The Continuous Glucose Monitoring System (CGMS) in type 1 diabetic children is the way to reduce hypoglycemic risk

Association of Fructosamine Levels With Glycemic Control in Children With Type 1 Diabetes as Determined by Continuous Glucose Monitoring: Results From the CGM TIME Trial

OBJECTIVE

Our aim in this study was to determine the correlation between serum fructosamine and average blood glucose, as measured by continuous glucose monitoring (CGM) in children with type 1 diabetes.

METHODS

Ninety-seven blood samples were collected from 70 participants in the Timing of Initiation of continuous glucose Monitoring in Established pediatric diabetes (CGM TIME) Trial. Each eligible participant had 3 weeks of CGM data with at least 60% CGM adherence before blood collection. Ordinary least-squares linear regression incorporating restricted cubic splines was used to determine the association between fructosamine levels and mean blood glucose.

RESULTS

An association was found between fructosamine and mean blood glucose, with an F statistic of 9.543 (p<0.001). Data were used to create a formula and conversion chart for calculating mean blood glucose from fructosamine levels for clinical use.

CONCLUSIONS

There is a complex relationship between average blood glucose, as determined by CGM and fructosamine. Fructosamine levels may be clinically useful for assessing short-term glycemic control when CGM is not available.

Relationship between glycated hemoglobin level and duration of hypoglycemia in type 2 diabetes patients treated with sulfonylureas: A multicenter cross-sectional study

AIMS/INTRODUCTION

Sulfonylurea-related hypoglycemia increases the risk of cardiovascular sequela, such as cardiac arrhythmia. This study aimed to clarify the relationship between the level of glycated hemoglobin (HbA1c ) and the duration of hypoglycemia in type 2 diabetes patients treated with sulfonylureas.

MATERIALS AND METHODS

Glucose levels in the enrolled patients (n = 300) were investigated with a professional continuous glucose monitoring device in the outpatient setting at six diabetes centers in Japan.

RESULTS

A total of 269 participants completed the study. The duration of hypoglycemia with glucose values of <54 mg/dL was significantly longer in patients with an HbA1c level of ≤6.4% than in those with an HbA1c level of ≥8.0%, and that of hypoglycemia with glucose values of <70 mg/dL was significantly longer in patients with an HbA1c level of ≤6.4%, 6.5-6.9% or 7.0-7.4% than in those with an HbA1c level of ≥8.0%. Patients with an HbA1c level of ≤6.4% were exposed to glucose values of <70 mg/dL for >10% of the time in daily life (6.8 ± 5.6 min/h). The duration of hypoglycemia with glucose values of <70 mg/dL was longer at night than during the daytime, and the nadir of glucose values occurred between 03.00 and 05.00 hours irrespective of HbA1c level. The duration of hypoglycemia was associated with the duration of diabetes and sulfonylurea dose.

CONCLUSIONS

The duration of hypoglycemia was inversely correlated with HbA1c level and was longer during the night-time than daytime in type 2 diabetes patients treated with sulfonylureas.

Sydney Diabetes centre's experience of the Australian Government's roll out of subsidised continuous glucose monitoring for children with type 1 diabetes mellitus

AIM

To determine patient/carer expectations of continuous glucose monitoring (CGM) and short-term satisfaction, to assess the efficacy of CGM in improving: fear of hypoglycaemia and glycaemic control (HbA_1c , ketosis, hypoglycaemia) and to determine time requirements of diabetes clinic staff in commencing and administering CGM.

METHODS

We assessed CGM-naïve patients starting on CGM at a Sydney Diabetes Centre following the introduction of a nationwide government subsidy for CGM. A standardised questionnaire was administered collecting demographic and glycaemic information in addition to Likert scale assessment of expectations and satisfaction. Clinic staff reported time dedicated to CGM education, commencement and follow-up.

RESULTS

A total of 55 patients or parents/carers completed baseline questionnaires, with 37 completing a 3-month follow-up questionnaire. There were high expectations of CGM prior to commencement and high satisfaction ratings on follow-up. CGM improved fear of hypoglycaemia, and total daily insulin dose increased after commencement of CGM. There was a trend towards lower HbA_1c that was not statistically significant and no statistically significant reduction in ketosis or hypoglycaemia. Comments were mostly positive, with some concern raised regarding technical issues and a lack of subsidy after 21 years of age. Staff time requirements were substantial, with an estimated average of 7.7 h per patient per year.

CONCLUSIONS

Patients and families have high expectations of CGM, and satisfaction levels are high in the short term. Total insulin delivery increased after CGM commencement. Time requirements by staff are substantial but are worthwhile if families' overall satisfaction levels are high.

Practical implementation, education and interpretation guidelines for continuous glucose monitoring: A French position statement

The use by diabetes patients of real-time continuous interstitial glucose monitoring (CGM) or the FreeStyle Libre^® (FSL) flash glucose monitoring (FGM) system is becoming widespread and has changed diabetic practice. The working group bringing together a number of French experts has proposed the present practical consensus. Training of professionals and patient education are crucial for the success of CGM. Also, institutional recommendations must pay particular attention to the indications for and reimbursement of CGM devices in populations at risk of hypoglycaemia. The rules of good practice for CGM are the precursors of those that need to be enacted, given the oncoming emergence of artificial pancreas devices. It is necessary to have software combining user-friendliness, multiplatform usage and average glucose profile (AGP) presentation, while integrating glucose and insulin data as well as events. Expression of CGM data must strive for standardization that facilitates patient phenotyping and their follow-up, while integrating indicators of variability. The introduction of CGM involves a transformation of treatment support, rendering it longer and more complex as it also includes specific educational and technical dimensions. This complexity must be taken into account in discussions of organization of diabetes care.

Insulin degludec is associated with less frequent and milder hypoglycemia in insulin-deficient patients with type 1 diabetes compared with insulin glargine or detemir

Introduction

The aim of this study was to determine the efficacy of insulin degludec (IDeg) relative to insulin glargine (IGlar) or insulin detemir (IDet) in glycemic control, as evaluated by continuous glucose monitoring (CGM) in insulin-deficient patients with type 1 diabetes.

Methods

We studied 28 outpatients treated with IGlar or IDet (IGlar/IDet). Basal insulin was switched to IDeg when glycemic control was considered unstable, as judged by the dawn phenomenon or nocturnal hypoglycemia. Whole-day CGM data were also divided into daytime and nighttime data.

Results

The dawn phenomenon or nocturnal hypoglycemia under IGlar/IDet treatment was observed in all patients. Among 26 patients who completed the study, there were no significant differences in parameters representing glycemic variability, hyperglycemia, mean glycemic control, and HbA1c or insulin therapy-related quality of life at the night score. Measures of hypoglycemia [whole-day %Low and area under the curve (AUC) below 70] were significantly lower under IDeg treatment than under IGlar/IDet treatment (%Low, 9.6 ± 11.5 vs. 14.7 ± 14.9%, p = 0.045; AUC below 70, 85.5 ± 126.0 vs. 145.0 ± 178.6 mg/dl h, p = 0.030). Dividing patients into two groups according to percentage or degree of hypoglycemia under IGlar/IDet treatment, the whole-day, daytime and nighttime %Low in the high-percentage groups and AUC below 70 in the high-degree groups were significantly ameliorated, respectively (p < 0.05).

Conclusion

Patients with unstable glycemic control under IGlar/IDet treatment did not improve glycemic control upon switching to IDeg, but the frequency and the degree of hypoglycemia was reduced in insulin-deficient outpatients with type 1 diabetes, especially in those suffering from severe hypoglycemia.

The Evolving Role of Short-Term Professional Continuous Glucose Monitoring on Glycemic Control and Hypoglycemia Among Saudi Patients with Type 1 Diabetes: A Prospective Study

INTRODUCTION

The aim of this study was to find out the evolving role of professional continuous glucose monitoring (PCGM) on hemoglobin A1c (HbA1c) and the frequency of hypoglycemia.

METHODS

This was a 3-month, prospective study conducted among patients (aged 15-24 years) with type 1 diabetes mellitus who attended a diabetes clinic [Diabetes Treatment Center, Prince Sultan Military Medical City (PSMMC), Riyadh, Saudi Arabia] due to recurrent unexplained hypoglycemia unawareness episodes between July 2014 and December 2014. The respondents were purposively and conveniently selected and they were asked to wear the PCGM device (iPro(®)2; Medtronic MiniMed, Inc., Northridge, CA, USA) for 5 days. The PCGM results were collected by the diabetic educator and reviewed by the treating physician on the same day as removal of the device. Clinical and demographic data were also collected.

RESULTS

Overall, 56 patients were included in the study. The mean (±SD) age of the study cohort was 18.1 ± 1.82 years and 27 (48.2%) patients were male. Compared with baseline, non-significant but positive differences were observed in HbA1c levels in both male and female patients and in those who were older (aged 20-24 years). Similar results were observed in the frequency of hypoglycemia and a significant change was observed for female patients (P < 0.05). Compared with baseline, a significant positive difference was observed in patients' overall frequency of hypoglycemia by the end of the study (P < 0.001).

CONCLUSIONS

Professional continuous glucose monitoring is a valuable tool for detecting episodes of hypoglycemia and may help to decrease HbA1c levels and reduce the frequency of hypoglycemia.

Is the masked continuous glucose monitoring system clinically useful for predicting hemoglobin A1C in type 1 diabetes?

BACKGROUND

The masked continuous glucose monitoring system (Masked-CGMS) differs from standard CGMSs in three ways: (1) there is no feedback to the user so that no immediate regimen changes can be made; (2) it can only be worn for up to 5 days; and (3) there are no alarms to warn of hyperglycemia or hypoglycemia. Since 2008 masked-CGMS has become popular for identifying reasons that a patient's hemoglobin A1C does not correlate closely with his or her capillary blood glucose measurements. To date only one study addressing the clinical utility of Masked-CGMS for improving A1C in diabetes has been published. No studies are available specifically examining the variability and correlation of Masked-CGMS and A1C.

SUBJECTS AND METHODS

We performed 156 Masked-CGMS studies (40 patients studied sequentially a maximum of four times each) in type 1 diabetes patients. We then analyzed the resulting interstitial glucose levels obtained from the Masked-CGMS compared with an A1C measurement performed within 1 week of the Masked-CGMS study.

RESULTS

There was a very low correlation between the A1C and the Masked-CGMS-derived mean interstitial glucose level. This statistic did not provide sufficiently predictive information to be clinically useful for changing an individual patient's intensive insulin therapy regimen.

CONCLUSIONS

Our data demonstrate that a very weak correlation exists between 5 days of masked CGMS and a concurrently measured A1C level. For the individual type 1 diabetes patient, this relationship would unlikely to be clinically useful in altering the individual's treatment regimen.

Treatment recommendations following 3-day masked continuous glucose monitoring (CGM) in youth with type 1 diabetes

Glycemic control remains suboptimal in youth with type 1 diabetes. Retrospective continuous glucose monitoring (CGM) has demonstrated utility in fine-tuning diabetes management by detecting postprandial hyperglycemia and hypoglycemia. In this study, we explored the process of 3-day masked CGM use, subsequent treatment recommendations, and impact on A1c in a clinic-based sample of youth with type 1 diabetes. Over 2 years, 122 youth were referred for masked CGM. Patients/families completed a diary of blood glucose levels, insulin doses, food intake, and exercise during CGM use. A1c was assessed pre- and 2-3 months post-CGM. Treatment recommendations were formulated using data from CGM reports and diaries. Mean age was 14.3 ± 3.9 years, diabetes duration was 7.5 ± 4.7 years, and A1c was 8.5 ± 1.1% (69 ± 12 mmol/mol); 61% were pump-treated. Patients received an average of 3.1 ± 1.1 treatment recommendations following review of the CGM report. Most (80%) received reinforcement of the importance of preprandial bolusing; 37% received a recommendation regarding advanced insulin management (use of combination boluses/attend to active insulin). Receipt of the latter recommendation was related to A1c improvement ≥0.5% (OR: 4.0, P < .001). Masked CGM offers opportunities to guide advanced insulin management (by injection or pump), which may yield A1c improvements in youth with type 1 diabetes.

Transitory beneficial effects of professional continuous glucose monitoring on the metabolic control of patients with type 1 diabetes

BACKGROUND

The benefit of professional continuous glucose monitoring (PCGM) in the metabolic control of patients with type 1 diabetes mellitus (T1DM) is uncertain.

SUBJECTS AND METHODS

This was a retrospective study of all consecutive T1DM patients who underwent a 6-day PCGM in our Diabetes Unit over the course of 17 months. According to the indication, two groups were arbitrarily defined: "hyperglycemic" and "hypoglycemic." Data from medical files and sensor reports were reviewed. Glycated hemoglobin (HbA1c) was evaluated 2-4 weeks prior to PCGM, as well as 3-5 and 12 months after PCGM. In the hypoglycemic group, the number of self-reported mild hypoglycemic episodes (as defined by the American Diabetes Association) was collected.

RESULTS

Of the 67 patients reviewed, 43 were in the hyperglycemic group, and 24 were in the hypoglycemic group. In the hyperglycemic group, the HbA1c level dropped at 3-5 months post-intervention from 8.45 ± 0.72% to 8.04 ± 0.9%, with the decline being statistically significant (-0.4%; P = 0.001) and positively correlated with the initial HbA1c value (0.366; P=0.016). One year after the PCGM study, the HbA1c level tended to return to the initial values: 8.20 ± 1.05% (-0.24%; P = 0.081). In the hypoglycemic group, HbA1c did not change either 3-5 or 12 months after PCGM, although the percentage of patients in whom the number of mild hypoglycemic episodes was significantly reduced was 86% (P=0.001).

CONCLUSIONS

Although a transient phenomenon, PCGM can be useful in the short term in improving metabolic and clinical profile of suboptimally controlled T1DM subjects, including those with repeated hypoglycemia.

Recommendations for self-monitoring in pediatric diabetes: a consensus statement by the ISPED

A panel of experts of the Italian Society of Pediatric Endocrinology and Diabetology comprehensively discussed and approved the Italian recommendations regarding self-monitoring of blood glucose, continuous glucose monitoring and other measures of glycemic control in children and adolescents with type 1 diabetes. After an extensive review of the literature, we took these issues into account: self-monitoring blood glucose, continuous glucose monitoring, glycemic variability, glycosuria, ketonuria, ketonemia, glycated hemoglobin, fructosamine and glycated albumin, logbook, data downloading, lancing devices, carbohydrate counting, and glycemic measurements at school. We concluded that clinical guidelines on self-management should be developed in every country with faithful adaptation to local languages and taking into account specific contexts and local peculiarities, without any substantial modifications to the international recommendations. We believe that the National Health Service should provide all necessary resources to ensure self-monitoring of blood glucose and possibly continuous glucose monitoring of all children and adolescents with type 1 diabetes, according to the standards of care provided by these recommendations and internationally.

Use of technology when assessing adherence to diabetes self-management behaviors

During the last several decades, a proliferation of sophisticated technology has taken place to facilitate diabetes self-management and improve health outcomes. Blood glucose monitors, insulin pumps, and continuous glucose monitors have significant data storage capacity, which can be used to summarize diabetes health management and outcomes. In the absence of technology errors or failures, and in the context of the multiple psychosocial factors associated with nonadherence, these data have the potential to elucidate diabetes care because they reflect actual patient behaviors. This review provides a summary of the diabetes adherence literature in the context of current American Diabetes Association Clinical Practice Recommendations with a focus on studies that have used objective methods (ie, data derived from technology) to assess diabetes care provider and patient adherence in the areas of glucose monitoring; insulin administration and antihyperglycemic medications; medical nutrition therapy; and physical activity.

The role of continuous glucose monitoring in the care of children with type 1 diabetes

Continuous glucose monitoring (CGM), while a relatively new technology, has the potential to transform care for children with type 1 diabetes. Some, but not all studies, have shown that CGM can significantly improve hemoglobin A1c levels and reduce time spent in the hypoglycemic range in children, particularly when used as part of sensor-augmented pump (SAP) therapy. Despite the publication of recent clinical practice guidelines suggesting CGM be offered to all children 8 years of age or older who are likely to benefit, and studies showing that younger children can also benefit, this technology is not yet commonly used by children with type 1 diabetes. Effects of CGM are enhanced when used on a near-daily basis (a use-dependent effect) and with insulin pump therapy. Therefore, coordinated strategies are needed to help children and their families initiate and continue to use this resource for diabetes care. This review introduces CGM to pediatric endocrinologists who are not yet familiar with the finer details of this technology, summarizes current data showing the benefits and limitations of CGM use in children, reviews specific case examples demonstrating when CGM can be helpful, and shows the value of both retrospective and real-time CGM. It is hoped that this information leads to discussion of this technology in pediatric endocrinology clinics as an important next step in improving the care of children with type 1 diabetes.

Relationship between interstitial and blood glucose during hypoglycemia in subjects with type 2 diabetes

BACKGROUND

Continuous glucose monitoring devices measure interstitial glucose and are commonly used to investigate hypoglycemia. The relationship between interstitial glucose and blood glucose is not completely understood, particularly at low blood glucose concentrations. Interstitial glucose during hypoglycemia is generally lower than blood glucose in young subjects without diabetes and those with type 1 diabetes, but the effect of insulin resistance and obesity in type 2 diabetes on this relationship has not been examined previously. We studied the relationship between blood and interstitial glucose during experimental hypoglycemia in subjects with type 2 diabetes treated with insulin or sulfonylureas and matched controls without diabetes.

METHODS

Twenty subjects with type 2 diabetes (10 sulfonylurea-treated and 10 insulin-treated) and 10 controls without diabetes of similar age and weight underwent stepped hyperinsulinemic hypoglycemic clamps. We compared blood and interstitial glucose at different levels of hypoglycemia using random effects modeling.

RESULTS

Interstitial glucose was significantly higher than blood glucose at all levels of hypoglycemia (P<0.001), and this difference increased as glucose fell. For every 1 mmol/L drop in blood glucose, the difference increased by 0.32 mmol/L (P<0.001). This difference was not affected by presence of type 2 diabetes or by modality of treatment (P=0.10).

CONCLUSIONS

In older subjects with or without type 2 diabetes, interstitial glucose is significantly higher than blood glucose, and this difference increases with increasing severity of hypoglycemia. Continuous glucose monitors may underestimate hypoglycemia in this group, and this should be taken into account when interpreting results obtained using this technology.

Use of continuous glucose monitoring systems in children with type 1 diabetes

Continuous glucose monitoring systems (CGMS) offer a recent technological solution to fear of hypoglycemia and reduction in hyperglycemia. With glucose readings every 5 minutes, and the alarm capabilities to signal rapid increases or decreases in blood glucose, they afford a sense of security for both children and parents. Although children and parents must continue to be vigilant in the treatment of diabetes, CGMS may effectively allow tight diabetes control with earlier detection of hypoglycemia onset. This article provides an overview of CGMS available at the time of publication; new generations of systems have been introduced annually with improvements in sensitivity and user friendliness.

Benefits of blinded continuous glucose monitoring during a randomized clinical trial

BACKGROUND

Real-time, personal continuous glucose monitoring (CGM) is a validated technology that can help patients improve glycemic control. Blinded CGM is a promising technology for obtaining retrospective data in clinical research where the quantity and quality of blood glucose information is important. This study was designed to investigate the use of novel procedures to enhance data capture from blinded CGM.

METHODS

Following a 4-week run-in, 46 patients with type 1 diabetes were randomized to one of two prandial insulins for a 12-week treatment period, after which they were crossed over to the alternate treatment for 12 weeks. Continuous glucose monitoring was implemented at the end of run-in (practice only) and during the last 2 weeks of each treatment period. Eighty percent of 288 possible daily glucose values were required for at least three days. Continuous glucose monitoring was extended for an additional week if these criteria were not met, and patients were allowed to insert sensors at home when necessary. Continuous glucose monitoring results were compared to reference eight-point self-monitoring of blood glucose (SMBG).

RESULTS

Higher than expected sensor failure rate was approximately 25%. During run-in, 12 of 45 attempted profiles failed adequacy criteria. However, treatment periods had only 1 of 82 attempted profiles considered inadequate (6 cases required an additional week of CGM). Using SMBG as reference, 93.7% of 777 CGM values were in Clarke error grid zones A+B.

CONCLUSIONS

With appropriate training, adequate practice, and opportunity to repeat blinded CGM as needed, nearly 100% of attempted profiles can be obtained successfully.

The evidence for medical nutrition therapy for type 1 and type 2 diabetes in adults

This article reviews the evidence and nutrition practice recommendations from the American Dietetic Association's nutrition practice guidelines for type 1 and type 2 diabetes in adults. The research literature was reviewed to answer nutrition practice questions and resulted in 29 recommendations. Here, we present the recommendations and provide a comprehensive and systematic review of the evidence associated with their development. Major nutrition therapy factors reviewed are carbohydrate (intake, sucrose, non-nutritive sweeteners, glycemic index, and fiber), protein intake, cardiovascular disease, and weight management. Contributing factors to nutrition therapy reviewed are physical activity and glucose monitoring. Based on individualized nutrition therapy client/patient goals and lifestyle changes the client/patient is willing and able to make, registered dietitians can select appropriate interventions based on key recommendations that include consistency in day-to-day carbohydrate intake, adjusting insulin doses to match carbohydrate intake, substitution of sucrose-containing foods, usual protein intake, cardioprotective nutrition interventions, weight management strategies, regular physical activity, and use of self-monitored blood glucose data. The evidence is strong that medical nutrition therapy provided by registered dietitians is an effective and essential therapy in the management of diabetes.

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.

Effect of short-term use of a continuous glucose monitoring system with a real-time glucose display and a low glucose alarm on incidence and duration of hypoglycemia in a home setting in type 1 diabetes mellitus

BACKGROUND

The objective of this study was to examine whether setting the low glucose alarm of a Guardian® REAL-Time continuous glucose monitoring system (CGMS) to 80 mg/dl for 3 days and providing instructions to users reduce the risk of hypoglycemia under free-living conditions in individuals with type 1 diabetes mellitus (T1DM).

METHODS

Fourteen participants with T1DM aged 26.1±6.0 years (mean±standard deviation) were fitted with a CGMS and assigned for 3 days to either an alarm [low and high blood glucose (BG) alarms set at 80 and 200 mg/dl, respectively] or no alarm condition, with each treatment administered to all participants following a counterbalanced design. All participants were given detailed instructions on how to respond appropriately to low glucose alarms.

RESULTS

The CGMS with alarm reduced the incidence of hypoglycemia (CGMS readings≤65 mg/dl) by 44% as well as the time spent below this hypoglycemic threshold by 64% without increasing average BG levels. However, the CGMS with alarm had no effect on the incidence of symptomatic hypoglycemia.

CONCLUSIONS

Short-term use of the CGMS with alarm, together with appropriate instructions for users, reduces the incidence and duration of hypoglycemia, but only to a limited extent, in part because it overestimates BG in the low glucose range.

Evaluating the clinical accuracy of GlucoMen®Day: a novel microdialysis-based continuous glucose monitor

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.

Sustained efficacy of continuous subcutaneous insulin infusion in type 1 diabetes subjects with recurrent non-severe and severe hypoglycemia and hypoglycemia unawareness: a pilot study

BACKGROUND

This study evaluated the effect of CSII on hypoglycemia awareness and on glucose profile in type 1 diabetes (T1D) subjects with repeated non-severe or severe hypoglycemia (NS or SH, respectively).

METHODS

We included subjects (1) older than 18 years, (2) with T1D duration of >5 years, (3) on multiple doses of insulin, and (4) without micro- or macrovascular complications and more than four NS events per week (in the last 8 weeks) and more than two SH events (in the last 2 years). NS/SH episodes and hypoglycemia awareness were evaluated. A 72-h continuous glucose monitoring (CGM) was performed before continuous subcutaneous insulin infusion (CSII). A hypoglycemia-induced test was used to evaluate each patient's symptoms in euglycemia/hypoglycemia. Quality of life (QoL) was also evaluated. After 6, 12, and 24 months, all the subjects were reevaluated.

RESULTS

Twenty subjects were included (34.0 +/- 7.5 years old, 12 women, A1c 6.7 +/- 1.1%, 16.2 +/- 6.6 years of diabetes' duration). At baseline, 19 out of 20 subjects displayed hypoglycemia unawareness, which diminished significantly during the follow-up (3 out of 20). NH episodes per week diminished from 5.40 +/- 2.09 at baseline to 2.75 +/- 1.74 at the end of the follow-up (P < 0.001). SH episodes fell from 1.25 +/- 0.44 per subject-year to 0.05 +/- 0.22 after 24 months (P < 0.001). Hemoglobin A1c remained unaltered. With CGM, the percentage of values within 70-180 mg/dL increased (53.2 +/- 11.0% to 60.3 +/- 17.1%, P = 0.13), and the percentage of values <70 mg/dL decreased (13.7 +/- 9.4% to 9.1 +/- 5.2%, P = 0.07), after 24 months. Mean amplitude of glycemic excursions diminished after 24 months of CSII (136 +/- 28 mg/dL to 115 +/- 19 mg/dL; P < 0.02). An improvement in all the aspects of QoL was observed. The basal alteration in symptom response to an induced hypoglycemia improved after 24 months of initiating CSII leading to a response indistiguishable from that observed in a control group of subjects with T1D without repeated NH and SH.

CONCLUSIONS

CSII prevents hypoglycemic episodes, improves hypoglycemia awareness, and ameliorates glycemic profile in T1D subjects with repeated NS/SH. Its use is also associated with an improvement in diabetes QoL.

Professional continuous glucose monitoring in clinical practice 2010

Professional continuous glucose monitoring (PCGM) is a 3-5 day test done to evaluate diabetes control. The PCGM test uses interstitial glucose measurements done every 5 min with a glucose-oxidase-impregnated membrane. The PCGM test evaluates glucose control retrospectively with the glucose results being unknown to the patient until the results are downloaded after the testing period. The PCGM test allows the practitioner and patient to evaluate the effect of diet, physical activity, medications, and lifestyle events on glucose control during the 24 h period. Developing a PCGM program at a medical office involves understanding reimbursement issues and having trained staff and a process in place to initiate the test and download and interpret the data.

New features and performance of a next-generation SEVEN-day continuous glucose monitoring system with short lag time

BACKGROUND

The purpose of this study was to evaluate new features and performance of the SEVEN PLUS System (DexCom, Inc., San Diego, CA), a real-time continuous glucose monitoring (CGM) device. This study is the first to evaluate the SEVEN PLUS device.

METHODS

Fifty-three subjects were enrolled at three U.S. centers; 43 (81%) of the subjects had type 1 diabetes mellitus, and 10 (19%) had insulin-requiring type 2 diabetes mellitus. Subjects inserted and wore either one or two sensors for 7 days. A subgroup (n = 18) wore two sensors to track precision. Subjects participated in one 8-h in-clinic session with blood draws every 15 min on study Day 1, 4, or 7 to collect laboratory reference YSI instrument (YSI, Yellow Springs, OH) and self-measured plasma glucose (SMPG) reference measurements. For the remainder of the week, CGM was used as an adjunct to SMPG during home use.

RESULTS

The overall median absolute relative difference (ARD) versus YSI was 13.0%. Zones A and B of the Clarke Error Grid of CGM measurements were 73.8% and 22.1%, respectively. Precision ARD was 15.3 +/- 6.2% (mean +/- SD). The median ARD versus SMPG was 12.1%. Sensor life (89% lasted 7 days) was improved compared to the SEVEN device. The lag time obtained with various statistical measures between CGM and YSI were similar and estimated as a median of 8 min (interquartile range, 11 min) using the Pearson correlation coefficient. No serious adverse events or infectious complications were reported.

CONCLUSIONS

The performance of this new system compares favorably to the previous SEVEN device in terms of accuracy, precision, lag time, sensor life, and rate of data capture.

An overview and commentary on retrospective, continuous glucose monitoring for the optimisation of care for people with diabetes

INTRODUCTION

Normoglycaemia in people with diabetes results in improved outcome. Continuous glucose monitoring provides detailed diagnostic information used to optimise therapy with the goal of achieving normoglycaemia. The objective of this study was to review the published literature evaluating the single device available for blinded, professional clinical use of continuous glucose monitoring; in particular all randomised controlled trials (RCTs) and relevant observational studies.

METHODS

Published studies (to 31 March 2009) using the Medtronic MiniMed Continuous Glucose Monitoring System (CGMS System Gold, Medtronic MiniMed, Inc., Northridge, CA) were identified using appropriate search terms in a series of clinical databases including: Medline, Pubmed, Google Scholar and Scientific Web of Knowledge. Other measures were also taken such as reviewing the reference lists.

FINDINGS

In addition to an extensive range of non-randomised studies using the device, seven randomised controlled trials were identified, of which five were in children. Although HbA1c was explicitly stated as the primary endpoint in four studies, the studies were only adequately powered to detect large, between-group minimum differences (range 0.5 to 1.0% HbA1c). Only two studies included subjects with type 2 diabetes. Other endpoints included the frequency of hypoglycaemia and hyperglycaemia. Within-group HbA1c decreases were observed in all but one study. The crude, weighted mean improvement in HbA1c across the studies using the device was 0.6% (range 0% to 0.8%). When compared to a control measure the weighted, mean marginal benefit in HbA1c was 0.2%. No studies recorded how the information was utilised to modify treatment, such as changes in dose titration or treatment regimen.

CONCLUSIONS

Devices such as the professional CGMS provide detailed diagnostic information. However, any consequent changes in care and outcome can only result from the appropriate application of this information. Although there was a notable improvement in glucose control (HbA1c), existing studies were largely underpowered and did not capture the resulting treatment changes that could lead to improved outcome.

Accuracy of the SEVEN continuous glucose monitoring system: comparison with frequently sampled venous glucose measurements

BACKGROUND

The purpose of this study was to compare the accuracy of measurements obtained from the DexCom SEVEN system with Yellow Springs Instrument (YSI) laboratory measurements of venous blood glucose.

METHODS

Seventy-two subjects with insulin-requiring diabetes, aged 18-71, were enrolled in a multicenter, prospective single-arm study. All participants wore the SEVEN continuous glucose monitoring (CGM) system for one, 7-day wear period. Calibration with capillary finger stick measurements was performed 2 hours after sensor insertion and once every 12 hours thereafter. A subset of subjects (28) wore two systems simultaneously to assess precision. All subjects participated in one, 10-hour in-clinic session on day 1, 4, or 7 of the study to compare CGM measurements against a laboratory method (YSI analyzer) using venous measurements taken once every 20 minutes. Carbohydrate consumption and insulin dosing were adjusted in order to obtain a broad range of glucose values.

RESULTS

Comparison of CGM measurements with the laboratory reference method (n = 2318) gave mean and median absolute relative differences (ARDs) of 16.7 and 13.2%, respectively. The percentage was 70.4% in the clinically accurate Clarke error grid A zone and 27.5% in the benign error B zone. Performance of the SEVEN system was consistent over time with mean and median ARD lowest on day 7 as compared to YSI (13.3 and 10.2%, respectively). Average sensor time lag was 5 minutes.

CONCLUSIONS

Measurements of the DexCom SEVEN system were found to be consistent and accurate compared with venous measurements made using a laboratory reference method over 7 days of wear.

Multicentre, randomised, controlled study of the impact of continuous sub-cutaneous glucose monitoring (GlucoDay) on glycaemic control in type 1 and type 2 diabetes patients

AIM

This randomised study was designed to investigate the impact of continuous glucose monitoring (CGM) for 48h on glycaemic control with a 3-month follow-up in patients with type 1 (T1D) or type 2 (T2D) diabetes.

METHODS

A total of 48 patients with poor glycaemic control (HbA(1c): 8-10.5%) underwent CGM for 48h using the GlucoDay((R)) system (A. Menarini Diagnostics), after which they were randomly assigned to treatment adjustments based on either their CGM profile (CGM group) or their usual self-monitoring of blood glucose (SMBG group). HbA(1c) measurement and 48-h CGM were repeated 3 months later.

RESULTS

Altogether, 34 patients with either T1D (n=9) or T2D (n=25) completed the study; seven patients chose to leave the study, and seven patients in the CGM group were excluded because their baseline CGM graphs were not interpretable. HbA(1c) levels decreased significantly in the CGM group (n=14, -0.63+/-0.27%; P=0.023), but not in the controls (n=20, -0.28+/-0.21%; P=0.30). In T2D patients, the improvement associated with CGM vs SMBG was due to HbA(1c) decreases (mean: -0.63+/-0.34%; P=0.05 vs -0.31+/-0.29%; P=0.18, respectively). However, HbA(1c) did not change significantly with CGM in T1D patients. Comparisons of CGM data at baseline and after 3 months showed no significant changes in glucose control, glucose variability or hypoglycaemia. No major adverse events related to the GlucoDay system were reported.

CONCLUSION

This is the first randomised study showing that CGM improves glycaemic control in patients with T2D.

Continuous glucose monitoring: a review of biochemical perspectives and clinical use in type 1 diabetes

Self-monitoring of blood glucose is a fundamental part of diabetes management. It is mandatory for tight glucose control. For the past 30 years, intermittent measurement of capillary blood glucose has been the method of choice for self-monitoring. The main disadvantage of such measurements is that they provide isolated glucose values which do not reflect variations occurring throughout the day and night. Hence systems monitoring blood glucose concentrations on a "continuous basis" have been developed. In clinical studies, different devices were shown to provide useful information on glycemic excursions in people with diabetes with sufficient accuracy. Thus, in clinical practice, this approach has also been shown to help in the medical management leading to a reduction in glycated hemoglobin and glycemic variability. However, because of lack of experience, this technology has yet to replace standard capillary blood glucose monitoring. In this paper, we review the biochemical perspectives of continuous glucose monitoring and its clinical use in type 1 diabetes.

A review of current evidence with continuous glucose monitoring in patients with diabetes

Devices that measure glucose on a near-continuous basis may provide a better insight into glycemic profiles, allowing patients with diabetes to make therapeutic adjustments to improve metabolic control, thereby reducing the risk of diabetic complications. Motivated and technologically adept patients with brittle diabetes, hypoglycemia unawareness, diabetic pregnancy, or who use pumps might benefit.Current evidence of continuous glucose monitoring (CGM) on health outcome in patients with diabetes is critically reviewed. No data are available on chronic complications or mortality. Therefore, surrogate endpoints need to be investigated, particularly HbA1c, number of hypo- and hyperglycemic episodes, time within normal, high, or low glucose concentrations, glycemic variability, and quality of life.Randomized controlled trials (RCTs) using CGM in a retrospective way did not show metabolic improvement. In contrast, most RCTs applying real-time CGM showed a decrease in HbA1c, reduced glycemic variability, and a diminished number and length of hypo- and hyperglycemic events. Using accurate, real-time CGM devices improves quality of life by reducing the fear of unexpected hypoglycemic events. These beneficial effects were observed despite the fact that in most studies no clear treatment algorithm based on CGM results was provided to the patients. However, most trials were too short in duration, with a variable use of CGM, and were performed in small study samples.In conclusion, real-time CGM systems can improve metabolic control, reduce hypoglycemic episodes, and improve quality of life. Whether this holds true for longer time periods and in the majority of patients remains to be proven. In the long term, CGM might help to reduce chronic diabetes complications and perhaps also mortality, thereby reducing health care costs.

[How the continuous glucose monitoring system can contribute to HbA1c interpretation in type 1 diabetes mellitus?]

The aim of the present study is a literature revision of the contribution of continuous glucose monitoring system (CGMS) in the interpretation of HbA1c levels in type 1 diabetes (T1DM). We performed a revision of the efficacy, benefits, interpretation of methods and experience with this system. The CGMS could be useful in T1DM patients that present great glycemic variability or severe hypoglycemia (mainly nocturnal) and postprandial hyperglycemia. The identification of altered patterns or the glycemic variability allows therapeutic adjustment and improvement of the metabolic control. CGMS is a safe method with a rare occurrence of side effects and it is well-tolerated by patients. The extension of the procedure for more days, over the 72h period recommended by the standard test, allows us to get important data to changes and adjustments on the insulin management of the type 1 diabetes mellitus patients.

Reduction in hemoglobin A1C with real-time continuous glucose monitoring: results from a 12-week observational study

BACKGROUND

Real-time continuous glucose monitoring (CGM) was studied in 140 adults with diabetes over a 12-week period of home use. Hemoglobin A(1c)(HbA1c) was measured on day 1 (baseline) and at weeks 6 and 12.

METHODS

On day 1, participants received the CGM device (STS(R) System, DexCom, Inc., San Diego, CA) and underwent training on proper use. Insertion of the first sensor was performed under staff supervision. Subjects inserted subsequent sensors on their own. After calibration, the device (a 3-day sensor, receiver, and transmitter) provided users with real-time glucose values updated at 5-min intervals, glucose trend graphs, configurable high/low alerts, and a hypoglycemia alarm (<or=55 mg/dL). Study participants were given supplies sufficient for 3 weeks of device use. Follow-up visits were performed at 3-week intervals for resupply and to download CGM data, with a final visit at the end of week 12.

RESULTS

Overall, a reduction in HbA1c of 0.4 +/- 0.05% (least squares mean +/- SE) was observed, P < 0.0001. Significant HbA1c reductions were observed across subgroups of subjects with both type 1 and 2 diabetes, and those delivering insulin by multiple daily injections and pumps. The largest HbA1c reduction (1.4 +/- 0.4%) was observed in subjects with baseline HbA1c >9.0%. Increased CGM use was associated with greater reductions in HbA1c.

CONCLUSIONS

This observational study showed that home use of real-time GCM was safe and well tolerated and associated with a clinically and statistically significant reduction in HbA1c. Large-scale randomized, controlled outcome studies of CGM are indicated.

Tissue response to subcutaneous implantation of glucose-oxidase-based glucose sensors in rats

Considerable progress in improved control of disturbed glucose metabolism can be expected by continuous glucose monitoring. The aim of the study was to evaluate in male Sprague-Dawley rats tissue response to implantation of a new amperometric glucose-oxidase-based glucose sensor (NTS) compared to a commercially available sensor system CGMS of MiniMed. Both sensors were tested under working conditions over a period of 3 days. Using NTS, glucose in interstitial fluid reflected glucose in arterial blood even in rapidly changing hyper- and hypoglycaemia whereas the CGMS did not detect the experimentally induced glucose changes adequately. Gene expression profiling was performed using Affymetrix chips. Acute phase response to injury by sensor application for a short time is indicated by down regulation of the increase in mRNA of proteases e.g. metallothionein-1alpha and matrix metalloprotease-3 at day 3. Improvement of anabolic situation is suggested by decrease in mRNA of insulin-like growth factor binding protein whereas increase of heme oxygenase and hypoxia-inducible factor may be related to defense mechanisms. Changes of mRNA together with slight fibrous capsule formation suggest good histocompatibility. Comparability of the patterns of changed mRNA in tissue surrounding SCGM with and without operating voltage as shown in dendrogram indicates no contribution of hydrogen peroxide to worsening biocompatibility. Beside established histological investigations of foreign body reaction weeks or months after implantation, gene expression profiling provides additional information to biocompatibility already early after implantation.

Relationship of fasting and hourly blood glucose levels to HbA1c values: safety, accuracy, and improvements in glucose profiles obtained using a 7-day continuous glucose sensor

OBJECTIVE

In this study, we evaluated the safety and efficacy of 7-day transcutaneous, real-time, continuous glucose monitoring (CGM) in subjects with insulin-requiring diabetes.

RESEARCH DESIGN AND METHODS

Eighty-six subjects were enrolled at five U.S. centers. Subjects wore a sensor inserted under the skin of the abdomen for 7 days during each of three consecutive periods. Data were blinded during period 1 and unblinded during periods 2 and 3.

RESULTS

Of the 6,811 matched self-monitoring of blood glucose to sensor values prospectively analyzed, 97.2% fell in the Clarke error grid zones A and B, and median absolute relative difference was 11.4%. After unblinding, subjects reduced time spent at <55 mg/dl by 0.3 h/day, reduced time spent at >240 mg/dl by 1.5 h/day, and increased time in the target zone (81-140 mg/dl) by 1.4 h/day (P < 0.05 for all three comparisons). Improvements were seen in both types 1 and 2 diabetes and with use of both multiple daily injections and continuous subcutaneous insulin infusion. Modal day graphs were generated in six groups of subjects based on HbA1c (A1C) (<or=6, 6-7, 7-8, 8-9, 9-10, and >10%). Mean glucose levels from midnight to 7:00 a.m. (fasting and dawn phenomenon periods) were only normal for subjects with A1C <or=6%. All other groups were hyperglycemic during this and all periods. Reductions in overall mean glucose were achieved for the four highest A1C groupings with unblinded device use.

CONCLUSIONS

This is the first report of a real-time, transcutaneous glucose sensor that functioned for 7 days. The use of CGM in the unblinded phase resulted in improvements in target-range glycemia across all A1C values.

Continuous glucose monitoring in interstitial fluid using glucose oxidase-based sensor compared to established blood glucose measurement in rats

Glucose monitoring is of importance for success of complex therapeutic interventions in diabetic patients. Its impact on treatment and glycemic control is demonstrated in large clinical trials. Up to eight blood glucose measurements per day are recommended. Notwithstanding, a substantial number of diabetic patients cannot or will not monitor their blood glucose appropriately. Considerable progress in control of disturbed metabolism in diabetic patients can be expected by continuous glucose monitoring. The aim of the study was to evaluate the performance of a new amperometric glucose oxidase-based glucose sensor in vitro and in vivo after subcutaneous implantation into rats. For in vitro testing current output of sensors was measured by exposure to increasing and decreasing glucose concentrations up to 472 mg dL(-1) over a time period of 7 days. After subcutaneous implantation of sensors into interscapular region of male rats glucose in interstitial fluid was evaluated and compared to glucose in arterial blood up to 7 days. Hyper- and hypoglycaemia were induced by intravenous application of glucose and insulin, respectively. Current of each implanted sensor was converted into glucose concentration using the first blood glucose measurement only. A change of current with glucose of 0.35 nA mg(-1)dL(-1) indicates high sensitivity of the sensor in vitro. The response time (90% of steady state) was calculated by approximately 60s. Test strips for blood glucose measurement as reference for sensor readings was found as an appropriate and rapidly available method in rats by comparison with established hexokinase method in an automated lab analyzer with limits of agreement of +32.8 and -25.7 mg dL(-1) in Bland-Altman analysis. In normo- and hypoglycaemic range sensor readings in interstitial fluid correlated well with blood glucose measurements whereas hyperglycaemia was not reflected by the sensor completely when blood glucose was changing rapidly. The data given characterize a sensor with high sensitivity, long term stability and short response time. A single calibration of the sensor is required only in measurement periods up to 7 days. The findings demonstrate that the sensor is a highly promising candidate for assessment in humans.

Evaluation of the accuracy of a microdialysis-based glucose sensor during insulin-induced hypoglycemia, its recovery, and post-hypoglycemic hyperglycemia in humans

BACKGROUND

These studies were designed to evaluate the accuracy of a microdialysis-based subcutaneous glucose sensor (GlucoDay, A. Menarini Diagnostics, Firenze, Italy) compared with a standard reference method of plasma glucose measurement during insulin-induced hypoglycemia.

RESEARCH DESIGN AND METHODS

Nine subjects without diabetes were studied in eu-, hypo-, and hyperglycemia (clamp technique). The GlucoDay was calibrated against one arterialized plasma glucose measurement (Glucose Analyzer, Beckman, Brea, CA), and plasma glucose estimates every 3 min were compared with paired plasma glucose values.

RESULTS

Accuracy of glucose estimates was not homogeneously distributed among subjects and depended on stability of the sensor's current signal during spontaneous euglycemia (R +/- -0.68). Linear regression analysis showed a good correlation between the two methods of measurement (R = 0.9), Deming regression showed the inclusion of the unit in the confidence interval of the slope (slope 0.95, 95% confidence interval 0.87-1.02), and the accuracy of the GlucoDay reached 40 +/- 15% (American Diabetes Association criteria). The mean relative difference was 6 +/- 8% in euglycemia, 13 +/- 14% during plasma glucose fall, 5 +/- 22% in the hypoglycemic plateau, and -14 +/- 16% during recovery from hypoglycemia. The Bland-Altman analysis indicated a bias of -1.9 +/- 16.6 mg/dL, whereas the Error Grid Analysis showed 94% of the Gluco- Day measurements in the acceptable zones of the grid. The time to reach the glycemic nadir was longer when measured with the GlucoDay (90 +/- 5 vs. 72.5 +/- 9 min, P < 0.05). However, absolute values of glycemic nadir, time spent in hypoglycemia, and the rate of fall of glycemia and the rate of recovery from the hypoglycemia were not statistically different.

CONCLUSIONS

GlucoDay closely monitors changes in plasma glucose before, during, and after hypoglycemia. However, these results can be achieved only if calibration of the GlucoDay is performed under conditions of sensor signal stability. Similar studies have to be performed in subjects with diabetes to validate the GlucoDay system.

Value and limitations of the Continuous Glucose Monitoring System in the management of type 1 diabetes

The CGMS (Continuous Glucose Monitoring System) is a portable device allowing continuous measuring of glucose. It provides recordings of at least 72 h, during which 288 measures/day are performed. Results are visualised in the form of a set of curves, illustrating the variations in blood glucose levels over time. The quality of the records has often been questioned by several authors. Some of the system's physiologically related limitations can be explained by the less than perfect coincidence of variations in glucose levels observed in the interstitial tissue, where CGMS measurings are done, and in the blood, where calibrations are performed. Other limitations, such as defects in accuracy or in reproducibility of tracings or premature curtailments of recordings, are due to technical weaknesses which were considerably improved during the past few years, particularly with regard to the quality of the electrodes providing a more stable signal over time. In clinical practice, CGMS is a tool for investigating the glycaemic patterns of diabetic patients in conjonction with SMBG. It allows the identification of overlooked hyper- or hypoglycaemia. Generally well accepted, it is a usefull tool to analyse the nocturnal period, or any situation where glucose checks are rare. The visual nature of its results provides a facilitating support in the discussion between the patient and the care-provider during consultations or educational sessions. CGMS utilisation was proposed for guiding treatment adjustment. At present, it is still difficult to state with certainty that this tool allows effective improvement in the metabolic control of patients with type 1 diabetes, in view of the paucity of controlled studies showing an impact on HbA1c values or on the frequency of hypoglycaemia, even if such a tendency emerges from most non-controlled intervention trials.

Continuous glucose monitoring and closed-loop systems

BACKGROUND

The last two decades have witnessed unprecedented technological progress in the development of continuous glucose sensors, resulting in the first generation of commercial glucose monitors. This has fuelled the development of prototypes of a closed-loop system based on the combination of a continuous monitor, a control algorithm, and an insulin pump.

METHOD

A review of electromechanical closed-loop approaches is presented. This is followed by a review of existing prototypes and associated glucose sensors. A literature review was undertaken from 1960 to 2004.

RESULTS

Two main approaches exist. The extracorporeal s.c.-s.c. approach employs subcutaneous glucose monitoring and subcutaneous insulin delivery. The implantable i.v.-i.p. approach adopts intravenous sampling and intraperitoneal insulin delivery. Feasibility of both solutions has been demonstrated in small-scale laboratory studies using either the classical proportional-integral-derivative controller or a model predictive controller. Performance in the home setting has yet to be demonstrated.

CONCLUSIONS

The glucose monitor remains the main limiting factor in the development of a commercially viable closed-loop system, as presently available monitors fail to demonstrate satisfactory characteristics in terms of reliability and/or accuracy. Regulatory issues are the second limiting factor. Closed-loop systems are likely to be used first by health-care professionals in controlled environments such as intensive care units.

Seizures as the only clinical manifestation of reactive hypoglycemia: a case report

A 45-yr old diabetic patient, who had received a diagnosis of grand mal epilepsy, for two episodes of nocturnal tonic-clonic convulsions, underwent continuous glucose monitoring (CGM). During CGM, the patient had an episode of tonic-clonic convulsion, and at the same time a prolonged nocturnal hypoglycemia (<2.2 mmol/l) was observed. CGM revealed that tonic-clonic convulsions, which had been interpreted as a manifestation of epilepsy, were in fact a symptom of severe hypoglycemia. In order to assess the pathogenesis of hypoglycemia, the patient underwent a 75-g oral glucose tolerance test, that was interrupted shortly afterwards for hypoglycemic symptoms (i.e., reactive hypoglycemia). To our knowledge, this is the first case ever reported of reactive hypoglycemia associated with Type 2 diabetes.

Glycemic characteristics in continuously monitored patients with type 1 and type 2 diabetes: normative values

OBJECTIVE

The purpose of this study was to generate normative values for periods of euglycemia as well as for daily patterns of glycemic excursions in patients with type 1 and type 2 diabetes monitored continuously for a maximum period of 21 days and blinded to glucose levels.

RESEARCH DESIGN AND METHODS

This was a multicenter, prospective observational study in which 101 consecutive patients with type 1 (n = 60) or type 2 (n = 41) diabetes underwent blinded continuous glucose monitoring. Serial glucose measurements were divided into periods of euglycemia (70-180 mg/dl), hyperglycemia (>180 mg/dl), and hypoglycemia (<70 mg/dl). The proportions of time patients were hypoglycemic, euglycemic, and hyperglycemic and the total areas under the curves (AUCs) were determined.

RESULTS

During the observation period the 101 subjects contributed an average 287 +/- 132 h of continuous glucose values. Subjects remained in the euglycemic range for approximately 63% of the total day, were hypoglycemic 8%, and were hyperglycemic 29%. Hypoglycemia was more prevalent nocturnally (11 vs. 7%) and hyperglycemia diurnally (31 vs. 25%). Compared with subjects with type 2 diabetes, type 1 diabetic subjects had more frequent hypoglycemic episodes per day (2.1 vs. 1.0; P < 0.001) that were of longer duration (1.1 vs. 0.7 h; P < 0.0001), reflecting a greater number of hours per day in the hypoglycemic range (2.3 vs. 1.0 h; P < 0.0001). The mean hypoglycemic AUC values were >150% higher for type 1 compared with type 2 diabetic subjects (41 vs. 16, respectively; P < 0.0001).

CONCLUSIONS

These normative data will assist in study and sample size planning for future investigations of continuous glucose monitoring and allow for qualitative comparisons with trials of therapeutic interventions aimed at reducing the occurrence of glycemic excursions.

Hypoglycemia, hypoglycemia unawareness and counterregulation in children and adolescents with type 1 diabetes mellitus

Three clinical phenomena have been defined in the last decade in patients with diabetes mellitus as a dangerous iatrogenic sequel of hypoglycemia. These are hypoglycemia unawareness, defective glucose counterregulation and a lowered hypoglycemic threshold for hypoglycemic symptoms. Former mild hypoglycemia episodes cause a decrease and a delay in the protective hormonal counterregulatory response and warning symptoms in subsequent episodes, and in the absence of these, risk of severe hypoglycemia increases considerably. It has been demonstrated that when protection is provided against hypoglycemia with strict monitoring programs designed to avoid even mild hypoglycemia episodes, blunted autonomic symptoms and counterregulatory hormonal responses are rectified. Therefore, the best course of action in the treatment of pediatric diabetes mellitus is frequent blood sugar measurements, flexible multiple dose insulin regimens facilitating insulin dose adjustments as required, and a diet. In order to implement this, it is essential to organize an intensive training program with the patient and family, and to provide psychological support and close coordination with the diabetes treatment team.

An observational study comparing continuous subcutaneous insulin infusion (CSII) and insulin glargine in children with type 1 diabetes

OBJECTIVE

The advantages of continuous subcutaneous insulin infusion (CSII) or insulin glargine have been demonstrated both in adult and paediatric diabetic patients; however, as no data comparing these two approaches during childhood are available, we have examined the efficacy of these two intensive approaches.

RESEARCH DESIGN AND METHODS

We retrospectively evaluated data from 36 diabetic children, who had changed their previous insulin regimen [with isophane insulin (NPH) at bedtime] because of HbA1c levels >8.0%. Twenty patients underwent CSII, while the other 16 (significantly younger for age) started insulin glargine at bedtime.

RESULTS

At 6 and 12 months, CSII-treated patients showed a significant reduction in HbA1c values from 8.5 +/- 1.8 to 7.4 +/- 1.1% and to 7.6 +/- 1.2%, respectively. The insulin requirement significantly decreased from 0.93 +/- 0.2 IU/kg to 0.73 +/- 0.2 IU/kg of body weight and to 0.74 +/- 0.15 IU/kg of body weight, respectively, while no significant differences were observed for BMI SDS, fructosamine and severe hypoglycaemic events. The patients treated with glargine showed a small decline in HbA1c values from 8.9 +/- 1.7 to 8.3 +/- 0.9% (not significant) in the first 6 months of treatment and to 8.2 +/- 0.9% after 12 months.

CONCLUSION

The basal insulin supplementation can be supplied effectively in children with type 1 diabetes by either CSII or insulin glargine. As previously reported for adults, it is confirmed that CSII is the best current intensive approach aimed to the improvement of glycaemic control.

Continuous glucose monitoring system signals the occurrence of marked postprandial hyperglycemia in the elderly

BACKGROUND

The aim of this study was to ascertain whether dysglycemic episodes occur in institutionalized elderly persons and, if that is the case, to determine whether such episodes are related to meal patterns. Another objective was to investigate the feasibility of subcutaneous (s.c.) glucose measurements in the elderly using a Medtronic MiniMed (Sylmar, CA) continuous glucose monitoring system (CGMS).

METHODS

Nine nursing home residents (74-95 years old) without known diabetes or other metabolic disorders were included. The s.c. glucose level was measured for 3 days with the Medtronic MiniMed CGMS. Capillary blood glucose was measured four times daily with a Glucometer Elite device (Bayer, Leverkusen, Germany). Body mass index and basal metabolic rate were calculated, and food intake was recorded.

RESULTS

The s.c. glucose level fluctuated noticeably over time; 22.5% of the values recorded during the 3-day period were > or = 8 mmol/L, and values < 3.5 mmol/L were rarely seen. A marked (> 5 mmol/L) and short-term (2-4 h) increase in s.c. glucose was seen after a meal. The mean capillary blood glucose concentration was 7.5 +/- 1.8 mmol/L. Capillary blood glucose > or = 8 mmol/L was recorded on 32.5% of the measurement occasions, and no values were < 3.5 mmol/L. The s.c. glucose values agreed with corresponding capillary blood glucose levels (mean r = 0.75; range 0.43-0.86). Five participants consumed less energy than recommended according to their age, weight, and physical activity level.

CONCLUSIONS

Postprandial hyperglycemia frequently occurs in elderly people living in nursing homes. The CGMS is convenient to use to detect hyperglycemia in this age group.

Self-monitoring of blood glucose in children and teens with diabetes

Improved metabolic control has unequivocally been demonstrated to delay the onset and slow the progression of microvascular complications in adolescents and adults with diabetes mellitus. Growing evidence also supports the association of tighter glucose control and more frequent blood glucose monitoring. Therefore, self-monitoring of blood glucose (SMBG) has become a fundamental part of diabetes care in children. Here, we review recent advances and ongoing trends in glucose monitoring in children with diabetes. Technologies have been developed to improve patient compliance with recommended monitoring, requiring less blood, involving less pain, and providing results more quickly. Alternate-site testing (AST) is also a potential means of improving patient compliance with SMBG by avoiding the sensitive fingertip area. The Continuous Glucose Monitoring System (CGMS) and the GlucoWatch Biographer are two recent tools that can track glucose levels continuously. However, inconsistency in their accuracy and precision remain challenges when using these technologies to guide management.