How To Set Freestyle Lite Glucometer
J Diabetes Sci Technol. 2008 Jul; 2(iv): 546–551.
No-Coding Strategies for Glucose Monitors
FreeStyle Lite—A Claret Glucose Meter That Requires No Coding
Abstract
Groundwork
Abbott Diabetes Intendance introduced the FreeStyle® Lite blood glucose monitoring arrangement, which simplifies the management of diabetes. The FreeStyle Lite system relies on FreeStyle engineering science but eliminates the need for coding the meter for individual strip lots. The meter is precoded for the FreeStyle Lite strips. FreeStyle systems use coulometry engineering where the glucose bespeak is calculated from the total charge generated as a event of the glucose reaction in the sample. FreeStyle strip scale parameters tin can be controlled by controlling the sample book. Coulometry engineering is less sensitive to measurement conditions such as temperature and hematocrit. FreeStyle chemistry is less sensitive to interference from electroactive compounds. The ability to command scale parameters coupled to a robust measurement technology enabled the development of a claret glucose monitoring system that does not require coding by the user.
Methods
Laboratory studies were performed to make up one's mind analytical performance, such equally linearity, precision, and sensitivity to operating temperature. Clinical accurateness for finger tip capillary blood testing was assessed with v lots of FreeStyle Lite exam strips. FreeStyle Lite results in these studies were compared to the plasma equivalent glucose values of finger tip blood samples measured by the Yellow Springs Instrument glucose analyzer.
Results
In the analytical performance evaluation, repeatability (within-run precision) of the FreeStyle Light system showed an average standard difference of 3.4 mg/dl (0.19 mmol/liter) at glucose concentrations <100 mg/dl (<five.56 mmol/liter) and an boilerplate coefficient of variation of 4.three% at glucose concentrations ≥100 mg/dl (≥v.56 mmol/liter). Linearity demonstrated beyond the measuring range of the FreeStyle Lite system was 20–500 mg/dl (1.1–27.8 mmol/liter) with r 2 > 0.99. The FreeStyle Lite system was also shown to maintain accuracy across the operating temperature range of four to twoscore°C.
Conclusions
The FreeStyle Lite arrangement has good analytical operation and clinical accuracy. While simplifying the procedure of blood glucose monitoring, the FreeStyle Lite organization continues to provide the performance that users have come to wait from FreeStyle products.
Keywords: coulometry, FreeStyle Lite, no coding
Introduction
Electrochemical blood glucose monitoring systems have evolved since the launch of Exactech in 1987 by MediSense Inc., now a part of Abbott Diabetes Care. The time required to complete a test has changed from over 30 seconds to just less than five seconds. The volume of blood book required to perform a successful exam has dropped from over ten μl to just about 300 nl. Lower blood book requirements accept decreased the pain of claret glucose testing, making tests at alternating sites a reality.
Diabetic patients perform blood glucose testing to manage their disease. They rely on the accuracy of the measurement to make appropriate medical interventions. Clarkeone and consensus2 mistake grids accept been developed to graphically represent the clinical bear on of errors in glucose measurements performed using handheld devices equally compared to a laboratory reference. A high caste of clinical accuracy of blood glucose measurement with handheld devices is very essential in minimizing agin effects of the treatment.
Some of the common initiating causes of inaccuracies in an electrochemical blood glucose monitoring systems are insufficient sample provided for the exam and the effect of endogenous or exogenous interfering compounds. Inaccuracies caused past insufficient sample are minimized by introducing fill indicators to ensure that sufficient sample is provided to the strip. The assay does not start until sufficient claret sample is provided to the strip. Interference from endogenous and/or exogenous compounds that may be nowadays in the sample can be minimized by selecting chemistries with improved substrate specificity and/or mediators that require lower oxidation voltages to perform the measurement.
Each strip lot has a unique calibration parameter (e.k., gradient and intercept) that defines the operation of the strips from that strip lot. The manufacturer makes multiple lots of exam strips using unlike lots of agile (e.g., enzyme and mediator) and/or inactive (due east.yard., buffers and polymers) reagents. The composition of reagents could vary from ane lot to the other. These variations from lot to lot would result in variation of calibration parameters. Therefore, the meter has to be configured to the strip lot that is being used for the measurement. This is achieved by the user either past inserting lot-specific calibration data to the meter using a smart chip or a calibrator or past selecting a calibration lawmaking from i of the preset calibration codes from the meter appropriate for the strip lot. This process is essential to ensure analytical functioning of the system. If the manufacturer can control these variations, then the need for the user to configure the meter to the strip lot can be eliminated. This simplifies the process of blood glucose monitoring.
FreeStyle Strips
TheraSense, now a part of Abbott Diabetes Care, introduced the FreeStyle® claret glucose monitoring organization in 2000 to improve the lives of diabetic patients.three These systems crave only 300 nl of blood sample to perform a test and enable alternate site testing. The FreeStyle organisation uses pyrroloquinoline quinone dependent glucose dehydrogenase4 with an osmium compound every bit the mediator. The mediator is oxidized at a very low oxidation voltage. The reaction scheme of FreeStyle strips is provided in Figure 1 .
Reaction scheme of a FreeStyle strip.
The components of a FreeStyle test strip are shown in Figure 2 . The strip consists of a working electrode on one of the substrates and a reference and two indicator electrodes on the other substrate. The agile chemistry is coated on the working electrode. The 2 substrates are assembled to obtain an opposing arrangement of the electrodes past using an adhesive layer. The channel is cut out in the agglutinative across the width of the strip. The strip insertion to the meter is detected by the turn-on bar located at the contact finish of the strip. The dual-fill indicator electrodes across the fill channel ensure that the desired amount of the sample is provided to the strip earlier completion of the assay, minimizing test errors.
Structure of a FreeStyle examination strip.
The FreeStyle system uses coulometry engineering science for glucose measurement. Coulometry is an electrochemical technique where the glucose concentration is determined from the total charge generated as a effect of the reaction of the glucose in the sample. Figure 3 shows the plot of charge as a function of time at various glucose levels. The time for completion of the reaction increases with the glucose level. The measurement time in FreeStyle technology is dependent on the glucose concentration and increases with glucose, unlike an amperometric technique. This variable measurement time also compensates for the variations in reaction rates caused by measurement temperature, diffusion of glucose due to changes in hematocrit of the sample, and so on. FreeStyle technology also uses a depression potential for the oxidation of the mediator, minimizing the interference from electrochemically agile compounds, such every bit acetaminophen, ascorbic acrid, and uric acid.
Signal profiles from FreeStyle strips as a part of time at dissimilar glucose levels.
No-Coding FreeStyle Strips
In a coulometric measurement, the total charge measured from the sample at a given concentration of glucose is dependent only on the volume of the electrochemical cell. Therefore, in a coulometric engineering science, lot-to-lot variation can be minimized by controlling the volume of the sensor. The volume of the sample required to perform a test is defined past the channel dimensions. The length of the aqueduct is divers by the width of the strip, which is fixed. The width and top of the channel tin exist varied independently to obtain the desired volume.
Abbott Diabetes Care introduced FreeStyle Lite blood glucose monitors that exercise not require coding. These meters are preconfigured with one set of calibration parameters representative of the FreeStyle Lite strips. Blood glucose measurement is affected past inherent imprecision in the manufacturing of the strip, as well as blood-to-claret variations in the clinical samples. Accounting for this variability in the system performance, the slope and intercept tin have finite ranges without affecting the clinical accuracy of the device. When these meters are used with strips that have calibration parameters that are substantially identical (within this allowed range of slopes and intercepts) to that preconfigured in the meter, the analytical functioning of the system is sufficient to requite clinically accurate results.
Prior to the release of FreeStyle Lite strips that require no coding by the user, there was no control on the release of FreeStyle strip lots to the end user based on the distribution of calibration parameters. Therefore, the use of strips that are already in the marketplace with meters that require no coding had to be disabled. FreeStyle meters are activated past the plow-on bar electrode graphics on the top side of the strip. FreeStyle and FreeStyle Lite strips are differentiated past the plow-on electrode as shown in Figure iv . The strip port of the FreeStyle Lite meters was reconfigured not to exist activated by the FreeStyle strips and only activated by FreeStyle Lite strips that have the correct blueprint of the turn-on bar electrode.
(a) FreeStyle and (b) FreeStyle Calorie-free strips.
Performance of a claret glucose monitoring organisation is determined past clinical accuracy and repeatability. Laboratory studies were performed on the FreeStyle Lite organisation to determine the linearity, repeatability, and sensitivity to temperature across the measurement range of 20 to 500 mg/dl. Clinical accuracy of the FreeStyle Lite system was determined past comparing the glucose results of finger capillary samples against the Yellow Springs Musical instrument (YSI) glucose analyzer.
Materials
Production FreeStyle Lite strips and meters were used for the study. Venous blood from healthy volunteers was drawn into heparinized tubes. The glucose concentration of the sample was adapted to the desired level by either spiking with 1 Thousand glucose solution or allowing the sample to glycolyze. Reference glucose measurements were performed using a YSI 2300 STAT Plus blood glucose analyzer.
Methods for Determining Analytical Performance
Linearity
Three heparinized venous claret samples were collected and each was adjusted to create nine glucose concentrations spanning the glucose measurement range. 3 lots of FreeStyle Lite test strips were tested on six meters, with indistinguishable measurements performed for each lot of examination strips, meter, and glucose level.
Precision
Repeatability (inside run precision) of the FreeStyle Light organization was assessed by analyzing heparinized venous blood samples at five glucose levels. Three lots of test strips and 16 FreeStyle Lite meters were used. X replicates were performed on each meter for each glucose level and test strip lot. For glucose concentrations <100 mg/dl (<5.56 mmol/liter), the standard departure (SD) values were averaged across the 3 strip lots. For glucose concentrations ≥100 mg/dl (≥5.56 mmol/liter), the coefficient of variation (CV) values of the three strip lots were averaged.
Temperature Sensitivity
Three heparinized venous blood samples were nerveless and each was adapted to create 3 glucose levels at approximately 40, ninety, and 360 mg/dl (2.2, v.0, and 20.0 mmol/liter). All nine samples were tested at three temperatures (4 ± 1, 25 ± 1, and 40 ± one°C) with three lots of FreeStyle Lite test strips on six FreeStyle Lite meters. All tests were performed at a relative humidity of 50 ± 5% with 25 ± 1°C serving as the control condition. Duplicate measurements were performed for each lot of test strips, meter, glucose level, and temperature. Averaged over three test strip lots, the difference in the bias from the YSI reference between the test conditions and the control condition (25 ± 1°C) was measured.
Clinical Performance
The accuracy of the FreeStyle arrangement for finger tip capillary blood testing was evaluated using five different strip lots. Each strip lot was tested with finger tip capillary blood samples from at to the lowest degree 50 patients in duplicate. Finger tip capillary blood glucose results obtained with the FreeStyle Lite organization compared to results obtained on the YSI. Plasma equivalent glucose results were calculated from whole claret YSI measurements using the empirical relationship YSIplasma = YSIwhole blood * 1.12.
Results and Word
Linearity
A total of 972 tests were conducted (duplicate tests using 3 venous samples each at nine glucose levels, three lots of exam strips, and vi meters). The average bias from the regression line was −0.5 mg/dl (−0.03 mmol/liter) at glucose <100 mg/dl (<5.56 mmol/liter) and −0.1% at glucose ≥100 mg/dl (≥5.56 mmol/liter). A graphic presentation of linearity data across the measurement range is shown in Figure 5 .
Linearity of FreeStyle Calorie-free system across the measurement range.
Precision
In the repeatability (within-run precision) written report, 3 lots of FreeStyle Lite test strips, sixteen FreeStyle Lite meters, and v fresh venous blood samples were tested. Tabular array 1 summarizes repeatability data of FreeStyle Light meters beyond the measurement range. Averaged over the iii strip lots, the SD was 2.eight–3.9 mg/dl (0.16–0.22 mmol/liter) at glucose concentrations <100 mg/dl (<5.56 mmol/liter) and the CV was 3.9–5.0% at glucose concentrations ≥100 mg/dl (≥5.56 mmol/liter).
Table one
Repeatability of FreeStyle Light Meters (n = 480)
| Mean glucose value (mg/dl) | 29.iv | 66.two | 138.four | 176.eight | 386.vi |
| SD (mg/dl) | ii.8 | 3.9 | 6.9 | seven.1 | 14.nine |
| CV (%) | nine.4 | 6.0 | 5.0 | four.0 | 3.8 |
Temperature Sensitivity
The bias (i.e., the difference between the FreeStyle Calorie-free system consequence and the YSI result) at three operating temperatures (4 ± 1, 25 ± one, and forty ± 1°C) was measured at three glucose levels (40, 91, and 358 mg/dl; 2.2, 5.1, and 19.9 mmol/liter). Table 2 summarizes temperature sensitivity data of FreeStyle Lite meters across the measurement range. At glucose ≤75 mg/dl (≤4.2 mmol/liter), the difference in the bias at the extreme temperatures (4 ± 1 and xl ± 1°C) was inside iii mg/dl (0.17 mmol/liter) from the control condition (25 ± 1°C). At glucose >75 mg/dl (>iv.2 mmol/liter), the divergence in bias was within 4% from the control status. Thus, operating temperatures between 4 and 40°C did not significantly affect the functioning of the FreeStyle Lite system.
Table 2
Temperature Sensitivity of FreeStyle Low-cal Meters (n = 108)
| Mean glucose value (mg/dl) | Bias at 4°C compared to 25°C | Bias at 40°C compared to 25°C | ||
|---|---|---|---|---|
| mg/dl | % | mg/dl | % | |
| 40.5 | –2.ix | –viii.0 | 2.nine | 6.v |
| 91.0 | –1.8 | –1.ix | 3.8 | iv.four |
| 357.9 | 9.3 | two.half dozen | 13.eight | three.8 |
Clinical Performance
In finger tip testing, the accurateness of the FreeStyle Calorie-free system was demonstrated past comparing results from 512 measurements with the YSI plasma equivalent glucose values [r 2 = 0.98, slope = 1.04, intercept = i mg/dl (0.one mmol/liter) by regression analysis; hateful absolute residual = 5.2%]. Figure 6 shows the consensus (Parke) fault grid analysis of the FreeStyle Calorie-free results against YSI reference. Nosotros found 98.eight% of the results in zone A and ane.2% of the results in Zone B of the filigree. Nosotros found 96.9% of the individual FreeStyle Lite system results within the International Organization for Standardization (ISO) accuracy limits. ISO 15197 specifies that 95% of the individual meter results shall fall inside ± fifteen mg/dl (± 0.83 mmol/liter) of the reference measurement process at glucose concentrations <75 mg/dl (<4.2 mmol/liter) and within ± 20% at glucose concentrations ≥75 mg/dl (≥4.2 mmol/liter).v
Clinical results from five test strip lots plotted on a Parke error grid: zone A, clinically accurate (no event on clinical action); zone B, clinically acceptable (altered clinical action—petty or no effect on clinical effect); zone C, contradistinct clinical activeness—likely to bear upon clinical effect; zone D, altered clinical activeness—could have significant medical take a chance; and zone E, altered clinical activeness—could have dangerous consequences.
The hematocrit range of the capillary blood specimens in the study was 31 to 52%. Over this hematocrit range, the exam results did not show any hematocrit sensitivity (average sensitivity of the glucose results to the hematocrit of the sample was -0.09%/% hematocrit). This high level of clinical accuracy tin be attributed to FreeStyle coulometry technology, which uses the total point from the glucose reaction, thus reducing the effects of hematocrit.
Conclusions
FreeStyle coulometry technology uses the full signal from the glucose reaction for calculating the glucose concentration, thus minimizing the furnishings of hematocrit and measurement conditions such as temperature. The strip is designed with dual-fill indicators across the fill aqueduct, minimizing exam errors. Lower measurement voltage reduces interference from electroactive compounds that may be present in the sample. The charge measured in coulometry technology used in FreeStyle products is dependent on the sample book. Precise control of the sample volume past optimizing the sample bedroom dimensions allows for minimum variation between strip lots, assuasive the evolution of FreeStyle Low-cal strips that require no coding.
Abbreviations
| CV | coefficient of variation |
| ISO | International Organisation for Standardization |
| SD | standard difference |
| YSI | Yellow Springs Instrument |
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Articles from Periodical of Diabetes Science and Technology are provided here courtesy of Diabetes Technology Guild
How To Set Freestyle Lite Glucometer,
Source: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2769754/
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