Home Glucose Meters Research Articles

Human Serum Phenylpyruvate Quantification Using Responsive 2D Photonic Crystal Hydrogels via Chemoselective Oxime Ligation: Progress toward Developing Phenylalanine-Sensing Elements

There is a need to develop at-home phenylalanine (Phe) test kits, analogous to home glucose meters, for phenylketonuria patients who must measure their blood Phe levels frequently to adjust their diet. Unfortunately, such test kits are not available yet because of the lack of simple and inexpensive Phe-sensing elements. With the goal of developing a Phe-sensing element, we fabricated two-dimensional photonic crystal (2DPC) hydrogels that quantify human serum phenylpyruvate (PhPY), which is the product of the reaction between Phe and the enzyme phenylalanine dehydrogenase. The PhPY-sensing hydrogels have oxyamine recognition groups that link PhPY to the hydrogel polymer network via chemoselective oxime ligation. This structural modification induces the hydrogel to swell, which then increases interparticle spacings within the embedded 2DPC. The PhPY-induced particle spacing changes are measured from light diffraction and used to quantify the PhPY concentrations. The estimated limit of detection of PhPY in human serum for a detection time of 30 min is 19 μM, which is comparable to the minimum blood Phe concentrations of healthy people. Besides the potential application for developing Phe-sensing elements, this new hydrogel sensing approach via chemoselective oxime ligation is generalizable to the development of other chemical sensors working in complex biological environments.

Continuous Glucose Monitoring Systems: Are They Useful for Evaluating Glycemic Control in Children with Hyperinsulinism?

Background: Effective treatment and close monitoring in children with congenital hyperinsulinism (HI) are important to prevent hypoglycemic-associated brain damage. The current monitoring approach involves measuring plasma glucose intermittently, but this does not provide a comprehensive assessment of glycemic control and may fail to detect episodes of hypoglycemia. Objective: To determine whether Dexcom G5®, a continuous glucose monitoring system (CGMS), is an accurate and effective method for monitoring glycemic control in children with HI. Methods: Cross-sectional, observational study in 15 children with HI. Participants wore a blinded Dexcom G5® device for 2 weeks. At the end of 2 weeks, data from the Dexcom G5® and home glucose meter were downloaded and analyzed. Results: Fourteen children (15–67 months) completed the study. Using Bland-Altman analysis, the mean (SD) difference between 1,155 paired CGM and glucose meter readings was –8.09 (53.76). The sensitivity and specificity of CGM to detect hypoglycemia (<70 mg/dL) were 86 and 81.4%, respectively. The positive predictive values for hypoglycemia and severe hypoglycemia (<54 mg/dL) detected by CGM were low (50.3 and 14.8%, respectively), while the negative predictive values were high (96.4% for glucose <70 mg/dL and 99.1% for glucose <54 mg/dL). Conclusion: Our study showed that CGM is not a reliable method to monitor for hypoglycemia, given the high number of false positive hypoglycemia readings. However, CGM can be useful in preventing unnecessary checks by glucose meter during times of normoglycemia. Therefore, the benefits of using CGM in patients with HI would be in guiding the need to check plasma glucose by glucose meter rather than point accuracy.

Mean blood glucose-independent HbA1c racial disparity and iron status in youth with Type 1 DM.

Black patients have higher HbA1c than Whites even after adjustment for mean blood glucose (MBG). Decreased iron status has been associated with increased HbA1c independently of glucose. We hypothesized that decreased iron status might account for higher HbA1c in Black patients. Pediatric patients with T1D in the Diabetes Center at Children's Hospital of New Orleans who self-identified as either Black or White were recruited for the study. At the time of their clinic visit labs were obtained for ferritin (Fer), soluble transferrin receptor (sTfR), HbA1c, and CBC. MBG was derived from patient's home glucose meter records over the last 30 days. Total body iron (TBI) and sTfr/log10 Fer (R/lFer) were calculated. A total of 80 (35 Blacks/45 Whites; 41 female/39 male) patients were recruited. Unadjusted levels of HbA1c, MBG, sTfR, Fer, RDW-CV, and RDW-SD were all higher in Blacks than Whites. TBI and R/lFer were not different between groups. Fer was correlated with Hb, MBG but not HbA1c. sTfR was correlated with HbA1c, MCV, MCH, and RDW-SD. In multiple variable analysis with HbA1c as the dependent variable, race and MBG were statistically significant in the model. However, measures of iron status: Fer, sTfR, R/lFer and TBI were not statistically influential. After adjustment for race, MBG and RDW-CV, iron indices were not statistically significant independent predictors of HbA1c levels. These observations indicate that factors besides iron status and CBC indices contribute to MBG-independent racial disparity in HbA1c.

WITHDRAWN: Performance of Community Blood Glucose Meters in Calgary, Alberta: An Analysis of Quality Assurance Data

The self-monitoring of blood glucose plays a critical role in management of diabetes mellitus. Although laboratory comparisons of glucose meter accuracy are often acceptable, clinical comparisons show frequent inaccuracies. In this paper, we evaluate the accuracy of self-monitoring blood glucose meters using glucose meter and serum comparisons from a large Canadian laboratory. This study was performed using secondary data obtained from the Laboratory Information System of Calgary Services, the sole provider of laboratory testing to Calgary and surrounding areas. We examined anonymous quality assurance data for glucose meter comparisons performed on home glucose meters between January 1, 2010, and April 30, 2013. A total of 39 542 comparisons were recorded on 18 540 different subjects. Overall, 6.7% of differences were greater than the current International Standards Organization standard of 15%, and 3.7% exceeded the Canadian guideline of 20%. Glucose meter checks were infrequently performed (on average, once per 1.6 years). A significant subset of meter results was inaccurate.

Self-monitoring of blood glucose

Self-monitoring of blood glucose

Index of Suspicion * Case 1: Leg Cramps, Hand Spasms, Diarrhea, and Substantial Weight Loss in a 12 Year Old * Case 2: Hypothermia, Hypoglycemia, and Hyperbilirubinemia in a Neonate * Case 3: Recurrent Fevers, Abdominal Pain, and Cervical Lymphadenopathy in a 7 Year Old

A 12-year-old previously healthy boy presents with leg cramps for 2 weeks and spasms of his hands since yesterday. He also complains of nausea, bloating, epigastric pain, and recurrent watery and loose stools for 1 month. Currently, he is taking lansoprazole for epigastric pain without any relief. He also has a history of involuntary weight loss of 10 lb over 2 months. The family history contains no findings of note. On physical examination, the boy's weight is 36 kg (25th percentile) and height is 140 cm (10th percentile) and he exhibits a positive Trousseau sign and negative Chvostek sign. Remaining physical signs, including on abdominal examination, are normal. Laboratory evaluation shows hypocalcemia (total calcium of 5.3 mg/dL [1.3 mmol/L], ionized calcium of 2 mg/dL [0.5 mmol/L], and corrected calcium of 6.1 mg/dL [1.5 mmol/L]) as well as hypoalbuminemia (3 g/dL [30 g/L]). Serum magnesium measures 1.6 g/dL. CBC shows Hgb of 9.3 g/dL (93 g/L), Hct of 29% (0.29), WBC count of 9.9×103/μL (9.9×109/L), platelet count of 471×103/μL (471×109/L), mean corpuscular volume of 67 fL, and reticulocyte count of 1% (0.01). Results of the iron studies are consistent with iron deficiency anemia, with a serum iron concentration of 6 μg/dL (1.07 μmol/L) (31 to 144 μg/dL [5.5 to 25.8 μmol/L]), transferrin saturation of 3% (0.3), and serum ferritin less than 5 ng/mL (11.23 pmol/L) (21 to 275 ng/mL [47.2 to 617.9 pmol/L]). ESR is 46 mm/h and CRP is 9.5 mg/dL (normal <0.05 mg/dL). His serum 25-hydroxyvitamin D concentration is low at 5.7 ng/mL (14.2 nmol/L) (normal, 32 to 100 ng/mL [79.9 to 249.6 nmol/L]) and serum parathyroid hormone, urine calcium, and creatinine values are within normal limits. His tetany and hypocalcemia resolve with calcium replacement. Additional evaluation leads to the diagnosis. …

Point-of-Sale: A Review of Home Blood Glucose Meters

Objective: To provide pharmacy technicians with a review of selected home blood glucose meters, enabling them to be more effective in aiding patients at the point-of-sale. Data Source: Primary literature and review articles were identified by searching MEDLINE (1950–September 2010) and Google Scholar, using the key terms glucometers, glucose meters, home glucose meters, blood glucose meters, blood glucose monitoring, and self-monitoring of blood glucose. Additional articles were identified from the bibliographies of obtained literature. User manuals were obtained from the manufacturers' Web sites to determine specific characteristics for each blood glucose meter. Study Selection and Data Extraction: Reviewed literature was restricted to English-language articles. Blood glucose meter reviews have mostly compared standard meter functions. Eleven meters were selected for review and identified as currently marketed by their manufacturers and commonly sold in community pharmacies. Data Synthesis: Eleven home blood glucose meters, by Abbott, Bayer, LifeScan, and Roche, were selected for review. The selected meters have a wide range of features. They are mostly differentiated by meter size and shape, blood sample size, second blood drop allowed, coding, memory capacity, and advanced features that allow patients to customize the settings. Conclusions: There is a variety of home blood glucose meters on the market. When aiding patients with blood glucose meter selection, the best meter should include all of the features that address their monitoring needs.

Validation of Measures of Satisfaction with and Impact of Continuous and Conventional Glucose Monitoring

The evaluation of patient-reported outcomes (e.g. impact, satisfaction) is important in trials of continuous glucose monitoring (CGM). We evaluated psychometric properties of the CGM Satisfaction Scale (CGM-SAT) and the Glucose Monitoring Survey (GMS). CGM-SAT is a 44-item scale on which patients (n=224) or parents (n=102) rated their experience with CGM over the prior 6 months. GMS is a 22-item scale on which patients (n=447) or parents (n=221) rated the blood glucose monitoring system they were using (home glucose meter with or without CGM) at baseline and 6 months. The alpha coefficient for the CGM-SAT was > or = 0.94 for all respondents and for the GMS was > or = 0.84 for all respondents at baseline and 6 months. Parent-youth agreement was 0.52 for the CGM-SAT at 6 months and 0.24 and 0.20 for the GMS at baseline and 6 months for the Standard Care Group, respectively. Test-retest reliability of the GMS at 6 months for controls was r=0.76 for adult patients, 0.63 for pediatric patients, and 0.43 for parents. Factor analysis isolated measurement factors for the CGM-SAT labeled Benefits of CGM and Hassles of CGM, accounting for 33% and 9% of score variance, respectively. For the GMS, two factors emerged: Glucose Control and Social Complications, accounting for 28% and 9% of variance, respectively. Significant correlations of CGM-SAT with frequency of CGM use between 6 months and baseline and GMS with frequency of conventional daily self-monitoring of blood glucose at baseline support their convergent validity. The CGM-SAT and GMS are reliable and valid measures of patient-reported CGM outcomes.

The Accuracy of Home Glucose Meters in Hypoglycemia

Home glucose meters (HGMs) may not be accurate enough to sense hypoglycemia. We evaluated the accuracy and the capillary and venous comparability of five different HGMs (Optium Xceed [Abbott Diabetes Care, Alameda, CA, USA], Contour TS [Bayer Diabetes Care, Basel, Switzerland], Accu-Chek Go [Roche Ltd., Basel, Switzerland], OneTouch Select [Lifescan, Milpitas, CA, USA], and EZ Smart [Tyson Bioresearch Inc., Chu-Nan, Taiwan]) in an adult population. The insulin hypoglycemia test was performed to 59 subjects (56 males; 23.6 +/- 3.2 years old). Glucose was measured from forearm venous blood and finger capillary samples both before and after regular insulin (0.1 U/kg) was injected. Venous samples were analyzed in the reference laboratory by the hexokinase method. In vitro tests for method comparison and precision analyses were also performed by spiking the glucose-depleted venous blood. All HGMs failed to sense hypoglycemia to some extend. EZ Smart was significantly inferior in critical error Zone D, and OneTouch Select was significantly inferior in the clinically unimportant error Zone B. Accu-Chek Go, Optium Xceed, and Contour TS had similar performances and were significantly better than the other two HGMs according to error grid analysis or International Organization for Standardization criteria. The in vitro tests were consistent with the above clinical data. The capillary and venous consistencies of Accu-Chek Go and OneTouch Select were better than the other HGMs. The present results show that not all the HGMs are accurate enough in low blood glucose levels. The patients and the caregivers should be aware of these restrictions of the HGMs and give more credit to the symptoms of hypoglycemia than the values obtained by the HGMs. Finally, these results indicate that there is a need for the revision of the accuracy standards of HGMs in low blood glucose levels.

Genetic markers in diabetes mellitus: the need and promise for specific drug therapies in defined subtypes of diabetes patients

frequency or severity of hypoglycemia. Further benefit is often attained from additional treatment directed to normalizing blood pressure and circulating lipids, as well as specific interventions for diabetes complications, such as laser therapy for retinopathy. This article will focus on current approaches to blood glucose control. The management of glycemia in diabetes typically includes attention to diet and exercise combined with pharmacologic agents selected from a palette of injectable and oral drugs. Advances in available forms of insulin and other drugs over the past two to three decades, plus home glucose meters and, for some patients, devices such as insulin pumps and continuous glucose monitoring systems, has substantially increased the capacity of diabetes patients to control their blood glucose levels and to decrease the associated long-term risks. However, current therapeutic strategies still often fail to bring patients to glycemic targets. In the USA, data from the National Health and Nutrition Examination Survey (NHANES) indicates that only approximately 50% of diabetes patients are at or below the conservative hemoglobin A1c goal of 7% [2]. In considering strategies for improving glycemic therapy, there is increasing interest in approaches that better link treatment to specific diabetes subtypes in individual patients. It has long been known that diabetes is a heterogeneous disorder. Recognition of different forms of the disease corresponding to today’s Type 1 and 2 diabetes is evident in medical writing dating back 2000 years [3]. Standard treatment approaches to these two forms of diabetes differ, with early initiation of insulin in patients recognized to have Type 1 diabetes and often long periods of management with oral hypoglycemic agents in patients with Type 2 diabetes. More refined examination of individual phenotypes, biochemical markers, and inheritance patterns over the past several decades has progressively identified additional diabetes subtypes, such as maturity onset diabetes of the young (MODY), An estimated 24 million people in the USA (>8% of the population) and approximately 250 million people worldwide have diabetes [101]. When it is poorly controlled, diabetes has acute medical consequences resulting from osmotic diuresis, disturbed fluid and electrolyte balance, compromised immune function and, in extremely insulin-deficient patients, ketoacidosis. Of equal or greater importance, the diagnosis of diabetes brings with it a markedly increased risk of longterm complications. Diabetes-associated macrovascular disease contributes to an increased occurrence of myocardial infarction, congestive heart failure, stroke and peripheral vascular disease, and microvascular complications of diabetes often lead to loss of vision, renal insufficiency and disabling symptomatic neuropathies. In the USA, diabetes is the seventh leading cause of death, largely from the impact of its long-term complications, with financial costs that exceed US$150 billion per year [101]. The development of diabetes in most individuals results from an unfavorable confluence of environmental and genetic factors. In Type 1 diabetes, it is thought that yet unidentified environ mental insults (toxic, infectious or other), acting in a susceptible genetic background, lead to initiation and progression of autoimmune b-cell destruction. In Type 2 diabetes, lifestyle factors (excess calorie intake, decreased exercise and possibly specific dietary components), again acting in a susceptible genetic background, typically result in both insulin resistance and compromised insulin secretion. The common defining biomarker for diabetes is hyperglycemia and, irrespective of the underlying cause, compelling data indicate that improved control of blood glucose in diabetes relieves acute symptoms, reduces long-term complications, and decreases associated morbidity and mortality. Although there is ongoing debate on the preferred target level for glycemia [1], the accepted fundamental principle is one of bringing blood glucose as close as possible to normal without inducing an unacceptable

Glucose Measurement in the Operating Room

Abnormalities of blood glucose are common in patients undergoing surgery, and in recent years there has been considerable interest in tight control of glucose in the perioperative period. Implementation of any regime of close glycemic control requires more frequent measurement of blood glucose, a function for which small, inexpensive, and rapidly responding point-of-care devices might seem highly suitable. However, what is not well understood by many anesthesiologists and other staff caring for patients in the perioperative period is the lack of accuracy of home glucose meters that were designed for self-monitoring of blood glucose by patients. These devices have been remarketed to hospitals without appropriate additional testing and without an appropriate regulatory framework. Clinicians who are accustomed to the high level of accuracy of glucose measurement by a central laboratory device or by an automated blood gas analyzer may be unaware of the potential for harmful clinical errors that are caused by the inaccuracy exhibited by many self-monitoring of blood glucose devices, especially in the hypoglycemic range. Knowledge of the limitations of these meters is essential for the perioperative physician to minimize the possibility of a harmful measurement error. In this article, we will highlight these areas of interest and review the indications, technology, accuracy, and regulation of glucose measurement devices used in the perioperative setting.

For diabetes specialists, estimated average glucose makes sense

Pharmacists who specialize in diabetes treatment are embracing a recommendation from the American Diabetes Association (ADA) to talk to patients about their estimated average glucose (eAG) value. ADA made the recommendation after results from the A1c-Derived Average Glucose (ADAG) study were published in the August 2008 issue of Diabetes Care. The study verified that eAG, which is expressed as milligrams of glucose per deciliter of blood, correlates with glycosylated hemoglobin A1c (HbA1c) levels as a measure of long-term blood glucose control in patients with type 1 or type 2 diabetes. “We all were kind of waiting for this study to come out,” said Lisa Kroon, executive vice chair of the Department of Clinical Pharmacy at the University of California at San Francisco (UCSF) School of Pharmacy and the clinical pharmacist at the UCSF Diabetes Clinic. Kroon said the benefit of eAG for patients is that it describes their three-month blood glucose control in the same units that display on their home glucose meters.

On the Shoulders of Giants

I would like to start my remarks by thanking the American Diabetes Association for selecting me for this special recognition. I am deeply honored. I want to explain the title of my talk. Once, when Sir Isaac Newton was being given an award, the person introducing him suggested that he had seen “further than others” in the field of science. To this Newton replied, “If I have seen further it is by standing on the shoulders of giants.” Now trust me, I am not trying to compare myself to Sir Isaac Newton. But I do appreciate what he was trying to say; the reason that I am here today is ostensibly for recognition of my achievements in diabetes education. But my accomplishments are, in part, because of what I have learned from so many others, some who have stood here before me and many others who deserve to be recognized as I am today. So this morning, I want to tell you a bit of my story and how so many people have helped to shape my experience, influenced what I chose to do with my life, and taught me to see farther than perhaps I would have by myself. My story begins with my own discovery of type 1 diabetes. In 1977, while I was in graduate school at the University of California, Irvine, I had a weekend job in a hardware store. One day, during a break, a group of us employees were talking in the break room. The cashier, Patty, pulled out a bottle of ketodiastix. Being the inquisitive boy that I was, I asked what they were. She explained that she was a “juvenile diabetic,” and she used these to test her control. Remember, this was 1977; “type 1” wasn't a term, and home glucose meters …

The Accuracy of the Guardian®RT Continuous Glucose Monitor in Children with Type 1 Diabetes

The aim of this study was to determine the accuracy of the Guardian RT system (Medtronic Minimed, Northridge, CA) in young children and adolescents with type 1 diabetes (T1D) during different scenarios of glucose levels and sensor age. At five clinical centers, 30 subjects between 4 and 17 years old with T1D were recruited. All subjects had a glycosylated hemoglobin level of <or=10.0% and were using an insulin pump. Subjects initially used a Guardian RT for approximately 1 week at home. Each subject was then hospitalized overnight for about 18 h in a clinical research center, during which time insulin-induced hypoglycemia occurred, along with frequently sampled glucose. There were 1,511 laboratory glucose measurements paired with glucose measurements from 48 Guardian RT sensors. Overall, the median absolute difference (AD) was 21 mg/dL, and the median relative AD (RAD) was 14%, with 64% of sensor values meeting International Organization for Standardization home glucose meter criteria. The median AD was 27 mg/dL for reference glucose values<or=60 mg/dL and 25 mg/dL for reference glucose values<or=70 mg/dL. The median RAD was 19% for reference glucose values 71-120 mg/dL, 14% for reference glucose values 121-180 mg/dL, and 10% for reference glucose values>180 mg/dL. The Guardian RT appears to perform as well in children with T1D as it has been reported to perform in adults with diabetes. The Guardian RT has an accuracy similar to that of other available continuous glucose monitors and can give important and useful clinical information.

Diabetes research in children network:availability of protocol data sets.

The Diabetes Research in Children Network (DirecNet) was established in 2001 by the National Institute of Child Health and Human Development and the National Institute of Diabetes and Digestive and Kidney Diseases through special congressional funding for type 1 diabetes research. The network consists of five clinical centers, a coordinating center, and a central laboratory. Since its inception, DirecNet has conducted nine protocols, resulting in 28 published manuscripts with an additional 2 under review and 5 in development. The protocols have involved evaluation of technology available for the treatment of type 1 diabetes, including home glucose meters (OneTouch Ultra, FreeStyle, and BD Logic), continuous glucose monitoring systems (GW2B, CGMS, FreeStyle Navigator, and Guardian RT), and hemoglobin A1c (HbA1c) devices (DCA 2000 and A1cNow). In addition, the group has conducted several studies evaluating factors affecting hypoglycemia, including exercise and bedtime snack composition. The data sets that have resulted from these studies include data from the devices being evaluated, central laboratory glucose, HbA1c and hormone data, clinical center glucose and HbA1c data, accelerometer data, and pump data depending on the procedures involved with each protocol. These data sets are, or will be, available at no charge on the study group's public Web site. Several psychosocial questionnaires developed by DirecNet are also available.

Real-time continuous glucose monitoring

To summarize the current literature on real-time continuous glucose monitors, focusing on devices that have been approved or are pending approval. Real-time continuous glucose sensors are new tools to assist in diabetes management. Several devices are currently being sold and additional monitors are expected to be available shortly. These sensors measure interstitial glucose - a distinct physiologic space when compared with the blood glucose. The ability to recognize trends in blood glucose levels provides a new paradigm for making insulin dose decisions and treating hypo- and hyperglycemia. Real-time continuous glucose monitoring systems are currently less accurate than home glucose meters, but provide information every 1-5 min throughout the day and night with alarms for hyper- and hypoglycemia, providing information on glucose trends and nocturnal glycemic excursions. Current real-time sensors are behavior modification tools. Thus, improvements in diabetes control depend on the willingness of patients to modify their diabetes management based on information provided by these devices.

The Accuracy of the FreeStyle Navigator Continuous Glucose Monitoring System in Children With Type 1 Diabetes

To evaluate the accuracy and precision of the FreeStyle Navigator continuous glucose monitoring system in children with type 1 diabetes. 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. 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%. 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.

Extended Use of a New Continuous Glucose Monitoring System with Wireless Data Transmission in Children with Type 1 Diabetes Mellitus

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. 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. 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. 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.

Psychological aspects of continuous glucose monitoring in pediatric type 1 diabetes

Clinical use of near-continuous glucose monitors (CGMs) could have substantial impact on family management of pediatric type 1 diabetes and could generate both beneficial and adverse psychological reactions. In addition to glycemic benefits, CGM could possibly yield educational and motivational benefits. Conversely, CGM may also lead to information overload and increased treatment burden. Further, patients and families with certain affective, behavioral, and cognitive characteristics might derive greater benefit from CGM use. As information about these processes could facilitate optimal clinical use of CGM, the Diabetes Research in Children Network (DirecNet) included measurement of selected psychological variables in a recent randomized trial of the GlucoWatch G2 Biographer (GW2B, Cyngus, Inc., Redwood City, CA, USA). A multicenter sample of 200 youths with type 1 diabetes was randomized to 6 months of either continued usual care (UC) using a conventional home glucose meter for diabetes or supplementation of standard care with use of the GW2B. Diabetes treatment adherence, diabetes-specific quality of life, and diabetes-related anxiety were measured at baseline and at the end of the study. Satisfaction with use of the GW2B was measured at the end of the study. The results indicated neither adverse nor beneficial psychological effects of CGM use. More frequent GW2B use over the 6-month study was found among youths whose parents reported higher scores for treatment adherence and diabetes-related quality of life at baseline. The study illustrates the empiric assessment of the psychological context of CGM use and establishes methods that are applicable to new CGM devices as they emerge.

Accuracy of Newer-Generation Home Blood Glucose Meters in a Diabetes Research in Children Network (DirecNet) Inpatient Exercise Study

The objective of this study was to assess how the accuracy of the FreeStyle Flash (Abbott Diabetes Care, Alameda, CA) meter compares with that of the One Touch Ultra (Lifescan, Milpitas, CA) home glucose meter (HGM). Fifty children with type 1 diabetes (T1D), 10-17 years old, were admitted for two separate 24-h periods to assess the effect of exercise on subsequent nocturnal hypoglycemia. Resulting data were used in a preplanned analysis of the accuracy of the Ultra and FreeStyle HGMs. Glucose levels were measured throughout the day and night and every 15-20 min during a standardized exercise protocol. Reference samples were assayed in a central laboratory using a hexokinase enzymatic method. These reference glucose measurements were paired with HGM values from venous blood obtained within +/- 5 min. The median relative absolute difference was 5% for both the Ultra and FreeStyle HGMs, and the percentages of pairs meeting the International Organisation for Standardization criteria were 99% and 98%, respectively. The FreeStyle tended to read slightly higher than the reference method (median difference = +3 mg/dL; P < 0.001), and there was trend in this direction for the Ultra (median difference = +2 mg/dL, P = 0.15). Sensitivities for detection of hypoglycemia (reference < or = 60 and HGM < or = 70 mg/dL) were 96% and 100% for the Ultra and FreeStyle, respectively, and corresponding false-positive rates were both 5%. In a controlled clinical setting using venous blood samples, both the Ultra and FreeStyle meters demonstrated a high degree of accuracy compared with the laboratory reference over a broad range of glucose concentrations in children with T1D.