Assessment of a simple colorimetric procedure to determine smoking status in diabetic subjects.

The performance of a colorimetric assay for nicotine metabolites to validate self-reported smoking classification (nonsmoker, ex-smoker, and smoker) was assessed in a group of diabetic patients (n = 201). Comparison of the results with those of cotinine immunoassay (ELISA), by comparing respective areas under receiver operating characteristic curves, established the superiority of the cotinine immunoassay method. Adjusting the urinary concentrations of nicotine metabolites for creatinine excretion significantly lowered test performance. The sensitivity and specificity for the assay of nicotine metabolites to discriminate smoking classification within the diabetic patients at a threshold of > or = 28 mumol/L "cotinine carboxylic acid equivalents" were 68.4% and 98.6%, respectively; the corresponding sensitivity and specificity for urinary cotinine at a cutoff of > or = 0.5 mumol/L were 94.7% and 100%. The low sensitivity of the colorimetric urinary nicotine metabolites assay precludes its application as an objective assessment of smoking status in our patient population.

Enzymatic quantification of 1,5-anhydro-D-glucitol: evaluation and clinical application.

We investigated an enzymatic colorimetric procedure for quantification of plasma 1,5-anhydro-D-glucitol (AG) with respect to its reproducibility and application for evaluation of diabetes mellitus. Assay specificity is critically dependent on the two-layer ion-exchange column chromatography procedure to remove glucose from the sample. For female nondiabetic subjects (n = 110, ages 22-36 years) the median plasma AG concentration was 143 mumol/L (range 70-209 mumol/L); there was no relation to body mass index (BMI), fasting plasma glucose, or insulin, but an inverse association was noted for age. For a group of older subjects (n = 69, 70-85 years), no association between AG concentrations and sex, age, BMI, or various medical conditions was found. In diabetic subjects (n = 170) a significant inverse nonlinear relation existed between plasma AG and glycohemoglobin (GHb) such that at GHb > 8.5%, AG concentrations were typically < 50 mumol/L. The findings confirm that plasma AG, in the presence of normal renal function, is a reliable marker for hyperglycemia.

Variability of urinary albumin excretion in patients with microalbuminuria.

OBJECTIVE: To estimate the within-person variability (SDi) for the overnight urinary albumin excretion rate (AER) in diabetic patients with persistent microalbuminuria. RESEARCH DESIGN AND METHODS: Thirteen normotensive diabetic patients in stable medical control, with normal renal function and without any associated cardiovascular or other clinical disorders, collected overnight urines at monthly intervals during one year. AER was determined by radioimmunoassay. RESULTS: Analysis of individual series of AER showed a significant trend (P < or = 0.01) in three cases. The remaining patients (eight men, two women; seven with insulin-dependent diabetes mellitus) had a median mean AER 102 micrograms/min (range 30-238 micrograms/min). Because the individual mean AERs were significantly associated with their respective SDis, the data was loge transformed. LogeSDi was estimated as 0.420, and its 90% probability range (0.353-0.490) was calculated using the bootstrap method. CONCLUSIONS: The high within-person variance for AER means that only people with an initial AER in the range of 53-76 micrograms/min have a high probability (P > or = 0.95) of being classified as microalbuminuric (20-200 micrograms/min) on a subsequent specimen. However, subjects with an initial AER > or = 53 or > or = 80 micrograms/min have a 95 and 99% probability of persistent microalbuminuria. The large variability of AER limits its potential as a serial marker to detect any gradual deterioration of established renal dysfunction.

Capillary blood glucose measurements in hospital inpatients using portable glucose meters.

BACKGROUND: The use of portable glucose meters by nursing staff to perform bedside capillary blood glucose measurements is standard practice in the management of diabetic hospital inpatients. Few studies, however, have examined the practical limitations or the cost of this technology. AIM: To investigate the performance and cost of capillary blood glucose measurements using portable glucose meters in a hospital inpatient population being managed for diabetes mellitus. METHODS: The setting was a 500 bed metropolitan University Teaching hospital, with 22 meters (Glucometer-M) in routine use by about 450 accredited nursing staff. The Glucometer-M was also compared with an operator-independent meter (Hemocue) to assess the effect of operator bias on the overall efficacy and cost of the programme. RESULTS: Retrospective analysis of Glucometer-M reagent strips and comparison of measurements (n = 72) with the Hemocue revealed a marked operator bias which diminished accuracy and increased costs. The significant proportion of low haematocrits (< 30%) in the hospital population limited the applicability of the Glucometer-M which only operates reliably over the haematocrit range 35-50%. The excess of blood glucose measurements was highlighted by both a hospital ward audit and the frequency which exceeded that of routine electrolyte assays. CONCLUSIONS: Reliable bedside estimation of capillary blood glucose levels in hospitals requires a meter which is accurate, has negligible operator bias, is largely unaffected by haematocrit, and has insignificant risk of cross-contamination. At present only the Hemocue fulfils these specifications. Irrespective of meter choice, it is necessary to develop criteria for glucose measurements and monitor adherence.

Intraindividual variation of glycohemoglobin: implications for interpretation and analytical goals.

Intraindividual variation (CVi) for glycohemoglobin (GHb) was estimated from serial measurements in patients with diabetes in either stable or variable clinical control. GHb determinations were performed by an affinity column procedure with an analytical imprecision of 4.9% (weighted average; GHb 8.2-14.7%). Within the groups of patients, both a short- (28-32 days) and long-term (approximately 85 days) sampling protocol was used. The derived CVi for each category was 4.2% (n = 16, stable, short-term), 7.1% (n = 23, stable, long-term), 5.1% (n = 13, variable, short-term), and 9.8% (n = 21, variable, long-term). The mean GHb within each category was similar (approximately 11%), and there was no statistically significant difference in GHb values between categories. The results establish that the CVi for GHb is affected by both clinical control and the sampling time interval. These findings have important implications for the estimation of significant differences between serial GHb measurements and the setting of appropriate analytical precision goals.

Prediction of pregnancy-induced hypertension by means of the urinary calcium:creatinine ratio.

OBJECTIVE: To investigate the importance of the urinary calcium:creatinine ratio as a prognostic marker for pregnancy-induced hypertension. DESIGN: A prospective study which measured the urinary calcium:creatinine ratio at 20-30 weeks' gestation. Patients' medical records were examined, blind to all urinary assay results, to determine the development of pre-eclampsia or gestational hypertension. SETTING AND SUBJECTS: A first-morning urine sample was collected from 456 normotensive pregnant women, at 20-30 weeks' gestation, attending a hospital maternity outpatients' clinic for routine antenatal care. RESULTS: The mean urinary calcium:creatinine ratio for women (n = 392) with a normotensive outcome of pregnancy, 0.52 (SD 0.32), was not significantly different from the ratios in those women who developed pre-eclampsia (n = 16), 0.49 (SD 0.32) or gestational hypertension (n = 48), 0.57 (SD 0.41). Significant risk factors for development of gestational hypertension, as estimated by logistic regression, were mean arterial blood pressure greater than 87.6 mmHg, Caucasian race, non-smoking and nulliparity. CONCLUSIONS: Within the cohort studied, the calcium:creatinine ratio measured in asymptomatic women at 20-30 weeks' gestation was an unsatisfactory prognostic marker for development of pregnancy-induced hypertension. The major interpopulation, as well as intrapopulation, variation in calcium levels suggests that previous reported findings may not be readily generalised.

Graphical display of capillary blood glucose data using Chernoff faces.

Five indices derived from twice-daily capillary blood glucose levels, taken pre-breakfast and pre-bedtime, in diabetic patients over a 5-day period have been graphically presented as Chernoff faces. Particular attention has been focussed on the linkage between features and indices. Examples are shown which illustrate varying degrees of blood glucose control amongst diabetic subjects. The results suggest that this type of graphic representation may allow better assimilation of collected blood glucose data by patients or health care personnel.

The 1-h 50-g glucose challenge does not predict large-for-gestational-age infants.

The relationship between the 1-h 50-g glucose challenge performed at 24-28 weeks and subsequent birth of a large-for-gestational-age infant was examined in a cohort of 368 Europid women who had no pre-existing medical condition and experienced no pregnancy complications. The results established that the 1-h 50-g glucose challenge blood glucose level had no predictive power with respect to the birth of a large-for-gestational-age infant. However, the 1-h blood glucose value was found to be significantly related to maternal height, weight and age, indicating that its level also represents processes unconnected to glucose intolerance. The study findings also re-confirmed the importance of parity, height, sex, and weight as determinants of large-for-gestational-age infants.

Relationship between normal oral glucose tolerance test in women at risk for gestational diabetes and large for gestational age infants.

OBJECTIVE: To determine whether the glycemic status of pregnant women with a normal 3-h 100-g oral glucose tolerance test (OGTT) is related to outcome with respect to large for gestational age (LGA) infants. RESEARCH DESIGN AND METHODS: A prospective study of 2631 women was conducted. One hundred seventy-six women had an OGTT based either on a 1-h 50-g OGTT (n = 105) or clinical risk factors (n = 71). Thirty-three women were diagnosed as having gestational diabetes mellitus. RESULTS: Negligible discriminatory capacity for the variables with respect to prediction of LGA infants was indicated by the areas under the receiver operating characteristic (ROC) curves for fasting blood glucose, 2-h OGTT blood glucose, and the OGTT response curve area for women with a normal OGTT (n = 143). However, a statistically significant increased incidence of LGA infants was established for both the OGTT-positive and normal OGTT groups (P less than 0.0001). Multiparity, a maternal weight greater than or equal to 70 kg, and birth of a male infant were other factors associated with a significantly increased frequency of LGA infants. CONCLUSIONS: The results may be interpreted as either indicating a role for confounding variables, i.e., maternal weight, multiparity, and birth of a male infant, or the imprecision of the OGTT in assessing physiologically important changes in maternal hyperglycemia.

Computer based quality assessment of hospital capillary blood glucose monitoring.

A quality control (QC) programme to continually monitor the reliability of hospital ward capillary blood glucose levels has been developed based on a memory blood glucose meter interfaced to a portable microcomputer. Over a 38-week period some 12,500 ward QC tests were performed by approximately 200 accredited operators. Although the mean weekly coefficients of variation were all less than 15%, there was a marked variation between wards, with the frequency of testing of patients the major factor influencing reliability. However an external laboratory-based QC programme suggested a high degree of proficiency which was not achieved by any ward on internal QC assessment.