诊断标准;麦邦数据远程传输型血糖仪的数据传输功能,方便医生根据患者情况适时调整血糖控制方案,降低并发症的发生。     

Technical evaluation of five glucose meters with data management capabilities

Technical performance and data management features are prominent criteria in the selection of an appropriate meter for a point-of-care glucose testing program. We evaluated the technical performance of 5 currently available glucose meters with data management capabilities. The performance of all 5 meters was technically equivalent. Linear regression slopes vs the reference method are in the range of 0.94 to 1.02 and indicate correlation more to plasma values than to whole blood values. The percentage of glucose meter results within +/- 15% of the laboratory value was at least 90%; however, the percentage within +/- 10% was 75% to 87% for most meters. Within-day and between-day precision ranged from 2% to 5% coefficient of variation. Evaluation of linearity with glucose-spiked venous specimens demonstrated that the linearity of each meter agreed with the manufacturer's stated range in most cases. Meter glucose values tended to bias negative as the hematocrit increased, an effect that may be more pronounced at higher glucose concentrations. No volume effects were noted between 5 microL and 40 microL. The results suggest that all meters tested will likely satisfy technical performance criteria in a hospital setting and that selection of a system for point-of-care glucose testing will be influenced by the institution's data management requirements.     

Measurement of both protein-bound and total S-2-(3-aminopropylamino)ethanethiol (WR-1065) in blood by high-performance liquid chromatography

A high-performance liquid chromatographic method for automated analysis of both protein-bound and total S-2-(3-aminopropylamino)ethanethiol (WR-1065) in blood has been developed in our laboratory. WR-1065 is the active thiol metabolite of the radio- and chemo-protector drug amifostine (WR-2721). Using WR-1065 quality control levels over the experimental range: 7.0, 45.0 and 85.0 micromol/l spiked into plasma, method validation for total WR-1065 included between-run assessment of imprecision (SD/C.V.%: 1.11/16.7%, 6.58/15.5% and 9.24/11.3%, respectively) and % accuracy (94.7, 106.0 and 97.2%).     

Feasibility of precise and reliable glucose quantification in human whole blood samples by 1 tesla benchtop NMR

The standard procedure for blood glucose measurements is enzymatic testing. This method is cheap, but requires small samples of open blood with direct contact to the test medium. In principle, NMR provides non‐contact analysis of body fluids, but high‐field spectrometers are expensive and cannot be easily utilized under clinical conditions. Low‐field NMR systems with permanent magnets are becoming increasingly smaller and more affordable. The studies presented here aim at exploring the capabilities of low‐field NMR for measuring glucose concentrations in whole blood. For this purpose, a modern 1 T benchtop NMR spectrometer was used. Challenges arise from broad spectral lines, the glucose peak locations close to the water signal, low SNR and the interference with signals from other blood components. Whole blood as a sample comprises even more boundary conditions: crucial for reliable results are avoiding the separation of plasma and cells by gravitation and reliable reference values. First, the accuracy of glucose levels measured by NMR was tested using aqueous glucose solutions and commercially available bovine plasma. Then, 117 blood samples from oral glucose tolerance testing were measured with minimal preparation by simple pulse‐acquire NMR experiments. The analysis itself is the key to achieve high precision, so several approaches were investigated: peak integration, orthogonal projection to latent structure analysis and support vector machine regression. Correlations between results from the NMR spectra and the routine laboratory automated analyzer revealed an RMSE of 7.90 mg/dL for the best model. 91.5% of the model output lies within the limits of the German Medical Association guidelines, which require the glucose measurement to be within 11% of the reference method. It is concluded that spectral quantification of glucose in whole blood samples by high‐quality NMR spectrometers operating at 1 T is feasible with sufficient accuracy.     

Anti-diabetic effect of ginsenoside Rb(3) in alloxan-induced diabetic mice

As one of the main active component of protopanaxdiol type ginsenosides, ginsenoside Rb(3) is rarely reported in the treatment of diabetes. The anti-diabetic activity of ginsenoside Rb(3) was investigated in a model of alloxan-induced diabetic mice in the present study. The physiological parameter such as fasting blood glucose level, oral glucose tolerance, body weight, food intake and water intake were measured. Glucose consumption in C2C12 myotubes was also determined in order to investigate the molecular mechanism of ginsenoside Rb(3) in anti-diabetes. The alloxan-induced diabetic mice were treated with ginsenoside Rb(3) for 2 weeks at doses of 5 mg/kg, 15 mg/kg and 25 mg/kg. After 2 weeks treatment of ginsenoside Rb(3), the fasting blood glucose levels of DG 15 and DG 25 were respectively reduced by 36.70% and 37.50% compared to control group. At a dose of 25 mg/kg, oral glucose tolerance was significantly improved compared to control group (P < 0.05). The AUC decreased by 34.47% (from 2442 ± 291 mmol·min/L to 1600 ± 109 mmol·min/L). Both food intake and water intake were remarkably lowered. The injury of pancreas tissues was repaired, which was observed by using HE staining and optic microscope. In vitro, at concentrations of 100 and 200 μM, ginsenoside Rb(3) increased glucose consumption in C2C12 myotubes by 76.83% and 97.20%, respectively, as compared to the control group. However, the body weight of diabetic mice was not significantly altered. In conclusion, our results showed that ginsenoside Rb(3) reduced fasting blood glucose level, food intake, water intake, improved oral glucose tolerance, and repaired injured pancreas tissues of alloxan-induced diabetic mice. Therefore, it was suggested that ginsenoside possesses the potential of the clinical use in preventing and treating diabetes.     

Accuracy of roche accu-chek inform whole blood capillary, arterial, and venous glucose values in patients receiving intensive intravenous insulin therapy after cardiac surgery

Intravenous insulin protocols are increasingly common in the intensive care unit to maintain normoglycemia. Little is known about the accuracy of point-of-care glucometers for measuring glucose in this patient population or the impact of sample source (capillary, arterial, or venous whole blood) on the accuracy of glucometer results. We compared capillary, arterial, and venous whole blood glucose values with laboratory plasma glucose values in 20 patients after cardiac surgery. All 4 samples (capillary, arterial, and venous whole blood and laboratory plasma glucose) were analyzed hourly for the first 5 hours during intravenous insulin therapy in the intensive care unit. There were no significant differences between median capillary whole blood (149 mg/dL [8.3 mmol/L]) and laboratory plasma (151 mg/dL [8.4 mmol/L]) glucose levels. The median arterial (161 mg/dL [8.9 mmol/L]) and venous (162 mg/dL [9.0 mmol/L]) whole blood glucose levels were significantly higher than the median laboratory plasma glucose level. Capillary whole blood glucose levels correlate most closely with laboratory plasma glucose levels in patients receiving intensive intravenous insulin therapy after cardiac surgery.     

Effects of different hematocrit levels on glucose measurements with handheld meters for point-of-care testing

OBJECTIVES: To determine the effects of low, normal, and high hematocrit levels on glucose meter measurements and to assess the clinical risks of hematocrit errors. DESIGN: Changes in glucose measurements between low and high hematocrit levels were calculated to determine hematocrit effects. The differences between glucose measured with meters and with a plasma glucose method (YSI 2300) also were compared. SETTING: Six hand-held glucose meters were assessed in vitro at low (19.1%), normal (38.5%), and high (58.3%) hematocrit levels, and at 6 glucose concentrations ranging from 2.06 mmol/L (37.1 mg/dL) to 30.24 mmol/L (544.7 mg/dL). RESULTS: Most systems, regardless of the reference to which they were calibrated, demonstrated positive bias at lower hematocrit levels and negative bias at higher hematocrit levels. Low, normal, and high hematocrit levels progressively lowered Precision G and Precision QID glucose measurements. Hematocrit effects on the other systems were more dependent on the glucose concentration. Overall, Accu-Chek Comfort Curve showed the least sensitivity to hematocrit changes, except at the lowest glucose concentration. CONCLUSIONS: We strongly recommend that clinical professionals choose glucose systems carefully and interpret glucose measurements with extreme caution when the patient's hematocrit value changes, particularly if there is a simultaneous change in glucose level.     

高糖高脂对人脐带间充质干细胞增殖及凋亡的影响

背景：研究证实,间充质干细胞移植进入糖尿病患者体内后,疗效受多种因素影响,其中血糖、血脂起着关键作用。 目的：模拟糖尿病患者体内高糖高脂环境,进一步验证高糖高脂对体外培养脐带间充质干细胞的影响。 方法：葡萄糖和软质酸不同浓度分别体外干预人脐带间充质干细胞,分为对照组、低糖组、低脂组、低糖低脂组、高糖组、高脂组及高糖高脂组。干预48 h后通过CCK-8方法酶标仪测定细胞增殖,Annexin-V/PI方法流式细胞仪检测各组细胞的凋亡情况。 结果与结论：在高糖高脂的条件下,短期培养后细胞增殖及凋亡明显改变,与对照组相比,人脐带间充质干细胞增殖率明显减低(P < 0.01)、凋亡率明显增高(P < 0.01),且随着血糖血脂浓度的增加,人脐带间充质干细胞增殖率明显受到抑制,凋亡率明显上升;低糖低脂组和高脂组均抑制细胞增殖(均P < 0.05),促进细胞凋亡(均P < 0.01),高糖则促进人脐带间充质干细胞生长(P < 0.01)。结果提示,糖尿病患者体内处于高糖高脂状态,将抑制脐带间充质干细胞的生长。在间充质干细胞移植之前,控制患者血糖血脂水平,将更有利于干细胞在体内发挥作用。     

Are certain peculiarities in the distribution of somatostatin-like immunoreactivity (SLI) in the brain of sand rats (Psammomys obesus) possibly connected with an altered carbohydrate metabolism?

The hypothalamic and extrahypothalamic distribution of somatostatin-like immunoreactivity (SLI) was investigated in fed adult sand rats (Psammomys obesus) of both sexes using the immunofluorescence technique. Blood glucose and insulin concentrations were determined in these animals prior to decapitation. In a blind study, the amount of immunofluorescence of certain CNS areas and the glucose: Insulin ratio were compared and found to be connected: High amounts of SLI were detected in the dorsal hippocampus, in some hypothalamic nuclei and the median eminence of rats displaying low glucose levels. Sand rats with high blood glucose values did not show SLI in the hippocampal formation and the immunofluorescence of the circumventricular (hypothalamic) regions and the Eminentia mediana was drastically reduced. A possible correlation of SLI with insulin concentrations in the blood could not be revealed. The data obtained are discussed as a possible expression of a CNS influence on glucoregulation in this species.     

Glycated haemoglobin (HbG) as a stable indicator of blood glucose status in ostrich

Glycated haemoglobin (HbG) concentration is a retrospective measure of mean blood glucose level and is not affected by recent stresses, food ingestion or exercise. HbG has been determined in various wild and domestic animals such as kestrels, mankhor, mouflon, aoudad, deer, goat, sheep, dog, camel and horse. But there is no information regarding HbG in ostrich and its relation to blood glucose. The purposes of this study were to determine the normal values of HbG in ostriches and to investigate its relation to fasting plasma glucose. Blood samples were collected from jugular veins of 30 clinically healthy ostriches after 12 h of fasting. After separation and washing of red blood cells, haemolysate was prepared and subjected to weak cation exchange chromatography for determination of HbG. Glucose was measured in plasma samples. Fasting plasma glucose and HbG were 11.23 ± 0.80 mmol/l and 1.20 ± 0.2% of total haemoglobin, respectively. It was shown that HbG percent and fasting plasma glucose were correlated (P < 0.05; r = 0.93). To determine if low HbG percent in ostrich is related to low permeability of erythrocytes to blood glucose, haemolysates incubated with glucose (11.21 mmol/l final glucose concentrations) were subjected to chromatography under the same conditions. It was shown that HbG was significantly increased in glycosylated haemolysates. It was concluded that low HbG percent in ostrich is related to low glucose permeability of erythrocytes.     

Outcome of the glucagon test depends upon the prevailing blood glucose concentration in type I (insulin-dependent) diabetic patients

The outcome of 97 paired glucagon and meal tests was related to the prevailing fasting blood glucose concentrations on the two test days. At blood glucose concentration less than 7 mmol/l both the C-peptide responses and the maximal (6 min) C-peptide concentrations during the glucagon tests were significantly lower than the corresponding values found during the meal tests. During the glucagon tests, a direct relationship was found between the responsiveness of the pancreatic beta-cells and fasting blood glucose values when these were between 3 and 7 mmol/l. No significant difference was found between the outcome of the two tests when the fasting blood glucose concentration was greater than 7 mmol/l. The results indicate that the outcome of the glucagon test in Type I patients depends upon the prevailing fasting blood glucose concentration and that the predictive value of the glucagon test as to how the beta-cells will respond to a meal during everyday life is low when fasting blood glucose is less than 7 mmol/l.