Continuous Glucose Monitoring: A Perspective on Its Past, Present, and Future Applications for Diabetes Management

Chronobiologically-informed features from CGM data provide unique information for XGBoost prediction of longer-term glycemic dysregulation in 8,000 individuals with type-2 diabetes

Type 2 Diabetes causes dysregulation of blood glucose, which leads to long-term, multi-tissue damage. Continuous glucose monitoring devices are commercially available and used to track glucose at high temporal resolution so that individuals can make informed decisions about their metabolic health. Algorithms processing these continuous data have also been developed that can predict glycemic excursion in the near future. These data might also support prediction of glycemic stability over longer time horizons. In this work, we leverage longitudinal Dexcom continuous glucose monitoring data to test the hypothesis that additional information about glycemic stability comes from chronobiologically-informed features. We develop a computationally efficient multi-timescale complexity index, and find that inclusion of time-of-day complexity features increases the performance of an out-of-the-box XGBoost model in predicting the change in glucose across days. These findings support the use of chronobiologically-inspired and explainable features to improve glucose prediction algorithms with relatively long time-horizons.

Retained Continuous Glucose Monitor Sensor Wire Fragments Presenting as a Swollen Nodule of the Thigh

A 2-year-old male with genetic-negative, diazoxide-responsive hyperinsulinism presented with a knot in his left, lateral thigh. His hypoglycemia was managed with diazoxide, chlorothiazide, and monitoring via a Dexcom G6 continuous glucose monitor (CGM). X-ray showed 3 metallic wire foreign bodies, consistent with retained Dexcom sensor wires. He was referred to surgery for foreign body removal. Intraoperative fluoroscopy revealed 4 pieces of wire. Two superficial pieces were removed, but 2 small pieces deep to the fascia remained because of significant risk of injury or bleeding if removal was attempted. We present this case to increase awareness in the literature regarding retention of CGM wires. Raised nodules at sites of CGM insertion without fluctuation or erythema and persistent pain should raise suspicion for retention of sensor wires.

Exploring Symptom Management Experiences Among College Students With Type 1 Diabetes Mellitus Using a Theoretical Framework: A Qualitative Study

PURPOSE

The purpose of this study was to explore symptom management experiences among college students with type 1 diabetes mellitus (T1DM). Limited qualitative data using a theoretical framework exist that explore the self-care behavior processes for symptom management.

METHODS

A qualitative approach was used for this study. The middle-range theory of self care of chronic illness served as a framework for data collection and analysis procedures. Data collection included distributing a survey to collect participants' demographic and sociodemographic data and utilizing a semi-structured interview guide to conduct one-on-one interviews with 31 participants. Interviews occurred via Zoom (n = 28) and in person (n = 3). Interview transcripts were uploaded in NVivo for data management. The research team created a codebook using theoretical constructs to assist with thematic analysis. Data are representative of a sample whose characteristics include undergraduate students ages 18 to 23 living with T1DM for 2 years or more who attended large, public, 4-year universities located in the southeastern United States.

RESULTS

Three main themes were created using theoretical constructs: symptom detection experiences, symptom interpretation experiences, and symptom response experiences. Two subthemes were identified for each theme. Participants engaged in symptom management for blood glucose regulation through detecting changes in their blood glucose physiologically and via technology. Additionally, symptom interpretation involved analyzing blood glucose trends and determining common causes of blood glucose changes. Symptom response included immediately addressing hypoglycemia but delayed responses addressing hyperglycemia.

CONCLUSIONS

Challenges were present responding to hypoglycemia; therefore, additional research is warranted to improve symptom response skills.

Probing glucose-sensitive hydrogel resonators with a portable medical ultrasound imaging system

Diabetes, a prevalent chronic disease, necessitates effective blood glucose monitoring to manage and mitigate its serious complications. Recent studies have introduced a novel approach for implantable continuous glucose monitoring (CGM) utilizing glucose-sensitive smart hydrogel-based resonator sensing elements with ultrasound (US) readout. By using mechanically compliant and potentially highly biocompatible smart hydrogel materials as well as medical ultrasound, this approach provides an effective and minimally invasive CGM solution. While previous results demonstrated proof-of-principle in both in vitro and in vivo experiments, they still used standard and less mobile medical ultrasound equipment, and thus limits the ease-of-use of the approach. In this study, the transition from this full-size and less mobile module to a portable benchtop medical US equipment for exciting and reading out the hydrogel resonators is explored. The results demonstrate the ability of the portable US module to detect the small changes in Mean Gray Value (MGV) in ultrasound images that correspond to the altered state of the smart hydrogel structures in varying glucose environments while maintaining good signal quality. This development represents a step towards a more mobile smart hydrogel resonator-based CGM system that aims to enhance diabetes management and improve patient outcomes.

Detection of Hypoglycemia and Hyperglycemia Using Noninvasive Wearable Sensors: Electrocardiograms and Accelerometry

BACKGROUND

Monitoring glucose excursions is important in diabetes management. This can be achieved using continuous glucose monitors (CGMs). However, CGMs are expensive and invasive. Thus, alternative low-cost noninvasive wearable sensors capable of predicting glycemic excursions could be a game changer to manage diabetes.

METHODS

In this article, we explore two noninvasive sensor modalities, electrocardiograms (ECGs) and accelerometers, collected on five healthy participants over two weeks, to predict both hypoglycemic and hyperglycemic excursions. We extract 29 features encompassing heart rate variability features from the ECG, and time- and frequency-domain features from the accelerometer. We evaluated two machine learning approaches to predict glycemic excursions: a classification model and a regression model.

RESULTS

The best model for both hypoglycemia and hyperglycemia detection was the regression model based on ECG and accelerometer data, yielding 76% sensitivity and specificity for hypoglycemia and 79% sensitivity and specificity for hyperglycemia. This had an improvement of 5% in sensitivity and specificity for both hypoglycemia and hyperglycemia when compared with using ECG data alone.

CONCLUSIONS

Electrocardiogram is a promising alternative not only to detect hypoglycemia but also to predict hyperglycemia. Supplementing ECG data with contextual information from accelerometer data can improve glucose prediction.

Reproducibility of continuous glucose monitoring results under real-life conditions in an adult population: a functional data analysis

Continuous glucose monitoring systems (CGM) are a very useful tool to understand the behaviour of glucose in different situations and populations. Despite the widespread use of CGM systems in both clinical practice and research, our understanding of the reproducibility of CGM data remains limited. The present work examines the reproducibility of the results provided by a CGM system in a random sample of a free-living adult population, from a functional data analysis approach. Functional intraclass correlation coefficients (ICCs) and their 95% confidence intervals (CI) were calculated to assess the reproducibility of CGM results in 581 individuals. 62% were females 581 participants (62% women) mean age 48 years (range 18-87) were included, 12% had previously been diagnosed with diabetes. The inter-day reproducibility of the CGM results was greater for subjects with diabetes (ICC 0.46 [CI 0.39-0.55]) than for normoglycaemic subjects (ICC 0.30 [CI 0.27-0.33]); the value for prediabetic subjects was intermediate (ICC 0.37 [CI 0.31-0.42]). For normoglycaemic subjects, inter-day reproducibility was poorer among the younger (ICC 0.26 [CI 0.21-0.30]) than the older subjects (ICC 0.39 [CI 0.32-0.45]). Inter-day reproducibility was poorest among normoglycaemic subjects, especially younger normoglycaemic subjects, suggesting the need to monitor some patient groups more often than others.

Is graphene the rock upon which new era continuous glucose monitors could be built?

Diabetes mellitus' (DM) prevalence worldwide is estimated to be around 10% and is expected to rise over the next decades. Monitoring blood glucose levels aims to determine whether glucose targets are met to minimize the risk for the development of symptoms related to high or low blood sugar and avoid long-term diabetes complications. Continuous glucose monitoring (CGMs) systems emerged almost two decades ago and have revolutionized the way diabetes is managed. Especially in Type 1 DM, the combination of a CGM with an insulin pump (known as a closed-loop system or artificial pancreas) allows an autonomous regulation of patients' insulin with minimal intervention from the user. However, there is still an unmet need for high accuracy, precision and repeatability of CGMs. Graphene was isolated in 2004 and found immediately fertile ground in various biomedical applications and devices due to its unique combination of properties including its high electrical conductivity. In the last decade, various graphene family nanomaterials have been exploited for the development of enzymatic and non-enzymatic biosensors to determine glucose in biological fluids, such as blood, sweat, and so on. Although great progress has been achieved in the field, several issues need to be addressed for graphene sensors to become a predominant material in the new era of CGMs.

Community-based non-pharmacological interventions for pregnant women with gestational diabetes mellitus: a systematic review

BACKGROUND

Non-pharmacological interventions are the first line of Gestational diabetes mellitus (GDM) management. Community-based interventions are cheaper, more accessible, with higher patient satisfaction.

OBJECTIVES

To systematically review community-based non-pharmacological interventions and evaluate their effectiveness for GDM.

SEARCH STRATEGY

Twelve bibliographic databases and reference list of related studies from inception until January 2022.

SELECTION CRITERIA

All primary studies of community-based non-pharmacological interventions for GDM reported in English which investigated any behavioural or clinical outcome(s).

DATA COLLECTION AND ANALYSIS

Data were extracted using modified Cochrane's data extraction template. Studies were evaluated using Cochrane Collaboration's risk of bias tool. Narrative synthesis was used to summarise findings. This study is registered with PROSPERO (CRD42021257634).

MAIN RESULTS

Twenty-seven studies involving 6,242 pregnant women with GDM investigated self-management programmes, medical nutrition/diet therapy, exercise/physical activity, combined diet and exercise, calcium plus vitamin D supplementation, and continuous glucose monitoring. Self-management programmes were more effective than routine care in improving self-efficacy, two-hour postprandial blood glucose, and lifestyle behaviours but were as effective as routine care in improving infant birth weight. Self-management programmes were superior to or as effective as usual care in improving fasting blood glucose, blood glucose control, glycated haemoglobin, macrosomia, and preterm delivery. Medical nutrition/diet therapy was more effective than usual care in improving postprandial blood glucose levels. Postprandial blood glucose levels were better improved by regular supervised exercise plus daily brisk walks or a daily walking intervention than routine obstetric care or no treatment. The effects of exercise/physical activity programmes were mostly inconsistent for other outcomes. Diet and exercise were superior to diet alone in reducing maternal weight gain although there were similar outcomes for other pregnancy and foetal outcomes. Limited or conflicting evidence was found for other outcomes and interventions including calcium and vitamin D supplementation and continuous glucose monitoring intervention.

CONCLUSIONS

Community-based non-pharmacological interventions are more effective than placebo; and are more or as effective as usual care. Self-management programmes and medical nutrition/diet therapy had the most promising GDM outcomes.

FUNDING

There was no funding for this study. The study design, data collection, data analysis and interpretation, and writing of this manuscript were not influenced externally by any funder.

Human continuous glucose monitors for measurement of glucose in dairy cows

If validated for use in dairy cattle, interstitial continuous glucose monitors (CGMs) could be easily implemented, informative tools for research, clinical, and perhaps even on-farm applications. To evaluate their efficacy, 2 experiments were conducted, during which lactating Holstein cows were fit with indwelling jugular catheters, as well as FreeStyle Libre (FSL; Abbott) and Dexcom G6 (DexCom Inc.) CGMs secured either behind their polls, lateral to their ears, or beneath their pin bones on their upper rear legs. During the first experiment, blood (measured with a handheld glucometer) and interstitial glucose measurements were collected from 13 cows every 4 h for 96 h. In the second experiment, the same measurements were collected from 8 cows every 15 min for 6 h. At the mid-point of the sampling period (3 h), cows received a bolus dose of dextrose to facilitate comparisons across a broad range of glucose concentrations. Results from both experiments determined that functional longevity of the sensors was greatest for those sensors secured near the ear. Likewise, interstitial measurements from the ear sensors were most closely correlated with blood glucose concentrations (r = 0.82 and r = 0.71 for FSL ear and Dexcom G6 ear, respectively). Unfortunately, accuracy calculated as absolute relative error was low, at 60.7% or less. As a result of the low accuracy, even though both ear sensors detected an increase in glucose concentrations following the bolus dose, neither produced results exactly matching blood glucose measurements. The results of this work indicate that the FSL and Dexcom G6 CGMs are not currently capable of replacing blood-based glucose measurements.

The Short-Term Effects and Tolerability of Low-Viscosity Soluble Fibre on Gastroparesis Patients: A Pilot Clinical Intervention Study

Gastroparesis is a motility disorder that causes severe gastric symptoms and delayed gastric emptying, where the majority of sufferers are females (80%), with 29% of sufferers also diagnosed with Type-1 or Type-2 diabetes. Current clinical recommendations involve stringent dietary restriction and includes the avoidance and minimization of dietary fibre. Dietary fibre lowers the glycaemic index of food, reduces inflammation and provides laxation. Lack of dietary fibre in the diet can affect long-term gastrointestinal health. Our previously published rheological study demonstrated that "low-viscosity" soluble fibres could be a potentially tolerable source of fibre for the gastroparetic population. A randomised controlled crossover pilot clinical study was designed to compare Partially-hydrolysed guar gum or PHGG (test fibre 1), gum Arabic (test fibre 2), psyllium husk (positive control) and water (negative control) in mild-to-moderate symptomatic gastroparesis patients (requiring no enteral tube feeding). The principal aim of the study was to determine the short-term physiological effects and tolerability of the test fibres. In n = 10 female participants, post-prandial blood glucose, gastroparesis symptoms, and breath test measurements were recorded. Normalized clinical data revealed that test fibres PHGG and gum Arabic were able to regulate blood glucose comparable to psyllium husk, while causing far fewer symptoms, equivalent to negative control. The test fibres did not greatly delay mouth-to-caecum transit, though more data is needed. The study data looks promising, and a longer-term study investigating these test fibres is being planned.

Non-invasive Monitoring of Three Glucose Ranges Based On ECG By Using DBSCAN-CNN

Autonomic nervous system (ANS) can maintain homeostasis through the coordination of different organs including heart. The change of blood glucose (BG) level can stimulate the ANS, which will lead to the variation of Electrocardiogram (ECG). Considering that the monitoring of different BG ranges is significant for diabetes care, in this paper, an ECG-based technique was proposed to achieve non-invasive monitoring with three BG ranges: low glucose level, moderate glucose level, and high glucose level. For this purpose, multiple experiments that included fasting tests and oral glucose tolerance tests were conducted, and the ECG signals from 21 adults were recorded continuously. Furthermore, an approach of fusing density-based spatial clustering of applications with noise and convolution neural networks (DBSCAN-CNN) was presented for ECG preprocessing of outliers and classification of BG ranges based ECG. Also, ECG's important information, which was related to different BG ranges, was graphically visualized. The result showed that the percentages of accurate classification were 87.94% in low glucose level, 69.36% in moderate glucose level, and 86.39% in high glucose level. Moreover, the visualization results revealed that the highlights of ECG for the different BG ranges were different. In addition, the sensitivity of prediabetes/diabetes screening based on ECG was up to 98.48%, and the specificity was 76.75%. Therefore, we conclude that the proposed approach for BG range monitoring and prediabetes/diabetes screening has potentials in practical applications.

Continuous Glucose Monitoring Devices: Past, Present, and Future Focus on the History and Evolution of Technological Innovation

The concept of implantable glucose sensors has been promulgated for more than 40 years. It is now accepted that continuous glucose monitoring (CGM) increases quality of life by allowing informed diabetes management decisions as a result of more optimized glucose control. The focus of this article is to provide a brief overview of the CGM market history, emerging technologies, and the foreseeable challenges for the next CGM generations as well as proposing possible solutions in an effort to advance the next generation of implantable sensor.

New Paradigm of Personalized Glycemic Control Using Glucose Temporal Density Histograms

BACKGROUND

Current methods used to assess glycemic control use averaged measures and provide little information on the glycemic pathology of the patients. In this article we propose visual tools and their related mathematical formulas that allow for improved characterization of the glycemic behavior and achieve better glycemic control.

METHODS

We present a reanalysis of published data, based on SMBG measurements from clinical trials of both men and women older than 18 years who were either healthy volunteers, prediabetes, or type 1 or type 2 diabetes. New graphic visualizations of glycemia as well as mathematical formulas that describe the glycemic behavior are presented and described, as well as suggested methods for their use to improve glycemic control.

RESULTS

Patients with different problems in their glycemic control had different histogram shapes. In addition, patients who had the same HbA1c level at the time of the trial revealed significantly different glucose histograms with different shapes, variability and glycemic burden. The derived graphic visualizations provided information about the temporal evolution of the glycemic control.

CONCLUSIONS

A paradigm change of the existing model of diabetes control is proposed, shifting from standardized treatment algorithms based on HbA1c follow-up to a new controlling approach that is based on the personal glucose density histogram. The histogram is an informative, detailed tool for the current patient glycemic behavior, and a future histogram can be targeted for a successful treatment. In addition, the glucose burden and the glucose severity index are proposed as informative markers for successful treatment. This is applicable to any glycemic data, by means of invasive and noninvasive glucometers.

Adoption Barriers for Continuous Glucose Monitoring and Their Potential Reduction With a Fully Implanted System: Results From Patient Preference Surveys

IN BRIEF A patient-centered approach to device design can provide important advantages in optimizing diabetes care technology for broadened adoption and improved adherence. Results from two surveys of people with diabetes and the parents of children with diabetes (n = 1,348) regarding continuous glucose monitoring (CGM) devices reveal the importance of the concept of "user burden" in patients' and caregivers' evaluations of the acceptability of available devices. Survey respondents' strongly favorable reactions to a proposed 1-year, fully implanted CGM device with no skin-attached components further confirm that minimizing system obtrusiveness will likely be of significant value in reducing hurdles to CGM device use and adherence.