scholarly journals Delays in Minimally Invasive Continuous Glucose Monitoring Devices: A Review of Current Technology

2009 ◽  
Vol 3 (5) ◽  
pp. 1207-1214 ◽  
Author(s):  
D. Barry Keenan ◽  
John J. Mastrototaro ◽  
Gayane Voskanyan ◽  
Garry M. Steil
Keyword(s):  
Blood Glucose ◽  
Minimally Invasive ◽  
Continuous Glucose Monitoring ◽  
Ex Vivo ◽  
Time Lag ◽  
Glucose Monitoring ◽  
Time Lags ◽  
Continuous Glucose Monitor ◽  
Continuous Glucose Monitors

Through the use of enzymatic sensors—inserted subcutaneously in the abdomen or ex vivo by means of microdialysis fluid extraction—real-time minimally invasive continuous glucose monitoring (CGM) devices estimate blood glucose by measuring a patient's interstitial fluid (ISF) glucose concentration. Signals acquired from the interstitial space are subsequently calibrated with capillary blood glucose samples, a method that has raised certain questions regarding the effects of physiological time lags and of the duration of processing delays built into these devices. The time delay between a blood glucose reading and the value displayed by a continuous glucose monitor consists of the sum of the time lag between ISF and plasma glucose, in addition to the inherent electrochemical sensor delay due to the reaction process and any front-end signal-processing delays required to produce smooth traces. Presented is a review of commercially available, minimally invasive continuous glucose monitors with manufacturer-reported device delays. The data acquisition process for the Medtronic MiniMed (Northridge, CA) continuous glucose monitoring system—CGMS® Gold—and the Guardian® RT monitor is described with associated delays incurred for each processing step. Filter responses for each algorithm are examined using in vitro hypoglycemic and hyperglycemic clamps, as well as with an analysis of fast glucose excursions from a typical meal response. Results demonstrate that the digital filters used by each algorithm do not cause adverse effects to fast physiologic glucose excursions, although nonphysiologic signal characteristics can produce greater delays.

scholarly journals Assessment of a Noninvasive Chronic Glucose Monitoring System in Euglycemic and Diabetic Swine (Sus scrofa)

2020 ◽  
Author(s):  
Rebecca A Ober ◽  
Gail E Geist
Keyword(s):  
Blood Glucose ◽  
Monitoring System ◽  
Continuous Glucose Monitoring ◽  
Point Of Care ◽  
Glucose Monitoring ◽  
Continuous Glucose Monitoring System ◽  
Serum Chemistry ◽  
Continuous Glucose Monitor ◽  
Glucose Levels ◽  
Skin Patch

Models of type-I diabetes are well-characterized and commonly used in the preclinical evaluation of drugs and medical devices. The diabetic minipig is an excellent example of a translational model. However, chronic glucose monitoring in this species can be challenging; frequent blood sampling can be technically difficult and poorly tolerated in conscious swine. Skin-patch continuous blood glucose monitors are FDA-approved for human use and offer a potential refinement to cageside blood collection. However, this modality has not been evaluated in pigs. In this study, young adult male STZ-induced diabetic Yucatan minipigs (n = 4) and healthy York pigs (n = 4) were implanted with a 14-d skin-patch continuous glucose monitor. Readings from continuous glucose monitors were time-matched to whole blood samples, with glucose measurements performed using point-of-care blood glucose monitors, serum chemistry or both. The aims of the study were to assess if a continuous glucose monitoring system could accurately detect glucose levels in swine, and to compare the readings toboth point-of-care glucometers and serum chemistry results. We hypothesized that a continuous glucose monitoring system would accurately detect glucose levels in swine in comparison with a validated analyzer and could serve as an animal welfarerefinement for studies of diabetes. We found that the continuous glucose monitor used in this study provided an adequateadjunct for clinical management in the stable diabetic pig and a minimally invasive and inexpensive option for colony maintenanceof chronically diabetic swine.

scholarly journals In Vitro Model of Mycobacterial Growth Arrest Using Nitric Oxide with Limited Air

2008 ◽  
Vol 53 (1) ◽  
pp. 157-161 ◽  
Author(s):  
Syed Hussain ◽  
Muhammad Malik ◽  
Lanbo Shi ◽  
Maria Laura Gennaro ◽  
Karl Drlica
Keyword(s):  
Nitric Oxide ◽  
In Vitro Model ◽  
Transition Period ◽  
Time Lag ◽  
Growth Arrest ◽  
Ring Structure ◽  
Time Lags ◽  
Vitro Model ◽  
Mycobacterial Growth

ABSTRACT An in vitro model of mycobacterial growth arrest was developed using Mycobacterium bovis BCG. When an exponentially growing culture was transferred to an evacuated tube, growth continued; treatment with a source of nitric oxide (diethylenetriamine-nitric oxide adduct [DETA-NO] at 50 μM) halted growth immediately, and aeration restored growth. When the period of growth arrest exceeded 4 h, a time lag occurred before aeration could restore growth. The lag time was maximal (24 h) after 16 h of growth arrest. These time lags indicated that one transition period was required for cells to achieve full arrest of growth and another for them to recover fully from growth arrest. DETA-NO-induced growth arrest failed to protect from the lethal effects of anaerobic shock, which caused rapid lysis of both growing and growth-arrested cells. While growth arrest had little effect on the lethal action of rifampin, it eliminated isoniazid lethality. Growth arrest reduced but did not eliminate fluoroquinolone lethality. Two fluoroquinolones, moxifloxacin and gatifloxacin, were equally lethal to exponentially growing cells, but moxifloxacin was more active during growth arrest. This difference is attributed to the fluoroquinolone C-7 ring structure, the only difference between the compounds. Collectively these data characterize a new system for halting mycobacterial growth that may be useful for evaluating new antituberculosis agents.

scholarly journals Real-time continuous glucose monitoring versus self-monitoring of blood glucose in adults with insulin-treated type 2 diabetes: a protocol for a randomised controlled single-centre trial

BMJ Open ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. e040648
Author(s):  
Nanna Lind ◽  
Dorte Lindqvist Hansen ◽  
Signe Sætre Rasmussen ◽  
Kirsten Nørgaard
Keyword(s):  
Type 2 Diabetes ◽  
Blood Glucose ◽  
Peer Support ◽  
Continuous Glucose Monitoring ◽  
Data Protection ◽  
Treatment Options ◽  
Glucose Monitoring ◽  
Single Centre ◽  
Self Monitoring

IntroductionMedical treatment options for type 2 diabetes (T2D) have increased over the last decade and enhance the possibility of individualised treatment strategies where insulin is still one of them. In spite of the advancements in treatment options, less than one-third of the population with T2D obtain their optimal glycaemic goal. In persons with type 1 diabetes, continuous glucose monitoring (CGM) has shown to be the most important driver for improvement in glycaemic control, even more than insulin-pump therapy. The use of technology in T2D has only been investigated in few studies.The overall objective of the research study is to examine the effectiveness of the use of CGM versus self-monitoring of blood glucose (SMBG) in persons with insulin-treated T2D on glycaemic variables and patient-reported outcomes on treatment satisfaction, health behaviour and well-being. The independent effect of peer support will also be studied.Methods and analysisThe study is a single centre, prospective, randomised, open-labelled, three-armed study with the randomisation 2:1:2 in group A with CGM, group B with CGM and peer support, and group C as a control group with SMBG. The participants receive a training course unique for the allocation group. The study runs for 12 months and includes 100 adult participants with insulin-treated T2D, treated at the outpatient clinic at Steno Diabetes Center Copenhagen. Primary outcome is difference in change in time in range. Recruitment begins in August 2020 and ends in July 2021. Final 12-month follow-up is anticipated to be in August 2022.Ethics and disseminationThe study will be carried out in accordance with the Helsinki Declaration and is approved by the Scientific Ethics Committee of the Capital Region (H-20000843). Data collection and handling will be performed in accordance with the General Data Protection Regulation and is approved by the Danish Data Protection Agency (J-2020-100). Dissemination will be in international peer-reviewed journals, conferences and a plain-language summary for participants.Trial registration numberClinicalTrials.gov Registry (NCT04331444).Protocol versionV.3, 11 December 2020.

Interstitial fluid glucose time-lag correction for real-time continuous glucose monitoring

2013 ◽  
Vol 8 (1) ◽  
pp. 81-89 ◽  
Author(s):  
D. Barry Keenan ◽  
John J. Mastrototaro ◽  
Stuart A. Weinzimer ◽  
Garry M. Steil
Keyword(s):  
Real Time ◽  
Continuous Glucose Monitoring ◽  
Interstitial Fluid ◽  
Time Lag ◽  
Glucose Monitoring

In Vitro Evaluation of Miniaturized Amperometric Enzyme Sensor Based on the Direct Electron Transfer Principle for Continuous Glucose Monitoring

2022 ◽  
pp. 193229682110706
Author(s):  
Yutaro Inoue ◽  
Yasuhide Kusaka ◽  
Kotaro Shinozaki ◽  
Inyoung Lee ◽  
Koji Sode
Keyword(s):  
Electron Transfer ◽  
Continuous Glucose Monitoring ◽  
Glucose Sensor ◽  
Direct Electron Transfer ◽  
Glucose Dehydrogenase ◽  
Glucose Monitoring ◽  
Reference Electrode ◽  
Enzyme Sensor

Background: The bacterial derived flavin adenine dinucleotide (FAD)-dependent glucose dehydrogenase (FADGDH) is the most promising enzyme for the third-generation principle-based enzyme sensor for continuous glucose monitoring (CGM). Due to the ability of the enzyme to transfer electrons directly to the electrode, recognized as direct electron transfer (DET)-type FADGDH, although no investigation has been reported about DET-type FADGDH employed on a miniaturized integrated electrode. Methods: The miniaturized integrated electrode was formed by sputtering gold (Au) onto a flexible film with 0.1 mm in thickness and divided into 3 parts. After an insulation layer was laminated, 3 openings for a working electrode, a counter electrode and a reference electrode were formed by dry etching. A reagent mix containing 1.2 × 10−4 Unit of DET-type FADGDH and carbon particles was deposited. The long-term stability of sensor was evaluated by continuous operation, and its performance was also evaluated in the presence of acetaminophen and the change in oxygen partial pressure (pO2) level. Results: The amperometric response of the sensor showed a linear response to glucose concentration up to 500 mg/dL without significant change of the response over an 11-day continuous measurement. Moreover, the effect of acetaminophen and pO2 on the response were negligible. Conclusions: These results indicate the superb potential of the DET-type FADGDH-based sensor with the combination of a miniaturized integrated electrode. Thus, the described miniaturized DET-type glucose sensor for CGM will be a promising tool for effective glycemic control. This will be further investigated using an in vivo study.

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