Improved Accuracy of Continuous Glucose Monitoring Systems in Pediatric Patients with Diabetes Mellitus: Results from Two Studies

A Critical Discussion of Alert Evaluations in the Context of Continuous Glucose Monitoring System Performance

Many continuous glucose monitoring (CGM) systems provide functionality which alerts users of potentially unwanted glycemic conditions. These alerts can include glucose threshold alerts to call the user's attention to hypoglycemia or hyperglycemia, predictive alerts warning about impeding hypoglycemia or hyperglycemia, and rate-of-change alerts. A recent review identified 129 articles about CGM performance studies, of which approximately 25% contained alert evaluations. In some studies, real alerts were assessed; however, most of these studies retrospectively determined the timing of CGM alerts because not all CGM systems record alerts which necessitates manual documentation. In contrast to assessment of real alerts, retrospective determination allows assessment of a variety of alert settings for all three types of glycemic condition alerts. Based on the literature and the Clinical and Laboratory Standards Institute's POCT05 guideline, two common approaches to threshold alert evaluation were identified, one value-based and one episode-based approach. In this review, a critical discussion of the two approaches, including a post hoc analysis of clinical study data, indicates that the episode-based approach should be preferred over the value-based approach. For predictive alerts, fewer results were found in the literature, and retrospective determination of CGM alert timing is complicated by the prediction algorithms being proprietary information. Rate-of-change alert evaluations were not reported in the identified literature, and POCT05 does not contain recommendations for assessment. A possible approach is discussed including post hoc analysis of clinical study data. To conclude, CGM systems should record alerts, and the episode-based approach to alert evaluation should be preferred.

Assessing satisfaction, quality of life, and HbA1c changes in type 1 diabetes patients who are using freestyle libre glucose monitoring

Introduction

Type 1 diabetes mellitus (T1DM) is a chronic auto-immune disease in which loss of pancreatic islet β-cells leads to the deficiency of insulin in the body thus resulting in enhanced blood sugar levels. Effective blood glucose monitoring is crucial in T1DM management to prevent complications, particularly hypoglycemia.

Method

The study adopted a cross-sectional survey to assess satisfaction and quality of life among T1DM patients using the freestyle libre continuous glucose monitoring (FSL-CGM), and a retrospective cohort study design to evaluate changes in HbA1c over a year.

Result

The study involved 98 Saudi subjects, with 46.9% (n = 46) being male. The results indicated a high level of user satisfaction, with more than 85% of the participants responding positively, yielding a total satisfaction score of 30.86. User satisfaction with FSL-CGM was found to be significantly associated with the level of education. The use of FSL-CGM was also found to significantly improve the patients' quality of life. However, the levels of HbA1c had an impact on both satisfaction and quality of life. Before using the FSL-CGM system, the mean HbA1c was 9.83%, which significantly decreased to 8.63% after using the system (P-value <0.001).

Conclusion

The study's findings align with previous literature on satisfaction and quality of life, but there are conflicting results regarding the reduction of HbA1c levels using FSL-CGM. Given the limited sample size, future research could explore the topic more comprehensively, potentially utilizing a longitudinal study design to better measure changes in HbA1c level.

Clinical Performance Evaluation of Continuous Glucose Monitoring Systems: A Scoping Review and Recommendations for Reporting

The use of different approaches for design and results presentation of studies for the clinical performance evaluation of continuous glucose monitoring (CGM) systems has long been recognized as a major challenge in comparing their results. However, a comprehensive characterization of the variability in study designs is currently unavailable. This article presents a scoping review of clinical CGM performance evaluations published between 2002 and 2022. Specifically, this review quantifies the prevalence of numerous options associated with various aspects of study design, including subject population, comparator (reference) method selection, testing procedures, and statistical accuracy evaluation. We found that there is a large variability in nearly all of those aspects and, in particular, in the characteristics of the comparator measurements. Furthermore, these characteristics as well as other crucial aspects of study design are often not reported in sufficient detail to allow an informed interpretation of study results. We therefore provide recommendations for reporting the general study design, CGM system use, comparator measurement approach, testing procedures, and data analysis/statistical performance evaluation. Additionally, this review aims to serve as a foundation for the development of a standardized CGM performance evaluation procedure, thereby supporting the goals and objectives of the Working Group on CGM established by the Scientific Division of the International Federation of Clinical Chemistry and Laboratory Medicine.

Beyond A1C: exploring continuous glucose monitoring metrics in managing diabetes

Hemoglobin A1c (HbA1c) has long been considered a cornerstone of diabetes mellitus (DM) management, as both an indicator of average glycemia and a predictor of long-term complications among people with DM. However, HbA1c is subject to non-glycemic influences which confound interpretation and as a measure of average glycemia does not provide information regarding glucose trends or about the occurrence of hypoglycemia and/or hyperglycemia episodes. As such, solitary use of HbA1c, without accompanying glucose data, does not confer actionable information that can be harnessed to guide targeted therapy in many patients with DM. While conventional capillary blood glucose monitoring (BGM) sheds light on momentary glucose levels, in practical use the inherent infrequency of measurement precludes elucidation of glycemic trends or reliable detection of hypoglycemia or hyperglycemia episodes. In contrast, continuous glucose monitoring (CGM) data reveal glucose trends and potentially undetected hypo- and hyperglycemia patterns that can occur between discrete BGM measurements. The use of CGM has grown significantly over the past decades as an ever-expanding body of literature demonstrates a multitude of clinical benefits for people with DM. Continually improving CGM accuracy and ease of use have further fueled the widespread adoption of CGM. Furthermore, percent time in range correlates well with HbA1c, is accepted as a validated indicator of glycemia, and is associated with the risk of several DM complications. We explore the benefits and limitations of CGM use, the use of CGM in clinical practice, and the application of CGM to advanced diabetes technologies.

Use of Continuous Glucose Monitors to Manage Type 1 Diabetes Mellitus: Progress, Challenges, and Recommendations

Type 1 diabetes (T1D) management has been revolutionized with the development and routine utilization of continuous glucose monitoring (CGM). CGM technology has allowed for the ability to track dynamic glycemic fluctuations and trends over time allowing for optimization of medical therapy and the prevention of dangerous hypoglycemic events. This review details currently-available real-time and intermittently-scanned CGM devices, clinical benefits, and challenges of CGM use, and current guidelines supporting its use in the clinical care of patients with T1D. We additionally describe future issues that will need to be addressed as CGM technology continues to evolve.

Continuous glucose monitoring reveals similar glycemic variability in individuals with obesity despite increased HOMA-IR

Background/aims

Continuous glucose monitoring is a well-tolerated and versatile tool for management of diabetes and metabolic disease. While its use appears to be feasible to monitor glycemic profiles in diabetics, there is a paucity of data in individuals with obesity and normal glucose tolerance. The aim of this study is to investigate glucose fluctuations and insulin resistance patterns in normoglycemic participants with obesity vs. without obesity and contextualize these results against leading models for obesity.

Materials and methods

We designed a prospective, observational pilot study of two cohorts including 14 normoglycemic participants with obesity and 14 normoglycemic participants without obesity. Participants were monitored with continuous glucose monitoring (CGM) for five consecutive days. Insulin resistance levels were measured and glucometric data were extracted from CGM for all participants.

Results

Fasting serum insulin and homeostasis model assessment of insulin resistance (HOMA-IR) were significantly higher in the group with obesity (P < 0.05). While the group with obesity had a higher mean blood glucose (MBG), mean amplitude of glycemic excursions (MAGE), and continuous overall glycemic action-1 h (CONGA-1), these differences were not significant. On univariate linear regression, insulin resistance (HOMA-IR) was associated with body mass index (BMI), waist circumference (WC), cohort with obesity, cohort consuming a high glycemic diet, hemoglobin A1c (HbA1c), and fasting insulin levels. WC and fasting insulin levels remained predictors of HOMA-IR in our multivariable model.

Conclusion

While there is much excitement surrounding the use of commercial CGM products in obesity management, our results suggest that fasting insulin and HOMA-IR values may be more clinically useful than CGM data alone.

An Examination of the Glucose Management Indicator in Young Children with Type 1 Diabetes

BACKGROUND

Previous studies utilizing glucose data from continuous glucose monitors (CGM) to estimate the Glucose Management Indicator (GMI) have not included young children or determined appropriate GMI formulas for young children with type 1 diabetes (T1D).

METHODS

We extracted CGM data for 215 children with T1D (0-6 years) from a repository. We defined sampling periods ranging from the 3-27 days prior to an HbA1c measurement and compared a previously established GMI formula to a young child-specific GMI equation based on the sample's CGM data. We examined associations between HbA1c, GMI values, and other CGM metrics for each sampling period.

RESULTS

The young child-specific GMI formula and the published GMI formula did not evidence significant differences when using 21-27 days of CGM data. The young child-specific GMI formula demonstrated higher correlations to laboratory HbA1c when using 18 or fewer days of CGM data. Overall, the GMI estimate and HbA1c values demonstrate a strong relationship in young children with T1D.

CONCLUSIONS

Future research studies may consider utilizing the young child-specific GMI formula if the data collection period for CGM values is under 18 days. Further, researchers and clinicians may consider changing the default number of days of data used to calculate glycemic metrics in order to maximize validity of CGM-derived metrics.

Insulin pump therapy is associated with higher rates of mild diabetic ketoacidosis compared to injection therapy: A 2-year Swedish national survey of children and adolescents with type 1 diabetes

OBJECTIVES

Diabetic ketoacidosis (DKA) in type 1 diabetes (T1D) can occur during both insulin pump therapy (continuous subcutaneous insulin infusion, CSII) and insulin injection therapy (multiple daily injections, MDI). The primary aim of this study was to compare CSII and MDI regarding DKA frequency. A secondary aim was to compare metabolic derangement between CSII and MDI at hospital admission for DKA. RESEARCH DESIGN AND METHODS: Children 0-17.99 years with established T1D admitted for DKA in Sweden from February 1, 2015 to January 31, 2017 were invited to participate. Data regarding demographics, laboratory data, CSII or MDI, and access to ketone meters and CGM were provided through questionnaires and medical records. The Swedish National Diabetes Registry (SWEDIABKIDS) was used to compare the distribution of CSII and MDI in the national population with the population admitted for DKA, using the chi-square goodness-of-fit test. Distribution of CSII and MDI was then categorized in clinical severity grades for mild (pH 7.20-7.29), moderate (pH 7.10-7.29) and severe DKA (pH <7.10).

RESULTS

The distribution of CSII at DKA admission was significantly larger than in the national pediatric population with T1D (74.7% vs. 59.7%, p = 0.002). CSII was overrepresented in mild DKA (85.2% vs. with CSII, p < 0.001), but not in moderate/severe DKA (57.9% with CSII, p = 0.82). Mean HbA1c at hospital admission was 73.9 mmol/mol with CSII and 102.7 mmol/mol with MDI.

CONCLUSIONS

CSII was associated with higher risk of mild DKA than MDI. MDI was associated with markedly higher HbA1c levels than CSII at hospital admission for DKA.

Mean Absolute Relative Difference of Blood Glucose Monitoring Systems and Relationship to ISO 15197

BACKGROUND

The analytical quality of a blood glucose monitoring system (BGMS) is often assessed according to the requirements described in the international standard ISO 15197. However, the mean absolute relative difference (MARD) is sometimes used as well. This analysis aims at providing empirical data from BGMS evaluation studies conducted according to ISO 15197 and at providing an estimation of how MARD and percentage of measurement results within ISO accuracy limits are related.

METHODS

Results of 77 system accuracy evaluations conducted according to ISO 15197 were used to calculate MARD between BGMS and a laboratory comparison method's results (glucose oxidase or hexokinase method). Additionally, bias and 95%-limits of agreement (LoA) using the Bland and Altman method were calculated.

RESULTS

MARD results ranged from 2.3% to 20.5%. The lowest MARD of a test strip lot that showed <95% of results within ISO limits was 6.1%. The distribution of MARD results shows that only 3.6% of test strip lots with a MARD equal to or below 7% showed <95% of results within ISO limits (2.2% of all test strip lots). Bias of test strip lots that showed ≥95% of results within the limits ranged from -10.3% to +7.4%. The half-width of the 95%-LoA of test strip lots that showed ≥95% of results within the limits ranged from 4.8% to 24.0%.

CONCLUSION

There is a threshold MARD that may allow an estimate whether ISO 15197 requirements are fulfilled, but this statement cannot be made with certainty.

Accuracy Assessment of the GlucoMen® Day CGM System in Individuals with Type 1 Diabetes: A Pilot Study

The aim of this study was to evaluate the accuracy and usability of a novel continuous glucose monitoring (CGM) system designed for needle-free insertion and reduced environmental impact. We assessed the sensor performance of two GlucoMen® Day CGM systems worn simultaneously by eight participants with type 1 diabetes. Self-monitoring of blood glucose (SMBG) was performed regularly over 14 days at home. Participants underwent two standardized, 5-h meal challenges at the research center with frequent plasma glucose (PG) measurements using a laboratory reference (YSI) instrument. When comparing CGM to PG, the overall mean absolute relative difference (MARD) was 9.7 [2.6–14.6]%. The overall MARD for CGM vs. SMBG was 13.1 [3.5–18.6]%. The consensus error grid (CEG) analysis showed 98% of both CGM/PG and CGM/SMBG pairs in the clinically acceptable zones A and B. The analysis confirmed that GlucoMen® Day CGM meets the clinical requirements for state-of-the-art CGM. In addition, the needle-free insertion technology is well tolerated by users and reduces medical waste compared to conventional CGM systems.

The utility of continuous glucose monitoring systems in the management of children with persistent hypoglycaemia

OBJECTIVES

Glucose monitoring is vital in children with persistent hypoglycaemia to reduce the risk of adverse neuro-behavioural outcomes; especially in children with hyperinsulinism. The role of continuous glucose monitoring (CGM) systems in monitoring glucose levels in this cohort is limited. The objective of this study was to ascertain the effectiveness of CGM and to evaluate parents' experience of using CGM for monitoring glucose levels in children with hypoglycaemia.

METHODS

Retrospective analysis of sensor glucose (SG) values from Dexcom G4 CGM with paired finger-prick blood glucose (BG) values was performed to determine the accuracy of CGM. The parent experience of CGM was assessed using a questionnaire administered to families of children with congenital hyperinsulinism currently attending the clinic.

RESULTS

SG data from 40 children (median age 6 months) with persistent hypoglycaemia (60% Hyperinsulinism) were analysed. The mean difference between 5,650 paired BG and SG values was 0.28 mmol/L. The sensitivity and specificity of CGM to identify severe hypoglycaemia (BG < 3.0 mmol/L) were 54.3% (95% CI: 39.0%, 69.1%) and 97.4% (95% CI: 96.9%, 97.8%) respectively. Parents (n=11) reported less anxiety (n=9), better sleep at night (n=7) and preferred to use CGM for monitoring (n=9).

CONCLUSIONS

Although the high number of false-positive readings precludes the routine use of CGM in the evaluation of hypoglycaemia, it avoids unnecessary BG testing during normoglycaemia. It is an acceptable tool for parents for monitoring their children who are at risk of hypoglycaemia. Newer CGM systems with improved accuracy at lower glucose levels have the potential to further improve monitoring.

Non-invasive and minimally invasive glucose monitoring devices: a systematic review and meta-analysis on diagnostic accuracy of hypoglycaemia detection

BACKGROUND

The use of minimally and non-invasive monitoring systems (including continuous glucose monitoring) has increased rapidly over recent years. Up to now, it remains unclear how accurate devices can detect hypoglycaemic episodes. In this systematic review and meta-analysis, we assessed the diagnostic accuracy of minimally and non-invasive hypoglycaemia detection in comparison to capillary or venous blood glucose in patients with type 1 or type 2 diabetes.

METHODS

Clinical Trials.gov, Cochrane Library, Embase, PubMed, ProQuest, Scopus and Web of Science were systematically searched. Two authors independently screened the articles, extracted data using a standardised extraction form and assessed methodological quality using a review-tailored quality assessment tool for diagnostic accuracy studies (QUADAS-2). The diagnostic accuracy of hypoglycaemia detection was analysed via meta-analysis using a bivariate random effects model and meta-regression with regard to pre-specified covariates.

RESULTS

We identified 3416 nonduplicate articles. Finally, 15 studies with a total of 733 patients were included. Different thresholds for hypoglycaemia detection ranging from 40 to 100 mg/dl were used. Pooled analysis revealed a mean sensitivity of 69.3% [95% CI: 56.8 to 79.4] and a mean specificity of 93.3% [95% CI: 88.2 to 96.3]. Meta-regression analyses showed a better hypoglycaemia detection in studies indicating a higher overall accuracy, whereas year of publication did not significantly influence diagnostic accuracy. An additional analysis shows the absence of evidence for a better performance of the most recent generation of devices.

CONCLUSION

Overall, the present data suggest that minimally and non-invasive monitoring systems are not sufficiently accurate for detecting hypoglycaemia in routine use.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO 2018 CRD42018104812.

Continuous Glucose Monitoring Use in Clinical Trials for On-Market Diabetes Drugs

To the best of our knowledge, there are no published data on the historical and recent use of CGM in clinical trials of pharmacological agents used in the treatment of diabetes. We analyzed 2,032 clinical trials of 40 antihyperglycemic therapies currently on the market with a study start date between 1 January 2000 and 31 December 2019. According to ClinicalTrials.gov, 119 (5.9%) of these trials used CGM. CGM usage in clinical trials has increased over time, rising from <5% before 2005 to 12.5% in 2019. However, it is still low given its inclusion in the American Diabetes Association's latest guidelines and known limitations of A1C for assessing ongoing diabetes care.

Effect of CGM in the HbA1c and Coefficient of Variation of glucose in a pediatric sample

AIM OF THE STUDY

Previous studies have found no significant improvements in glycated hemoglobin (HbA1c), while using Continuous Glucose Monitoring (CGM), with children and adolescents. The aim of this paper is to measure the change in HbA1c, and the Coefficient of Variation in glucose levels, when using CGM, once the effect of other relevant variables, such as gender, actual age, the years the patient has had diabetes, use of an insulin pump, the presence of autoimmune disease, other associated pathologies, and weekly hours of exercise, are controlled for.

METHODS

This is a retrospective study that uses a linear regression model. Data was collected from Type 1 Diabetes Mellitus (T1DM), children diagnosed between 2003 and 2017 in the Pediatric Unit for Diabetes in Zaragoza, Spain. We used a linear regression and the method of estimation is Ordinary Least Squares.

RESULTS

Results show that the use of CGM decreased the HbA1c value by 3.5% and the Coefficient of Variation by 14%.

CONCLUSIONS

The implication of these results is that this device helped in the management of diabetes, although more research is needed to distinguish between different devices in terms of their efficacy.

Evaluation of Hemoglobin A1c before and after initiation of continuous glucose monitoring in children with type 1 diabetes mellitus

OBJECTIVES

The development of continuous glucose monitoring (CGM) systems has allowed for identification of blood sugar variations and trends in real-time that is not feasible with conventional self-monitoring of blood glucose. However, there is inconsistent data to show that the use of CGM leads to better glycemic control as measured by Hemoglobin A1c (HbA1c) in pediatric patients with type 1 diabetes mellitus. Our study aimed to compare the average HbA1c level in the 1-2 years prior to starting a CGM to the average HbA1c level in the 1-2 years immediately following CGM initiation in a sample of 1-20 year olds with type 1 diabetes mellitus.

METHODS

Participants were 90 youth (ages 1-20) followed for type 1 diabetes care at our institution who used a CGM for at least a 6 month time period. We performed a retrospective chart review to obtain up to four HbA1c values pre and post-CGM initiation each. We evaluated pre- and post-CGM initiation changes in mean HbA1c via dependent samples t-tests using IBM SPSS 24.0.

RESULTS

The mean HbA1c was 8.7% pre-CGM and decreased to 8.27% 9-12 months after CGM initiation in the overall sample. A statistically significant decrease in HbA1c was seen in patients who used multiple daily injections (p=0.02), those with a pre-CGM HbA1c greater than 9% (p=0.01), and those with a diabetes duration of 5-10 years (p=0.02).

CONCLUSION

CGM use was associated with a decrease in HbA1c over time which was statistically significant in some subgroups.

Comparative Accuracy Analysis of a Real-time and an Intermittent-Scanning Continuous Glucose Monitoring System

BACKGROUND

Currently, two different types of continuous glucose monitoring (CGM) systems are available: real time (rt) CGM systems that continuously provide glucose values and intermittent-scanning (is) CGM systems. This study compared accuracy of an rtCGM and an isCGM system when worn in parallel.

METHODS

Dexcom G5 Mobile (DG5) and FreeStyle Libre (FL) were worn in parallel by 27 subjects for 14 days including two clinic sessions with induced glucose excursions. The percentage of CGM values within ±20% or ±20 mg/dL of the laboratory comparison method results (YSI 2300 STAT Plus, YSI Inc., Yellow Springs, OH, United States; glucose oxidase based) or blood glucose meter values and mean absolute relative difference (MARD) were calculated. Consensus error grid and continuous glucose error grid analyses were performed to assess clinical accuracy.

RESULTS

Both systems displayed clinically accurate readings. Compared to laboratory comparison method results during clinic sessions, DG5 had 91.5% of values within ±20%/20 mg/dL and a MARD of 9.5%; FL had 82.5% of scanned values within ±20%/20 mg/dL and an MARD of 13.6%. Both systems showed a lower level of performance during the home phase and when using the blood glucose meter as reference.

CONCLUSION

The two systems tested in this study represent two different principles of CGM. DG5 generally provided higher accordance with laboratory comparison method results than FL.

A Randomized Clinical Trial Assessing Continuous Glucose Monitoring (CGM) Use With Standardized Education With or Without a Family Behavioral Intervention Compared With Fingerstick Blood Glucose Monitoring in Very Young Children With Type 1 Diabetes

OBJECTIVE

This study evaluated the effects of continuous glucose monitoring (CGM) combined with family behavioral intervention (CGM+FBI) and CGM alone (Standard-CGM) on glycemic outcomes and parental quality of life compared with blood glucose monitoring (BGM) in children ages 2 to <8 years with type 1 diabetes.

RESEARCH DESIGN AND METHODS

This was a multicenter (N = 14), 6-month, randomized controlled trial including 143 youth 2 to <8 years of age with type 1 diabetes. Primary analysis included treatment group comparisons of percent time in range (TIR) (70-180 mg/dL) across follow-up visits.

RESULTS

Approximately 90% of participants in the CGM groups used CGM ≥6 days/week at 6 months. Between-group TIR comparisons showed no significant changes: CGM+FBI vs. BGM 3.2% (95% CI -0.5, 7.0), Standard-CGM vs. BGM 0.5% (-2.6 to 3.6), CGM+FBI vs. Standard-CGM 2.7% (-0.6, 6.1). Mean time with glucose level <70 mg/dL was reduced from baseline to follow-up in the CGM+FBI (from 5.2% to 2.6%) and Standard-CGM (5.8% to 2.5%) groups, compared with 5.4% to 5.8% with BGM (CGM+FBI vs. BGM, P < 0.001, and Standard-CGM vs. BGM, P < 0.001). No severe hypoglycemic events occurred in the CGM+FBI group, one occurred in the Standard-CGM group, and five occurred in the BGM group. CGM+FBI parents reported greater reductions in diabetes burden and fear of hypoglycemia compared with Standard-CGM (P = 0.008 and 0.04) and BGM (P = 0.02 and 0.002).

CONCLUSIONS

CGM used consistently over a 6-month period in young children with type 1 diabetes did not improve TIR but did significantly reduce time in hypoglycemia. The FBI benefited parental well-being.

Factors Associated with Adherence to Self-Monitoring of Blood Glucose Among Young People with Type 1 Diabetes in China: A Cross-Sectional Study

BACKGROUND

Self-monitoring of blood glucose (SMBG) plays a crucial role in the maintenance of glycemic control in young people with type 1 diabetes mellitus (T1DM), but most of them do not perform SMBG as recommended. Few studies comprehensively explored factors that correlate with adherence to SMBG among this population on the basis of a framework. Hence, the aims of this study were to describe adherence to SMBG among young people with T1DM in China and explore its associating factors according to the Self and Family Management (SFM) framework.

METHODS

A cross-sectional study was conducted on young people with T1DM in Hunan Province of China from July to August 2020. Based on the SFM framework, self-reported questionnaires were organized for the collection of data on adherence to SMBG, socio-demographic and clinical factors, resources, health care system, and personal factors. Factors associated with adherence to SMBG were determined through multivariate logistic regression analysis.

RESULTS

A total of 165 young people were invited, of which 122 (73.9%) completed the questionnaires. The mean age was 12.41 years (SD = 3.18), and the proportion of young people who adhered to SMBG was 53.3%. Multivariate logistic regression analysis revealed that children aged 8-12 years (OR = 0.188, P = 0.002), from two-parent families (OR = 0.232, P = 0.019), and with better personal factors (eg, with more information of SMBG, OR = 1.072, P = 0.020; lower diabetes-related worry, OR = 0.917, P = 0.031; higher level of pain during SMBG, OR = 1.852, P = 0.001), had better adherence to SMBG.

CONCLUSION

Nearly half of the young people with T1DM were not adherent to SMBG in China. Clinicians need to pay more attention to adolescents from single-parent families with regard to their adherence to SMBG. Providing management strategies of SMBG, including delivering SMBG-related information, decreasing diabetes-related worry, and relieving pain related to SMBG, may improve adherence.

Associations Between the Time in Hypoglycemia and Hypoglycemia Awareness Status in Type 1 Diabetes Patients Using Continuous Glucose Monitoring Systems

Background: Continuous glucose monitoring (CGM) systems help reduce hypoglycemia in patients with type 1 diabetes (T1D). It remains unclear whether T1D patients with impaired awareness of hypoglycemia (IAH) continue to develop more hypoglycemia than those with normal hypoglycemia awareness (NA) despite CGM use. Materials and Methods: For this cross-sectional observational study, 99 T1D patients using real-time CGMs for ≥86% of time were recruited. Fifty and 49 patients were found to have NA and IAH (based on the Clarke questionnaire), respectively. Two-week CGM hypoglycemia data were collected. Results: IAH was associated with greater percentages of CGM values <70 and <54 mg/dL (P = 0.012, P = 0.004) compared to NA. Clarke scores correlated positively with the percentage of CGM values <70 and <54 mg/dL (P = 0.013, P = 0.004). IAH was also related to more events with glucose <70 and <54 mg/dL determined either with at ≥1 time point (P = 0.048, P = 0.003) or lasting ≥20 min (P = 0.016, P = 0.004). IAH patients presented with more day-time events with glucose <54 mg/dL (P = 0.015), nocturnal events with glucose levels <70 and <54 mg/dL (P = 0.009, P = 0.007) and longer day-time event duration with glucose levels <70 and <54 mg/dL (P < 0.001, P = 0.006), respectively. Conclusions: T1D patients with IAH continue to experience more hypoglycemia despite dedicated CGM use.

A Three-Way Accuracy Comparison of the Dexcom G5, Abbott Freestyle Libre Pro, and Senseonics Eversense Continuous Glucose Monitoring Devices in a Home-Use Study of Subjects with Type 1 Diabetes

Background: There is a dearth of comparative accuracy studies of continuous glucose monitoring (CGM) devices in the home-use setting, and none with the Eversense implantable CGM. Methods: We evaluated the accuracy of the Dexcom G5, Abbott Freestyle Libre Pro, and Senseonics Eversense during a 6-week free-living home-use bionic pancreas study involving 23 subjects with type 1 diabetes who wore all three devices concurrently. The primary outcome was the mean absolute relative difference (MARD) between CGM readings and point-of-care (POC) plasma-glucose (PG) values obtained approximately twice daily by the subjects. We compared PG values with CGM readings when available from all three CGMs in the 5 min preceding the PG values (n = 829 sets). Since the Libre Pro records readings every 15 min, we also did a two-way comparison between the G5 and the Eversense with a higher number of comparisons (n = 2277 sets). Results: All three CGM systems produced higher average MARDs than during in-clinic studies. However, since all three CGM systems were worn by the same individuals and used the same meter for comparator PG measurements, we could directly compare their performances. In the three-way comparison, Eversense achieved the lowest nominal MARD (14.8%) followed by Dexcom G5 (16.3%) and Libre Pro (18.0%) (Eversense vs. Libre Pro P = 0.004, other comparisons P = NS). There was a statistically significant difference (P = 0.008) in the two-way comparison of the MARDs for Eversense (15.1%) and G5 (16.9%). Conclusions: The point accuracy of the Eversense was better than two other CGMs when compared with POC PG values.

Use of Diabetes Technology in Children: Role of Structured Education for Young People with Diabetes and Families

The current era has witnessed an explosion of advanced diabetes technologies. Young people with diabetes and their families require detailed, structured diabetes education in order to optimize use of such devices. There is need for youth and their families to participate in the selection of particular devices for personal use and comprehensive education regarding the safe and effective use of such technologies. The education process should ensure that youth and their families receive realistic expectations of what the advanced technologies can and cannot do to avoid disappointment and the premature discontinuation of such systems.

Cutaneous Complications With Continuous or Flash Glucose Monitoring Use: Systematic Review of Trials and Observational Studies

BACKGROUND

Continuous glucose monitoring (CGM)/flash glucose monitoring (FGM) use in diabetes management is increasing. Cutaneous complications associated with these devices were reported. We conducted a systematic review to provide an overview of cutaneous complications with CGM/FGM use.

METHODS

We identified observational studies and intervention trials that report on cutaneous complications with CGM/FGM use up to January 14, 2019. Studies were identified through Medline, Embase, and PubMed, or with hand searching of the previous publications. Screening was duplicated and data extracted to consider four main themes: incidence rate and severity, participant perspectives of cutaneous complications, potential solutions, and future directions in diabetic technology relevant to reducing cutaneous complications.

RESULTS

A total of 54 eligible studies were identified. The overall event rate of cutaneous complications reported from 19 trials was one event per eight weeks of sensor wear-time of which 1.5% were considered severe. The most common cutaneous complications were wear-related erythema, itching, and induration. Although skin irritations were the most common cause of CGM/FGM discontinuation, most users experienced less pain or discomfort with CGM/FGM than capillary blood glucose testing. Future technological advances may reduce, but not eliminate cutaneous complications.

CONCLUSION

The incidence rate of reported cutaneous complications with CGM/FGM use from the available literature is low, with one event per eight weeks of sensor wear-time. Reported complication severity was also low, leading to low rates of CGM/FGM discontinuation. However, there appear to be discrepancies between reporting in trial and observational data. Greater constancy in reporting is necessary to understand the frequency of this issue.

Benefits and Limitations of MARD as a Performance Parameter for Continuous Glucose Monitoring in the Interstitial Space

High-quality performance of medical devices for glucose monitoring is important for a safe and efficient usage of this diagnostic option by patients with diabetes. The mean absolute relative difference (MARD) parameter is used most often to characterize the measurement performance of systems for continuous glucose monitoring (CGM). Calculation of this parameter is relatively easy and comparison of the MARD numbers between different CGM systems appears to be straightforward on the first glance. However, a closer look reveals that a number of complex aspects make interpretation of the MARD numbers provided by the manufacturer for their CGM systems difficult. In this review, these aspects are discussed and considerations are made for a systematic and appropriate evaluation of the MARD in clinical trials. The MARD should not be used as the sole parameter to characterize CGM systems, especially when it comes to nonadjunctive usage of such systems.

Distinct Patterns of Daily Glucose Variability by Pubertal Status in Youth With Type 1 Diabetes

OBJECTIVE

To evaluate glycemia and metrics of glucose variability in youth with type 1 diabetes, and to assess patterns of 24-h glucose variability according to pubertal status.

RESEARCH DESIGN AND METHODS

Metrics of glycemia, glucose variability, and glucose patterns were assessed by using 4 weeks of continuous glucose monitoring (CGM) data from 107 youth aged 8-17 years with type 1 diabetes for ≥1 year. Glucose values per hour were expressed as percentages relative to the mean glucose over 24 h for a 4-week period. Glucose data were compared on the basis of pubertal status-prepubertal (Tanner stage [T] 1), pubertal (T2-4), and postpubertal (T5)-and A1C categories (<7.5% [<58 mmol/mol], ≥7.5% [≥58 mmol/mol]).

RESULTS

Youth (50% female, 95% white) had a mean ± SD age of 13.1 ± 2.6 years, diabetes duration of 6.3 ± 3.5 years, and A1C of 7.8 ± 0.8% (62 ± 9 mmol/mol); 88% were pump treated. Prepubertal youth had a higher mean glucose SD (86 ± 12 mg/dL [4.8 ± 0.7 mmol/L]; P = 0.01) and coefficient of variation (CV) (43 ± 5%; P = 0.06) than did pubertal (SD 79 ± 13 mg/dL [4.4 ± 0.7 mmol/L]; CV 41 ± 5%) and postpubertal (SD 77 ± 14 mg/dL [4.3 ± 0.8 mmol/L]; CV 40 ± 5%) youth. Over 24 h, prepubertal youth had the largest excursions from mean glucose and the highest CV across most hours compared with pubertal and postpubertal youth. Across all youth, CV was strongly correlated with the percentage of time with glucose <70 mg/dL (<3.9 mmol/L) (r = 0.79; P < 0.0001).

CONCLUSIONS

Prepubertal youth had greater glucose variability independent of A1C than did pubertal and postpubertal youth. A1C alone does not capture the full range of glycemic parameters, highlighting the added insight of CGM in managing youth with type 1 diabetes.

Estimating plasma glucose with the FreeStyle Libre Pro continuous glucose monitor during oral glucose tolerance tests in youth without diabetes

Few studies have assessed the accuracy of the FreeStyle Libre Pro (FLP) continuous glucose monitor for estimating plasma glucose (PG) in non-diabetic children.

OBJECTIVE

Determine the accuracy of FLP compared to PG during OGTT in healthy children.

SUBJECTS

Children (7-11.99 years) with healthy weight and overweight/obesity (n = 33; 52% male).

METHODS

Participants wore the FLP before and during a 2-hour OGTT; PG was measured at 30 minutes intervals. Potential systematic- and magnitude-related biases for FLP vs PG were examined.

RESULTS

FLP 15-minute averages and PG were correlated at most timepoints during OGTT (r2 = 0.35-0.69, P's < .001 for time point 30-120 minutes) and for PG area under the curve (AUC) (r2 = 0.65, P < .0001). There were no systematic biases as assessed by Bland-Altman analyses for FLP AUC or for FLP at each OGTT timepoint. However, for fasting glucose, a significant magnitude bias was noted (r2 = 0.38, P < .001), such that lower PG was underestimated, and higher PG was overestimated by FLP readings; further, there was poor correlation between fasting PG and FLP (r2 = 0.06, P = .22). BMIz was also associated with FLP accuracy: FLP overestimated PG in children with low BMIz and underestimated PG in those with overweight/obesity for OGTT AUC and OGTT PG at baseline, 60, and 120 minutes (all P's ≤ .015). No adverse events occurred with FLP.

CONCLUSIONS

Among children without diabetes, the FLP was well tolerated and correlated with post-OGTT glucose, but had magnitude bias affecting fasting glucose and appeared to underestimate plasma glucose in those with overweight/obesity. These results suggest potential limitations for the utility of the FLP for research.

Benefits and Barriers of Continuous Glucose Monitoring in Young Children with Type 1 Diabetes

Background: Continuous glucose monitoring (CGM) has potential to address challenges of type 1 diabetes (T1D) management for young children. CGM use is increasing, yet remains underutilized. Characterizing parents' experiences with CGM can inform clinical strategies to help parents make decisions about diabetes management, overcome obstacles to initiating and sustaining CGM use, and maximize benefits of CGM use in their children's diabetes care. Methods: Transcripts from semistructured qualitative interviews with 55 parents of children aged 1 to <8 years, with T1D duration ≥6 months, and whose child currently or previously used CGM were coded and analyzed to derive themes about their experiences with CGM. Results: Participants were 88% mothers and the mean child age was 5.0 ± 1.5 years. Parents described benefits of CGM use: decreased worry about glucose excursions, improved sleep, increased sense of safety with children who cannot recognize or express symptoms of hypo- or hyperglycemia, and greater comfort with other caregivers, especially using remote monitoring functionality when away from children. Challenges included painful insertions, wearing multiple devices on small bodies, disruptive alerts, data gaps due to lost signals, skin/adhesive problems, and difficulty interpreting the amount of information generated by CGM. For some, the challenges outweighed potential benefits and they stopped CGM use. Conclusions: CGM may address unique challenges of T1D in young children and increase parental comfort with diabetes management, yet there are multiple barriers to initiating or maintaining CGM use. Education and behavioral support to address these benefits and barriers may equip caregivers with skills to address challenges of CGM use.

Freestyle libre flash glucose monitoring improves patient quality of life measures in children with Type 1 diabetes mellitus (T1DM) with appropriate provision of education and support by healthcare professionals

BACKGROUND

In 2017 the UK's Association of Children's Diabetes Clinicians (ACDC) launched a national educational package to provide training in the use of Freestyle Flash glucose monitoring (GM) to healthcare professionals.

OBJECTIVE

To evaluate metabolic outcomes and quality of life (QoL) of children with T1DM trained in the use of the Freestyle Flash GM system adopting the ACDC guidelines.

METHODS

Prospective study conducted at a single UK children's diabetes unit from 2017 to 2018.52 children with T1DM (age 5-18 yrs) were commenced on the Freestyle Flash GM system, received education and were followed up for 12 months. The Peds QL 3.2 diabetes questionnaire was used to assess QoL before and after the use of the system. HbA1c was measured at 3, 6 and 12 months pre and post use of Freestyle.

RESULTS

52 children (33 M,19 F) with a mean age of 11.6 yrs (range 4 m-17.2 yrs) were evaluated. Mean HbA1c 3 months post Freestyle Flash GM showed a significant improvement when compared with HbA1c values at 12, 6 and 3 months pre Freestyle (p-value 0.040, 0.040, 0.012 respectively). This improvement was not sustained at 6 and 12 months (p-value 0.15, 0.50). The PedsQL3.2 diabetes scores demonstrated significant improvement in patient QoL, reduction of diabetes symptoms and treatment barriers following the use of the new technology (p-values 0.014; 0.018; 0.035 respectively).

CONCLUSIONS

Freestyle Flash GM technology associated with appropriate education and regular support by healthcare professionals improves patient quality of life measures in children with T1DM.

Comparison of Continuous Glucose Monitoring Accuracy Between Abdominal and Upper Arm Insertion Sites

Background: The aim was to compare the accuracy of the Dexcom^® G4 Platinum continuous glucose monitor (CGM) sensor inserted on the upper arm and the abdomen in adults. Methods: Fourteen adults with type 1 diabetes wore two CGMs, one placed on the upper arm and one placed on the abdomen. Three in-clinic visits of 5 h with YSI (2300 STAT, Yellow Springs Instrument) measurements as comparator were performed. Each visit was followed by 4 days with seven-point self-monitoring of blood glucose (SMBG) in free-living conditions. Accuracy analyses on the paired CGM-YSI and CGM-SMBG measurements of the two CGM sensors were performed. Results: Using YSI as comparator, the overall Mean Absolute Relative Difference (MARD) for the CGM_abd was 12.3% and CGM_arm was 12.0%. The percentage of the CGM measurements in zone A of Clarke error grid analysis for the CGM_abd was 85.6% and CGM_arm was 86.0%. The hypoglycemia sensitivity for the CGM_abd and CGM_arm was 69.3%. Using SMBG as comparator, the overall MARD for the CGM_abd was 12.5% and CGM_arm was 12.0%. The percentage of the CGM measurements in zone A for the CGM_abd was 84.1% and the CGM_arm was 85.0%. The hypoglycemia sensitivity for the CGM_abd was 60.0% and the CGM_arm was 71.1%. All the P-values from the comparisons between the accuracy of CGM_abd and CGM_arm were >0.05. Conclusion: The accuracy of a Dexcom G4 Platinum CGM sensor placed on the upper arm was not different from the accuracy of the sensor placed on the abdomen in adults with type 1 diabetes.

Measures of Accuracy for Continuous Glucose Monitoring and Blood Glucose Monitoring Devices

Currently, patients with diabetes may choose between two major types of system for glucose measurement: blood glucose monitoring (BGM) systems measuring glucose within capillary blood and continuous glucose monitoring (CGM) systems measuring glucose within interstitial fluid. Although BGM and CGM systems offer different functionality, both types of system are intended to help users achieve improved glucose control. Another area in which BGM and CGM systems differ is measurement accuracy. In the literature, BGM system accuracy is assessed mainly according to ISO 15197:2013 accuracy requirements, whereas CGM accuracy has hitherto mainly been assessed by MARD, although often results from additional analyses such as bias analysis or error grid analysis are provided. The intention of this review is to provide a comparison of different approaches used to determine the accuracy of BGM and CGM systems and factors that should be considered when using these different measures of accuracy to make comparisons between the analytical performance (ie, accuracy) of BGM and CGM systems. In addition, real-world implications of accuracy and its relevance are discussed.

Accuracy, Utilization, and Effectiveness Comparisons of Different Continuous Glucose Monitoring Systems

BACKGROUND

Accuracy and feature sets of continuous glucose monitoring (CGM) systems may influence device utilization and outcomes. We compared clinical trial accuracy and real-world utilization and effectiveness of two different CGM systems.

MATERIALS AND METHODS

Separately conducted accuracy studies of a fifth-generation and a sixth-generation CGM system involved 50 and 159 adults, respectively. For between-system performance comparisons, propensity score methods were utilized to balance cohort characteristics. Real-world outcomes were assessed in 10,000 anonymized patients who had switched from the fifth-generation to the sixth-generation system and had used connected mobile devices to upload data from both systems, allowing pairwise comparisons of device utilization and glucose concentration distributions.

RESULTS

Propensity score-adjusted mean absolute relative differences for the fifth- and sixth-generation systems were 9.0% and 9.9%, and the percentages of values within ±20%/20 mg/dL were 93.1% and 92.5%, respectively. The sixth-generation system, but not the fifth-generation system, met accuracy criteria for interoperable CGM systems. Both systems had high real-world utilization rates (93.8% and 95.3% in the fifth- and sixth-generation systems, respectively). Use of the sixth-generation system was associated with fewer glucose values <55 mg/dL (<3.1 mmol/L) (0.7% vs. 1.1%, P < 0.001) and more values 70-180 mg/dL (3.9-10.0 mmol/L) (57.3% vs. 56.0%, P < 0.001) than the fifth-generation system.

CONCLUSIONS

CGM performance outcomes can be compared through the propensity score analysis of clinical trial data and pairwise comparisons of real-world data. The systems compared here had nearly equivalent accuracy and utilization rates. Longer term biochemical and psychosocial benefits observed with the fifth-generation system are also expected with the sixth-generation system.

Performance of a Factory-Calibrated, Real-Time Continuous Glucose Monitoring System in Pediatric Participants With Type 1 Diabetes

BACKGROUND

The perceived value and consistent use of continuous glucose monitoring (CGM) systems depends in part on their accuracy. We assessed the performance of a sixth-generation CGM system (Dexcom G6) in children and adolescents.

METHODS

Forty-nine participants (6-17 years of age, mean ± SD of 13.5 ± 3.3 years), all with type 1 diabetes, enrolled and data were available from 37. Each participant wore 1 sensor for up to 10 days and was asked to undergo an in-clinic visit lasting 6-12 hours for frequent blood glucose (BG) sample testing on one of the sensor wear days. Estimated glucose values (EGVs) from the G6 system were compared with venous BG values measured with a laboratory reference instrument (YSI).

RESULTS

The overall mean absolute relative difference (MARD) for 1387 EGV-YSI pairs was 7.7%, and the overall percentage of EGVs within 20% or 20 mg/dL of the YSI reference value (for YSI > or ⩽100 mg/dL, respectively, the "%20/20") was 96.2%. The %20/20 was 92.1% on Day 1 and 91.0% on Day 10 of sensor wear. For EGVs <70 mg/dL, 92.6% of the YSI values were within 20 mg/dL and for EGVs >250 mg/dL, 100% of the YSI values were within 20%. Differences between EGVs and YSI values in over 99.9% of the pairs posed no or only slight clinical risk as evaluated by surveillance error grid analysis.

CONCLUSIONS

The accuracy of the G6 CGM system in pediatrics may encourage consistent use of the system and contribute to improved glycemic outcomes in this population.

Role of continuous glucose monitoring in the management of glycogen storage disorders

Management of liver glycogen storage diseases (GSDs) primarily involves maintaining normoglycemia through dietary modifications and regular glucose monitoring. Self-monitoring of blood glucose is typically done 3-6 times per day, and may not sufficiently capture periods of asymptomatic hypoglycemia, particularly during sleep. Continuous glucose monitoring systems (CGMS) provide 24-h continuous glucose data and have been used effectively in diabetes mellitus to monitor metabolic control and optimize treatment. This is a relatively new approach in GSDs with only a handful of studies exploring this modality. In this study we used Dexcom CGMS to study the glycemic profile of 14 pediatric and six adult patients with GSD I, III, and IX. A total of 176 days of CGMS data were available. The CGMS was found to be a reliable tool in monitoring glucose levels and trends at all times of the day with good concordance with finger-stick glucose values. This study revealed that in addition to overnight hypoglycemia, CGMS can uncover previously undetected, subclinical, low glucose levels during daytime hours. Additionally, the CGMS detected daytime and overnight hyperglycemia, an often overlooked concern in liver GSDs. The CGMS with concurrent dietary adjustments made by a metabolic dietitian improved metabolic parameters and stabilized blood glucose levels. The CGMS was found to be a safe, effective, and reliable method for optimizing treatment in patients with GSD I, III, and IX.

Non-adjunctive flash glucose monitoring system use during summer-camp in children with type 1 diabetes: The free-summer study

BACKGROUND

A factory-calibrated sensor for intermittently scanned continuous glucose monitoring (isCGM) is accurate and safe in children with type 1 diabetes (T1D). Data on isCGM effectiveness as a replacement for self-monitoring of blood glucose (SMBG) in this population is scarce.

OBJECTIVE

The aim of this study was to evaluate the non-adjunctive use of isCGM in children with T1D during 2 weeks in a challenging summer-camp setting.

METHODS

In this two-arm, parallel, randomized, outpatient clinical trial we enrolled 46 children (25 females, mean ± SD: age 11.1 ± 2.6 years, glycated hemoglobin (HbA1c) 7.4% ± 0.7%): 26 in the isCGM group were blinded for the SMBG and insulin dosing was isCGM-based, whereas 20 in the control group were blinded for isCGM and performed SMBG-based insulin dosing. The primary outcome of intention-to-treat analysis was between-group difference in the proportion of time within range 3.9 to 10 mmol/L (TIR).

RESULTS

There was no significant difference in TIR (3.9-10 mmol/L) between the two groups. In participants with suboptimal metabolic control (HbA1c > 7%) we observed a significant reduction in time spent above 10 mmol/L (P < 0.05) and an improvement in TIR (P = 0.05) in the isCGM group. No severe hypoglycemic events or serious adverse events occurred. Overall mean absolute relative difference (MARD) between isCGM and SMBG was 18.3%, with median absolute relative difference (ARD) of 8%. Consensus error grid analysis demonstrated 82.2% and 95.2% of results in zone A, and zone A + B, respectively.

CONCLUSION

The non-adjunctive use of isCGM was as safe and effective as SMBG, and reduced time spent in hyperglycemia in a sub-population of children with T1D with suboptimal glycemic control.

TRIAL REGISTRATION

NCT03182842.

Biopsychosocial Factors Associated With Satisfaction and Sustained Use of Artificial Pancreas Technology and Its Components: a Call to the Technology Field

PURPOSE OF REVIEW

Summarize biopsychosocial factors associated with using continuous glucose monitors (CGMs), insulin pumps, and artificial pancreas (AP) systems and provide a "call to the field" about their importance to technology uptake and maintained use.

RECENT FINDINGS

Insulin pumps and CGMs are becoming standard of care for individuals with type 1 diabetes (T1D). AP systems combining a CGM, insulin pump, and automated dosing algorithm are available for commercial use. Despite improved glycemic control with AP system use, numerous barriers exist which may limit their benefit. Studies on components of AP systems (pumps, CGMs) are limited and demonstrate mixed results of their impact on fear of hypoglycemia, adherence, quality of life, depression and anxiety, and diabetes distress. Studies examining biopsychological factors associated specifically with sustained use of AP systems are also sparse. Biological, psychological and social impacts of AP systems have been understudied and the information they provide has not been capitalized upon.

Accuracy of a Fourth-Generation Continuous Glucose Monitoring System in Children and Adolescents with Type 1 Diabetes

BACKGROUND

This study evaluated the safety and performance of the Guardian™ continuous glucose monitoring (CGM) system in children and adolescents with type 1 diabetes (T1D).

MATERIALS AND METHODS

Subjects 2-18 years of age (mean ± standard deviation [SD] 13.1 ± 3.9 years) with T1D and duration of diagnosis ≥1 year were enrolled at 11 sites in the United States and wore two Guardian Sensor 3 sensors in the abdomen and/or buttock. Sensors were connected to a transmitter paired with either a Guardian Connect system (i.e., mobile device with software application allowing display of sensor glucose [SG] values) or a Guardian Link 3 transmitter used as a Glucose Sensor Recorder (GSR). There were 145 participants who underwent a 6-h in-clinic frequent sample testing (FST) on day 1 (n = 54), day 3 (n = 48), or day 7 (n = 43) postsensor insertion. During FST, SG values were compared with a Yellow Springs Instrument (YSI) plasma reference every 5-15 min (n = 124, 7-18 years of age; n = 2, 2-6 years of age), or to a self-monitoring of blood glucose (SMBG) reference every 5-30 min (n = 19, 2-6 years of age).

RESULTS

The overall mean absolute relative difference (ARD ± SD) between SG and reference values (YSI or SMBG) when calibrating approximately every 12 h, was 10.9% ± 10.7% (3102 paired points) for sensors communicating with the Guardian Connect system and 11.1% ± 10.6% (2624 paired points) for sensors connected to the GSR. The overall percentage of SG values within ±20% of reference values >80 mg/dL or within 20 mg/dL of reference values ≤80 mg/dL was 87.8% for the Guardian Connect system and 86.7% for the GSR, respectively. There was one device-related adverse event of contact dermatitis, but no serious device-related adverse events.

CONCLUSIONS

The Guardian CGM system demonstrated good accuracy in children and adolescents. These findings support its use in sensor-integrated insulin pump platforms, as well as a standalone technology, for managing diabetes in pediatric populations.

Traceability to a primary reference measurement procedure (ID-LCMS); A key step in validating the clinical accuracy and safety of hospital blood glucose monitoring systems

OBJECTIVE

A key step in the evaluation of the accuracy of blood glucose monitoring systems (BGMS) is using a comparator method aligned to a high order definitive reference method. We describe how we achieved traceability to an isotope dilution liquid chromatography mass spectrometry (ID-LCMS) method. We used ID-LCMS to evaluate the accuracy and specificity of two hospital BGMS used in China.

METHOD

ID-LCMS was used to verify the calibration alignment of the laboratory plasma hexokinase reference method using NIST standard reference material and clinical samples. The ID-LCMS aligned hexokinase method was used to evaluate the clinical accuracy of two BGMS in hospitalized patients. System accuracy was evaluated using Chinese consensus guidelines. BGMS accuracy was also assessed with interference factors known to be present in critically ill patients' blood.

RESULTS

The laboratory plasma hexokinase reference method was shown to calibrate closely with ID-LCMS. Two BGMS demonstrated good correlation with this reference method. Only one BGMS met the Chinese guidelines. The interference factors didn't influence this BGMS but adversely affected the clinical accuracy of the other.

CONCLUSIONS

We advocate that our IDMS calibration alignment approach for ensuring the accuracy of the glucose reference method should be adopted in evaluations assessing the accuracy of blood glucose monitoring systems.

The Effect of Reduced Self-Monitored Blood Glucose Testing After Adoption of Continuous Glucose Monitoring on Hemoglobin A1c and Time in Range

The effectiveness of real-time continuous glucose monitoring (rtCGM) in adults with diabetes treated with insulin injections was evaluated in the 24-week DIAMOND clinical trial comparing rtCGM users to a control group using self-monitored blood glucose (SMBG) testing ( Clinicaltrials.gov : NCT02282397). All participants were instructed to use SMBG results for diabetes management decisions; however, SMBG testing frequency varied within the rtCGM group. This brief report evaluated how SMBG frequency changes in the rtCGM group were correlated with glycemic outcomes in the same trial. Baseline and end-of-study hemoglobin A1c (HbA1c) levels, percentages of CGM values in the 70-180 mg/dL target range (time in range [TIR]), mean of daily differences (MODD), and glycemic coefficients of variation (CVs) were compared. The rtCGM group analyzed included 175 participants-99 with type 1 diabetes (T1D) and 76 with type 2 diabetes (T2D). When comparing participants whose SMBG testing frequency decreased by >1/day versus ≤1/day, mean change in HbA1c was similar (-0.9 ± 0.7 percentage points in both groups, P = 0.59), as was change in TIR (+3.9 ± 14.3 vs. +5.7 ± 13.7 percentage points, respectively, P = 0.39). Likewise, when comparing participants in the highest and lowest quartiles of SMBG frequency reduction (≥2.2 vs. ≤0.4 fewer tests/day, respectively), changes in HbA1c (-0.8 ± 0.6 vs. -0.9 ± 0.6 percentage points, respectively, P = 0.52) and TIR (+4.8 ± 13.2 vs. +5.6 ± 12.7 percentage points, respectively, P = 0.98) were similar. The mean (standard deviation [SD]) change in MODD was -8.3 mg/dL (14.8) and -5.5 mg/dL (14.7) for participants who reduced their SMBG frequency by >1 test/day and ≤1 test/day, respectively; the mean (SD) change in CV was -3.6% (5.0) and -1.6% (5.1) for participants who reduced their SMBG frequency by >1 test/day and ≤1 test/day, respectively. These findings suggest that individuals who decrease the frequency of SMBG testing can effectively base some of their diabetes-related treatment decisions on glucose concentrations, trend information, and alarms provided by their rtCGM systems.

Technology in the management of type 1 diabetes mellitus - current status and future prospects

Type 1 diabetes mellitus (T1DM) represents 5-10% of diabetes cases worldwide. The incidence of T1DM is increasing, and there is no immediate prospect of a cure. As such, lifelong management is required, the burden of which is being eased by novel treatment modalities, particularly from the field of diabetes technologies. Continuous glucose monitoring has become the standard of care and includes factory-calibrated subcutaneous glucose monitoring and long-term implantable glucose sensing. In addition, considerable progress has been made in technology-enabled glucose-responsive insulin delivery. The first hybrid insulin-only closed-loop system has been commercialized, and other closed-loop systems are under development, including dual-hormone glucose control systems. This Review focuses on well-established diabetes technologies, including glucose sensing, pen-based insulin delivery, data management and data analytics. We also cover insulin pump therapy, threshold-based suspend, predictive low-glucose suspend and single-hormone and dual-hormone closed-loop systems. Clinical practice recommendations for insulin pump therapy and continuous glucose monitoring are presented, and ongoing research and future prospects are highlighted. We conclude that the management of T1DM is improved by diabetes technology for the benefit of the majority of people with T1DM, their caregivers and guardians and health-care professionals treating patients with T1DM.

Accuracy of a Factory-Calibrated, Real-Time Continuous Glucose Monitoring System During 10 Days of Use in Youth and Adults with Diabetes

BACKGROUND

Frequent use of continuous glucose monitoring (CGM) systems is associated with improved glycemic outcomes in persons with diabetes, but the need for calibrations and sensor insertions are often barriers to adoption. In this study, we evaluated the performance of G6, a sixth-generation, factory-calibrated CGM system specified for 10-day wear.

METHODS

The study enrolled participants of ages 6 years and up with type 1 diabetes or insulin-treated type 2 diabetes at 11 sites in the United States. Participation involved one sensor wear period of up to 10 days. Adults wore the system on the abdomen; youth of ages 6-17 years could choose to wear it on the abdomen or upper buttocks. Clinic sessions for frequent comparison with reference blood glucose measurements took place on days 1, 4-5, 7, and/or 10. Participants of ages 13 years and up underwent purposeful supervised glucose manipulation during in-clinic sessions. During the study, participants calibrated the systems once daily. However, analysis was performed on glucose values that were derived from reprocessed raw sensor data, independently of self-monitored blood glucose values used for calibration. Reprocessing used assigned sensor codes and a factory-calibration algorithm. Performance evaluation included the proportion of CGM values that were within ±20% of reference glucose values >100 mg/dL or within ±20 mg/dL of reference glucose values ≤100 mg/dL (%20/20), the analogous %15/15, and the mean absolute relative difference (MARD, expressed as a percentage) between temporally matched CGM and reference values.

RESULTS

Data from 262 study participants (21,569 matched CGM reference pairs) were analyzed. The overall %15/15, %20/20, and MARD were 82.4%, 92.3%, and 10.0%, respectively. Matched pairs from 134 adults and 128 youth of ages 6-17 years were similar with respect to %20/20 (92.4% and 91.9%) and MARD (9.9% and 10.1%). Overall %20/20 values on days 1 and 10 of sensor wear were 88.6% and 90.6%, respectively. The system's "Urgent Low Soon" (predictive of hypoglycemia within 20 min) hypoglycemia alert was correctly provided 84% of the time within 30 min before impending biochemical hypoglycemia (<70 mg/dL). The 10-day sensor survival rate was 87%.

CONCLUSION

The new factory-calibrated G6 real-time CGM system provides accurate readings for 10 days and removes several clinical barriers to broader CGM adoption.

Limits to the Evaluation of the Accuracy of Continuous Glucose Monitoring Systems by Clinical Trials

Systems for continuous glucose monitoring (CGM) are evolving quickly, and the data obtained are expected to become the basis for clinical decisions for many patients with diabetes in the near future. However, this requires that their analytical accuracy is sufficient. This accuracy is usually determined with clinical studies by comparing the data obtained by the given CGM system with blood glucose (BG) point measurements made with a so-called reference method. The latter is assumed to indicate the correct value of the target quantity. Unfortunately, due to the nature of the clinical trials and the approach used, such a comparison is subject to several effects which may lead to misleading results. While some reasons for the differences between the values obtained with CGM and BG point measurements are relatively well-known (e.g., measurement in different body compartments), others related to the clinical study protocols are less visible, but also quite important. In this review, we present a general picture of the topic as well as tools which allow to correct or at least to estimate the uncertainty of measures of CGM system performance.

Accuracy of flash glucose monitoring and continuous glucose monitoring technologies: Implications for clinical practice

Continuous glucose monitoring and flash glucose monitoring technologies measure glucose in the interstitial fluid and are increasingly used in diabetes care. Their accuracy, key to effective glycaemic management, is usually measured using the mean absolute relative difference of the interstitial fluid sensor compared to reference blood glucose readings. However, mean absolute relative difference is not standardised and has limitations. This review aims to provide a consensus opinion on assessing accuracy of interstitial fluid glucose sensing technologies. Mean absolute relative difference is influenced by glucose distribution and rate of change; hence, we express caution on the reliability of comparing mean absolute relative difference data from different study systems and conditions. We also review the pitfalls associated with mean absolute relative difference at different glucose levels and explore additional ways of assessing accuracy of interstitial fluid devices. Importantly, much data indicate that current practice of assessing accuracy of different systems based on individualised mean absolute relative difference results has limitations, which have potential clinical implications. Healthcare professionals must understand the factors that influence mean absolute relative difference as a metric for accuracy and look at additional assessments, such as consensus error grid analysis, when evaluating continuous glucose monitoring and flash glucose monitoring systems in diabetes care. This in turn will ensure that management decisions based on interstitial fluid sensor data are both effective and safe.

Real-time continuous glucose monitoring in adults with type 1 diabetes and impaired hypoglycaemia awareness or severe hypoglycaemia treated with multiple daily insulin injections (HypoDE): a multicentre, randomised controlled trial

BACKGROUND

The effectiveness of real-time continuous glucose monitoring (rtCGM) in avoidance of hypoglycaemia among high-risk individuals with type 1 diabetes treated with multiple daily insulin injections (MDI) is unknown. We aimed to ascertain whether the incidence and severity of hypoglycaemia can be reduced through use of rtCGM in these individuals.

METHODS

The HypoDE study was a 6-month, multicentre, open-label, parallel, randomised controlled trial done at 12 diabetes practices in Germany. Eligible participants had type 1 diabetes and a history of impaired hypoglycaemia awareness or severe hypoglycaemia during the previous year. All participants wore a masked rtCGM system for 28 days and were then randomly assigned to 26 weeks of unmasked rtCGM (Dexcom G5 Mobile system) or to the control group (continuing with self-monitoring of blood glucose). Block randomisation with 1:1 allocation was done centrally, with the study site as the stratifying variable. Masking of participants and study sites was not possible. Control participants wore a masked rtCGM system during the follow-up phase (weeks 22-26). The primary outcome was the baseline-adjusted number of hypoglycaemic events (defined as glucose ≤3·0 mmol/L for ≥20 min) during the follow-up phase. The full dataset analysis comprised participants who wore the rtCGM system during the baseline and follow-up phases. The intention-to-treat analysis comprised all randomised participants. This trial is registered with ClinicalTrials.gov, number NCT02671968.

FINDINGS

Between March 4, 2016, and Jan 12, 2017, 149 participants were randomly assigned (n=74 to the control group; n=75 to the rtCGM group) and 141 completed the follow-up phase (n=66 in the control group, n=75 in the rtCGM group). The mean number of hypoglycaemic events per 28 days among participants in the rtCGM group was reduced from 10·8 (SD 10·0) to 3·5 (4·7); reductions among control participants were negligible (from 14·4 [12·4] to 13·7 [11·6]). Incidence of hypoglycaemic events decreased by 72% for participants in the rtCGM group (incidence rate ratio 0·28 [95% CI 0·20-0·39], p<0·0001). 18 serious adverse events were reported: seven in the control group, ten in the rtCGM group, and one before randomisation. No event was considered to be related to the investigational device.

INTERPRETATION

Usage of rtCGM reduced the number of hypoglycaemic events in individuals with type 1 diabetes treated by MDI and with impaired hypoglycaemia awareness or severe hypoglycaemia.

FUNDING

Dexcom Inc.

Automated Insulin Delivery Systems: Hopes and Expectations of Family Members

BACKGROUND

This study examines the hopes and expectations that children, adolescents, and adults with type 1 diabetes and their families have for new automated insulin delivery systems. The study also aims to examine how the automated insulin delivery system may impact family functioning and individual members' psychosocial adjustment.

METHODS

Forty-eight semistructured focus groups (n = 195) and 89 individual interviews were conducted with children, adolescents, and adults with type 1 diabetes and parents and partners. Coders reviewed results in key themes most likely to contain references to the family system. Clusters were analyzed using thematic analysis to identify participants' salient hopes and expectations of how new technology may impact family relationships and individual psychosocial functioning.

RESULTS

Three main themes emerged for participants' hopes and expectations for implementation of the automated insulin delivery system. First, there is an expectation that this diabetes technology will alleviate diabetes-specific worry and burden for the people with diabetes and other family members. Second, there is also hope that this system may reduce day-to-day stress and, third, improve family relationships.

CONCLUSIONS

The unique perspective of a broad age group provides insight into how individuals and families creatively address the multiple tasks required in daily diabetes management. Study findings elucidate the very high hopes and expectations held by those managing type 1 diabetes and the impact this new technology may have on family relationships. Awareness of these hopes and expectations is important for developers and clinicians in addressing potential challenges to uptake and to ensure that expectations are set appropriately.

Accuracy, User Acceptability, and Safety Evaluation for the FreeStyle Libre Flash Glucose Monitoring System When Used by Pregnant Women with Diabetes

BACKGROUND

Accuracy of the FreeStyle Libre™ Flash Glucose Monitoring System has not been evaluated in pregnant women with diabetes. The aim of this study was to determine accuracy (compared to self-monitoring of blood glucose [SMBG]), clinical safety, and acceptability of the FreeStyle Libre System when used at home by this population.

MATERIALS AND METHODS

Seventy-four participants, with type 1 (T1D, n = 24), type 2 (T2D, n = 11), or gestational (n = 39) diabetes, were enrolled across 13 sites (9 in United Kingdom, 4 in Austria). Average gestation was 26.6 ± 6.8 weeks (mean ± standard deviation), age was 30.5 ± 5.1 years, diabetes duration was 13.1 ± 7.3 years for T1D and 3.2 ± 2.5 years for T2D, and 49/74 (66.2%) used insulin to manage their diabetes. Sensors were worn for up to 14 days. Sensor glucose values (masked) were compared with capillary SMBG values (made at least 4 times/day).

RESULTS

Clinical accuracy of sensor results versus SMBG results was demonstrated, with 88.1% and 99.8% of results within Zone A and Zones A and B of the Consensus Error Grid, respectively. Overall mean absolute relative difference was 11.8%. Sensor accuracy was unaffected by the type of diabetes, the stage of pregnancy, whether insulin was used, age or body mass index. User questionnaires indicated high levels of satisfaction with sensor wear, system use, and comparison to SMBG. There were no unanticipated device-related adverse events.

CONCLUSIONS

Good agreement was demonstrated between the FreeStyle Libre System and SMBG. Accuracy of the system was unaffected by patient characteristics, indicating that the system is safe and accurate to use by pregnant women with diabetes.

Could Age, Sex and Physical Fitness Affect Blood Glucose Responses to Exercise in Type 1 Diabetes?

Closed-loop systems for patients with type 1 diabetes are progressing rapidly. Despite these advances, current systems may struggle in dealing with the acute stress of exercise. Algorithms to predict exercise-induced blood glucose changes in current systems are mostly derived from data involving relatively young, fit males. Little is known about the magnitude of confounding variables such as sex, age, and fitness level-underlying, uncontrollable factors that might influence blood glucose control during exercise. Sex-related differences in hormonal responses to physical exercise exist in studies involving individuals without diabetes, and result in altered fuel metabolism during exercise. Increasing age is associated with attenuated catecholamine responses and lower carbohydrate oxidation during activity. Furthermore, higher fitness levels can alter hormonal and fuel selection responses to exercise. Compounding the limited research on these factors in the metabolic response to exercise in type 1 diabetes is a limited understanding of how these variables affect blood glucose levels during different types, timing and intensities of activity in individuals with type 1 diabetes (T1D). Thus, there is currently insufficient information to model a closed-loop system that can predict them accurately and consistently prevent hypoglycemia. Further, studies involving both sexes, along with a range of ages and fitness levels, are needed to create a closed-loop system that will be more precise in regulating blood glucose during exercise in a wide variety of individuals with T1D.

Effect of BGM Accuracy on the Clinical Performance of CGM: An In-Silico Study

BACKGROUND

Standard management of type 1 diabetes (T1D) relies on blood glucose monitoring based on a range of technologies from self-monitoring of blood glucose (BGM) to continuous glucose monitoring (CGM). Even as CGM technology matures, patients utilize BGM for calibration and dosing. The question of how the accuracy of both technologies interact is still not well understood.

METHODS

We use a recently developed data-driven simulation approach to characterize the relationship between CGM and BGM accuracy especially how BGM accuracy impacts CGM performance in four different use cases with increasing levels of reliance on twice daily calibrated CGM. Simulations are used to estimate clinical outcomes and isolate CGM and BGM accuracy characteristics that drive performance.

RESULTS

Our results indicate that meter (BGM) accuracy, and more specifically systematic positive or negative bias, has a significant effect on clinical performance (HbA1c and severe hypoglycemia events) in all use-cases generated for twice daily calibrated CGMs. Moreover, CGM sensor accuracy can amplify or mitigate, but not eliminate these effects.

CONCLUSION

As a system, BGM and CGM and their mode of use (use-case) interact to determine clinical outcomes. Clinical outcomes (eg, HbA1c, severe hypoglycemia, time in range) can be closely approximated by linear relationships with two BGM accuracy characteristics, namely error and bias. In turn, the coefficients of this linear relationship are determined by the use-case and by CGM accuracy (MARD).

Accuracy of a CGM Sensor in Pediatric Subjects With Type 1 Diabetes. Comparison of Three Insertion Sites: Arm, Abdomen, and Gluteus

BACKGROUND

Patients with diabetes, especially pediatric ones, sometimes use continuous glucose monitoring (CGM) sensor in different positions from the approved ones. Here we compare the accuracy of Dexcom® G5 CGM sensor in three different sites: abdomen, gluteus (both approved) and arm (off-label).

METHOD

Thirty youths, 5-9 years old, with type 1 diabetes (T1D) wore the sensor during a clinical trial where frequent self-monitoring of blood glucose (SMBG) measurements were obtained. Sensor was inserted in different sites according to the patient habit. Accuracy metrics include absolute relative difference (ARD) and absolute difference (AD) of CGM with respect to SMBG. The three sites were compared with ANOVA. If the test detected a difference, an additional pair-wise comparison was performed.

RESULTS

Overall, no accuracy difference was detected: the mean ARD was 13.3% (SD = 13.5%) for abdomen, 13.4% (12.9%) for arm and 12.9% (20.2%) for gluteus ( P value = .83); the mean AD was 17.0 mg/dl (17.2 mg/dl) for abdomen, 17.2 mg/dl (17.1 mg/dl) for arm and 18.3 mg/dl (18.5 mg/dl) for gluteus ( P value = .30). In hypo- and euglycemia ARD ( P value = .87 and .15, respectively), and AD ( P value = .68 and .37, respectively) were not statistically different. At variance, in hyperglycemia, a significant difference was detected between the two approved sites, abdomen and gluteus (ΔARD = -2.2% [CI = -4.2%, -0.1%], P value = .04), whereas the comparisons with the off-label location, arm-abdomen, and arm-gluteus were not significant.

CONCLUSIONS

These results suggest that the accuracy of the sensor placed on the arm was not significantly different with respect to the two approved insertion sites (abdomen and gluteus). Larger, randomized trials are needed to draw final conclusions.