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PubMed2002

Performance of a continuous glucose monitoring system during controlled hypoglycaemia in healthy volunteers.

It has been suggested that the continuous glucose monitoring system may be a useful tool for detecting unrecognised hypoglycaemia, especially at times when finger prick testing is difficult or impossible (e.g., at night). Studies suggest that subcutaneous glucose levels closely mimic blood glucose levels with a lag time of only a few minutes. However, no studies have been published to show how well the sensor performs during sustained or in recovery from hypoglycaemia. This study involved using a hyperinsulinaemic glucose clamp (60 mU/m2) in nine healthy volunteers. Each subject had two sensors inserted the day before the study. Blood glucose levels were maintained at euglycaemia for the first 60 min, then decreased to 45 mg/dL (2.5 mmol/L) for 60 min, and finally restored to euglycaemia. Blood glucose measurements were compared with interstitial values recorded by the sensor. Sensor profiles showed acceptable agreement with blood glucose levels at each of the three plateaus with a correlation coefficient of 0.79, slope of 0.85, and mean absolute error of 7%. The sensor drop closely matched the drop in blood glucose, but the recovery from hypoglycaemia was delayed by an average of 26 min. Continuous glucose sensing provides a useful means of detecting unrecognised hypoglycaemia in type 1 diabetes, although the duration of hypoglycaemia may be overestimated.

Adult↗

PubMed2005

Eight-point glucose testing versus the continuous glucose monitoring system in evaluation of glycemic control in type 1 diabetes.

CONTEXT: Advantages/disadvantages of continuous vs. discrete glucose monitoring are not well documented. OBJECTIVE: Compare glucose profiles from home meters vs. continuous sensors. DESIGN: Randomized clinical trial conducted by the Diabetes Research in Children Network (DirecNet) to assess the utility of the GlucoWatch G2 Biographer. SETTING: Home glucose measurements. PATIENTS: Two hundred children (age, 7 to < 18 yr) with type 1 diabetes. INTERVENTION: At baseline, subjects were asked to wear the continuous glucose monitoring system (CGMS) sensor and perform meter tests at eight prespecified times of the day (eight-point testing) each for 3 d (2 d using both, 1 d eight-point testing only, 1 d CGMS only). Hemoglobin A1c was measured in a central laboratory. MAIN OUTCOME MEASURE: Six-month hemoglobin A1c. This analysis looked at baseline glucose profiles/hemoglobin A1c. RESULTS: Only 10% of subjects completed full eight-point testing for 3 d, but median CGMS use was 70 h. Mean glucose was lower when measured by the CGMS compared with eight-point testing (183 +/- 37 vs. 188 +/- 41 mg/dl; 10.2 +/- 2.1 vs.10.4 +/- 2.3 mmol/liter; P = 0.009), especially overnight (2400-0400 h; 174 vs. 199 mg/dl; 9.7 vs. 11.1 mmol/liter; P < 0.001). Associations of hemoglobin A1c with mean glucose were similar for eight-point testing [slope 23 mg/dl per 1% (1.3 mmol/liter); correlation 0.40; P < 0.001] and CGMS [slope 19 mg/dl per 1% (1.1 mmol/liter); correlation 0.39; P < 0.001]. Postprandial excursions were lower for eight-point testing vs. CGMS, especially after dinner (mean excursion -17 vs. 63 mg/dl; -1.0 vs. 3.5 mmol/liter; P < 0.001). CONCLUSIONS: Both methods gave similar mean glucose profiles and associations with hemoglobin A1c. Advantages of the CGMS were higher density of data and better detection of postprandial peaks. However, the CGMS may overestimate the frequency of low glucose levels, especially overnight.

Biosensing Techniques↗

PubMed2002

Nocturnal hypoglycemia detected with the Continuous Glucose Monitoring System in pediatric patients with type 1 diabetes.

OBJECTIVE: To use the Continuous Glucose Monitoring System (CGMS, MiniMed, Sylmar, Calif) to determine if bedtime blood glucose levels were associated with the occurrence of nocturnal hypoglycemia. STUDY DESIGN: Patients (n = 47, 18 boys, mean age 11.8 +/- 4.6 years) with type 1 diabetes used CGMS for 167 nights. Data were analyzed for glucose </=40 or </=50 mg/dL, comparing bedtime blood glucose levels of </=100 or >100 mg/dL and </=150 or >150 mg/dL. RESULTS: A glucose value of </=40 mg/dL occurred on 27% of nights and </=50 mg/dL on 35% of nights. There was a 2-fold increase (45% vs 22%, P =.015) in the incidence of hypoglycemia with a bedtime glucose </=100 mg/dL and a 1.7-fold increase (46% vs 26%, P =.01) with a value of </=150 mg/dL; most episodes occurred between 9 PM and 1 AM. There was no difference in hypoglycemia duration (86.4 minutes for glucose </=100 mg/dL vs 84.5 minutes for >100 mg/dL, P = NS), and no bedtime glucose value between 110 and 300 mg/dL decreased the incidence of nocturnal hypoglycemia to </=10%. The incidence of nocturnal hypoglycemia was similar for patients using insulin pump and injection therapy, and there was no correlation between hemoglobin A1c and incidence or duration of hypoglycemia. CONCLUSIONS: Nocturnal hypoglycemia is frequent, of long duration, associated with bedtime glucose values </=100 to 150 mg/dL, and predominately in the early part of the night. CGMS is a useful tool to diagnose asymptomatic nocturnal hypoglycemia.

Adult↗

PubMed2003

Evaluation of a continuous glucose monitoring system for use in dogs, cats, and horses.

OBJECTIVE: To evaluate a continuous glucose monitoring system (CGMS) for use in dogs, cats, and horses. DESIGN: Prospective clinical study. Animals-7 horses, 3 cats, and 4 dogs that were clinically normal and 1 horse, 2 cats, and 3 dogs with diabetes mellitus. PROCEDURE: Interstitial glucose concentrations were monitored and recorded every 5 minutes by use of a CGMS. Interstitial glucose concentrations were compared with whole blood glucose concentrations as determined by a point-of-care glucose meter. Interstitial glucose concentrations were also monitored in 2 clinically normal horses after oral and i.v. administration of glucose. RESULTS: There was a positive correlation between interstitial and whole blood glucose concentrations for clinically normal dogs, cats, and horses and those with diabetes mellitus. Events such as feeding, glucose or insulin administration, restraint, and transport to the clinic were recorded by the owner or clinician and could be identified on the graph and associated with time of occurrence. CONCLUSIONS AND CLINICAL RELEVANCE: Our data indicate that use of CGMS is valid for dogs, cats, and horses. This system alleviated the need for multiple blood samples and the stress associated with obtaining those samples. Because hospitalization was not required, information obtained from the CGMS provided a more accurate assessment of the animal's glucose concentrations for an extended period, compared with measurement of blood glucose concentrations. Use of the CGMS will promote the diagnostic and research potential of serial glucose monitoring.

Animals↗

PubMed2005

Novel micromachined silicon sensor for continuous glucose monitoring.

The construction and the application properties of a micro-machined silicon sensor for continuous glucose monitoring are presented. The sensor uses the conventional enzymatic conversion of glucose with amperometric detection of H(2)O(2). The innovation is the precise diffusion control of the analyte through a porous silicon membrane into a silicon etched cavity containing the immobilised enzyme. A variation of the number and size of the membrane pores allows to adjust the linear range of the sensor to the respective requirement. The sensor was tested in vitro as well as in clinical studies, being supplied with interstitial fluid. The cavity sensor was designed for a linear range between 0.5 and 20 mM. A signal response time of below 30 s and a signal stability exceeding 1 week is shown. By using a double cavity sensor falsification of the glucose signal by interfering substances can be compensated. In clinical trials the sensor measured continuously in interstitial fluid for up to 18 h without any signal drift and with good correlation to blood glucose reference values.

Biosensing Techniques↗

PubMed2003

Unrecognized hypo- and hyperglycemia in well-controlled patients with type 2 diabetes mellitus: the results of continuous glucose monitoring.

The aim of this study was to determine the prevalence and extent of glycemic excursions (hypo- and hyperglycemic) in elderly patients with well-controlled type 2 diabetes using a Continuous Glucose Monitor System (CGMS) (Medtronic MiniMed). Elderly patients (>65 years old) with type 2 diabetes were recruited if their glycosylated hemoglobin (HbA1c) was <7.5% and if their oral hypoglycemic therapy included a sulfonylurea. Patients were asked to undergo two consecutive 72-h periods of continuous glucose monitoring at baseline and then again at 1 month (total 288 h). Patients were asked to record four self-monitored capillary blood glucose levels each day for calibration of the monitor and also to record meal times, exercise, and symptoms of hypoglycemia. The number of hyperglycemic (>144 mg/dL), hypoglycemic (<50 mg/dL), and borderline-hypoglycemic (50-65 mg/dL) events were determined (an event was defined as a glucose value that persisted for at least 15 min with or without symptoms). Twenty-five patients (21 men, four women) 73.9 +/- 4.4 years old with an HbA1c of 6.2 +/- 0.8% were each monitored for an average of 187.57 h. The mean glucose values were: fasting, 139 +/- 40 mg/dL; 2 h post-breakfast, 167 +/- 58 mg/dL; 2 h post-lunch, 157 +/- 53 mg/dL; and 2 h post-dinner, 149 +/- 49 mg/dL. Twenty patients (80%) experienced a total of 103 hypoglycemic events, and 14 of these patients experienced 54 events where the glucose levels were </=40 mg/dL. Twenty-four patients (96%) experienced borderline-hypoglycemia (n = 229 events). Patients experienced a mean of 0.62 +/- 0.72 episodes of hypoglycemia (interstitial glucose <50 mg/dL) per day (four to five episodes overall), 0.35 +/- 0.6 episodes per day where the interstitial glucose was </=40 mg/dL (two to three episodes overall), and 1.37 +/- 1.22 episodes of borderline-hypoglycemia (nine to 10 episodes overall). Each episode of hypoglycemia persisted for 78 +/- 73 min, and borderline-hypoglycemia for 45 +/- 11 min. Patients were hypoglycemic 3.3% of the time and borderline-hypoglycemic 3.7% of the time. No episode of hypoglycemia was recorded by any patient in his or her daily diary. High postprandial glucose values (>144 mg/dL 2 h postprandial) were recorded after 57% of all meals (breakfast 60%, lunch 57.5%, dinner 55.2%). The CGMS was generally well tolerated, but 52% of patients could not be studied for the full 12 days of monitoring. Thus hypoglycemia and excessive postprandial glycemic excursions are common in well-controlled patients with type 2 diabetes treated with a sulfonylurea with or without metformin. The CGMS is a useful research and clinical tool to assess glycemia in patients with type 2 diabetes but is not tolerated by all subjects.

Aged↗

PubMed2006

Extended use of a new continuous glucose monitoring system with wireless data transmission in children with type 1 diabetes mellitus.

BACKGROUND: A new continuous glucose monitoring system (CGMS Datalogger, Medtronic MiniMed, Northridge, CA) potentiates extended sensor use by eliminating the cable connection to a monitor and by being waterproof. We evaluated the performance, safety, and patient tolerance of using the CGMS for 7 continuous days in children with type 1 diabetes mellitus who were encouraged to participate fully in their usual sports and activities in their home environment. METHODS: Twenty pediatric subjects (12.2 +/- 4.6 years old [mean +/- SD] and glycosylated hemoglobin of 8.06 +/- 1.22%) wore two CGMS devices simultaneously for 7 days. Sensor function was assessed by paired sensor-meter values obtained from the CGMS and their Paradigm Link (Medtronic Minimed) home glucose meter and a daily patient log of sensor and Datalogger sites. RESULTS: Subjects were wearing 90% of the sensors at the end of 7 days. The devices were well tolerated except for pruritus at the adhesive sites in 29% of subjects, and one sensor site (3%) became infected. Once a correction was made to the connection between the cable and Datalogger, 89% of the 18 sensors that initialized were functional at the end of 5 days [r = 0.91; percent mean absolute relative difference (%MARD) = 12.4%], and 78% were functioning at the end of 7 days (r = 0.91; %MARD s 15.4%). Patient comfort while wearing the device decreased after 5 days of sensor wear. CONCLUSIONS: This study demonstrates that the life of the glucose sensor can be extended well beyond the current labeling of 72 h. Once the cable connection was corrected, there was no statistically significant change in sensor performance over 7 days. Patients preferred to wear the device for a maximum of 5-6 days.

Adolescent↗

PubMed2006

Evaluation of the superiority of insulin glargine as basal insulin replacement by continuous glucose monitoring system.

To evaluate the superiority of insulin glargine as basal insulin replacement by continuous glucose monitoring system (CGMS). Twenty-four patients with type 2 diabetes mellitus (T2DM) whose blood glucose was not well controlled with sulphanylureas were enrolled. At first, they were treated with extended-release glipizide (glucotrol XL) 5mg/d before breakfast for 2 weeks, then randomized to combination treatment with glargine (16 patients) or NPH (8 patients) and treated for 12 weeks. CGMS were carried in the second week after treatment with glucotrol XL, and in the 12th week after combination treatment. The data of CGMS showed: (1) When FPG were well controlled in both groups (glargine group versus NPH group: 6.0+/-1.0 mmol/L versus 5.8+/-1.3 mmol/L), the blood glucose level at 3:00 a.m. (5.1+/-0.9 mmol/L versus 4.2+/-0.8 mmol/L) were higher (P<0.05), TPG< or =3.0 mmol/L at night were lower (2.56+/-1.79 versus 5.88+/-1.96), and the rate of nocturnal hypoglycemia (1/16 versus 4/8) were less (P=0.028) in glargine group than those in NPH group. (2) CGMS showed that the daily blood glucose profile excursion were more smoother in glargine group than those in NPH group. In conclusion, it was confirmed with CGMS that compared with traditionally basal insulin replacement with NPH, the combination treatment with glargine injection at bedtime may be predominant for stabilizing the daily blood glucose profile excursion and decreasing the nocturnal hypoglycemia events incidence. So glargine may be a more ideal basal insulin replacement than NPH.

Blood Glucose↗

PubMed2005

Nocturnal differences in subcutaneous tissue glucose between forearm and abdominal sites during continuous glucose monitoring in normal subjects.

OBJECTIVE: A number of short-term studies using the continuous glucose monitoring system (CGMS) indicate that improved metabolic control can be observed in patients with type 1 diabetes when CGMS is applied in clinical practice. Data have also accumulated to suggest that spot measurements of glucose performed four times a day would not detect as much as 70% of all hypoglycaemic episodes registered by CGMS. When more frequent reference values were obtained however it was inferred that nighttime hypoglycaemia reported by CGMS may be spurious. As most assessments with CGMS have been utilizing abdominal subcutaneous tissue, we were interested to evaluate whether differences between blood glucose and sensor readings obtained from different sites exist. RESEARCH DESIGN AND METHODS: Two viscometric affinity glucose sensors, applicable to subcutaneous tissue of both forearm and abdomen, were inserted subcutaneously in 12 non-diabetic subjects. Sensors generated glucose data at 3 min intervals and venous blood glucose was determined in duplicates by HemoCue at 15-90 min intervals for 24 hours. Each subject consumed three carbohydrate-rich meals, performed an exercise test, and was observed during nocturnal bed-rest at the research center. RESULTS: The initial decrease of blood glucose during exercise was not fully detected by the sensors. Otherwise, no significant differences between sensor values and blood glucose were observed during day-time. During nocturnal bed-rest abdominal sensor values came approximately 20% lower than blood glucose (P<0.001) and forearm sensor readings. CONCLUSION: It is concluded that a difference between glucose values obtained from abdominal and forearm subcutaneous fat can be observed during nocturnal bed-rest in non-diabetics.

Abdomen↗

PubMed2005

Continuous glucose monitoring in interstitial subcutaneous adipose tissue and skeletal muscle reflects excursions in cerebral cortex.

Continuous glucose monitoring (CGM) is being explored using several types of glucose sensors. Some are designed for subcutaneous adipose tissue. It is important to determine to which extent these glucose fluctuations in different tissues reflect changes taking place in the central nervous system, where glucose sensing is thought to occur. We studied the ability of subcutaneous adipose interstitial fluid measurements to parallel glucose propagations in blood, muscle, and central nervous system (CNS) during hyper- and hypoglycemia. A subcutaneous CGM system was applied in the CNS, subcutaneous adipose tissue, and skeletal muscle of nine Vietnamese potbellied pigs, and data were compared with frequent sampling in blood. Alterations in glucose levels were induced with intravenous glucose and insulin. During hyperglycemia, no difference was detected in delay between blood and interstitial glucose levels in subcutaneous adipose tissue (18.0 +/- 0.8 min), muscle (18.0 +/- 0.9 min), and CNS (20.3 +/- 1.2 min), respectively. During hypoglycemia, we found no time difference between interstitial parameters in the three tissues. However, the amplitude of glucose changes varied considerably, with a smaller magnitude of glucose change taking place in the brain. The timing of glucose excursions in subcutaneous adipose tissue and muscle reflect excursions in CNS. The reduced magnitude of glucose excursions in the brain suggests that different mechanisms of glucose transport are operative in CNS compared with subcutaneous adipose tissue and muscle.

Adipose Tissue↗

PubMed2006

Real-time continuous glucose monitoring in pediatric patients during and after cardiac surgery.

OBJECTIVES: Given the demonstrated benefit of euglycemia in critically ill patients as well as the risk for hypoglycemia during insulin infusion in children, we sought to validate a subcutaneous sensor for real-time continuous glucose monitoring in pediatric patients during and after cardiac surgery. METHODS: Children up to 36 months of age who were undergoing cardiac bypass surgery were recruited. After anesthetic induction, a continuous glucose-monitoring system sensor (CGMS, Medtronic Minimed, Northridge, CA) was inserted subcutaneously. Sensors remained in place for up to 72 hours. Arterial blood glucose was measured intermittently in the central laboratory (Bayer Rapidlab 860, Tarrytown, NY). Sensor data, after prospective calibration with 6-hourly laboratory values using the proprietary Medtronic Minimed Guardian RT algorithm, were compared with all laboratory glucose values. Statistical analysis was performed to test whether sensor performance was affected by body temperature, inotrope dose, or body-wall edema. RESULTS: Twenty patients were enrolled in the study for a total of 40 study days and 246 paired sensor and laboratory glucose values. Consensus error grid analysis demonstrated that 72.0% of sensor value comparisons were within zone A (no effect on clinical action), and 27.6% of comparisons were within zone B (altered clinical action of little or no effect on outcome), with a mean absolute relative deviation of 17.6% for all comparisons. One comparison (0.4%) was in zone C (altered clinical action likely to affect outcome). No significant correlations were found between sensor performance and body temperature, inotrope dose, or body-wall edema. All patients tolerated the sensors well without bleeding or tissue reaction. CONCLUSIONS: Guardian RT real-time subcutaneous blood glucose measurement is safe and potentially useful for continuous glucose monitoring in critically ill children. Subcutaneous sensors performed well in the setting of hypothermia, inotrope use, and edema. These sensors facilitate identifying and following the effects of interventions to control blood glucose.

Algorithms↗

PubMed1984

Improved bioassay for glucagon by continuous glucose monitoring.

A simplified and rapid in vivo bioassay for glucagon is described. The test involves continuous monitoring of blood glucose which makes possible an exact rendering of the glucose peaks induced by intravenous injection of glucagon. Two injections of known amounts of glucagon (0.002 and 0.004 U) are followed by an intravenous injection of a solution containing an unknown amount of glucagon for testing. The whole procedure can be completed in 8 h. The interassay variability of 6 bioassay procedures was +/- 12.4%. The intra-assay variability was +/- 3%.

Animals↗

PubMed2004

The Continuous Glucose Monitoring System during pregnancy of women with type 1 diabetes mellitus: accuracy assessment.

BACKGROUND: The Continuous Glucose Monitoring System (CGMS, Medtronic MiniMed, Northridge, CA) allows close monitoring of glucose patterns and might be helpful in explaining the persistence of high complication rates in pregnancies of women with type 1 diabetes. It was the aim of this study to determine whether the CGMS accurately reflects glucose levels in pregnant women with type 1 diabetes mellitus. METHODS: Fifteen pregnant women with type 1 diabetes used the CGMS and were asked to determine at least seven fingerstick blood glucose levels each day, of which four were used for calibration. The patients were asked to keep a diary of the non-calibration blood glucose values. The accuracy of the CGMS was studied by comparing the non-calibration blood glucose values with simultaneously measured sensor glucose values using the Pearson correlation coefficient, the mean of absolute differences, and the Clarke error grid analysis. RESULTS: A total of 239 non-calibration blood glucose values were analyzed. The correlation coefficient between non-calibration blood glucose and sensor glucose value was 0.94 (P < 0.001). The mean of the absolute difference was 0.74 mmol/L. Of the non-calibration data 93.8% fell in the clinically acceptable zone of the Clarke error grid analysis. CONCLUSIONS: The CGMS is an accurate tool for additional glucose monitoring in pregnant women with type 1 diabetes mellitus.

Blood Glucose↗

PubMed2005

[Accuracy, effect on insulin therapy and glycemic control and complications of the continuous glucose monitoring system in type 1 diabetic patients].

To evaluate the efficacy, safety and complications of continuous glucose monitoring system (CGMS) in type 1 diabetic patients (DM1), we retrospectively studied 30 patients (25.8 +/- 12.2 years) submitted to 72 hs CGMS (Medtronic; Northridge, CA) and analyzed: mean self monitoring blood glucose (SMBG) and mean CGMS sensors glycemic value; correlation coefficient (%), median absolute percent difference (MAD%), number of sensor reading, glycemic excursions (CGMS vs. SMBG), complications (trauma, local infection, disconnection) and therapeutic management after CGMS. A1c levels were measured 1 month before and 3 months after the study. Mean capillary glucose values were 186.5 +/- 43.3 mg/dl vs. 179.7 +/- 48.1 mg/dl by CGMS sensor, with significant correlation (p = 0.001). An average of 772.4 +/- 254.1 (VR > 680) glucose measurements was recorded for each patient, with 68.7 +/- 19.8 hs of exam. Correlation coefficient was 0.86 +/- 0.21 (VR > 0.79). Median absolute percent difference between sensor and glucometer values was 13.9 +/- 4.7% (VR < 28%). The CGMS was significant more efficient in detection of glycemic excursion related to capillary glycemia (p = 0.009). This data showed important decreased level of A1c in this population 3 months after the CGMS with statistical significance (p = 0.018). No complications were registered in 96.7% of patients. No trauma, local infection or bleeding were registered. The insulin therapeutic regimen was adjusted in 100% of patients. The CGMS showed to be a very safety method, well tolerated, with high accuracy in glycemic values and low complications rate. This method has to be more stimulated by physicians and patients.

Adolescent↗

PubMedDate not supplied

Can continuous glucose monitoring provide objective documentation of hypoglycemia unawareness?

OBJECTIVE: To establish criteria defining hypoglycemia as detected by the continuous glucose monitoring system (CGMS) in patients with type 1 diabetes that best predict hypoglycemia unawareness (HUN), established by a validated questionnaire. METHODS: Adult patients were selected for inclusion in this study if they had long-standing type 1 diabetes, a fasting level of C peptide of < or = 0.6 ng/mL, commitment to achieving glycemic control, and a hemoglobin A1c value no higher than 9%. After clinical data and self-monitoring of plasma glucose data were collected, patients underwent a 72-hour glucose monitoring session with use of a Medtronic-MiniMed CGMS. The presence of HUN was determined by a questionnaire. Factors independently associated with HUN were estimated by multivariate independent analysis. RESULTS: Our study group consisted of 60 patients (33 women and 27 men) who ranged in age from 18 to 84 years (mean, 50.4) and had had diabetes for 5 to 56 years (mean, 23.8). The best predictor of HUN was the maximal duration of hypoglycemia, as determined by the CGMS (P = 0.001). Detection of hypoglycemic episodes with a duration of more than 90 minutes identified patients who had HUN with an 88% specificity and 75% sensitivity. HUN was also significantly associated with use of angiotensin-converting enzyme inhibitors or angiotensin receptor blockers (P = 0.003) and with a longer duration of diabetes (P = 0.008). CONCLUSION: The CGMS can be used for objective detection of patients with HUN.

Adult↗

PubMed2004

Assessment of glycemic control by continuous glucose monitoring system in 50 children with type 1 diabetes starting on insulin pump therapy.

OBJECTIVE: To report experience with a continuous glucose monitoring system (CGMS) and to identify factors influencing glycemic control in a large cohort of children and adolescents with type 1 diabetes and change to insulin pump therapy via continuous subcutaneous insulin infusion (CSII). RESEARCH DESIGN AND METHODS: In 50 patients [21 boys, 29 girls; median age 12.6 yr (range: 1.3-16.4 yr); diabetes duration 5.0 yr (0.2-13.3)], hemoglobin A1c (HbA1c) and ambulatory CGMS were performed before and 6 wk after starting CSII. Average glucose concentration per 24 h, during day and night time as well as number of excursions, duration, and area under the curve (AUC) of glucose values above 180 mg/dL and below 60 mg/dL were calculated from CGMS data. Simultaneously, metabolic control was documented by standardized self-monitoring of blood glucose (SMBG). RESULTS: In the total cohort, HbA1c improved from 8.1 +/- 1.2% at baseline to 7.7 +/- 0.9% after 6 wk of CSII (p <0.001). This effect was more distinct in boys (8.0 +/- 1.4 vs. 7.5 +/- 1.1%, p=0.007) than in girls (8.1 +/- 1.1 vs. 7.8 +/- 0.7%, p=0.039) as well as in patients with poor glycemic control (HbA1c >8.0%) at baseline (8.9 +/- 0.6 vs. 8.1 +/- 0.8%, p <0.001) and in those older than 12 yr (8.2 +/- 1.2 vs. 7.7 +/- 1.0%, p <0.001). At 6 wk of CSII, the values of glucose average per 24 h, AUC and time above 180 mg/dL, particularly during the day, improved. HbA1c was correlated with AUC above 180 mg/dL (r=0.742, p <0.001) and CGMS average glucose per 24 h (r=0.628, p=0.002), but to a lesser extent with SMBG values (r=0.418, p=0.054). CONCLUSION: With the change to CSII, HbA1c improved significantly after 6 wk of therapy. CGMS usage provided additional information about glycemic control in these patients.

Adolescent↗

PubMed2006

Continuous glucose monitoring in normal mice and mice with prediabetes and diabetes.

It is well established that the key to minimizing diabetes-associated complications, in both type 1 and type 2 diabetes, is tight regulation of blood glucose levels. Currently the major approach to regulating blood glucose levels in patients with diabetes relies on external blood glucose monitors. However, poor patient compliance usually results in limited insights into the dynamic range of blood glucose levels (i.e., hyperglycemia vs. hypoglycemia), and inadequate prediction and control of blood glucose levels in these patients. Implantable glucose sensors hold promise for controlling blood glucose levels, but currently these sensors have only limited in vivo life span. Recently we have developed an extremely robust murine model for implantable glucose sensors. In the present study, we have extended this model by developing a complete system for real-time continuous glucose monitoring in normal mice and mice with prediabetes and diabetes (type 1). These studies demonstrated that (1) glucose sensors can be implanted and maintained subcutaneously in the mice; (2) continuous glucose sensor data can be obtained for at least 5 days; and (3) subcutaneous blood glucose sensing paralleled blood glucose levels in normal mice and mice with prediabetes and diabetes. Subcutaneous blood glucose sensing also successfully tracked changes in blood glucose levels induced in the mice with diabetes by administration of oral glucose or insulin. These results mirror the results for subcutaneous blood glucose sensing seen in both normal subjects and patients with diabetes, and therefore validate both our continuous glucose monitoring system in the mouse, and the use of the mouse as a model for implantable glucose sensing in vivo.

Animals↗

PubMed2007

The accuracy of the FreeStyle Navigator continuous glucose monitoring system in children with type 1 diabetes.

OBJECTIVE: To evaluate the accuracy and precision of the FreeStyle Navigator continuous glucose monitoring system in children with type 1 diabetes. RESEARCH DESIGN AND METHODS: In 30 children with type 1 diabetes (mean age 11.2 +/- 4.1 years), the Navigator glucose values were compared with reference serum glucose values of blood samples obtained in an inpatient clinical research center and measured in a central laboratory using a hexokinase enzymatic method and in an outpatient setting with a FreeStyle meter. Median absolute difference (AD) and median relative absolute difference (RAD) were computed for sensor-reference and sensor-sensor pairs. RESULTS: The median AD and RAD were 17 mg/dl and 12%, respectively, for 1,811 inpatient sensor-reference pairs and 20 mg/dl and 14%, respectively, for 8,639 outpatient pairs. The median RAD between two simultaneous Navigator measurements (n = 1,971) was 13%. Ninety-one percent of sensors in the inpatient setting and 81% of sensors in the outpatient setting had a median RAD < or = 20%. CONCLUSIONS: The Navigator's accuracy does not yet approach the accuracy of current-generation home glucose meters, but it is sufficient to believe that the device has the potential to be an important adjunct to treatment of youth with type 1 diabetes.

Adolescent↗