Patients' evaluation of nocturnal hypoglycaemia with GlucoDay continuous glucose monitoring in paediatric patients.

A study was conducted to evaluate the accuracy of GlucoDay (A. Menarini Diagnostics) during 48 h of continuous glucose monitoring (CGMS) in type 1 diabetic adolescents and use this novel approach to assess otherwise ignored nocturnal hypoglycaemias, in relationship to intermediate-acting insulin administration timing. Twenty type 1 diabetic adolescents with poor metabolic control were selected from our out-patient department. Equal doses of intermediate insulin were administered at 19:00 and at 22:00 of the first and second night of the study, respectively. Correlation coefficient between GlucoDay and standard glucometer was 0.94; 98.3% of data fall in the A + B area of Error Grid Analysis and 1.7% in the D area. The mean error was 13.9% overall and 16.4% with blood glucose values (BGV) <75 mg/dl. The accuracy, ±15 mg/dl, was 82% for BGV <75 mg/dl and 74% for BGV >75 mg/dl. The CGMS discovered nocturnal hypoglycaemia (NH) in 12/18 patients, but no severe hypoglycaemia. During the first night, 8 asymptomatic NH episodes were found with BGV <60 mg/dl and 12 with BGV <80. During the second night, 4 asymptomatic NH episodes with BGV <60 mg/dl and 5 with BGV <80 were found. Furthermore, during the second night, the mean duration of BGV <126 mg/dl was lower than in the first night. GlucoDay is a reliable device for CGMS in paediatric patients and able to determine asymptomatic NH. Bedtime insulin injections provided safer glycaemic profiles and a lower percentage of hypoglycaemic events, representing a safer insulin administration scheme.

Toward continuous glucose monitoring with planar modified biosensors and microdialysis. Study of temperature, oxygen dependence and in vivo experiment.

Glucose biosensors based on the use of planar screen-printed electrodes modified with an electrochemical mediator and with glucose oxidase have been optimised for their application in the continuous glucose monitoring in diabetic patients. A full study of their operative stability and temperature dependence has been accomplished, thus giving useful information for in vivo applications. The effect of dissolved oxygen concentration in the working solution was also studied in order to evaluate its effect on the linearity of the sensors. Glucose monitoring performed with serum samples was performed to evaluate the effect of matrix components on operative stability and demonstrated an efficient behaviour for 72 h of continuous monitoring. Finally, these studies led to a sensor capable of detecting glucose at concentrations as low as 0.04 mM and with a good linearity up to 2.0 mM (at 37 degrees C) with an operative stability of ca. 72 h, thus demonstrating the possible application of these sensors for continuous glucose monitoring in conjunction with a microdialysis probe. Moreover, preliminary in vivo experiments for ca. 20 h have demonstrated the feasibility of this system.

Postprandial glucose monitoring in type 1 diabetes mellitus: use of a continuous subcutaneous monitoring device.

BACKGROUND: Pre-prandial glucose gives insufficient information on glycemic excursions throughout the day. We aimed to test a continuous subcutaneous glucose-monitoring device (GlucoDay) to describe postprandial glucose changes. METHODS: In 23 T1DM patients, 24-h GlucoDay registrations were started about 14 h before receiving a standard breakfast B and 3 h later lunch L. RESULTS: The 3-min glucose values were computed into parameters describing the postprandial changes after B and L. Two-hour glucose was higher after B (243 +/- 69 vs 180 +/- 79 mg/dL after L, p < 0.0001). Maximum glycemia (313 +/- 105 mg/dL after B and 304 +/- 119 after L, p < 0.0001) was higher and was reached after 78 and 57 min respectively. Three-hour AUC was higher but 30-min AUC was lower after B (5725 +/- 2414 vs 7488 +/- 2208 min mg/dL after L, p = 0.004). Glucose spikes (maximum peak minus fasting plasma glucose) were similar after B and L but the difference between maximum and minimum values was smaller after B (165 +/- 110 vs 219 +/- 115 mg/dL after L, p = 0.020). Duration of hyperglycemic periods >200, 140 or 126 mg/dL were not different after B or L, but time spent at glucose <100 mg/dL was longer after L (p < 0.0001). CONCLUSIONS: These results illustrate the use of subcutaneous glucose registration to characterize postprandial glycemia patterns in T1DM. Application of such methods to evaluate this and other clinical situations in DM can lead to therapeutic and dietary adjustments and ultimately improve glycemic control.

Nocturnal hypoglycaemia in type 1 diabetes--consequences and assessment.

Hypoglycaemia is inevitable when striving for low HbA1c values. Nocturnal hypoglycaemia often occurs without symptoms, but results in diminished next day well-being and hypoglycaemia unawareness. Frequency of nocturnal hypoglycaemia was first assessed in research ward settings, but suffered from insufficient glucose sampling frequency. This may have resulted in overestimation of the duration of hypoglycaemic episodes. The advent of the first continuous glucose sensor, the needle-type MedtronicMiniMed Continuous Glucose Measurement System, revolutionized the assessment of glucose values. However, on scrutiny, the first version of this sensor showed a drift into the hypoglycaemic area and delayed recovery from hypoglycaemia. Using the microdialysis-based GlucoDay system, our group reported a lower frequency of nocturnal hypoglycaemia in type 1 diabetes patients using an insulin pump, than that expected from the existing literature. Today, more than 80 years after the introduction of insulin for the treatment of type 1 diabetes, the associated frequency of nocturnal hypoglycaemia still awaits its definitive assessment.

Continuous glucose monitoring in conditions other than diabetes.

BACKGROUND: The development of new systems for continuous glucose monitoring has recently increased the interest for their potential applications among physicians involved in diabetes care. One of the most common applications of such devices is the identification of hypoglycaemic events in insulin-treated diabetic patients (particularly during the night) and the evaluation of the full daily glucose excursions. METHODS: Among commercially available glucose sensors, the Glucoday system has been utilized for practical clinical application in the last two years. One of the most important features of this device is the accuracy in monitoring interstitial glucose values, specifically in the hypoglycaemic range. This feature is clinically relevant when applied in the clinical setting of patients with type 1 diabetes mellitus. The ability to monitor glucose continuously could be indeed a useful tool for the study of hypoglycaemic conditions other than diabetes. RESULTS: In patients with hyperinsulinaemic hypoglycaemia, recurrent episodes of asymptomatic hypoglycaemia are common, and in patients with glycogen storage diseases, avoidance of recurrent and prolonged hypoglycaemic episodes usually require frequent determinations by mean of home blood glucose monitoring. CONCLUSIONS: Experimental preliminary evidences suggest that this new technology could be applied in the clinical setting to help the physician to identify mainly nocturnal hypoglycaemic events, otherwise not revealed by traditional self blood-glucose monitoring, even in those patients who are not treated by conventional insulin therapy.

A microdialysis technique for continuous subcutaneous glucose monitoring in diabetic patients (part 2).

The aim of this study was to evaluate the reproducibility, the accuracy and the reliability of a continuous subcutaneous glucose measuring system. The GlucoDay system (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 (see part 1). This instrument has demonstrated high reliability coupled with a low degree of invasivity. The profiles of glucose monitoring allow to achieve an excellent knowledge of the real variation of glucose in diabetic patients. The reproducibility study showed a bias lower than 10% between instruments. The accuracy study showed a difference from the reference method lower than 15%.

Continuous subcutaneous glucose monitoring in diabetic patients: a multicenter analysis.

OBJECTIVE: To evaluate the accuracy of a new subcutaneous glucose sensor (Glucoday; A. Menarini Diagnostics) compared with venous blood glucose measurement in type 1 and type 2 diabetic patients. 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 = 0.9, P < 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 -2.0% in the hypoglycemic range (<70 mg/dl), 6.9% in the euglycemic range (70-180 mg/dl), and 11.2% in the hyperglycemic range (>180 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.