Diabetes Care Volume 41, October 2018 2053

A Perspective on the Accuracy of Jincy Immanuel and David Simmons Meters During

Pregnancy CARE IN PERSPECTIVES Care 2018;41:2053–2058 | https://doi.org/10.2337/dc18-0833

Blood glucose is fundamental for management during pregnancy, but are the devices up to the job? Studies assessing the accuracy of 10 commercially available glucose meters during pregnancy showed that al- though >98–99% of the meter values were in the acceptable zones of the error grid for the majority of the meters, the meter performance varied, with the major- ity showing positive bias and a few showing minimal negative bias. The mean difference between meter and laboratory plasma values varied between 20.33 and 0.73 mmol/L. Three meters showed deviations from laboratory results with a change in maternal hematocrit levels. No meters had a total analytical error <5%, and no studies evaluated meters using recent International Organization for Stan- dardization 15197:2013 criteria. The Continuous Glucose Monitoring in Women With in Pregnancy Trial (CONCEPTT) recently showed that an antenatal continuous glucose monitoring system (CGMS), as an adjunct to monitoring, was associated with a lower incidence of large-for-gestational-age babies, fewer neonatal intensive care unit admissions (>24 h), and a lower incidence of neonatal . The flash glucose monitoring system shows good accu- racy in pregnant women but has not been marketed widely in the U.S. We suggest that meters cannot be assumed to be sufficiently accurate during pregnancy and that manufacturers should ensure a total error <5%, with bias and impreci- sion <2% during pregnancy. Large studies are needed to evaluate the usefulness of CGMS among pregnant women with and gestational diabetes mellitus.

Blood glucose monitoring is an integral part of hyperglycemia management. The American Diabetes Association recommends the use of self-monitoring of blood glucose (SMBG) for pregnant women with gestational diabetes mellitus (GDM) and preexisting diabetes for achieving better glycemic control (1). This testing can augment the use of HbA1c (2,3), which is unable to monitor day-to-day changes in glycemia, particularly when the level is significantly lower in pregnant women than in School of Medicine, Western Sydney University, Campbelltown, New South Wales, nonpregnant women (4). Current new-generation meters have features that enhance fi Corresponding author: David Simmons, da their accuracy pro le, making them more accurate than older devices (5). However, [email protected]. despite technical advancement, many newer glucose meters fail to perform well in Received 17 April 2018 and accepted 28 June real-world situations (6). Numerous factors influence the accuracy of meter values, 2018. including meter and strip technology, operator knowledge and performance tech- © 2018 by the American Diabetes Association. nique, underlying clinical conditions (e.g., high triglyceride and uric acid concen- Readers may use this article as long as the work trations and changes in oxygen and hematocrit levels), environmental factors is properly cited, the use is educational and not for profit, and the work is not altered. More infor- (e.g., temperature, altitude, and ), and interfering substances (7). Because mation is available at http://www.diabetesjournals new meters are able to perform with a blood volume as small as 0.3 mL, any hand .org/content/license. 2054 Glucose Meter Accuracy Diabetes Care Volume 41, October 2018

contamination with sweat, moisture, and studies, studies performed outside the of the plasma values for all four meters traces of fruit may also interfere with pregnant population, and non-English evaluated. Three glucose meters (Accu- the accuracy of meter values. publications were ineligible. The primary Chek Advantage II [Roche Diagnostics], Glucose monitoring targets in preg- outcome measure for this review was Accu-Chek Performa [Roche Diagnostics], nancy need to be tight (1), with low thresh- the frequency of meters that met the and FreeStyle Lite [Abbott Diabetes Care]) olds for commencing pharmacotherapy analytical and clinical accuracy criteria as were evaluated in two different studies, or increasing the dosage. The Hy- per International Organization for Stan- and a significant variation in the accuracy perglycemia and Adverse Pregnancy Out- dardization (ISO) 15197:2003 (9) or the profiles was noted between the studies. comes (HAPO) study showed that a fasting ISO 15197:2013 recommendations (10). glucose of 5.1 mmol/L in the oral glucose The mean difference, mean bias, stability SMBG DEVICES: EXPECTATIONS tolerance test at 24–28 weeks of gesta- to hematocrit changes, and percentage DURING PREGNANCY tion was already associated with a 75% in- ofmetervalueswithin5%or10%error Performance Goal of Glucose Meters creased risk of adverse outcomes (8). Since were also reviewed and summarized. During Pregnancy the initiation of insulin/metformin/glyburide A literature search identified 355 ar- Meters have no specific performance therapy and the related dosage adjust- ticles, of which only a few were relevant “goal” for pregnancy alone. Current qual- ments depend solely on the SMBG results, to the review objective. Four studies ity specifications by different organizations inaccurate results may lead to insulin dos- (11–14) met the eligibility criteria and allow a maximum of 15% performance age errors and a greater chance of hypo- or were selected for the review. A total of error for 95% of the meter results in the hyperglycemia and may even fail to detect 10 different glucose meter devices man- nonpregnant population (10,15,16). A hypoglycemic episodes. Therefore, accurate ufactured by 5 different companies were simulation modeling study (17) using a SMBG results are crucial for management reviewed, 2 of which were available in Monte Carlo method outside of pregnancy of hyperglycemia during pregnancy. The the U.S. The glucose meters evaluated in reported that 8–23% of the insulin doses capabilities of continuous glucose mon- the studies were as follows: Accu-Chek were incorrect for meters with a total itoring systems (CGMS) during pregnancy Active, Accu-Chek Advantage II, Accu- analytical error of 5% and that the dosage have advanced with the technical aspects Chek Performa (Roche Diagnostics); Ascen- error rate was 16–45% for meters with of glucose meters, and therefore consider- sia EliteF ( HealthCare); CareSens a total error of 10%. Additionally, large in- ing these aspects is important in this Per- 505B (iSENS); Optium, Optium Xceed 5s, sulin dosage errors were reported when spective on SMBG during pregnancy. Optium Xceed 20s, Freestyle Lite (Abbott the coefficient of variation (CV) and/or bias Diabetes Care); and Stat-Strip (Nova Bio- was .10–15%. The study recommended TECHNICAL ACCURACY OF SMBG medical). Table 1 summarizes the bias and that both the bias and CV needed to be DEVICES IN PREGNANCY: clinical accuracy observed for each glu- ,1% or ,2% to ensure a rate of insulin dos- EVIDENCE FROM RECENT STUDIES cose meter. Our review of the studies age error ,5%. Because pregnancy demands We conducted an electronic search of during pregnancy showed that the accu- such tight glycemic control and pregnant four databases (PubMed, CINAHL, Em- racy of the glucose meters varied, with women have a lower glucose threshold for base, and Scopus) from January 2007 to the majority showing positive bias and a insulin therapy initiation than the nonpreg- April 2017 to identify studies that eval- few showing minimal negative bias. The nant population, the performance goal of uated the technical performance of glu- mean difference varied between 20.33 glucose meters during pregnancy should cose meters during pregnancy. The search and 0.73 mmol/L. The three glucose be to attain the lowest error possible to was performed using key words includ- meters evaluated using ISO criteria met prevent insulin dosage errors. ing “blood glucose meter,”“glucometer,” the ISO 15197:2003 recommended tar- “self-monitoring of blood glucose,”“blood gets. We did not identify any studies that Hematocrit Influence glucose monitoring,”“accuracy,”“precision,” evaluated the recent ISO 15197:2013 In addition to the technical capabilities “performance,”“evaluation,”“gestational criteria or any glucose meters with a of meters outside of pregnancy as well diabetes,”“antenatal,” and “pregnancy.” A total analytical error ,5%. The Roche as the tighter glycemic targets required manual search was also performed using the Accu-Chek Active glucose meter ex- within pregnancy, hemodilution lowers reference lists of the articles obtained from hibited the lowest mean bias and thus the hematocrit level, which can influence the search. Any studies that assessed the demonstrated the best analytical accu- the accuracy of glucose meter measure- accuracy of glucose meters against labora- racy. With the exception of one study ments. Blood glucose meters have been tory plasma measurements as a reference or (14), most glucose meters had a large shown to overestimate the glucose concen- comparative values during pregnancy were proportion (.98–99%) of the meter val- tration when the hematocrit level is low, eligible for inclusion regardless of the type ues in zones A and B of the error grid leading to positive bias (18). Currently, of device or diabetes (type 1 diabetes, type analysis, which led to clinically appropri- 26 different companies have marketed 2 diabetes, or GDM). Studies that assessed ate treatment. Three devices (Optium, more than 90 glucose meter devices in the accuracy of glucose meters for any clin- Optium Xceed 20s, and Optium Xceed the U.S. These meters differ in glucose ical outcome during pregnancy, including 5s) showed a discrepancy from the refer- measurement technology and sensitivity the screening, diagnosis, or treatment of ence values with a change in the mater- to hematocrit changes. Table 2 summarizes hyperglycemia, were also eligible for inclu- nal hematocrit level that rendered them the assay and hematocrit specification of sion. Studies that were published prior to unsuitable for use during pregnancy. each glucose meter device. Evidence has 2007 were excluded due to the progres- One study (12) reported that only one- shown that meters using coulometric and sive improvements in technology. Animal third of the meter values were within 5% colorimetric techniques are less sensitive to Immanuel and Simmons 2055 Table 1—Bias and clinical accuracy of blood glucose meters in pregnant women with diabetes Values affected by ISO Values Values Values that Mean Mean total hematocrit 15197:2003 within within met clinical Author, difference 95% limits of Mean analytical changes criteria met 5% error 10% error accuracy year (ref.) Devices (mmol/L) agreement bias (%) Imprecision CV (%) error (%) (yes/no) (yes/no) (%) (%) criteria (%) Dhatt et al., Accu-Chek d 20.2 2.9% (at 3.2 mmol/L), dd Yes dd100 2011 (11) Active 1.8% at (9.0 mmol/L) Kong et al., Elite 20.30 21.46 to 0.87 dd dNo d 28.6 58.0 99.8 2010 (12) Accu-Chek 0.14 20.99 to 1.26 dd dNo d 43.4 73.8 99.0 Advantage II CareSens 0.03 21.15 to 1.22 dd dNo d 36.6 66.0 99.3 Optium 0.17 21.08 to 1.43 dd dYes d 35.6 63.7 98.1 Parwaiz FreeStyle 20.33 21.22 to 0.57 d 4.6 d No Yes dd100 et al., Lite* 2014 (13) Accu-Chek 20.02 20.91 to 0.86 d 3.1 d No Yes dd100 Performa Perera et al., Accu-Chek 0.36 20.75 to 1.47 8.99 d 14.87 No ddd,50 2011 (14) Advantage II Optium 0.57 20.75 to 1.89 13.08 d 26.21 Yes ddd,50 Xceed 20s Accu-Chek 0.38 20.76 to 1.53 9.04 d 15.65 No ddd,50 Performa Optium 0.73 20.52 to 1.97 15.76 d 32.14 Yes ddd,50 Xceed 5s FreeStyle 0.23 21.16 to 1.62 6.37 d 17.07 No ddd,50 Lite* StatStrip* 0.26 20.82 to 1.33 6.10 d 12.29 No ddd,50 Bias was described as mean difference (95% CI). Mean difference = mean of the meters 2 plasma glucose. Mean percentage bias = ([meter value 2 reference value]/reference value) 3 100. Mean total analytical error = % bias + 1.96 CV. The table also shows meters that met the ISO 15197:2003 criteria (95% of the meter values should be within 0.83 mmol/L [15 mg/dL] of the reference values at blood glucose levels #4.2 mmol/L [75 mg/dL] and within 20% for blood glucose levels .4.2 mmol/L [75 mg/dL]). Clinical accuracy criteria as per the ISO 15197:2013 recommendations: 99% of the meter results should be within zones A and B of the consensus error grid, leading to clinically appropriate treatment. The empty cells denote data not reported. *Meter currently available for use in the U.S. care.diabetesjournals.org 2056 Glucose Meter Accuracy Diabetes Care Volume 41, October 2018

Table 2—List of glucose meter devices with hematocrit specification and assay method Hematocrit range (%) Glucose meter device (manufacturer) 20–60 AgaMatrix Presto,* AgaMatrix Premium,*§§ Jazz Wireless 2* (AgaMatrix); GLUCOCARD Shine,† GLUCOCARD Shine XL,† ReliOn Premier VOICE† (ARKRAY); Dario Smart Glucose Meter‡ (DarioHealth); Advocate Redi-Code+ Speaking,‡ Advocate Redi-Code+ Non-Speaking‡ (Diabetic Supply of Suncoast); MyGlucoHealth Wireless‡ (Entra Health); FIFTY 50 Glucose Meter 2.0† (FIFTY 50 Medical); FORA Premium V10 and FORA Premium V10 BLE,‡ FORA V30a,† FORA Premium V12,† FORA D40d and D40g 2-in-1,‡ FORA MD† (ForaCare); CareSens N,‡ CareSens N POP,‡ CareSens N Voice‡ (i-SENS); OneTouch Verio IQ,‡§§ OneTouch Verio,‡§§ OneTouch Verio Flex‡ (LifeScan); EasyMax NG,† EasyMax LTC,† FortisCare MU,† FortisCare V3† (Oak Tree Health); EmbracePRO† (Omnis Health); One Drop Chrome§ (One Drop); Prodigy Connect,‡ Prodigy AutoCode,‡ Prodigy Voice,‡ Prodigy Pocket† (Prodigy); Clever Choice Voice HD,‡ Clever Choice HD,‡ Clever Choice Pro+‡ (Simple Diagnostics); Infinity‡ (US Diagnostics) 30–55 On Call Express,‡ On Call Plus,‡|| On Call Pro‡ (ACON Laboratories); GLUCOCARD 01,‡ GLUCOCARD Expression| (ARKRAY); OneTouch UltraMini,¶ OneTouch Ultra 2,¶|| OneTouch Ping† (LifeScan); EasyMax EMV,† EasyMax EMV2,† FortisCare T1| (Oak Tree Health); Embrace,† EmbraceEVO† (Omnis Health); Telcare‡ (Telcare); TRUEtrack‡ (Trividia Health, formerly Nipro Diagnostics); EasyGluco‡ (US Diagnostics) 15–65 FreeStyle Freedom Lite,#|| FreeStyle Lite,# FreeStyle Precision Neo‡ (Abbott Diabetes Care); ReliOn Premier BLU† (ARKRAY); CONTOUR NEXT,‡ CONTOUR NEXT EZ,‡ CONTOUR NEXT LINK,‡ CONTOUR NEXT LINK 2.4,‡ CONTOUR NEXT ONE‡ (Ascensia Diabetes Care); VeraSens| (US Diagnostics) 20–70 On Call Vivid,†† On Call Vivid Pal†† (ACON Laboratories); Livongo InTouch† (Livongo); TRUE METRIX AIR,‡‡ TRUE METRIX GO,‡‡ TRUE METRIX‡‡ (Trividia Health, formerly Nipro Diagnostics) 10–65 Accu-Chek Aviva,**|| Accu-Chek Aviva Nano,‡|| Accu-Chek Guide‡ (Roche Diagnostics) 33–52 GLUCOCARD Vital,‡ ReliOn Prime† (ARKRAY) 30–54 ReliOn Confirm,‡ ReliOn Micro‡ (ARKRAY) 30–60 GE100,‡ Rightest GM550‡ (Bionime) 25–60 Nova Max Plus,‡§§ Nova Max Link‡§§ (Nova Biomedical); TRUE FOCUS‡ (Trividia Health, formerly Nipro Diagnostics) 25–55 FortisCare EM66† (Oak Tree Health) NA MyGlucoHealth Cellular,| BLE Smart Wireless System| (Entra Health); FIFTY 50 Glucose Meter 2.0 Sport| (FIFTY 50 Medical); FORA TN’G,† FORA TN’G VOICE,† FORA GD50,† Fora Gold Advance Plus| (ForaCare); GHT Blood Glucose Meter‡ (Genesis Health Technologies); iHealth Smart Wireless Glucose Monitoring,‡ iHealth Align‡ (iHealth Labs); 2-in-1 Glucose and Blood Pressure Monitor| (Simple Diagnostics) Information obtained from company websites, user guides, communication with customer service departments, and Internet searches. NA, not available (information could not be obtained via the above means). Assay methods: *WaveSense Dynamic electrochemistry, †unspecified electrochemistry, ‡amperometry, §dynamic electrochemistry, |NA, ¶colorimetry, #coulometry, **electrical biamperometry, ††amperometry with hematocrit autocorrection, and ‡‡amperometry with TRIPLE SENSE TECHNOLOGY. §§Meter that showed stability in hematocrit evaluation studies (20,21,22). ||Meter that failed hematocrit evaluation (20,21,22).

hematocrit changes than those using the the manufacturer-recommended hemat- during early pregnancy. Strict metabolic amperometric technique (19). While most ocrit levels (as seen in the study by Kong control via accurate SMBG data is vital to glucose meters (.50%) show hematocrit et al. [12]). Therefore, use of glucose improve outcomes among pregnancies dependence in evaluation studies, meters meters with on-strip hematocrit compen- complicated by type 2 diabetes because that use an additional electrode for hemat- sation should be encouraged during preg- of the high risk of serious adverse peri- ocrit measurement (Nova Biomedical) and nancy. Currently, it is not routine practice natal outcomes. In addition, the glycemic for clinicians to consider a low hematocrit thresholds used for the diagnosis and those that use dynamic electrochemistry when deciding on the next change in management of any hyperglycemia in (Sanofi, AgaMatrix) are unaffected by pharmacotherapy; perhaps we should? pregnancy are lower than those used – hematocrit changes (20 22). Addition- outside of pregnancy. Therefore, meters ally, certain meters (On Call Vivid and Why Pregnancy May Be Different with good accuracy profilesforlowergly- On Call Vivid Pal [ACON Laboratories]), Insulin dosage errors, leading to greater cemic ranges should be the ideal choice TRUE METRIX [Trividia Health, formerly chances of hyperglycemia or hypoglyce- for use during pregnancy. Nipro Diagnostics], and Accu-Chek Aviva mia, can detrimentally affect a fetus, [Roche Diagnostics]) have been reported whereas maternal underrecognition of to have special technologies that auto- hypoglycemia can lead to reduced hypo- CLINICAL USE OF CGMS DURING correct for hematocrit interference. When glycemia awareness. Pregnant women PREGNANCY choosing a glucose meter for use during with type 1 diabetes exhibit frequent CGMS appear to be a better option for pregnancy, users are expected to follow fluctuations in their glycemic profiles monitoring glucose if cost and technical the manufacturer’s instructions regarding and variation in their insulin require- issues (e.g., wearability and accuracy) are the recommended hematocrit ranges and ments throughout pregnancy. Therefore, addressed. CGMS use in the nonpregnant to limit the use of meters only to women additional caution should be taken when population has been shown to improve who meet the specified ranges. Bias has titrating an insulin dosage for these glycemic control (23). Studies in pregnant been reported in glucose meters even women based on SMBG results to pre- women show benefits from CGMS for after use among women who are within vent hypoglycemic episodes, particularly tracking glucose fluctuations as well as care.diabetesjournals.org Immanuel and Simmons 2057

predicting and detecting asymptomatic interstitial fluid (37). Caution must there- women with type 1 diabetes, but further hypoglycemia and postprandial peaks, fore be exercised when implementing work is required; it remains uncertain whichotherwisemaygounnoticedwith treatment changes in response to CGMS whether the technical aspects and cost the use of SMBG alone (24–27). Studies also values. In addition, other issues, such as issues can be addressed sufficiently. Al- show a good correlation between CGMS skin site reaction, device discomfort, though the new flash glucose monitoring values and reference measurements dur- calibration, and other technical diffi- system showed good agreement between ing pregnancy (24,28) except when rapid culties, may influence user motivation SMBG among the pregnant population and changes in glycemia occur (28,29). Recent and compliance with CGMS use. In- was well received in Europe, no recom- evidence supports the use of CGMS as an deed, in the CONCEPTT study, the sensor mendations have been made in the U.S. for adjunct to SMBG for managing pregnant compliance was only 70%. In the other use among the pregnant population. women with type 1 diabetes. The CONCEPTT two randomized controlled trials, com- (Continuous Glucose Monitoring in Women pliance was 64% (31) and 80% (32); thus, With Type 1 Diabetes in Pregnancy Trial) such devices are not suitable for all multicenter randomized controlled trial women. The new technology in glucose Funding. J.I. is supported by a postgraduate research scholarship from Western Sydney Uni- (30) involving 215 pregnant women with monitoring (the FreeStyle Libre Flash versity. type1diabetesreportedimprovedneo- Glucose Monitoring system [Abbott Di- Duality of Interest. D.S. has a study for which natal outcomes with a small reduction abetes Care]), which does not require Roche Diagnostics has provided the Accu-Chek in HbA among those in the CGMS group. calibration and eliminates the need for Guide glucose meter at no cost and has been on 1c speakers’ bureaus for Roche Diagnostics and The incidence of large-for-gestational- SMBG, has been well received in Europe Medtronic. The Macarthur Diabetes Service re- age infants (odds ratio 0.51, 95% CI 0.28– (38). A recent study in the U.K. and ceives all meters (Accu-Chek Guide and Accu-Chek 0.90), neonatal intensive care admissions (38) that evaluated the perfor- Performa [in the past]) from Roche Diagnostics at lasting .24 h (0.48, 95% CI 0.26–0.86), mance and utility of the FreeStyle Libre no cost with start test strips. No other potential fl and neonatal hypoglycemia (0.45, 95% CI system reported good accuracy for preg- con icts of interest relevant to this article were reported. 0.22–0.89) were significantly lower with nant women with diabetes with a mean CGMS. CGMS use was associated with an absolute relative difference of 11.8%, and increased time in the target range and less 99.8% of the glucose values within zones A References time in hyperglycemia without any im- and B of the consensus error grid com- 1. American Diabetes Association. 13. Manage- provement in hypoglycemic events (30). pared with capillary blood glucose refer- ment of diabetes in pregnancy: Standards of d Previous smaller trials in pregnant women ence values but not laboratory plasma Medical Care in Diabetes 2018. Diabetes Care 2018;41(Suppl. 1):S137–S143 with type 1 and 2 diabetes have reported values. This technology recently obtained 2. Church D, Simmons D. More evidence of the fl con icting outcomes (31,32). Food and Drug Administration approval problemsofusingHbA1c fordiagnosingdiabetes? At present, there is insufficient evi- in the U.S. but has not yet been mar- The known knowns, the known unknowns and dence to support the use of CGMS among keted widely for use among the pregnant the unknown unknowns. J Intern Med 2014;276: – pregnant women with type 2 diabetes and population. 171 173 3. Wei N, Zheng H, Nathan DM. Empirically GDM. The number of study participants establishing blood glucose targets to achieve CONCLUSIONS with type 2 diabetes among existing stud- HbA1c goals. Diabetes Care 2014;37:1048–1051 ies (31,32) is small (total n =56).Moreover, Glucose monitoring with tight glucose 4. Nielsen LR, Ekbom P, Damm P, et al. HbA1c a number of small randomized controlled control is imperative for managing preg- levels are significantly lower in early and late pregnancy. Diabetes Care 2004;27:1200–1201 trials performed among GDM women nant women with hyperglycemia. Stud- 5. WeitgasserR, Gappmayer B, Pichler M. Newer have reported reduced gestational weight ies have shown that the performance of portable glucose meters–analytical improvement gain (33) and higher detection rates for glucose meters cannot be assumed to be compared with previous generation devices? Clin those who required medication therapy sufficiently accurate during pregnancy. Chem 1999;45:1821–1825 (34) but have found no improvement in Meters have no quality specification for 6. Klonoff DC, Prahalad P. Performance of cleared blood glucose monitors. J Diabetes Sci Technol glycemic control or pregnancy outcomes pregnancy. Efforts should be made to 2015;9:895–910 with CGMS use (33,35).Conversely, a cohort achieve the lowest deviation possible 7. Ginsberg BH. Factors affecting blood glucose study performed among 340 GDM women (i.e., a total error ,5% with an impre- monitoring: sources of errors in measurement. showed better pregnancy outcomes in the cision [CV] ,2%). In addition, the choice J Diabetes Sci Technol 2009;3:903–913 CGMS group (36). Regardless, large studies of a meter for use during pregnancy 8. Metzger BE, Gabbe SG, Persson B, et al.; International Association of Diabetes and Preg- are warranted to evaluate the usefulness should take into account the potential nancy Study Groups Consensus Panel. Interna- of CGMS among pregnant women with influence of hematocrit changes on the tional Association of Diabetes and Pregnancy type 2 diabetes and GDM. meter values. A meter that features Study Groups recommendations on the diagno- There are several limiting factors for automatic measurement and correction sis and classification of hyperglycemia in pre- – CGMS. A good correlation with blood for hematocrit changes is the preferred gnancy. Diabetes Care 2010;33:676 682 9. International Organization for Standardiza- glucose values does not mean that either choice for use during pregnancy. These tion. ISO 15197:2003: In vitro diagnostic test the accuracy or the precision is adequate. meters need to have higher accuracy systemsdrequirements for blood-glucose mon- This type of monitoring can misrepresent profiles for low glucose ranges; when itoring systems for self-testing in managing dia- the extent of the hyperglycemic peak and they do not, efforts must be taken to val- betes mellitus. Geneva, , International Organization for Standardization, 2003 the time period of hypoglycemia dur- idate their accuracy in pregnant women 10. International Organization for Standardiza- ing the recovery phase due to the delays prior to making them publicly available. tion. ISO 15197:2013: In vitro diagnostic test in reflecting glucose changes in the CGMS show promise especially in pregnant systemsdrequirements for blood-glucose 2058 Glucose Meter Accuracy Diabetes Care Volume 41, October 2018

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