Fetal exposure to glycemic variability and hyperglycemia seems to be important in determining fetal overgrowth in pregnant women with diabetes. Optimal glucose control and less glucose variability are needed as early as possible in both type 1 diabetes and GDM patients to ensure normal fetal growth.

The performances and the stability of a novel subcutaneous glucose monitoring system have been evaluated. GlucoDay † (A. Menarini I.F.R. S.r.l, Florence Italy) is a portable instrument provided with a micro-pump and a biosensor coupled to a microdialysis system capable of recording the subcutaneous glucose level every 3 min. Long and short term stability of the biosensor are discussed and the results of some critical in vitro and in vivo (on rabbits) experiments are reported. A linear response up to 30 mM has been found for in vivo glucose concentration. The sensitivity referred to blood glucose is better than 0.1 mM and the zero current is typically below the equivalent of 0.1 mM. In the accuracy study a mean bias of 2.7 mg/dl and a correlation coefficient equal to 0.9697 have been found. At room temperature, an excellent membrane stability assures good performances up to 6 months from the first use. #

Background: The objective of this work was to determine the clinical accuracy of GlucoMen®Day, a new microdialysis-based continuous glucose monitoring system (CGMS) from A. Menarini Diagnostics (Florence, Italy). Accuracy evaluation was performed using continuous glucose-error grid analysis (CG-EGA), as recommended by the Performance Metrics for Continuous Interstitial Glucose Monitoring; Approved Guideline (POCT05-A). Methods: Two independent clinical trials were carried out on patients with types 1 and 2 diabetes mellitus, the glycemic levels of whom were monitored in an in-home setting for 100-hour periods. A new multiparametric algorithm was developed and used to compensate in real-time the GlucoMen®Day signal. The time lag between continuous glucose monitoring (CGM) and reference data was first estimated using the Poincaré plot method. The entire set of CGM/reference data pairs was then evaluated following the CG-EGA criteria, which allowed an estimation of the combined point and rate accuracy stratified by glycemic ranges. Results: With an estimated time lag of 11 minutes, the linear regression analysis of the CGM/reference glucose values yielded r = 0.92. The mean absolute error (MAE) was 11.4 mg/dl. The calculated mean absolute rate deviation (MARD) was 0.63 mg/dl/min. The data points falling within the A+B zones of CG-EGA were 100% in hypoglycemia, 95.7% in euglycemia, and 95.2% in hyperglycemia. Conclusions: The GlucoMen®Day system provided reliable, real-time measurement of subcutaneous glucose levels in patients with diabetes for up to 100 hours. The device showed the ability to follow rapid glycemic excursions and detect severe hypoglycemic events accurately. Its accuracy parameters fitted the criteria of the state-of-the-art consensus guideline for CGMS, with highly consistent results from two independent studies.

Point-of-care (POC) testing devices for monitoring glucose and ketones can play a key role in the management of dysglycemia in hospitalized diabetes patients. The accuracy of glucose devices can be influenced by biochemical changes that commonly occur in critically ill hospital patients and by the medication prescribed. Little is known about the influence of these factors on ketone POC measurements. The aim of this study was to assess the analytical performance of POC hospital whole-blood glucose and ketone meters and the extent of glucose interference factors on the design and accuracy of ketone results. StatStrip glucose/ketone, Optium FreeStyle glucose/ketone, and Accu-Chek Performa glucose were also assessed and results compared to a central laboratory reference method. The analytical evaluation was performed according to Clinical and Laboratory Standards Institute (CLSI) protocols for precision, linearity, method comparison, and interference. The interferences assessed included acetoacetate, acetaminophen, ascorbic acid, galactose, maltose, uric acid, and sodium. The accuracies of both Optium ketone and glucose measurements were significantly influenced by varying levels of hematocrit and ascorbic acid. StatStrip ketone and glucose measurements were unaffected by the interferences tested with exception of ascorbic acid, which reduced the higher level ketone value. The accuracy of Accu-Chek glucose measurements was affected by hematocrit, by ascorbic acid, and significantly by galactose. The method correlation assessment indicated differences between the meters in compliance to ISO 15197 and CLSI 12-A3 performance criteria. Combined POC glucose/ketone methods are now available. The use of these devices in a hospital setting requires careful consideration with regard to the selection of instruments not sensitive to hematocrit variation and presence of interfering substances.

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Novel planar glucose biosensors to be used for continuous monitoring have been developed. The electrodes are produced with the "screen printing" technique, and present a high degree of reproducibility together with a low cost and the possibility of mass production. Prior to enzyme immobilisation, electrodes are chemically modified with ferric hexacyanoferrate (Prussian Blue). This allows the detection of the hydrogen peroxide produced by the enzymatic reaction catalysed by GOD, at low applied potential (ca. 0.0 V versus Ag/AgCl), highly limiting any electrochemical interferences. The layer of Prussian Blue (PB) showed a high stability at the working conditions (pH 7.4) and also after 1 year of storage dry at RT, no loss of activity was observed. The assembled glucose biosensors, showed high sensitivity towards glucose together with a long-term operational and storage stability. In a continuous flow system, with all the analytical parameters optimised, the glucose biosensors detected glucose concentration as low as 0.025 mM with a linear range up to 1.0 mM.These probes were also tested over 50-60 h in a continuous flow mode to evaluate their operational stability. A 0.5 mM concentration of glucose was continuously fluxed into a biosensor wall-jet cell and the current due to the hydrogen peroxide reduction was continuously monitored. After 50-60 h, the drift of the signal observed was around 30%.Because of their high stability, these sensors suggest the possibility of using such biosensors, in conjunction with a microdialysis probe, for a continuous monitoring of glucose for clinical purposes.

A novel continuous lactate monitoring system has been developed modifying the GlucoDay ® portable medical device (A. Menarini Diagnostics), already present in the European market, and used to continuously measure glucose levels.Lactate oxidase based biosensors have been developed immobilising the enzyme on nylon net and placing it on a Pt electrode. The biosensor was connected to the portable device provided with a micro-pump and coupled to a microdialysis system. It is capable to record subcutaneous lactate every 3 min.In vitro analytical results confirmed that the sensors respond linearly in the interval of concentration between 0.1 and 10 mmol/L, covering the whole physiological range.During prolonged monitoring periods, the response of the biosensors remained stable, showing a limited drift of 8%, within 60 h. Stability tests are still on route. However, preliminary results have shown a shelf life of about 10 months.In vivo experiments performed on healthy rabbits have demonstrated the good accuracy and reproducibility of the system. A correlation coefficient equal to 0.9547 (N = 80) was found, which represents a good correlation between the GlucoDay ® and the laboratory reference analyser.A 16 h in vivo monitoring on a healthy volunteer has been also performed.

These results provide clear insights into the advantages offered by the use of a microdialysis-based CGM system that additionally relies on the detection of hydrogen peroxide at low operating potential. GlucoMen Day may become the CGM system of choice for those patients who require either regular administration of drugs or their glycemia to be tightly controlled in the intensive care unit or similar environments.