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Michael J Tansey

Publications and source records attributed to Michael J Tansey.

5 recordsLinked to original sources
PubMed2006

Evaluation of factors affecting CGMS calibration.

BACKGROUND: The optimal number/timing of calibrations entered into the CGMS (Medtronic MiniMed, Northridge, CA) continuous glucose monitoring system have not been previously described. METHODS: Fifty subjects with Type 1 diabetes mellitus (10-18 years old) were hospitalized in a clinical research center for approximately 24 h on two separate days. CGMS and OneTouch Ultra meter (LifeScan, Milpitas, CA) data were obtained. The CGMS was retrospectively recalibrated using the Ultra data varying the number and timing of calibrations. Resulting CGMS values were compared against laboratory reference values. RESULTS: There was a modest improvement in accuracy with increasing number of calibrations. The median relative absolute deviation (RAD) was 14%, 15%, 13%, and 13% when using three, four, five, and seven calibration values, respectively (P < 0.001). Corresponding percentages of CGMS-reference pairs meeting the International Organisation for Standardisation criteria were 66%, 67%, 71%, and 72% (P < 0.001). Nighttime accuracy improved when daytime calibrations (pre-lunch and pre-dinner) were removed leaving only two calibrations at 9 p.m. and 6 a.m. (median difference, -2 vs. -9 mg/dL, P < 0.001; median RAD, 12% vs. 15%, P = 0.001). Accuracy was better on visits where the average absolute rate of glucose change at the times of calibration was lower. On visits with average absolute rates <0.5, 0.5 to <1.0, 1.0 to <1.5, and >or=1.5 mg/dL/min, median RAD values were 13% versus 14% versus 17% versus 19%, respectively (P = 0.05). CONCLUSIONS: Although accuracy is slightly improved with more calibrations, the timing of the calibrations appears more important. Modifying the algorithm to put less weight on daytime calibrations for nighttime values and calibrating during times of relative glucose stability may have greater impact on accuracy.

Adolescent↗
PubMed2006

The effects of aerobic exercise on glucose and counterregulatory hormone concentrations in children with type 1 diabetes.

OBJECTIVE: To examine the acute glucose-lowering effects of aerobic exercise in children and adolescents with type 1 diabetes. RESEARCH DESIGN AND METHODS: Fifty children and adolescents with type 1 diabetes (ages 10 to <18 years) were studied during exercise. The 75-min exercise session consisted of four 15-min periods of walking on a treadmill to a target heart rate of 140 bpm and three 5-min rest periods. Blood glucose and plasma glucagon, cortisol, growth hormone, and norepinephrine concentrations were measured before, during, and after exercise. RESULTS: In most subjects (83%), plasma glucose concentration dropped at least 25% from baseline, and 15 (30%) subjects became hypoglycemic (< or = 60 mg/dl) or were treated for low glucose either during or immediately following the exercise session. The incidence of hypoglycemia and/or treatment for low glucose varied significantly by baseline glucose, occurring in 86 vs. 13 vs. 6% of subjects with baseline values <120, 120-180, and >180 mg/dl, respectively (P < 0.001). Exercise-induced increases in growth hormone and norepinephrine concentrations were marginally higher in subjects whose glucose dropped < or = 70 mg/dl. Treatment of hypoglycemia with 15 g of oral glucose resulted in only about a 20-mg/dl rise in glucose concentrations. CONCLUSIONS: In youth with type 1 diabetes, prolonged moderate aerobic exercise results in a consistent reduction in plasma glucose and the frequent occurrence of hypoglycemia when preexercise glucose concentrations are <120 mg/dl. Moreover, treatment with 15 g of oral glucose is often insufficient to reliably treat hypoglycemia during exercise in these youngsters.

Adolescent↗
PubMed2005

Accuracy of the modified Continuous Glucose Monitoring System (CGMS) sensor in an outpatient setting: results from a diabetes research in children network (DirecNet) study.

OBJECTIVE: We previously reported the results of an inpatient accuracy study in children with type 1 diabetes using the Continuous Glucose Monitoring System (CGMS, Medtronic MiniMed, Northridge, CA). During the course of that study, a new process was implemented for manufacturing the CGMS sensor. Accuracy from the resulting modified sensor used by only 14 children was significantly better than the original version [median relative absolute difference (RAD), 11% vs. 19%; P < 0.001]. Baseline data from a subsequent outpatient study provide an opportunity to further assess the accuracy of the modified sensor in a much larger sample of children with type 1 diabetes. RESEARCH DESIGN AND METHODS: As part of a randomized trial to assess the utility of the GlucoWatch G2 Biographer (Cygnus, Inc., Redwood City, CA), 200 children with type 1 diabetes were instructed to wear a CGMS for 48-72 h in an outpatient setting at baseline. Glucose measurements from a OneTouch UltraSmart (Lifescan, Inc., Milpitas, CA) home glucose meter were downloaded and used as reference values to calculate accuracy measures. RESULTS: The overall median RAD was 12%. Accuracy was better during hyperglycemia than during hypoglycemia (median RAD, 10% vs. 20%; P < 0.001) and on optimal versus non-optimal days but did not vary significantly by the number of calibrations entered. CONCLUSIONS: These data confirm the improved accuracy previously reported for the modified version of the CGMS sensor.

Blood Glucose↗
PubMed2004

A 36-year retrospective analysis of the efficacy and safety of radioactive iodine in treating young Graves' patients.

This report details the 26- and 36-yr outcomes of 116 patients under the age of 20 yr with Graves' disease who were treated with radioiodine between 1953 and 1973. Contacted by telephone and mail in 1991-1992, 107 of them supplied personal historical data, and their physicians furnished interval histories, physical examinations, and laboratory data. This was repeated in 2001-2002, with 98 of them being contacted. At the time of treatment, the patients' ages ranged between 3 yr, 7 months and 19 yr, 9 months. Six were less than 6 yr of age, 11 were between 6 and 11 yr, 45 were between 11 and 15 yr, and 45 were between 16 and 19 yr. The average length of follow-up in 1991-1992 was 26.1 yr; that in 2001-2002 was 36.2 yr. None of the patients developed cancer of the thyroid or leukemia. Early on, when the objective of treatment was euthyroidism, the dose of radioiodine was low, and retreatment was frequently needed. Later, the doses used were increased. Over time, all but two patients became hypothyroid. Pregnancies did not result in an unusual number of congenital anomalies or spontaneous abortions. Treating young people with Graves' disease with radioiodine is safe and effective over the long term.

Adolescent↗