Optimizing d-mannose and glyceraldehyde concentrations as glucose preservatives without clinically affecting biochemical test results.

Objectives: The objectives were to evaluate blood additives that combined lithium heparin (LH)-salt with glyceraldehyde (GLY) or d-mannose (MAN) for preserving glucose levels in plasma samples and to simultaneously determine the compatibility of these additives with 14 other biochemical tests. Methods: Blood samples from 40 subjects, equally divided into healthy and diabetic groups, were collected using five different additives. The three most effective additives, LH/GLY, LH/MAN, and LH/GLY/MAN, were selected for ensuring the best preservation of glucose levels and compatibility with 14 biochemical tests. One-way analysis of variance was used to analyze the mean paired differences of glucose level and biochemical tests. Simultaneously, the clinical criteria from Johns Hopkins Hospital were used to guide the interpretation and set acceptable thresholds for measurements that exceeded the standards. Results: The combination of 160 mmol/L GLY, 8.4 mmol/L MAN, and LH, maintained glucose levels at approximately 93.4-93.7 % for healthy subjects and 91.3-92.8% for subjects with diabetes mellitus over 8 h. The mean paired differences of glucose levels in preservation were statistically insignificant. The biases in 14 biochemical tests for LH/GLY/MAN and LH/MAN remained within the acceptable clinical criteria during the 8 h. Conclusions: Combining 160 mmol/L GLY, 8.4 mmol/L MAN, and LH, proved more effective in maintaining glucose levels than individual additives or the conventional sodium fluoride preservative. It did not yield clinical discrepancies in the 14 biochemical tests during 8 h at room temperature.

Commutable Blood Materials from the Fixed-Cell Method for Performance Evaluation of Blood Glucose by a Glucose Meter.

Glucose meters provide a rapid blood glucose status for evidence-based diagnosis, monitoring, and treatment of diabetes mellitus. We aimed to evaluate the commutability of processed blood materials (PBMs) and their use in the performance evaluation of glucose meters. Two PBMs obtained by the fixed-cell method were analyzed for homogeneity, stability, and commutability. The compatibility of ten pairs between mass spectrometry and each glucose meter was categorized as compatible (mean paired difference ≤ 5%) and incompatible (mean paired difference > 5%). The performance of glucose meter 1 (n = 767) and glucose meter 2 (n = 266) was assessed. The glucose in the PBMs remained homogenized and stable for at least 180 days. Six out of ten pairs had commutable PBMs. Commutability of PBMs was observed in both well-compatible and incompatible glucose results. Target glucose values from mass spectrometry were significantly different (p ≤ 0.05) from consensus values in one group of glucose meters. When commutable PBMs were used, glucose meter 1 showed better performance than glucose meter 2, and the percentage of satisfaction was associated when using target values for glucose from mass spectrometry and consensus values, but the performance of glucose meter 2 was not associated. PBM from a fixed-cell method could be mass produced with acceptable homogeneity and stability. Commutability testing of PBMs is required prior to use in the performance evaluation of glucose meters, as the commutability of glucose in the PBMs obtained by a fixed-cell method was variable and depended on the individual glucose meter.

Commutability and Uncertainty of Blood Hemoglobin A1c Testing Materials.

BACKGROUND: Hemoglobin A1C (HbA1C) is used to evaluate glycemic control over a three-month period. Blood matrix-based HbA1C materials are needed for quality control and evaluation of HbA1C measurements. This study investigated the commutability of blood materials (BMs) and aimed to upgrade BMs for HbA1C testing for use as proficiency test (PT) material. METHODS: We measured BMs from a DM blood donor (n = 1), an in vitro glycation procedure (n = 3), and from commercial sources (n = 2) for HbA1C in parallel with fresh unprocessed BMs (n = 3) and clinical blood samples (n = 25). Two NGSP-certified methods, including a turbidimetric and an enzymatic immunoassay, were used for HbA1C determinations. Commutability as investigated according to CLSI EP14-Ed4 guidelines. RESULTS: The commutable BMs exhibited a mean paired difference of 0% to 9% when compared to reference methods, whereas the non-commutable BMs represented a mean paired difference of 3% to 11%. Fresh, unprocessed BMs with a low HbA1C of 6.0% were more commutable than BMs with a high HbA1C. The values of HbA1C in BMs (mean and uncertainty following ISO Guide 35 for RM production) were applied to upgrade the PT material to be used as a reference material. The relative uncertainty of BM-Ndm-1 and BM-Gcb-3 were 1 and 0.4%, respectively. CONCLUSIONS: The commutability of hemoglobin in BMs is dependent on the preparation process. Blood materials with a high HbA1C content are usually less commutable versus materials with low HbA1C content when prepared by the same process. Our study showed BMs can be successfully used as quality control or PT materials.

Effects of Simulated Adverse Environmental Conditions Related to Actual Conditions at Health Promoting Hospitals on the Performance of Blood Glucose Testing by Glucose Meters.

BACKGROUND: Annual peaks in temperature and humidity exceed manufacturers' specifications for blood glucose test strip storage in Thailand. Health Promoting Hospitals (HPH) do not always provide the same level of health services that hospitals do since they often only turn on air-conditioning units during working hours. METHODS: The blood glucose testing performance of 4 glucose meters were investigated for short and long terms stress at 5 simulated conditions. Temperature and relative humidity (RH) at 5 HPHs in different regions of Thailand were monitored for 9 weeks during April to July 2019. The use of air conditioning in storage rooms for storing test strips was surveyed at 131 HPHs using questionnaires. RESULTS: Median-paired differences of glucose measurements with stressed test strips in 5 simulated conditions significantly differed (P < 0.05) both in the short term (3 days) and in the long term (30 days) with 4 glucose meters when compared to unstressed test strips. The average temperature of all HPHs exceeded 30°C (86°F). The average RH was 84%. There was only one HPH that occasionally turned on its air conditioners. Most HPHs kept both opened and unopened vials of test strips in rooms without air conditioners. Further, 21.4-32.0% of HPHs kept test strips at room with air conditioners. CONCLUSIONS: This study provides evidence for poor performance of blood glucose testing by glucose meters that are affected by adverse environmental conditions. The environmental for test strips storage at HPHs should be considered to prevent analytical errors of glucose measurement.