RESEARCH DESIGN -A multicenter study was performed in 70 diabetic patients. A microdialysis fiber was inserted subcutaneously into the periumbelical region and perfused with a buffer solution. Glucose concentrations in the dialysate were then measured every 3 min by the glucose sensor over a 24-h period, during which nine venous blood samples were also collected throughout the day.RESULTS -Both the insertion of the fiber and the wearing of the device were well tolerated by the patients. Subcutaneous glucose levels were well correlated with venous glucose measurements (r ϭ 0.9, P Ͻ 0.001) over a wide range (40 -400 mg/dl) for up to 24 h, with a single-point calibration. An analysis of 381 data pairs showed a linear relationship between the GlucoDay and serial venous blood glucose levels, and 97% of the data fell in the A and B regions of the error grid analysis. Percentage bias between the GlucoDay and the blood venous levels was Ϫ2.0% in the hypoglycemic range (Ͻ70 mg/dl), 6.9% in the euglycemic range (70 -180 mg/dl), and 11.2% in the hyperglycemic range (Ͼ180 mg/dl).CONCLUSIONS -The GlucoDay system demonstrated high reliability and reported values that closely agreed with venous blood glucose measurements. The system was well tolerated and thus constitutes a relatively easy method to monitor glucose excursions in diabetic patients. Diabetes Care 25:347-352, 2002T he benefits of strict metabolic control on microvascular complications of both type 1 and type 2 diabetes have been well established (1,2). In the last decade, self-monitoring of blood glucose levels has been the only available measure for diabetic patients to achieve a good metabolic control; however, glucose fluctuations during the day are often missed with this technique (3), and only continuous glucose measurements over prolonged periods can ensure optimal blood glucose management. Recently, minimally invasive techniques have been proposed for continuous monitoring of subcutaneous glucose in both normal and diabetic patients. Microdialysis of subcutaneous adipose tissue has been shown to identify glucose variations in vivo that closely mimic blood glucose patterns observed in patients on intensified insulin therapy. A monitoring system that provides automatic and frequent determinations would therefore identify the glycemic excursions and typical glucose trends in diabetic patients in a manner that is not possible even with frequent blood glucose meter readings. The ability to detect such fluctuations during the day, and particularly during the night, would enable appropriate changes in diabetes management in order to achieve the goal of optimal metabolic control in diabetic patients.We documented the efficacy of a new glucose sensor and its accuracy in monitoring glucose levels in type 1 and type 2 diabetic patients recruited in a multicenter study. The GlucoDay is composed of a subcutaneous microdialysis probe connected to a portable unit. The system takes a glucose measurement every second and stores an average value every 3 min, for a total of ...

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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. #

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