Subcutaneous Continuous Glucose Monitoring System Research Articles

Effects of Low-Intensity Resistance Exercise with Slow Movement and Tonic Force Generation on Short-Term Glycemic Variability in Healthy Subjects: A Randomized Controlled Study

Resistance exercise improves daily glycemic control. Low-intensity resistance exercise with slow movements and tonic force generation (LST) is a resistance exercise protocol that can increase skeletal muscle mass and strength without considerable physical burden; however, its effect on glycemic variability is unknown. The aim of this study was to investigate the effect of LST on short-term glycemic variability, expressed as the M-value, in healthy individuals. We recruited 20 healthy subjects (mean age: 27.9 ± 3.9 years) with normal glucose tolerance, and subjects were randomly assigned to the control (n = 10) or LST (n = 10) groups. Subjects in the LST group performed the resistance exercise with 40–50% of the one-repetition maximum for 40 min. All subjects wore a subcutaneous continuous glucose monitoring system and a triaxial accelerometer, and their daily glycemic variability and physical activity were measured. One hour after the intervention, in the LST group, the variability of blood glucose levels was significantly decreased compared to the control group (M-values in the LST group: pre 3.5 ± 6.2, post 2.7 ± 2.7, p = 0.575; M-values in the control group: pre 0.4 ± 0.7, post 2.7 ± 2.0, p = 0.017). However, there were no differences in total physical activity and daily glycemic control between groups. The findings of this study suggest that LST improves short-term glycemic variability in healthy subjects.

888-P: Day vs. Nighttime Performance of Continuous Glucose Monitoring Systems in Children with Type 1 Diabetes during a Diabetes Summer Camp

Continuous subcutaneous glucose monitoring (CGM) use is increasing in diabetes care. Still there are concerns with regard to sensor accuracy especially at night. Aim of the Study: To assess accuracy of commonly used CGM systems at a 2 week diabetes camp in children with type 1 diabetes (T1D) ages 9-14 years. Out of 38 children, 37 routinely wore a CGM system throughout the camp. Baseline characteristics: age 11.0 (9.9;12.1) years; 57% girls; HbA1c 7.2% (6.9; 7.7); diabetes duration 3.6 (2.7; 6.3) years (median (interquartile range)). Capillary glucose measurements were performed prior to main meals, at bedtime and whenever deemed necessary by medical staff after thoroughly cleaning the finger tips. Calibrations of Medtronic Enlite was performed twice daily when glycemia was stable. All concomitantly available data pairs were used for the analysis. Night-time was defined as period when children were supposed to be in bed (10 PM until 7 AM). Sensor distribution: 51% Abbott Libre, 35% Medtronic Enlite, 14% Dexcom G6. CGM accuracy shown in Table 1: MARD in % (interquartile range)). Sensor performance of the adequately calibrated Medtronic system outperformed the factory-calibrated sensors in most situations. All sensors performed worse in hypoglycaemia. During the nights the MARD was higher, potentially due to pressure artefacts. Disclosure B. Rami-Merhar: Advisory Panel; Self; Abbott. Speaker’s Bureau; Self; Eli Lilly and Company, Medtronic. K. Nagl: None. G. Berger: None. A. Schütz: None. F. Aberer: None. J.K. Mader: Advisory Panel; Self; Becton, Dickinson and Company, Eli Lilly and Company, Medtronic, Prediktor Medical, Sanofi-Aventis. Speaker’s Bureau; Self; Abbott, Eli Lilly and Company, Medtronic, Novo Nordisk A/S, Roche Diabetes Care, Sanofi-Aventis.

MON-086 Various Subcutaneous Continuous Glucose Monitors Comparably Lower HbA1c in Children

Background: Preliminary studies have demonstrated improvement in metabolic control of patients (PTs) using subcutaneous Continuous Glucose Monitoring systems (CGMs). In this study, we investigated the effect of CGMs on PTs’ glycemic control and compared the change in patient HbA1c levels between sensors. Objective: To determine how CGMs affect metabolic control in PTs and the effect of different sensors on glycemic control. Patients and Methods: 33 PTs with Type 1 diabetes mellitus (DM) who began using a CGM between 2017 and 2019 were selected for inclusion. CGM systems used included DexcomG6™, DexcomG5™, DexcomG4™, Enlite™, Guardian 3™, or Medtronic Sure-T™ sensors. Results: The mean (MN) age of PTs at initial visit was 15.3 ± 5.1 yrs and the MN age at second visit was 15.8 ± 5.1 yrs. The MN time between visits was 5.0 ± 2.4 months (mos). 6 PTs had follow up (F/U) times less than 3 mos, 18 PTs had F/U times between 3 and 6 mos, 6 PTs had F/U times between 6 and 9 mos, and 3 PTs had F/U times greater than 9 mos. The MN and median (MD) HbA1c at the initial visit for all PTs was 8.28% ± 1.48 and 8.10%, respectively. The MN and MD HbA1c at final F/U for all PTs was 7.57% ± 1.11 and 7.50%, respectively. The difference in MN HbA1c was significant (p<0.001).The MN and MD HbA1c at the initial visit for PTs with a F/U time less than 3 mos was 7.55% ± 0.77 and 7.75%, respectively. The MN and MD HbA1c at F/U for these PTs was 7.20% ± 0.79 and 7.20%, respectively. The difference in MN HbA1c was significant (p<0.05).The MN and MD HbA1c at the initial visit for all PTs with a F/U time greater than 3 mos was 8.44% ± 1.53 and 8.10%, respectively. The MN and MD HbA1c at F/U for these PTs was 7.66% ± 1.15 and 7.50%, respectively. The difference in MN HbA1c was significant (p<0.001).The MN change of HbA1c between visits was not significant between PTs who had 3–6 mo, 6–9 mo, and 9+ mo F/U times (p=0.96)15 PTs had HbA1c levels less than or equal to 8.0%. The MN and MD HbA1c at initial visit for these PTs was 7.20% ± 0.41 and 7.30%, respectively. The MN and MD HbA1c at F/U for these PTs was 6.75% ± 0.47 and 6.80%, respectively. The difference in MN HbA1c was significant (p<0.001).20 PTs had HbA1c levels greater than 8.0% at initial visit. The MN and MD HbA1c at the initial visit for these PTs was 9.18% ± 1.47 and 8.80%, respectively. The MN and MD HbA1c at F/U for these PTs was 8.26% ± 1.03 and 8.00%, respectively. The difference in MN HbA1c was significant (p<0.001). The MN change in HbA1c between the high HbA1c group (-.92% ± 1.02) and low HbA1c group (-0.45% ± 0.32) was not significant (p>0.05).25 PTs used a Dexcom™ sensor while 8 PTs used a Medtronic™ sensor. The MN change in HbA1c was not significant between these brands (p>0.05). Conclusion: CGMs improve metabolic control in pediatric PTs with Type 1 DM regardless of initial HbA1c. Further, this improved control is sustained over time. Sensor brands appear to be equally effective at achieving this goal.

CGM-Continuous Glucose Monitoring-Statement of the Austrian Diabetes Association (Update 2019)

This position statement represents the recommendations of the Austrian Diabetes Association regarding the clinical diagnostic and therapeutic application, safety and benefits of continuous subcutaneous glucose monitoring systems in patients with diabetes, based on current evidence.

Perioperative Characteristics of the Accuracy of Subcutaneous Continuous Glucose Monitoring: Pilot Study in Neurosurgery and Cardiac Surgery.

The aim of this study was to elucidate the characteristics of accuracy of subcutaneous continuous glucose monitoring (SCGM) in the perioperative period for neurosurgical and cardiac surgery patients. Forty-five subjects, including healthy volunteers (n = 15), neurosurgical patients (n = 15), and cardiac surgery patients (n = 15), were enrolled. A subcutaneous sensor of the MiniMed™ 620G SCGM system was inserted into the upper arm. On the day after sensor insertion, SCGM data and blood glucose data were collected simultaneously and compared. In cardiac surgery patients, data were continuously collected on postoperative day (POD) 1 and POD 3. Clarke error grid analysis and Bland-Altman analysis were performed to assess the accuracy of SCGM. Clarke error grid analysis showed clinical acceptance of the SCGM system with 82.7% and 86.8% of the data being within zone A for healthy volunteers and neurosurgical patients, respectively. Mean biases were -2.1 mg/dL in healthy volunteers and -8.3 mg/dL in neurosurgical patients. In cardiac surgery, although Clarke error grid analysis showed clinical acceptance, 65.3% of the data were within zone A and mean bias was -23.5 mg/dL. Changes in accuracy of SCGM in individuals occurred during cardiopulmonary bypass (CPB), and SCGM tended to show a lower glucose level. On POD 1 and POD 3, the accuracy improved, and 85.0% and 86.3% of the data were within zone A. Although the accuracy of the SCGM system was clinically acceptable in the perioperative period, sensor accuracy was affected by CPB and showed lower glucose levels.

Accuracy, reliability, feasibility and nurse acceptance of a subcutaneous continuous glucose management system in critically ill patients: a prospective clinical trial.

BackgroundContinuous glucose monitoring (CGM) has not yet been implemented in the intensive care unit (ICU) setting. The purpose of this study was to evaluate reliability, feasibility, nurse acceptance and accuracy of the Medtronic Sentrino® CGM system in critically ill patients.Methods Sensors were inserted into the subcutaneous tissue of the patient’s thigh, quantifying interstitial glucose concentration for up to 72 h per sensor. Reliability and feasibility analysis included frequency of data display, data gaps and reasons for sensor removal. We surveyed nurse acceptance in a questionnaire. For the accuracy analysis, we compared sensor values to glucose values obtained via blood gas analysis. Potential benefits of CGM were investigated in intra-individual analyses of factors, such as glycemic variability or time in target range achieved with CGM compared to that achieved with intermittent glucose monitoring.ResultsThe device generated 68,655 real-time values from 31 sensors in 20 critically ill patients. 532 comparative blood glucose values were collected. Data were displayed during 32.5 h [16.0/62.4] per sensor, which is 45.1 % of the expected time of 72 h and 84.8 % of 37.9 h actual monitoring time. 21 out of 31 sensors were removed prematurely. 79.1 % of the nursing staff rated the device as not beneficial; the response rate was one-third. Mean absolute relative difference was 15.3 % (CI 13.5–17.0 %). Clarke error grid: 76.9 % zone A, 21.6 % zone B, 0.2 % zone C, 0.9 % zone D, 0.4 % zone E. Bland–Altman plot: mean bias +0.53 mg/dl, limits of agreement +64.6 and −63.5 mg/dl. Accuracy deteriorated during elevated glycemic variability and in the hyperglycemic range. There was no reduction in dysglycemic events during CGM compared to 72 h before and after CGM. If CGM was measuring accurately, it identified more hyperglycemic events when compared to intermittent measurements. This study was not designed to evaluate potential benefits of CGM on glucose control.ConclusionsThe subcutaneous CGM system did not perform with satisfactory accuracy, feasibility, or nursing acceptance when evaluated in 20 medical-surgical ICU patients. Low point accuracy and prolonged data gaps significantly limited the potential clinical usefulness of the CGM trend data. Accurate continuous data display, with a MARD < 14 %, showed potential benefits in a subgroup of our patients.Trial registration NCT02296372; Ethic vote Charité EA2/095/14Electronic supplementary materialThe online version of this article (doi:10.1186/s13613-016-0167-z) contains supplementary material, which is available to authorized users.

CGM-Continuous Glucose Monitoring--Statement of the Austrian Diabetes Association

This position statement represents the recommendations of the Austrian Diabetes Association regarding the clinical diagnostic and therapeutic application, safety and benefits of continuous subcutaneous glucose monitoring systems in patients with diabetes mellitus, based on current evidence.

Electromagnetic Interference From Electronic Devices Used in the Management of Type 1 Diabetes Can Impair the Performance of an Avalanche Transceiver in Search Mode

Portable electronic devices play an important role in the management of type 1 diabetes mellitus. Electromagnetic interference from electronic devices has been shown to impair the function of an avalanche transceiver in search mode (but not in transmitting mode). This study investigates the influence of electromagnetic interference from diabetes devices on a searching avalanche beacon. The greatest distance at which an avalanche transceiver (in search mode) could accurately indicate the location of a transmitting transceiver was assessed when portable electronic devices (including an insulin pump and commonly used real-time continuous subcutaneous glucose monitoring system [rtCGMS]) were held in close proximity to each transceiver. The searching transceiver could accurately locate a transmitted signal at a distance of 30 m when used alone. This distance was unchanged by the Dexcom G4 rtCGMS, but was reduced to 10 m when the Medtronic Guardian rtCGMS was held close (within 30 cm) to the receiving beacon. Interference from the Animas Vibe insulin pump reduced this distance to 5 m, impairing the searching transceiver in a manner identical to the effect of a cell phone. Electromagnetic interference produced by some diabetes devices when held within 30 cm of a searching avalanche transceiver can impair the ability to locate a signal. Such interference could significantly compromise the outcome of a companion rescue scenario. Further investigation using other pumps and rtCGMS devices is required to evaluate all available diabetes electronics. Meantime, all electronic diabetes devices including rtCGMS and insulin pumps should not be used within 30 cm of an avalanche transceiver.

Reduced Glycemic Variability in Diazoxide-Responsive Children with Congenital Hyperinsulinism Using Supplemental Omega-3-Polyunsaturated Fatty Acids; A Pilot Trial with MaxEPAR

Objective: Congenital hyperinsulinism (CHI) is a rare condition of hypoglycemia where therapeutic options are limited and often complicated by side-effects. Omega-3-polyunsaturated fatty acids (PUFA), which can suppress cardiac myocyte electrical activity, may also reduce ion channel activity in insulin-secreting cells. PUFA supplements in combination with standard medical treatment may improve glucose profile and may reduce glycemic variability in diazoxide-responsive CHI.Design: Open label pilot trial with MaxEPAR liquid (eicosapentaenoic and docosahexaenoic acid) PUFA (3 ml/day for 21 days) in diazoxide-responsive CHI patients (https://eudract.ema.europa.eu/, EudraCT number 201100363333).Methods: Glucose levels were monitored pre-treatment, end of treatment, and at follow-up by subcutaneous continuous glucose monitoring systems (CGMS) in 13 patients (7 girls) who received PUFA. Outcome measures were an improved glucose profile, reduced glycemic variability quantified by a reduction in the frequency of glucose levels <4 and >10 mmol/l, and safety of PUFA. All children were analyzed either as intention to treat (n = 13) or as per protocol (n = 7).Results: Mean (%) CGMS glucose levels increased by 0.1 mmol/l (2%) in intention to treat and by 0.4 mmol/l (8%) in per protocol analysis (n = 7). The frequency of CGMS <4 mmol/l was significantly less at the end of treatment than in the pre-treatment period [556 (7%) vs. 749 (10%)]. Similarly, the frequency of CGMS >10 mmol/l, was also less at the end of treatment [27 (0.3%) vs. 49 (0.7%)]. Except for one child with increased LDL cholesterol, all safety parameters were normal.Conclusion: MaxEPAR was safe and reduced glycemic variability, but did not increase glucose profiles significantly in diazoxide-responsive CHI. The supplemental value of PUFA should be evaluated in a comprehensive clinical trial.

Continuous glucose monitoring in children with glycogen storage disease type I

Glycogen storage disease type I (GSD I) is an autosomal recessive metabolic disorder caused by defects in the glucose-6-phosphatase complex. Deficient activity in the glucose-6-phosphatase-α catalytic unit characterizes GSD Ia and defects in the glucose-6-phosphate transporter protein characterize GSD Ib. Type Ia involves the liver, kidney and intestine (and Ib also leukocytes), and the clinical manifestations are hepatomegaly, failure to thrive, severe fasting hypoglycemia within 3-4 h after a meal, hyperlactatemia, hyperuricemia and hyperlipidemia. The aim of the present study was to examine the safety and efficacy of a continuous subcutaneous glucose monitoring system to determine the magnitude and significance of hypoglycemia in GSD I and to evaluate the efficacy of the revised dietary treatment. Sixteen children with GSD I were studied over a 72-h period. Continuous glucose monitoring (CGM) was repeated in all patients 3-6 months after the first monitoring to examine the effects of revised dietary instructions on glycemic control. All the patients completed the study without any major adverse events. Significant periods of asymptomatic hypoglycemia (below 4 mmol/l, 70 mg/dl) were noted. There was a close correlation between CGM sensor and capillary blood glucose values measured by a glucometer. CGM indicated a considerable reduction in duration of hypoglycemia, liver size and improvements in secondary metabolic derangements such as hyperlacticacidemia and hyperlipidemia. CGM could be applied in the clinical setting to help the physician to identify hypoglycemic events, and repeated CGM may serve as a safe and useful tool for the assessment of the long-term management of patients with GSD I.

Role of continuous subcutaneous glucose monitoring in intensive care

Critical care associated with stress hyperglycaemia has gained a new view in the last decade since the demonstration of the beneficial effects of strong glycaemic control on the mortality in intensive care units. Strong glycaemic control may, however, induce hypoglycaemia, resulting in increased mortality, too. Pediatric population has an increased risk of hypoglycaemia because of the developing central nervous system. In this view there is a strong need for close monitoring of glucose levels in intensive care units. The subcutaneous continuous glucose monitoring developed for diabetes care is an alternative for this purpose instead of regular blood glucose measurements. It is important to know the limitations of subcutaneous continuous glucose monitoring in intensive care. Decreased tissue perfusion may disturb the results of subcutaneous continuous glucose monitoring, because the measurement occurs in interstitial fluid. The routine use of subcutaneous continuous glucose monitoring in intensive care units is not recommended yet until sufficient data on the reliability of the system are available. The Medtronic subcutaneous continuous glucose monitoring system is evaluated in the review partly based on the authors own results.

Real-Time Continuous Glucose Monitoring Shows High Accuracy within 6 Hours after Sensor Calibration: A Prospective Study

Accurate and timely glucose monitoring is essential in intensive care units. Real-time continuous glucose monitoring system (CGMS) has been advocated for many years to improve glycemic management in critically ill patients. In order to determine the effect of calibration time on the accuracy of CGMS, real-time subcutaneous CGMS was used in 18 critically ill patients. CGMS sensor was calibrated with blood glucose measurements by blood gas/glucose analyzer every 12 hours. Venous blood was sampled every 2 to 4 hours, and glucose concentration was measured by standard central laboratory device (CLD) and by blood gas/glucose analyzer. With CLD measurement as reference, relative absolute difference (mean±SD) in CGMS and blood gas/glucose analyzer were 14.4%±12.2% and 6.5%±6.2%, respectively. The percentage of matched points in Clarke error grid zone A was 74.8% in CGMS, and 98.4% in blood gas/glucose analyzer. The relative absolute difference of CGMS obtained within 6 hours after sensor calibration (8.8%±7.2%) was significantly less than that between 6 to 12 hours after calibration (20.1%±13.5%, p<0.0001). The percentage of matched points in Clarke error grid zone A was also significantly higher in data sets within 6 hours after calibration (92.4% versus 57.1%, p<0.0001). In conclusion, real-time subcutaneous CGMS is accurate in glucose monitoring in critically ill patients. CGMS sensor should be calibrated less than 6 hours, no matter what time interval recommended by manufacturer.

Positionspapier des Insulinpumpenausschusses der OEDG zur kontinuierlichen Glukosemessung (CGM – Continuous Glucose Monitoring)

This position statement represents the recommendations of the Austrian Diabetes Association regarding the clinical diagnostic and therapeutic application, safety and benefits of continuous subcutaneous glucose monitoring systems in patients with diabetes mellitus, based on current evidence.

Continuous monitoring of glucose concentration in diabetic dogs

DIABETES mellitus in dogs is caused by absolute or relative insulin deficiency and successful management typically requires lifelong monitoring and regular reappraisal of the treatment regimen. The two primary goals...

Home-based subcutaneous continuous glucose monitoring in 10 diabetic dogs

A subcutaneous continuous glucose monitoring system (GlucoDay; Menarini Diagnostics) based on microdialysis was investigated for its clinical applicability in veterinary medicine. Ten diabetic dogs, referred as clinically stable, were equipped...

Current Application of Continuous Glucose Monitoring in the Treatment of Diabetes

The ultimate goal of diabetes technology is to create an artificial pancreas, or closed-loop system. In the early 1970s, the first prototypes became available (1). Although recent advances are promising, the closed-loop system is currently confined to the clinical research center (2). The continuous subcutaneous insulin infusion (CSII) pump became commercially available in the 1980s, and it is now a common and accepted way of providing insulin (3,4). The emergence of continuous glucose monitoring (CGM) followed in the 1990s, with the first reports on CGM by microdialysis in 1992 (5,6). Retrospective needle-type CGM systems were introduced just before the turn of the century (7–10). Currently, there are four subcutaneous CGM systems on the market that have real-time glucose values on display every 1–5 min and feature an alarm function for hypo- and hyperglycemia: the Freestyle Navigator (Abbot Diabetes Care, Alameda, CA), the Guardian Real-Time (Medtronic MiniMed, Northridge, CA), the Dexcom SEVEN (Dexcom, San Diego, CA), and the GlucoDay (Menarini Diagnostics). The first three are needle-type CGMs and the latter is a microdialysis-type sensor. All of these measure glucose via the glucose-oxidase reaction. In this article, we will discuss the pros and cons of the current application of CGM in the treatment of diabetes. From the Diabetes Control and Complications Trial and the UK Prospective Diabetes Study, we learned that lowering HbA1c reduces morbidity and mortality (11,12) and that tight glycemic control is associated with an increased rate of severe hypoglycemic episodes. We therefore should judge the pros of CGM by its HbA1c-lowering potency and its influence on severe hypoglycemia rates. Table 1 summarizes all intervention trials that have been performed with real-time CGM regarding HbA1c and the incidence of severe hypoglycemia. View this table: Table 1 CGM trials in type 1 diabetes The …

Subcutaneous glucose measurements and glucose regulation (?)

Sir: Andrea Stoszkova et al. [1] conclude, based on a correlation coefficient of 0.69 comparing subcutaneous glucose values (Guardian RT) and blood glucose values (Central Laboratory) in 15 patients, that subcutaneous devices should not be used in critically ill patients. However, Holzinger et al. [2] in the August issue report a good correlation between subcutaneous and arterial glucose values, even in critically ill patients treated with norepinephrine. We also evaluated the accuracy and feasibility of a comparable continuous subcutaneous glucose monitoring system (CGMS System Gold, Medtronic Minimed) and found a correlation coefficient of 0.87 with the point-of-care blood gas/glucose analyzer ABL 715 (Radiometer Medical, Copenhagen, Denmark), which we validated in ICU patients previously [3]. We drew 786 arterial blood samples from 60 consecutive ICU patients, of whom 37 patients received vaso-active medication (only norepinephrine) and 13 patients were treated with steroids. Blood glucose ranged from 2.2 to 20.1 mmol/l. In the Clarke error grid (Fig. 1), 85.1% of measurements were in zone A (clinically accurate, leading to correct and safe treatment decisions), 13.2% were in zone B (clinically acceptable), 0.13% were in zone C, and 1.5% were in zone D. Zone D means failure-to-detect (high or low blood glucose) errors, resulting in failure to treat either low or high blood glucose results appropriately. The readings in zone D were found in nine patients, of whom eight were treated with vasopressors. One could argue that—with a correlation coefficient of 0.87 and 98.3% of glucose values in the clinically acceptable zones—rejection of s.c. glucose determination in the ICU seems premature. Fig. 1 Clarke error-grid analysis On the other hand, looking more precisely at zone D of the Clarke error grid (Fig. 1), a difference of nearly 4 mmol/l in the lower glucose zone (reference 2.8 mmol/l versus s.c. sensor 6.5 mmol/l) observed in one patient could have severe consequences in this individual patient, if this results in an inappropriate rise in insulin dose. Unlike other diagnostic procedures, which usually are interpreted in conjunction with additional findings, a single glucose measurement has direct consequences for treatment, with potentially detrimental effects. In other words, tight glucose regulation in ICU patients using a subcutaneous device may lead to more severe adverse events than the zone interpretation of the error grid suggests. The fact that we now have safe computerized protocols, which give excellent glucose regulation with a very low chance of hypoglycemic events [4], adds to the feeling that for glucose regulation in critically ill patients only the best point-of-care glucose analyzer and protocol should be used [5]. In an era where the beneficial effect of tight glucose regulation is questioned we cannot afford the introduction of treatment-related morbidity.

Continuous subcutaneous glucose monitoring: good enough to use in glucose regulation protocols?

Tight glucose regulation is benefi cial in subgroups of inten sive care unit (ICU) patients, but may harm other sub groups. Th is harm may be due to hypoglycemic events. In avoiding hypoglycemia, an accurate bedside glucometry method is essential [1]. Bridges and colleagues therefore evaluated the accuracy of a continuous subcutaneous glucose monitoring system (CGMS) in critically ill children, and concluded that the system proves highly accurate [2]. We have a problem with this resolute conclusion. Th ey report a Pearson’s correlation coeffi cient of 0.68, which is quite low. Vlkova and colleagues even conclude that, based on a correlation coeffi cient of 0.69 comparing subcutaneous glucose values and laboratory blood glucose values in 15 patients, subcutaneous devices should not be used in critically ill patients [3]. We found a correlation coeffi cient of 0.87 in evaluating the same CGMS in 60 critically ill patients, but were concerned with the inaccuracy in the low glucose zone: we found a diff erence of nearly 4 mmol/l (reference blood glucose 2.8 mmol/l versus subcutaneous sensor 6.5 mmol/l) in one patient [4]. Bridges and colleagues report 142 subcutaneous glucose readings <2.2 mmol/l that were falsely low, checked against blood glucose values. Th e Clarke error grid is a better way to evaluate the accuracy of a CGMS than Pearson’s correlation coeffi cient. In most published studies, the deviation of subcuta neous measurements stays in the (wide) clinically accep table zones of the Clarke error grid. Th ese deviations of the CGMS system, however, when used in a tight glucose regulation protocol – and adjusting the insulin dose based on the subcutaneous readings – could have severe consequences in the individual patient, if the deviations result in an unjust rise in insulin dose. Since computerized protocols based on arterial blood samples give excellent glucose regulation with a negligible chance of hypoglycemic events [5], we decided to continue using this computerized protocol to avoid treatment-related morbidity. Subcutaneous CGMS seems not good enough in aiming for tight glucose regulation in the ICU. Intravascular CGMS, used in a closed feedback loop with insulin infusion, is promising, but has not yet been evaluated in clinical studies in critically ill patients.

Impact of shock requiring norepinephrine on the accuracy and reliability of subcutaneous continuous glucose monitoring

To evaluate the impact of circulatory shock requiring norepinephrine therapy on the accuracy and reliability of a subcutaneous continuous glucose monitoring system (CGMS) in critically ill patients. A prospective, validation study of a medical intensive care unit at a university hospital was carried out. Continuous glucose monitoring was performed subcutaneously in 50 consecutive patients on intensive insulin therapy (IIT), who were assessed according to the a priori strata of circulatory shock requiring norepinephrine therapy or not. A total of 736 pairs of sensor glucose (SG)/blood glucose (BG) values were analysed (502 without and 234 with norepinephrine therapy). For all values, repeated measures Bland-Altman analysis showed a mean difference of 0.08 mmol/l (limits of agreement: -1.26 and 1.43 mmol/l). Circulatory shock requiring norepinephrine therapy did not influence the relation of arterial BG with SG in a multivariable random effects linear regression analysis. The covariates norepinephrine dose, body mass index (BMI), glucose level and severity of illness also had no influence. Insulin titration grid analysis showed that 98.6% of the data points were in the acceptable treatment zone. No data were in the life-threatening zone. Circulatory shock requiring norepinephrine therapy, as well as other covariates, had no influence on the accuracy and reliability of the CGMS in critically ill patients.

A pilot study to evaluate a novel subcutaneous continuous glucose monitoring system in healthy Beagle dogs

Serial blood glucose measurements are currently regarded as the 'gold standard' for evaluating glycaemic control of canine diabetic patients. The aim of this study was to investigate a subcutaneous continuous glucose monitoring system based on microdialysis. Analyses were performed by taking interstitial glucose samples from two different anatomical regions (interscapular region [IR], thoracic region [TR]) in six healthy Beagle dogs during induced hypoglycaemia and hyperglycaemia, the feeding period and a period of stable glucose values. For comparison, plasma glucose concentration was measured simultaneously by a hexokinase-based automated chemistry analyser. The mean absolute differences ranged from 11.7 mg/dL (SD 23.5 mg/dL, TR) to 5.3 mg/dL (SD 19.2 mg/dL, IR) with a correlation of r=0.43-0.92 (P<0.01). Sensitivity for the detection of hypoglycaemia was 85.0% TR and 93.3% IR, and the specificity was 99.5% TR and 99.7% IR, respectively. In a modified Clarke error grid analysis, 99.3% TR and 99.7% IR of the values fell into zone A and B. Collapse of the microdialysis fibre was a recurrent problem although this was easily detectable by fluctuations in system pressure. The microdialysis system reflects physiological as well as induced variations in blood glucose in a valid manner.