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W L Clarke

Publications and source records attributed to W L Clarke.

79 records · Page 5Linked to original sources
PubMedDate not supplied

Evaluating clinical accuracy of systems for self-monitoring of blood glucose.

Although the scientific literature contains numerous reports of the statistical accuracy of systems for self-monitoring of blood glucose (SMBG), most of these studies determine accuracy in ways that may not be clinically useful. We have developed an error grid analysis (EGA), which describes the clinical accuracy of SMBG systems over the entire range of blood glucose values, taking into account 1) the absolute value of the system-generated glucose value, 2) the absolute value of the reference blood glucose value, 3) the relative difference between these two values, and 4) the clinical significance of this difference. The EGA of accuracy of five different reflectance meters (Eyetone, Dextrometer, Glucometer I, Glucometer II, Memory Glucometer II), a visually interpretable glucose reagent strip (Glucostix), and filter-paper spot glucose determinations is presented. In addition, reanalyses of a laboratory comparison of three reflectance meters (Accucheck II, Glucometer II, Glucoscan 9000) and of two previously published studies comparing the accuracy of five different reflectance meters with EGA is described. EGA provides the practitioner and the researcher with a clinically meaningful method for evaluating the accuracy of blood glucose values generated with various monitoring systems and for analyzing the clinical implications of previously published data.

Blood Glucose↗
PubMedDate not supplied

Self-measurement of blood glucose. Accuracy of self-reported data and adherence to recommended regimen.

Reflectance meters containing memory chips were used in a study that addressed several questions concerning routine use of self-monitoring of blood glucose (SMBG), including accuracy of patient blood glucose (BG) diaries, reliability of self-reported frequency of SMBG, and adherence to recommended SMBG regimen. Thirty adults with insulin-dependent diabetes used memory meters and recorded test results in diaries for 2 wk while performing their normal SMBG regimen. Analysis of glucose diaries showed that only 23% of the subjects had no diary errors and 47% had clinically accurate diaries (less than 10% error rate). The most common types of errors were omissions of values contained in meter memory and additions of values not contained in meter memory, with significantly more omissions than additions. Alterations of test values (e.g., changing a 300-mg/dl reading to 200 mg/dl) were extremely rare. There was no difference in the rate of errors that resulted in a more positive clinical profile (omitting unacceptable values and adding acceptable values) or a more negative clinical profile (omitting acceptable values and adding unacceptable values). Examination of the actual frequency of SMBG showed that most subjects (56.6%) measured their BG an average of two to three times each day. Self-report of SMBG frequency correlated with both actual frequency and HbA1. Although actual frequency of SMBG was not related to physicians' recommendations, the majority (64%) of subjects were self-testing as often or more often than they had been instructed.

Adult↗
PubMedDate not supplied

Evaluation of a new reflectance photometer for use in home blood glucose monitoring.

A new reflectance photometer (Glucometer, Ames Division, Miles Laboratories, Elkhart, Indiana) has been developed for use with the Dextrostix reagent strip. The device measures 8 X 17 cm, weighs 330 g, uses AA batteries, and requires no warm-up. High (330 mg/dl) and low (50 mg/dl) calibrations are stored in memory and need be repeated only when: (1) a control solution (100 mg/dl) reading is in error, (2) ambient temperature changes by more than 5 degrees C, (3) a new bottle of Dextrostix is used, and (4) batteries are changed. A 60-s timer with alarm helps make timing of the procedure consistent. Nineteen insulin-dependent and one non-insulin-dependent diabetic subjects each performed a minimum of 20 blood glucose determinations over a 3-mo period in the investigators' laboratories. Simultaneous capillary blood samples were obtained for plasma glucose analysis by a comparative method. A total of 602 patient-determined glucose values ranging from 30 to 400 mg/dl were compared with simultaneous laboratory values. These values correlated significantly (r = 0.96, P less than 0.0001, y = 2.6 + 0.92x). The Glucometer-Dextrostix System is an accurate and convenient method for home blood glucose monitoring by diabetic patients.

Adolescent↗
PubMedDate not supplied

The effect of fenfluramine and caloric restriction on carbohydrate homeostasis in patients with lipodystrophy.

In an attempt to differentiate the effect of fenfluramine hydrochloride from that of caloric restriction on carbohydrate tolerance in patients with lipodystrophy, parameters of carbohydrate homeostasis were studied in patients with lipodystrophy during periods of fenfluramine treatment and during periods of caloric restriction. Although, carbohydrate tolerance appeared to improve initially in one patient when treated with fenfluramine, this improvement did not permit. No beneficial influence of fenfluramine on carbohydrate tolerance could be identified in the other patients studied. By contrast, all patients demonstrated an improvement in carbohydrate tolerance in response to caloric restriction. These data suggest that caloric restriction improved carbohydrate tolerance in patients with lipodystrophy whereas fenfluramine, in the absence of caloric restriction, has no long-term beneficial effect.

Adolescent↗
PubMedDate not supplied

Accuracy of perceiving blood glucose in IDDM.

Type I (insulin-dependent) diabetic individuals and health professionals often assume that the symptoms of extremely low or high blood glucose (BG) levels can be recognized and, consequently, appropriate treatment decisions can be based on symptom perception. Because no research has documented the validity of these assumptions, this study tested the ability to perceive BG concentration. Nineteen type I adults, experienced in self-monitoring of BG (SMBG), estimated their BG 40-54 times just before measurement of actual BG. This procedure was repeated under two conditions: (1) in the hospital (hospital condition) while connected to an insulin/glucose infusion system that artificially manipulated BG, leaving subjects only symptomatic, or internal, cues and (2) in the natural environment (home condition), where both internal and external cues, e.g., food and insulin consumption, were available. Estimates significantly correlated with actual BG for 7 of 16 subjects in the hospital condition and for 18 of 19 subjects in the home condition. Believed ability to estimate BG did not predict documented ability in either condition. An evaluation of the treatment significance of estimation errors showed that the majority of errors were relatively benign. The most common error affecting clinical outcome was estimated euglycemia when actual BG was hypoglycemic or hyperglycemic.

Adult↗