Performance of Cleared Blood Glucose Monitors

Importance of FDA-Integrated Continuous Glucose Monitors to Ensure Accuracy of Continuous Glucose Monitoring

Continuous glucose monitoring (CGM) has been shown to improve glycemic control and self-monitoring, as well as to reduce the risk of hypoglycemia. Integrated CGM (iCGM) FDA-cleared systems with published performance data are established nonadjunctive and accurate CGM tools that can directly inform decision-making in the treatment of diabetes (i.e., insulin dosing). Studies have assessed accuracy and safety data of CGMs that were eventually cleared for iCGM by the FDA and that informed the recommendation for their nonadjunctive use. Subsequent robust clinical trials and real-world studies demonstrated clinical effectiveness with improvements in a range of patient outcomes. In recent years, a number of non-iCGM-approved CGM devices have entered the market outside the United States worldwide. Some of these non-iCGM-approved CGM devices require additional user verification of blood glucose levels to be performed for making treatment decisions, termed adjunctive. Moreover, in many non-iCGM-approved CGM devices, accuracy studies published in peer-reviewed journals are scarce or have many limitations. Consequently, non-iCGM-approved CGM devices cannot be automatically perceived as having the same performance or quality standards than those approved for iCGM by the FDA. As a result, although these devices tend to cost less than iCGMs that carry FDA clearance and could therefore be attractive from the point of view of a health care payer, it must be emphasized that evaluation of costs should not be limited to the device (such as the usability preference that patients have for nonadjunctive sensors compared to adjunctive sensors) but to the wider value of the total benefit that the product provides to the patient.

Post-Market Surveillance Assessment of the Clinical Accuracy of a Blood Glucose Monitoring System with an Improved Algorithm for Enhanced Product Performance

BACKGROUND

On-going manufacturer-led post-market surveillance (PMS), assessing the clinical accuracy of blood glucose monitoring (BGM) systems, is critical to substantiate the performance of such products for people with diabetes.

MATERIALS AND METHODS

Batches of Verio test-strip product were randomly and routinely selected over the period from launch of an improved-algorithm product to reporting date and sent to 3 clinic sites for clinician-led accuracy assessment. Accuracy is reported as per recently adopted FDA guidance for BGM systems, EN ISO 15197:2015 and MARD/MAD (Mean absolute relative difference/Mean absolute difference).

RESULTS

Thirty-three individual test-strip batches were evaluated corresponding to 506 unique donors. Accuracy performance - FDA: 98.9% of values within ±15% of comparator; ISO: 99.0% within ±15 mg/dL or ±15% at <100 mg/dL (<5.55 mmol/L) or ≥100 mg/dL (≥5.55 mmol/L) glucose, respectively. Overall MARD was 4.19% with a MARD range of 3.54%-5.73% across all test strip batches.

CONCLUSIONS

This post-market surveillance program demonstrates the new BGM system consistently meets measures of clinical accuracy specified by regulators. This program supports a growing demand by regulators for real-world evidence demonstrating consistent in-market product efficacy as opposed to the current largely passive approach that relies on assessment of reports filed by device users.

Comparison of point-of-care glucometers and laboratory based glucose oxidase test in determining blood glucose levels

INTRODUCTION

Alterations in blood glucose levels are common and an important determinant of a patient's admission outcomes, point-of-care glucometers, which are affected by a variety of factors, are increasingly used in clinical care. In this study we compared blood glucose levels determined by two commonly used glucometers (One Touch^® and Accu-check^®) with those of a standard laboratory method and determined the effect of haematocrit on glucose readings.

METHODS

Blood glucose levels were measured with One Touch^® and Accu-Check^® glucometers and the glucose oxidase method at the same time in 295 children aged 0 to 15 years over a 6-month period. Bland-Altman and correlation analysis were used to explore biases among the three methods. For all statistical tests, a p-value of less than 0.05 was considered statistically significant.

RESULTS

Most were males (51.2%) and the median (range) age was 1 year (1 day, 12 years). There was a significant correlation between each of the glucometer methods and laboratory blood sugar, and the correlation between the two glucometers was strong and significant. This correlation remained statistically significant even after controlling for haematocrit values. There was an acceptable level of bias (3.9 mg/dL) between the One Touch^® and Accu-check^® glucometers, but each had a remarkably large bias compared with the glucose oxidase method.

CONCLUSION

The use of a tested glucometer in clinical settings can aid in rapid decision-making, but there is a need to periodically cross-check with the glucose oxidase method in the laboratory to optimise treatment outcomes for children with dysglycaemia.

Automated Adaptation of Insulin Treatment in Type 1 Diabetes

Individuals with type 1 diabetes (T1D) need life-long insulin therapy to compensate for the lack of endogenous insulin due to the autoimmune damage to pancreatic beta-cells. Treatment is based on basal and bolus insulin, to cover fasting and postprandial periods, respectively, according to three insulin dosing parameters: basal rate (BR), carbohydrate-to-insulin ratio (CR), and correction factor (CF). Suboptimal BR, CR, and CF profiles leading to incorrect insulin dosing may be the cause of undesired glycemic events, which carry dangerous short-term and long-term effects. Therefore, correct tuning of these parameters is of the utmost importance. In this work, we propose a new algorithm to optimize insulin dosing parameters in individuals with T1D who use a continuous glucose monitor and an insulin pump. The algorithm was tested using the University of Virginia/Padova T1D Simulator and led to an improvement in the quality of glycemic control. Future efforts will be devoted to test the algorithm in human clinical trials.

Point-of-care microvolume cytometer measures platelet counts with high accuracy from capillary blood

Background

Point-of-care (PoC) testing of platelet count (PLT) provides real-time data for rapid decision making. The goal of this study is to evaluate the accuracy and precision of platelet counting using a new microvolume (8 μL), absolute counting, 1.5 kg cytometry-based blood analyzer, the rHEALTH ONE (rHEALTH) in comparison with the International Society of Laboratory Hematology (ISLH) platelet method, which uses a cytometer and an impedance analyzer.

Methods

Inclusion eligibility were healthy adults (M/F) ages 18–80 for donation of fingerprick and venous blood samples. Samples were from a random N = 31 volunteers from a single U.S. site. Samples were serially diluted to test thrombocytopenic ranges. Interfering substances and conditions were tested, including RBC fragments, platelet fragments, cholesterol, triglycerides, lipids, anti-platelet antibodies, and temperature.

Results

The concordance between the rHEALTH and ISLH methods had a slope = 1.030 and R² = 0.9684. The rHEALTH method showed a correlation between capillary and venous blood samples (slope = 0.9514 and R² = 0.9684). Certain interferents changed platelet recovery: RBC fragments and anti-platelet antibodies with the ISLH method; platelet fragments and anti-platelet antibodies on the rHEALTH; and RBC fragments, platelets fragments, triglycerides and LDL on the clinical impedance analyzer. The rHEALTH’s precision ranged from 3.1–8.0%, and the ISLH from 1.0–10.5%.

Conclusions

The rHEALTH method provides similar results with the reference method and good correlation between adult capillary and venous blood samples. This demonstrates the ability of the rHEALTH to provide point-of-care assessment of normal and thrombocytopenic platelet counts from fingerprick blood with high precision and limited interferences.

Evidence From a Long-Term, Systematic Post-Market Surveillance Program: Clinical Performance of a Hematocrit-Insensitive Blood Glucose Test Strip

BACKGROUND

Described is a manufacturer's systematic post-market evaluation of the long-term clinical accuracy of a commercially available blood glucose monitoring (BGM) test strip product.

METHODS

Production batches of test strips were routinely and regularly sampled and evaluated in a clinical setting to assess product accuracy. Evaluations were performed on capillary blood samples from a minimum of 100 subjects with diabetes, by clinical staff according to instructions for use. Readings were compared against capillary blood samples collected at the same time and measured by a standard laboratory reference method. Clinical accuracy was calculated according to EN ISO 15197:2015.

RESULTS

A total of 21 115 paired results were obtained, equating to 209 production batches over the >3-year period since test strip launch. Of the results, 97.6% met the accuracy criterion (range: 97.1-98.1% by year), with 98.1% of values presenting zero risk as defined by the surveillance error grid. At the <5th (21.0-33.8%) and >95th (48.3-59.4%) percentile extremes of hematocrit distribution, 97.9% and 96.4% of values were clinically accurate. The product also demonstrated clinical accuracy across all seven glucose ranges ("bins") as defined by the standard. Under conditions of combined hematocrit and glucose (<80 mg/dL and ≥300 mg/dL) extremes, 97.7% of values were clinically accurate.

CONCLUSIONS

Methodologies and results from a manufacturer's self-imposed clinical accuracy surveillance program of a BGM product is presented. Given the publication of sometimes-conflicting data presented within ad hoc BGM clinical accuracy evaluations, usually of limited size, it is advocated that BGM manufacturers adopt similarly robust and systematic surveillance programs to safeguard patients.

Suicide and Self-inflicted Injury in Diabetes: A Balancing Act

Glycemic control in type 1 diabetes mellitus (T1DM) remains a challenge for many, despite the availability of modern diabetes technology. While technologies have proven glycemic benefits and may reduce excess mortality in some populations, both mortality and complication rates remain significantly higher in T1DM than the general population. Diabetes technology can reduce some burdens of diabetes self-management, however, it may also increase anxiety, stress, and diabetes-related distress. Additional workload associated with diabetes technologies and the dominant focus on metabolic control may be at the expense of quality-of-life. Diabetes is associated with significantly increased risk of suicidal ideation, self-harm, and suicide. The risk increases for those with diabetes and comorbid mood disorder. For example, the prevalence of depression is significantly higher in people with diabetes than the general population, and thus, people with diabetes are at even higher risk of suicide. The Center for Disease Control and Prevention reported a 24% rise in US national suicide rates between 1999 and 2014, the highest in 30 years. In the United Kingdom, 6000 suicides occur annually. Rates of preventable self-injury mortality stand at 29.1 per 100 000 population. Individuals with diabetes have an increased risk of suicide, being three to four times more likely to attempt suicide than the general population. Furthermore, adolescents aged 15 to 19 are most likely to present at emergency departments for self-inflicted injuries (9.6 per 1000 visits), with accidents, alcohol-related injuries, and self-harm being the strongest risk factors for suicide, the second leading cause of death among 10 to 24 year olds. While we have developed tools to improve glycemic control, we must be cognizant that the psychological burden of chronic disease is a significant problem for this vulnerable population. It is crucial to determine the psychosocial and behavioral predictors to uptake and continued use of technology in order to aid the identification of those individuals most likely to realize benefits of any intervention as well as those individuals who may require more support to succeed with technology.

Choosing a Mobile Sensor Technology for a Clinical Trial: Statistical Considerations, Developments and Learnings

The DIA Study Endpoints Community Working Group on Mobile Sensor Technology (MST) series addresses considerations that may be useful for selecting MST for use in a clinical trial. This article describes considerations regarding the selection of MST for clinical trials including expectations around technology specifications, verification (bench testing), regulatory clearance and certification status. We identify useful statistical methods needed to establish agreement of the MST with respect to a clinical 'gold' standard technology in terms of accuracy and precision, and to combine data across trials, data types or device versions. In addition to describing key considerations, this manuscript also serves as a central location citing those resources where additional detail can be found.

The Use of a Smart Bolus Calculator Informed by Real-time Insulin Sensitivity Assessments Reduces Postprandial Hypoglycemia Following an Aerobic Exercise Session in Individuals With Type 1 Diabetes

OBJECTIVE

Insulin dosing in type 1 diabetes (T1D) is oftentimes complicated by fluctuating insulin requirements driven by metabolic and psychobehavioral factors impacting individuals' insulin sensitivity (IS). In this context, smart bolus calculators that automatically tailor prandial insulin dosing to the metabolic state of a person can improve glucose management in T1D.

RESEARCH DESIGN AND METHODS

Fifteen adults with T1D using continuous glucose monitors (CGMs) and insulin pumps completed two 24-h admissions in a hotel setting. During the admissions, participants engaged in an early afternoon 45-min aerobic exercise session, after which they received a standardized dinner meal. The dinner bolus was computed using a standard bolus calculator or smart bolus calculator informed by real-time IS estimates. Glucose control was assessed in the 4 h following dinner using CGMs and was compared between the two admissions.

RESULTS

The IS-informed bolus calculator allowed for a reduction in postprandial hypoglycemia as quantified by the low blood glucose index (2.02 vs. 3.31, P = 0.006) and percent time <70 mg/dL (8.48% vs. 15.18%, P = 0.049), without increasing hyperglycemia (high blood glucose index: 3.13 vs. 2.09, P = 0.075; percent time >180 mg/dL: 13.24% vs. 10.42%, P = 0.5; percent time >250 mg/dL: 2.08% vs. 1.19%, P = 0.317). In addition, the number of hypoglycemia rescue treatments was reduced from 12 to 7 with the use of the system.

CONCLUSIONS

The study shows that the proposed IS-informed bolus calculator is safe and feasible in adults with T1D, appropriately reducing postprandial hypoglycemia following an exercise-induced IS increase.

Continuous Glucose Monitors and Activity Trackers to Inform Insulin Dosing in Type 1 Diabetes: The University of Virginia Contribution

Objective: Suboptimal insulin dosing in type 1 diabetes (T1D) is frequently associated with time-varying insulin requirements driven by various psycho-behavioral and physiological factors influencing insulin sensitivity (IS). Among these, physical activity has been widely recognized as a trigger of altered IS both during and following the exercise effort, but limited indication is available for the management of structured and (even more) unstructured activity in T1D. In this work, we present two methods to inform insulin dosing with biosignals from wearable sensors to improve glycemic control in individuals with T1D. Research Design and Methods: Continuous glucose monitors (CGM) and activity trackers are leveraged by the methods. The first method uses CGM records to estimate IS in real time and adjust the insulin dose according to a person’s insulin needs; the second method uses step count data to inform the bolus calculation with the residual glucose-lowering effects of recently performed (structured or unstructured) physical activity. The methods were tested in silico within the University of Virginia/Padova T1D Simulator. A standard bolus calculator and the proposed “smart” systems were deployed in the control of one meal in presence of increased/decreased IS (Study 1) and following a 1-hour exercise bout (Study 2). Postprandial glycemic control was assessed in terms of time spent in different glycemic ranges and low/high blood glucose indices (LBGI/HBGI), and compared between the dosing strategies. Results: In Study 1, the CGM-informed system allowed to reduce exposure to hypoglycemia in presence of increased IS (percent time < 70 mg/dL: 6.1% versus 9.9%; LBGI: 1.9 versus 3.2) and exposure to hyperglycemia in presence of decreased IS (percent time > 180 mg/dL: 14.6% versus 18.3%; HBGI: 3.0 versus 3.9), tending toward optimal control. In Study 2, the step count-informed system allowed to reduce hypoglycemia (percent time < 70 mg/dL: 3.9% versus 13.4%; LBGI: 1.7 versus 3.2) at the cost of a minor increase in exposure to hyperglycemia (percent time > 180 mg/dL: 11.9% versus 7.5%; HBGI: 2.4 versus 1.5). Conclusions: We presented and validated in silico two methods for the smart dosing of prandial insulin in T1D. If seen within an ensemble, the two algorithms provide alternatives to individuals with T1D for improving insulin dosing accommodating a large variety of treatment options. Future work will be devoted to test the safety and efficacy of the methods in free-living conditions.

Closed-Loop Control with Unannounced Exercise for Adults with Type 1 Diabetes using the Ensemble Model Predictive Control

This paper presents an individualized Ensemble Model Predictive Control (EnMPC) algorithm for blood glucose (BG) stabilization and hypoglycemia prevention in people with type 1 diabetes (T1D) who exercise regularly. The EnMPC formulation can be regarded as a simplified multi-stage MPC allowing for the consideration of N _en scenarios gathered from the patient's recent behavior. The patient's physical activity behavior is characterized by an exercise-specific input signal derived from the deconvolution of the patient's continuous glucose monitor (CGM), accounting for known inputs such as meal, and insulin pump records. The EnMPC controller was tested in a cohort of in silico patients with representative inter-subject and intra-subject variability from the FDA-accepted UVA/Padova simulation platform. Results show a significant improvement on hypoglycemia prevention after 30 min of mild to moderate exercise in comparison to a similarly tuned baseline controller (rMPC); with a reduction in hypoglycemia occurrences (< 70 mg/dL), from 3.08% ± 3.55 with rMPC to 0.78% ± 2.04 with EnMPC (P < 0.05).

Laboratory Evaluation of Linearity, Repeatability, and Hematocrit Interference With an Internet-Enabled Blood Glucose Meter

BACKGROUND

In recent clinical trials, use of the MyGlucoHealth blood glucose meter (BGM) and electronic diary was associated with an unusual reporting pattern of glycemic data and hypoglycemic events. Therefore, the performance of representative BGMs used by the patients was investigated to assess repeatability, linearity, and hematocrit interference in accordance with regulatory guidelines.

METHOD

Ten devices and 6 strip lots were selected using standard randomization and repeatability procedures. Venous heparinized blood was drawn from healthy subjects, immediately aliquoted and adjusted to 5 target blood glucose (BG) ranges for the repeatability and 11 BG concentrations for the linearity tests. For the hematocrit interference test, each sample within 5 target BG ranges was split into 5 aliquots and adjusted to hematocrit levels across the acceptance range. YSI 2300 STAT Plus was used as the laboratory reference method in all experiments.

RESULTS

Measurement repeatability or precision was acceptable across the target BG ranges for all devices and strip lots with coefficient of variation (CV) between 3.4-9.7% (mean: 5.7%). Linearity was shown by a correlation coefficient of .991; however, a positive bias was seen for BG <100 mg/dL (86% measurements did not meet ISO15197:2015 acceptance criteria). Significant hematocrit interference (up to 20%) was observed for BG >100 mg/dL (ISO15197:2015 acceptance criteria: ±10%), while the results were acceptable for BG <100 mg/dL.

CONCLUSIONS

The BGM met repeatability requirements but demonstrated a significant measurement bias in the low BG range. In addition, it failed the ISO15197:2015 criteria for hematocrit interference.

Efficacy and Safety of Degludec Compared to Glargine 300 Units/mL in Insulin-Experienced Patients With Type 2 Diabetes: Trial Protocol Amendment (NCT03078478)

BACKGROUND

A head-to-head trial (NCT03078478) between insulin degludec and insulin glargine U300 with the primary objective of comparing the risk of hypoglycemia is being conducted. During trial conduct, safety concerns related to the glycemic data collection system led to a postinitiation protocol amendment, described here.

METHODS

This randomized (1:1), open-label, treat-to-target, multinational trial was initiated in March 2017 with a planned treatment period of 52 weeks (16 weeks titration + 36 weeks maintenance). Overall, ~1600 insulin-experienced patients at risk of developing hypoglycemia based on predefined risk factors were included. The protocol amendment implemented in February 2018 resulted in assuring patient safety and an extension of the total treatment period up to 88 weeks (16 weeks titration + variable maintenance 1 + 36 weeks maintenance 2). The original glycemic data collection system (MyGlucoHealth blood glucose meter + electronic diary) was discontinued because of safety concerns and replaced with an Abbott blood glucose meter and paper diary to collect self-measured blood glucose and hypoglycemic episodes. The primary endpoint of number of severe or blood-glucose confirmed symptomatic hypoglycemic episodes will be evaluated with the same analysis duration and statistical methods as the original protocol. Only relevant changes were implemented to maintain patient safety while permitting evaluation of the scientific objectives of the trial.

CONCLUSIONS

These observations highlight the importance of safety surveillance during trial conduct despite the use of currently marketed glucose monitoring devices. The prompt protocol amendment and ensuing actions ensured that the scientific integrity of the trial was not compromised.

System Accuracy Assessment of a Blood Glucose Meter With Wireless Internet Access Associated With Unusual Hypoglycemia Patterns in Clinical Trials

BACKGROUND

In recent randomized clinical trials, an unusual reporting pattern of glycemic data and hypoglycemic events potentially related to an internet enabled blood glucose meter (MyGlucoHealth, BGM) was observed. Therefore, this clinical study was conducted to evaluate the system accuracy of the BGM in accordance with the ISO15197:2015 guidelines with additional data collection.

METHODS

To investigate system accuracy, 10 of 3088 devices and 6 of 23 strip lots, used in the trials, were selected by a randomization procedure and a standard repeatability assessment. YSI 2300 STAT Plus was used as the standard reference method. The samples were distributed as per the ISO15197:2015 recommendations with 20 additional samples in the hypoglycemic range. Each sample was tested with 6 devices and 6 strip lots with double determinations.

RESULTS

Overall, 121 subjects with blood glucose values 26-423 mg/dL were analyzed, resulting in 1452 data points. In all, 186/1452 readings (12.8%) did not meet the ISO acceptance criteria. Data evaluated according to the FDA guidelines showed that 336/1452 (23.1%) readings did not meet the acceptance criteria. A clear bias toward elevated values was observed for BG <100 mg/dL (MARD: 11.0%).

CONCLUSIONS

The results show that the BGM, although approved according to standard regulatory guidelines, did not meet the level of analytical accuracy required for clinical treatment decisions according to ISO 15197:2015 and FDA requirements. In general, caution should be exercised before selection of BGMs for patients and in clinical trials.

Blood glucose meters and test strips: global market and challenges to access in low-resource settings

Blood glucose meters and test strips for self-monitoring of blood glucose (SMBG) are often inaccessible to, and infrequently used by, people with diabetes in countries with limited resources for health care. Supplies for measuring blood glucose can also be scarce in health facilities, despite being needed in a myriad of clinical settings at all levels of the health system. Numerous studies and international guidelines emphasise the value of SMBG in diabetes care, particularly in people with type 1 diabetes. In this Review, we assess global access to blood glucose meters and test strips, collating published information on cost, availability, system accuracy, competitive bidding, technological trends, and non-financial barriers. We also provide new information on global market share data and prices, taxes and tariffs, and product availability. Blood glucose meters and test strips should be viewed similarly to essential medicines, with issues of access prioritised by relevant international agencies. Efforts are needed to reduce tariffs and taxes and to create unified global system accuracy requirements and accountable post-marketing evaluations. Preferential pricing arrangements, pooled procurement, and best-purchasing practices could help to lower direct costs. SMBG supplies should also be included in national health insurance schemes. Enhanced diabetes education of health professionals and patients is crucial to ensure effective use of SMBG. Finally, as technology advances for people who can afford new interstitial fluid glucose monitoring systems, blood glucose meters and test strips must remain available and become more affordable in low-resource settings.

A Review of Blood Glucose Monitor Accuracy

The aim of this study was to assess the accuracy of blood glucose monitors (BGMs) from studies reported in the medical literature. A literature review was performed of publications between 2010 and 2017 that presented data about the accuracy of BGMs using ISO 15197 2003 and/or ISO 15197 2013 as target standards. We found 58 publications describing the performance of 143 unique BGM systems, 59 of which were Food and Drug Administration (FDA) cleared. When compared with non-FDA-cleared BGMs, FDA-cleared BGMs were significantly more likely to pass both ISO 15197 2003 (OR = 2.39, CI 1.45-3.92, P < 0.01) and ISO 15197 2013 standards (OR = 2.20, CI 1.51-3.27, P < 0.01). Newer meters were more likely to pass both ISO 15197 2003 and ISO 15197 2013 standards. Many of the studies were supported by BGM manufacturers, and when compared with independent studies, an FDA-cleared BGM was significantly more likely to pass in a manufacturer-supported study for both ISO 15197 2003 (OR = 22.4, CI 8.73-21.57, P < 0.001) and ISO 15197 2013 (OR = 23.08, CI 10.16-60.03, P < 0.001). BGM accuracy should be assessed independently following regulatory clearance to ensure accurate performance. Failure to meet performance levels mandated by standards can result in deleterious clinical and economic effects.

Diabetes Technological Revolution: Winners and Losers?

Over recent years there has been an explosion in availability of technical devices to support diabetes self-management. But with this technology revolution comes new hurdles. On paper, the available diabetes technologies should mean that the vast majority of people with type 1 diabetes have optimal glycemic control and are using their preferred therapy choices. Yet, it does not appear to be universally the case. In parallel, suboptimal glycemic control remains stubbornly widespread. Barriers to improvement include access to technology, access to expert diabetes health care professionals, and prohibitive insurance costs. Until access can be improved to ensure the technologies are available and usable by those that need them, there are many people with diabetes who are still losing out.

A Perspective on the Accuracy of Blood Glucose Meters During Pregnancy

Blood glucose monitoring is fundamental for hyperglycemia 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 although >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 majority showing positive bias and a few showing minimal negative bias. The mean difference between meter and laboratory plasma values varied between -0.33 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 Standardization 15197:2013 criteria. The Continuous Glucose Monitoring in Women With Type 1 Diabetes in Pregnancy Trial (CONCEPTT) recently showed that an antenatal continuous glucose monitoring system (CGMS), as an adjunct to capillary 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 hypoglycemia. The flash glucose monitoring system shows good accuracy 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 imprecision <2% during pregnancy. Large studies are needed to evaluate the usefulness of CGMS among pregnant women with type 2 diabetes and gestational diabetes mellitus.

Continuous Glucose Monitoring and Insulin Informed Advisory System with Automated Titration and Dosing of Insulin Reduces Glucose Variability in Type 1 Diabetes Mellitus

BACKGROUND

Glucose variability (GV) remains a key limiting factor in the success of diabetes management. While new technologies, for example, accurate continuous glucose monitoring (CGM) and connected insulin delivery devices, are now available, current treatment standards fail to leverage the wealth of information generated. Expert systems, from automated insulin delivery to advisory systems, are a key missing element to richer, more personalized, glucose management in diabetes.

METHODS

Twenty four subjects with type 1 diabetes mellitus (T1DM), 15 women, 37 ± 11 years of age, hemoglobin A1c 7.2% ± 1%, total daily insulin (TDI) 46.7 ± 22.3 U, using either an insulin pump or multiple daily injections with carbohydrate counting, completed two randomized crossover 48-h visits at the University of Virginia, wearing Dexcom G4 CGM, and using either usual care or the UVA decision support system (DSS). DSS consisted of a combination of automated insulin titration, bolus calculation, and CHO treatment advice. During each admission, participants were exposed to a variety of meal sizes and contents and two 45-min bouts of exercise. GV and glucose control were assessed using CGM.

RESULTS

The use of DSS significantly reduced GV (coefficient of variation: 0.36 ± 08. vs. 0.33 ± 0.06, P = 0.045) while maintaining glycemic control (average CGM: 155.2 ± 27.1 mg/dL vs. 155.2 ± 23.2 mg/dL), by reducing hypoglycemia exposure (%<70 mg/dL: 3.8% ± 4.6% vs. 1.8% ± 2%, P = 0.018), with nonsignificant trends toward reduction of significant hyperglycemia overnight (%>250 mg/dL: 5.3% ± 9.5% vs. 1.9% ± 4.6%) and at mealtime (11.3% ± 14.8% vs. 5.8% ± 9.1%).

CONCLUSIONS

A CGM/insulin informed advisory system proved to be safe and feasible in a cohort of 24 T1DM subjects. Use of the system may result in reduced GV and improved protection against hypoglycemia.

Investigation of the Accuracy of 18 Marketed Blood Glucose Monitors

OBJECTIVE

Cleared blood glucose monitors (BGMs) for personal use may not always deliver levels of accuracy currently specified by international and U.S. regulatory bodies. This study's objective was to assess the accuracy of 18 such systems cleared by the U.S. Food and Drug Administration representing approximately 90% of commercially available systems used from 2013 to 2015.

RESEARCH DESIGN AND METHODS

A total of 1,035 subjects were recruited to have a capillary blood glucose (BG) level measured on six different systems and a reference capillary sample prepared for plasma testing at a reference laboratory. Products were obtained from consumer outlets and tested in three triple-blinded studies. Each of the three participating clinical sites tested a different set of six systems for each of the three studies in a round-robin. In each study, on average, a BGM was tested on 115 subjects. A compliant BG result was defined as within 15% of a reference plasma value (for BG ≥100 mg/dL [5.55 mmol/L]) or within 15 mg/dL (0.83 mmol/L) (for BG <100 mg/dL [5.55 mmol/L]). The proportion of compliant readings in each study was compared against a predetermined accuracy standard similar to, but more lenient than, current regulatory standards. Other metrics of accuracy included the overall compliance proportion; the proportion of extreme outlier readings differing from the reference value by >20%; modified Bland-Altman analysis including average bias, coefficient of variation, and 95% limits of agreement; and proportion of readings with no clinical risk as determined by the Surveillance Error Grid.

RESULTS

The different accuracy metrics produced almost identical BGM rankings. Six of the 18 systems met the predetermined accuracy standard in all three studies, 5 systems met it in two studies, and 3 met it in one study. Four BGMs did not meet the accuracy standard in any of the three studies.

CONCLUSIONS

Cleared BGMs do not always meet the level of analytical accuracy currently required for regulatory clearance. This information could assist patients, professionals, and payers in choosing products and regulators in evaluating postclearance performance.

'Knowing where I am': self-monitoring of blood glucose in diabetes

Although the prevalence of all types of chronic conditions is increasing, diabetes is one of the few long-term metabolic disorders that individuals can successfully manage, monitor and control on a day-to-day basis. Self-monitoring of blood glucose (SMBG) is considered an essential component of diabetes self-care management. When used appropriately, SMBG can help to identify factors associated with hyper- and hypoglycaemia, facilitate learning, and empower people with diabetes to make changes to improve their glycaemic control. SMBG can be a useful tool for healthcare providers, who can teach individuals to monitor glucose at specific times to assess the effectiveness of medications and guide medication management. However, there is an ongoing debate regarding whether, as is the case with type 1 diabetes, all people with type 2 diabetes should also be given the opportunity to learn about the value of, and skills required to, monitor blood glucose as appropriate to their specific needs.

Accuracy Beyond ISO: Introducing a New Method for Distinguishing Differences Between Blood Glucose Monitoring Systems Meeting ISO 15197:2013 Accuracy Requirements

BACKGROUND

Diabetes treatment is intended to maintain near-normal glycemic levels. Self-monitoring of blood glucose (SMBG) allows patients to track their BG levels compared with glycemic targets and is associated with improved health outcomes. Because of the importance of SMBG, it is essential that results are accurate to prevent errors in nutritional intake and drug dosing. This study presents a new methodology to evaluate the accuracy of BG monitoring systems (BGMSs).

METHODS

Sensitivity analyses were performed using real and simulated BGMS data to compute probabilities that, for any BG value, the BGMS result would be within prescribed error bounds and confidence limits compared with laboratory reference values. Multiple BG value ranges were used.

RESULTS

Probability curves were created using data from 3 simulated BGMSs and anonymized data from 3 real-world BGMSs. Accuracy probability curves from capillary fingertip blood samples (actual clinical data) showed that all 3 real-world BGMSs met EN ISO 15197:2015 accuracy criteria, since 99.63%, 99.63%, and 99.81% of results from the 3 BGMSs were within ±15 mg/dL or ±15% of reference for BG <100 mg/dL and ≥100 mg/dL, respectively. However, there was identifiable variability between BGMSs if BG was <70 mg/dL; one BGMS showed further reductions in accuracy if BG was <50 mg/dL.

CONCLUSIONS

Probability curves highlight the importance of BGMS accuracy to help achieve optimal glycemic control while avoiding hypoglycemia or hyperglycemia. This may be especially significant in very low BG ranges where small errors in BGMS measurements can have substantial impacts on patient-related outcomes, including hypoglycemia risk.

The Financial Impact of Inaccurate Blood Glucose Monitoring Systems

OBJECTIVE

An in silico study of type 1 diabetes (T1DM) patients utilized the UVA-PADOVA Type 1 Diabetes Simulator to assess the effect of patient blood glucose monitoring (BGM) system accuracy on clinical outcomes. We applied these findings to assess the financial impact of BGM system inaccuracy.

METHODS

The study included 43 BGM systems previously assessed for accuracy according to ISO 15197:2003 and ISO 15197:2013 criteria. Glycemic responses for the 100 in silico adult T1DM subjects were generated, using each meter. Changes in estimated HbA1c, severe hypoglycemic events, and health care resource utilization were computed for each simulation. The HbA1c Translator modeling approach was used to calculate the financial impact of these changes.

RESULTS

The average cost of inaccuracy associated with the entire group of BGM systems was £155 per patient year (PPY). The average additional cost of BGM systems not meeting the ISO 15197:2003 standard was an estimated £178 PPY more than an average system that fulfills the standard and an estimated £235 PPY more than an average system that appears to meet the ISO 15197:2013 standard.

CONCLUSION

There is a clear relationship between BGM system accuracy and cost, with the highest costs being associated with BGM systems not meeting the ISO 15197:2003 standard. Lower costs are associated with systems meeting the ISO 15197:2013 system accuracy criteria. Using BGM systems that meet the system accuracy criteria of the ISO 15197:2013 standard can help reduce the clinical and financial consequences associated with inaccuracy of BGM devices.

Why the Diabetes Technology Society Surveillance Protocol for Glucose Meters Needs to Be Revised

The Diabetes Technology Society surveillance protocol provides a seal of approval for a glucose meter if a sufficient number of a candidate glucose meter's results meet ISO 15197:2013 limits. The protocol provides clear details about how to conduct this study and analyze the data but has two flaws. There is no specification about the size of glucose meter errors that are outside of ISO limits. A meter that has a result in the E zone of a glucose meter error grid could receive the DTS seal of approval. In addition, the protocol uses the ISO standard, which could be considered a "state of the art" standard instead of an error grid, which is a clinical standard. Remedies for these problems are to replace the ISO standard with an error grid and to include requirements for errors found in C or higher zones of an error grid.

Do the New FDA Guidance Documents Help Improving Performance of Blood Glucose Monitoring Systems Compared With ISO 15197?

Recently, the Food and Drug Administration (FDA) published guidance documents for point-of-care testing (POCT) and over-the-counter (OTC) blood glucose monitoring systems (BGMS). These are expected to improve weaknesses of the already established ISO 15197:2013 standard accuracy evaluation for OTC BGMS; however, the proposed criteria and procedures rather raise new questions. As an example, the OTC guidance stipulates tighter accuracy criteria in the low glycemic range than the POCT guidance for no obvious reason. Furthermore, a clear definition of requirements for the reference method is missing under consideration of the strict accuracy criteria. External surveillance of BGMS after introduction to the market is an issue that is addressed neither in the FDA documents, nor in ISO 15197, but in the Clinical and Laboratory Standards Institute (CLSI) guideline POCT12-A3.

Analysis of "Seven Year Surveillance of the Clinical Performance of a Blood Glucose Test-Strip Product"

The article titled "Seven Year Surveillance of the Clinical Performance of a Blood Glucose Test-Strip Product" by Setford and coworkers in this issue of Journal of Diabetes Science and Technology is an impressive study showing that over 7 years in three clinics, using multiple reagent lots, a total of 73 600 samples met the ISO 15197 2015 standard with no results in the D or E zones of a Parkes glucose meter error grid. Three requirements are suggested for a clinically acceptable glucose meter. The authors provide strong evidence for meeting two requirements but fail to provide summarized data about the number of nonnumeric results. Finally, the authors overstate some results, called "spin" by some which is not necessary. The superb results should stand on their own.

Evaluation of Accuracy of Six Blood Glucose Monitoring Systems and Modeling of Possibly Related Insulin Dosing Errors

OBJECTIVE

Self-monitoring of blood glucose (BG) is an essential part of diabetes therapy. Accurate and reliable results from BG monitoring systems (BGMS) are important especially when they are used to calculate insulin doses. This study aimed at assessing system accuracy of BGMS and possibly related insulin dosing errors.

RESEARCH DESIGN AND METHODS

System accuracy of six different BGMS (Accu-Chek^® Aviva Nano, Accu-Chek Mobile, Accu-Chek Performa Nano, CONTOUR^® NEXT LINK 2.4, FreeStyle Lite, OneTouch^® Verio^® IQ) was assessed in comparison to a glucose oxidase and a hexokinase method. Study procedures and analysis were based on ISO 15197:2013/EN ISO 15197:2015, clause 6.3. In addition, insulin dosing error was modeled.

RESULTS

In the comparison against the glucose oxidase method, five out of six BGMS fulfilled ISO 15197:2013 accuracy criteria. Up to 14.3%/4.3%/0.3% of modeled doses resulted in errors exceeding ±0.5/±1.0/±1.5 U and missing the modeled target by 20 mg/dL/40 mg/dL/60 mg/dL, respectively. Compared against the hexokinase method, five out of six BGMS fulfilled ISO 15197:2013 accuracy criteria. Up to 25.0%/10.5%/3.2% of modeled doses resulted in errors exceeding ±0.5/±1.0/±1.5 U, respectively.

CONCLUSIONS

Differences in system accuracy were found, even among BGMS that fulfilled the minimum system accuracy criteria of ISO 15197:2013. In the error model, considerable insulin dosing errors resulted for some of the investigated systems. Diabetes patients on insulin therapy should be able to rely on their BGMS' readings; therefore, they require highly accurate BGMS, in particular, when making therapeutic decisions.

Demonstration of disinfection procedure for the development of accurate blood glucose meters in accordance with ISO 15197:2013

Despite measures to reduce disease transmission, a risk can occur when blood glucose meters (BGMs) are used on multiple individuals or by caregivers assisting a patient. The laboratory and in-clinic performance of a BGM system before and after disinfection should be demonstrated to guarantee accurate readings and reliable control of blood glucose (BG) for patients. In this study, an effective disinfection procedure, conducting wiping 10 times to assure a one minute contact time of the disinfectant on contaminated surface, was first demonstrated using test samples of the meter housing materials, including acrylonitrile butadiene styrene (ABS), polymethyl methacrylate (PMMA), and polycarbonate (PC), in accordance with ISO 15197:2013. After bench studies comprising 10,000 disinfection cycles, the elemental compositions of the disinfected ABS, PMMA, and PC samples were almost the same as in the original samples, as indicated by electron spectroscopy for chemical analysis. Subsequently, the validated disinfection procedure was then directly applied to disinfect 5 commercial BGM systems composed of ABS, PMMA, or PC to observe the effect of the validated disinfection procedure on meter accuracy. The results of HBsAg values after treatment with HBV sera and disinfectant wipes for each material were less than the LoD of each material of 0.020 IU/mL. Before and after the multiple disinfection cycles, 900 of 900 samples (100%) were within the system accuracy requirements of ISO 15197:2013. All of the systems showed high performance before and after the series of disinfection cycles and met the ISO 15197:2013 requirements. In addition, our results demonstrated multiple cleaning and disinfection cycles that represented normal use over the lifetime of a meter of 3-5 years. Our validated cleaning and disinfection procedure can be directly applied to other registered disinfectants for cleaning commercial BGM products in the future.

Hypoglycemia evaluation and reporting in diabetes: Importance for the development of new therapies

Hypoglycemia complicating diabetes therapy is well recognized to be an ever-present threat to patients, their families, providers, payers, and regulators. Despite this being widely acknowledged, the regulatory stance on hypoglycemia as an endpoint in clinical trials to support new product registration has not evolved in any meaningful way since the publication of a position paper by an American Diabetes Association (ADA) Workgroup in 2005. As the impact of hypoglycemia on persons affected by diabetes is of major importance when assessing new treatments, the historical position of regulatory agencies on hypoglycemia is reviewed with respect to product approvals. The purpose of this article is to present proposals for facilitating development of therapies that reduce hypoglycemia risk through (1) development of composite measures of benefit for regulatory endpoints and (2) facilitation of the fulfillment of an unmet clinical need for reducing hypoglycemia. In view of greater comprehension of the effects of hypoglycemia, coupled with improved methodology to assess its frequency, the authors recommend: (1) a numerical cut point of <54 mg/dl (<3.0 mmol/L) as a clinically relevant level with which to define meaningful hypoglycemia for trials of diabetes therapies; (2) utilization in clinical trials of mature glucose monitoring technologies for purposes of regulatory evaluation and clinical decision-making; and (3) development of primary efficacy endpoint composites that include hypoglycemia rates and glycemic control.

Accuracy Evaluation of a CE-Marked Glucometer System for Self-Monitoring of Blood Glucose With Three Reagent Lots Following ISO 15197:2013

Continuous standardized verification of the accuracy of blood glucose meter systems for self-monitoring after their introduction into the market is an important clinically tool to assure reliable performance of subsequently released lots of strips. Moreover, such published verification studies permit comparison of different blood glucose monitoring systems and, thus, are increasingly involved in the process of evidence-based purchase decision making.

If SMBG Accuracy Is Critical to Patient Safety, Why Are Inaccurate Meters Still on the Market?

In this issue of Journal of Diabetes Science and Technology, Christiansen and colleagues report results from two studies, laboratory and clinical, that assessed the accuracy of a new blood glucose monitoring system, the Contour®Next ONE (Ascensia Diabetes Care, Parsippany, NJ, USA). The new system comprises a blood glucose meter that can link (via Bluetooth®) to the Contour™ Diabetes app, which operates on a smartphone or tablet. Results from both studies showed that the system exceeded the accuracy standards defined by the International Organization for Standardization (ISO) 15197:2013. It is worrisome, however, that many FDA-cleared (and marketed) blood glucose monitoring systems do not meet ISO accuracy criteria. Significant improvements in regulatory oversight and enforcement are needed.

A Post-Marketing Surveillance Study to Evaluate Performance of the EXIMO™ Blood Glucose Monitoring System

INTRODUCTION

The performance of Blood Glucose Monitoring System (BGMS) is critical as the information provided by the system guide the patient or health care professional in making treatment decisions. However, besides evaluating accuracy of the BGMS in laboratory setting, it is equally important that the intended users (healthcare professionals and patients) should be able to achieve blood glucose measurements with similar level of high accuracy.

AIM

To assess the performance of EXIMO™ (Meril Diagnostics Pvt. Ltd., Vapi, Gujarat, India) BGMS as per International Organization for Standardization (ISO) 15197:2013 section 8 user performance criteria.

MATERIALS AND METHODS

This was a non-randomized and post-marketing study conducted at a tertiary care centre of India. A total of 1005 patients with diabetes themselves performed fingertip blood glucose measurement using EXIMO™ BGMS. Immediately after capillary blood glucose measurement using the blood glucose monitoring system, venous blood sample from each patient was obtained by a trained technician which was assessed by reference laboratory method- Cobas Integra 400 plus (Roche Instrument Centre, Rotkreuz, Switzerland). All the blood glucose measurements assessed by EXIMO™ were compared with laboratory results. Performance of the system was assessed as per ISO 15197:2013 criteria using Bland-Altman plot, Parkes-Consensus Error Grid (CEG) and Surveillance Error Grid analyses (SEG).

RESULTS

A total of 1005 patients participated in the study. Average age of the patients was 44.93±14.65 years. Evaluation of capillary fingertip blood glucose measurements demonstrated that 95.82% measurements fulfilled ISO 15197:2013 section 8 user performance criteria. All the results lie within clinically non-critical zones; Zone A (99.47%; n=1000) and Zone B (0.53%; n=05) of the CEG analysis. As per SEG analysis, majority of the results fell within "no-risk" zone (risk score 0 to 0.5; 90.42%).

CONCLUSION

The result of the study confirmed that intended users are able to obtain accurate glucose measurements when operating EXIMO™ BGMS, given only the instructions and training materials routinely provided with the system, in clinical practice.

Accuracy Evaluation of Four Blood Glucose Monitoring Systems in the Hands of Intended Users and Trained Personnel Based on ISO 15197 Requirements

BACKGROUND

Self-monitoring of blood glucose (BG) is an integral part in the therapy of people with diabetes, which is why blood glucose monitoring systems (BGMS) have to fulfill minimum accuracy requirements. However, accuracy is often assessed by trained operators, although such assessments do not necessarily allow for drawing conclusions on accuracy in the hands of lay users.

METHODS

The accuracy of 4 different BGMS (Accu-Chek^® Active, Accu-Chek^® Performa, Contour^®Plus, and OneTouch^® SelectSimple™) in the hands of lay users and trained study personnel was assessed in this study. Procedures were based on International Organization for Standardization (ISO) 15197:2013, clause 8, requirements. BGMS measurement results were compared against results from a glucose oxidase and a hexokinase laboratory analyzer. Handling errors made by lay users were documented. Accuracy was evaluated applying ISO 15197:2013/EN ISO 15197:2015 criteria (percentage of results within ±15 mg/dL or ±15%), more stringent criteria (10 mg/dL or 10%, and 5 mg/dL or 5%, respectively), and ISO 15197:2003 system accuracy criteria.

RESULTS

The level of accuracy differed among the four BGMS investigated independent from the operator. One system had less than 95% of the values within each of the limits and one system showed marked differences in accuracy when used by trained personnel and by lay users. Common lay user errors were not checking the test strip codes, incorrect application of blood, and not using the blood drop immediately.

CONCLUSIONS

BGMS accuracy can differ when used by trained personnel and when used by lay users. It is important that BGMS manufacturers provide systems that are as insensitive to operator errors as technically possible and easy to use.

How Much Accuracy of Interstitial Glucose Measurement Is Enough? Is There a Need for New Evidence?

This analytical comment discusses what standards are needed for the evaluation of the accuracy of glucose measurement systems continuously measuring glucose in the interstitial fluid. Since accuracy standards for continuous glucose monitoring (CGM)/flash glucose monitoring (FGM) systems are currently based on modeling studies or consensus of experts, we raised the question whether non-inferiority trials evaluating the safety and efficacy of CGM/FGM measurements compared to capillary blood glucose measurement with point-of-care devices could help to establish clarity about the needed accuracy standards of CGM/FGM. Such trials could also support the replacement of capillary blood glucose measurements by modern CGM/FGM systems.

Adherence of self-monitoring of blood glucose in persons with type 1 diabetes in Sweden

OBJECTIVE

The primary aim was to evaluate the extent to which persons with type 1 diabetes perform self-monitoring of blood glucose (SMBG) according to guidelines. Secondary objectives were to investigate predictors for good SMBG adherence, reasons for non-adherence, and association between SMBG frequency and hemoglobin A1c (HbA1c).

METHODS

This was a survey-based cross-sectional study. Questionnaires were sent out to 600 random patients at five sites. Patients were included if they were diagnosed with type 1 diabetes and ≥18 years old and excluded if they were currently using continuous glucose monitoring (CGM). Analysis of data was performed separately for the three sites where the answer frequency was ≥70%.

RESULTS

In total, 138 of 314 study participants, 43.9% (95% CI 38.5% to 49.4%) performed SMBG ≥4 times per day. For the three clinics where ≥70% of surveyed patients were included in the analysis, results were similar, 41.3% (95% CI 34.7% to 47.8%). Top three reported reasons for not performing more frequent SMBG were lack of time, not remembering, and self-consciousness. Frequency of SMBG was associated with HbA1c levels (p<0.0001). 30% of patients believed that ≤3 SMBG/day was recommended by healthcare providers.

CONCLUSIONS

Less than 50% of patients in Sweden follow guidelines of SMBG ≥4 times per day, despite glucose meters and strips being generally available at no cost. This indicates a need for further support in performing SMBG and increased availability of other tools for glucose monitoring.

Development of the Diabetes Technology Society Blood Glucose Monitor System Surveillance Protocol

BACKGROUND

Inaccurate blood glucsoe monitoring systems (BGMSs) can lead to adverse health effects. The Diabetes Technology Society (DTS) Surveillance Program for cleared BGMSs is intended to protect people with diabetes from inaccurate, unreliable BGMS products that are currently on the market in the United States. The Surveillance Program will provide an independent assessment of the analytical performance of cleared BGMSs.

METHODS

The DTS BGMS Surveillance Program Steering Committee included experts in glucose monitoring, surveillance testing, and regulatory science. Over one year, the committee engaged in meetings and teleconferences aiming to describe how to conduct BGMS surveillance studies in a scientifically sound manner that is in compliance with good clinical practice and all relevant regulations.

RESULTS

A clinical surveillance protocol was created that contains performance targets and analytical accuracy-testing studies with marketed BGMS products conducted by qualified clinical and laboratory sites. This protocol entitled "Protocol for the Diabetes Technology Society Blood Glucose Monitor System Surveillance Program" is attached as supplementary material.

CONCLUSION

This program is needed because currently once a BGMS product has been cleared for use by the FDA, no systematic postmarket Surveillance Program exists that can monitor analytical performance and detect potential problems. This protocol will allow identification of inaccurate and unreliable BGMSs currently available on the US market. The DTS Surveillance Program will provide BGMS manufacturers a benchmark to understand the postmarket analytical performance of their products. Furthermore, patients, health care professionals, payers, and regulatory agencies will be able to use the results of the study to make informed decisions to, respectively, select, prescribe, finance, and regulate BGMSs on the market.

The Rationale for Continuous Glucose Monitoring-based Diabetes Treatment Decisions and Non-adjunctive Continuous Glucose Monitoring Use

Self-monitoring of blood glucose (SMBG) is now recognised as a core component of diabetes self-management. However, there are many limitations to SMBG use in individuals with diabetes who are treated with intensive insulin regimens. Many individuals do not test at the recommended frequencies. Additionally, because SMBG only provides a blood glucose reading at a single point in time, hypoglycaemia and hyperglycaemia can easily go undetected, limiting the user's ability to take corrective action. Inaccuracies due to user error, environmental factors and weaknesses in SMBG system integrity further limit the utility of SMBG. Real-time continuous glucose monitoring (CGM) displays the current glucose, direction and velocity of glucose change and provides programmable alarms. This trending information and 'around-the-clock' vigilance provides a significant safety advantage relative to SMBG. No published clinical studies have evaluated outcomes when CGM is used as a replacement for SMBG; however, recent in silico studies support this indication. This article reviews the limitations of SMBG and discusses recent evidence that supports CGM-based decisions as an effective approach to managing insulin-treated diabetes.

AMERICAN ASSOCIATION OF CLINICAL ENDOCRINOLOGISTS AND AMERICAN COLLEGE OF ENDOCRINOLOGY 2016 OUTPATIENT GLUCOSE MONITORING CONSENSUS STATEMENT

This document represents the official position of the American Association of Clinical Endocrinologists and American College of Endocrinology. Where there were no randomized controlled trials or specific U.S. FDA labeling for issues in clinical practice, the participating clinical experts utilized their judgment and experience. Every effort was made to achieve consensus among the committee members. Position statements are meant to provide guidance, but they are not to be considered prescriptive for any individual patient and cannot replace the judgment of a clinician.

Comparison between capillary glucose measured with a Contour glucometer and plasma glucose in a population survey

Capillary glucose (CG) measured with point-of-care glucometers can provide useful approximation of plasma glucose (PG) in selected circumstances but the validity of measurements has been adequately assessed only for a few glucometers.

We assessed the difference between CG measured with a glucometer (Contour Ascensia, Bayer) and PG measured with a standard laboratory method in participants to a population-based cardiovascular survey in the Seychelles (sample size 1227).

CG correlated well with PG (r=0.94; p<0.001). The overall difference between PG and CG was –0.55 mmol/L for PG <4.0 mmol/L (n=19; 95% CI –0.92; –0.18); 0.14 mmol/L for PG 4.0–4.9 (n=344; 95% CI 0.08–0.20) and increased according to PG up to 1.64 mmol/L for PG >9.0 mmol/L (n=68; 95% CI 1.36; 1.91). The prevalence of diabetes in the study sample was 29% lower with CG than with PG (8.6% vs. 12.1%) but this bias could be corrected by analytical re-calibration.

CG underestimated PG, although the bias was small among persons with low glycemia. This systematic difference may bear little significance when the purpose is to simply monitor blood glucose but has large impact on prevalence estimates at the population level if CG values are not adequately calibrated.