ISO-based assessment of accuracy and precision of glucose meters in dogs

High carbohydrate is preferable to high lipid parenteral nutrition in healthy dogs undergoing prolonged sedation

Parenteral nutrition (PN) is commonly used in intensive care units (ICUs) and is associated with earlier hospital outcome. However, there is scarcity of information about the metabolic effects of PN caloric distribution for dogs. Considering the high tolerance of dogs to lipids and, also, that hospitalized animals usually present insulin resistance, PN formulation with high fat instead high glucose can provide metabolic benefits in this specie. This study evaluated two PN protocols, based on high lipid or high carbohydrate in 12 healthy dogs under sedation/ventilation during 24 h. For baseline data, blood samples were collected 24 h before the study beginning. After fasting, the dogs were anesthetized and put under mechanical ventilation without energy support for 12 h to obtain: daily energy expenditure (DEE), respiratory quotient (RQ), oxygen consumption (VO2), carbon dioxide production (VCO2), lactate, glucose, cholesterol, and triglycerides concentrations. After, the dogs were allocated into two groups: lipid-based energy group (LEG) and carbohydrate-based energy group (CEG). Both groups received the PN infusions at a rate of 3 mL/kg/h for 12 h. Blood tests were performed 12, 24, and 48 h after infusion's completion. VO2 increased after PN in LEG, increasing energy expenditure compared to CEG. RQ remained close to 1 in CEG, indicating carbohydrate preferential consumption. Triglycerides increased in both groups after propofol infusion, remaining higher in LEG until the end of the evaluation. Glycaemia increased in CEG compared to baseline. In conclusion, both PN protocols can be used in healthy animals undergoing prolonged sedation protocols. However, high lipid PN had higher VO2 and DEE, and resulted in higher triglycerides concentrations and lower glycaemia indexes than carbohydrate, making high carbohydrate PN preferable to high lipid PN. Therefore, for use in critically ill patients, the data obtained in this study should be extrapolated, taking into consideration the specificity of each case.

Impact on result interpretation of correct and incorrect selection of veterinary glucometer canine and feline settings

Veterinary glucometers should be correctly coded for the patient species; however, coding errors occur in clinical settings and the impact of such errors has not been characterized. We compared glucose concentrations in 127 canine and 37 feline samples using both canine and feline settings on a veterinary glucometer (AlphaTrak; Zoetis). All samples were measured first on the canine setting and then measured using the feline setting. Glucose concentration was also measured using a central laboratory biochemical analyzer (Cobas c311; Roche). Three data comparisons for each species were investigated: incorrectly coded glucometer vs. correctly coded glucometer, correctly coded glucometer vs. Cobas c311, and incorrectly coded glucometer vs. Cobas c311. For each comparison, the following analyses were conducted: Spearman rank correlation coefficient, Bland-Altman difference plot analysis, mountain plot analysis, and Deming regression. For clinical context, Clarke error grids were constructed. There was high positive correlation for all comparisons with both species. For all comparisons, mean difference was low (-0.7 to 0.5 mmol/L for canine samples, 1.0-2.0 mmol/L for feline samples). Incorrect glucometer coding resulted in proportional bias for canine samples and positive constant bias for feline samples, and individual differences could be large (-4.44 mmol/L for one dog, 6.16 mmol/L for one cat). Although the glucometer should be used per the manufacturer's recommendation, coding errors are unlikely to have severe adverse clinical consequences for most patients based on error grid analysis.

Evaluation of Three Human-Use Glucometers for Blood Glucose Measurement in Dogs

BACKGROUND

Glucometers or portable sensors are used to quickly measure blood glucose at low cost. They are used in veterinary practice and by guardians to monitor diseases that require, as in diabetes mellitus. However, not all commercially available glucometers (human and veterinary) are suitable for this purpose. Hypotheses/Objectives. The objective was to evaluate the analytical and clinical precision of three human-use portable glucometers. Animals. This study evaluated 115 samples in three glycemic ranges (hypoglycemia, normoglycemia, and hyperglycemia) from 82 dogs recruited from veterinary services.

METHODS

The portable glucometers are the FreeStyle Freedom Lite®, FreeStyle Optium Neo®, and On Call Plus® models. Glucometer results were compared with the enzymatic colorimetric glucose oxidase laboratory reference method. Using descriptive and comparative statistical analysis, there were correlations between these devices and the standard method, ISO 15197 : 2003 and ISO 15197 : 2013 standards, and error grid analysis.

RESULTS

Only the Freedom Lite® device observed a statistical difference when compared with the reference method. Despite the underestimated glucose concentrations assessed with humane devices, all three tested herein showed a positive coefficient. However, none of these achieved all ISO guidelines. Conclusion and Clinical Importance. Although there was wide use of portable humane devices for dog glucose measurements on routine, the results are generally inferior when compared to the reference method. The FreeStyle Optium Neo® glucometer obtained the best result and is therefore the best option among the glucometers evaluated; however, for the first attendance on veterinary routine, all three glucometers had a satisfactory glucose measurement until the reference method availability.

Pyometra-associated insulin resistance assessment by insulin binding assay and tyrosine kinase activity evaluation in canine muscle tissue

Diestrus is associated with insulin resistance in bitches and pyometra can further impair insulin sensitivity. This study aimed to compare insulin sensitivity, insulin binding, and tyrosine kinase activity in bitches in anestrus, diestrus, or with pyometra. Patients submitted to elective ovariohysterectomy were divided into anestrus (n = 11) or diestrus (n = 13) according to reproductive history, vaginal cytology, and uterine histology. The group pyometra (n = 8) included bitches diagnosed with the disease based on clinical presentation and abdominal ultrasound findings and further confirmed by uterine histopathology. All patients were submitted to an intravenous glucose tolerance test (IVGTT) before ovariohysterectomy, and rectus abdominis muscle samples were collected during surgery for plasmatic membrane suspension preparation. Muscle-membranes were submitted to cold saturation insulin binding assay for dissociation constant (Kd) and maximum binding capacity (Bmax) determination, as well as exogenous substrate Poly (Glu: Tyr 4:1) phosphorylation assay for basal tyrosine kinase evaluation. Bitches with pyometra showed higher basal insulin (P < 0.001) and higher area under the curve (AUC) for insulin (P = 0.01) and glucose (P < 0.001) response during the IVGTT in comparison with bitches in anestrus or diestrus. Diestrus (P < 0.0001) and pyometra (P = 0.001) were associated with reduced tyrosine kinase activity in comparison with anestrus. No differences were documented in Kd and Bmax results for the low-affinity/high-capacity insulin receptors; however, high-affinity/low-capacity insulin receptors showed higher Kd and Bmax results in bitches in diestrus or with pyometra (P < 0.05) in comparison with anestrus. Despite the pyometra group showed the highest Kd values (P < 0.01), its Bmax results did not differ from the diestrus group (P > 0.05). Diestrus' higher Kd values and reduced tyrosine kinase activity in muscle tissue were compensated by increased total insulin binding capacity. Absent differences in IVGTT results between diestrus and anestrus bitches corroborate this finding. However, in bitches with pyometra, the highest Kd values were not compensated by increased total insulin binding capacity. This finding was associated with insulin resistance and glucose intolerance in IVGTT results. Moreover, pyometra resolution restored insulin sensitivity and glucose tolerance. These features can play a key role in pyometra-associated CDM, as well as in diabetic remission after pyometra resolution.

Comparison of glucose concentrations in canine whole blood, plasma, and serum measured with a veterinary point-of-care glucometer

Previous studies have determined that, compared to whole blood, serum or plasma used in a portable blood glucometer (PBG) may provide more accurate results. We investigated the accuracy of a veterinary PBG (AlphaTRAK 2; Zoetis) for the measurement of glucose concentrations in serum, plasma, and whole blood compared to plasma glucose concentration measured by a biochemical analyzer. Blood samples from 53 client-owned dogs were collected. Lin concordance correlation coefficient (ρ_c) and Bland-Altman plots were used to determine correlation and agreement between the results obtained for the different sample types. Glucose concentration in whole blood measured by the veterinary PBG was more strongly correlated with the glucose concentration measured by the biochemical analyzer (ρ_c = 0.92) compared to plasma and serum glucose concentrations (ρ_c = 0.59 and 0.57, respectively). The mean differences between the glucose concentrations in whole blood, plasma, and serum measured by the veterinary PBG and the glucose concentration determined by the biochemical analyzer were 1.0, 6.3, and 6.7 mmol/L (18, 113, and 121 mg/dL), respectively. Our findings suggest that, when using this veterinary PBG, the accuracy of a glucose measurement obtained is higher when using whole blood compared to plasma or serum. Use of whole blood allows for more correct assessment and diagnosis, which are necessary for appropriate therapeutic intervention.

Transoperative glycemia in pets: validating old ones, and presenting lip mucosa as new sampling site

The aim of our study was to investigate the viability and validity of blood sampling from the upper lip mucosa in healthy dogs and cats for monitoring transoperative glycemia and compare the results with those obtained from samples taken from previously described blood sampling sites for determination of glycemia using a glucose meter. Blood glucose (BG) levels were determined in samples taken from the upper lip mucosa of 24 dogs and 31 cats undergoing neutering or spaying surgeries. These values were compared to those of samples obtained from other sites previously described for capillary blood glucose monitoring (marginal ear vein, carpal pad in dogs, metacarpal pad in cats) using a glucose meter. Additionally, BG from peripheral venous blood was determined using a glucose meter, and the gold standard enzymatic colorimetric assay. The clinical reliability of BG values taken from lip mucosa and from all the other BG values measured by the glucose meter was evaluated using the error grid analysis modified by Parkes et al (2000). The upper lip mucosa was an easily accessible site for the obtainment of appropriate blood samples, and glucose levels read in these samples correlated positively with glycemic values read in blood samples from all other sites in dogs and cats. All BG made using glucose meters taken from all sites were within the clinically acceptable range when compared with enzymatic colorimetric assay (gold standard), and were analytically accurate according to the error grid (zones A and B). All blood sampling sites described in this work can be used to assess transoperative glycemia. The upper lip mucosa is a viable blood sampling site for precise monitoring of transoperative glycemia in healthy dogs and cats and shows promise for alternative blood glucose monitoring.

Evaluation of a flash glucose monitoring system in dogs with diabetic ketoacidosis

The flash glucose monitoring system (FGMS) Freestyle Libre provides estimates of blood glucose by constantly measuring the glucose concentration of the interstitial fluid through a sensor inserted in the subcutaneous space. The aim of this study was to evaluate the applicability and accuracy of the FGMS in dogs with diabetic ketoacidosis (DKA). Seven dogs with DKA examined at the Veterinary Hospital of the State University of Londrina were included in this study. The sensor was placed on the dorsal cervical region, shortly after the diagnosis of DKA was confirmed and maintained for 5 d. The measurement of blood glucose was performed simultaneously with the veterinary portable blood glucose meter (PBGM) AlphaTRAK 2 every 2 to 4 h and with the hexokinase method every 12 h. The PBGM's precision was evaluated following the ISO15197:2013 criteria. Blood glucose estimates were strongly associated (r = 0.89; P < 0.0001), and the mean absolute relative difference in relation to the PBGM was 25.2% (-70.4% to 101.9%). The evaluation of these data using the consensus error grid analysis showed that 95.4% and 94.8% of the samples were in Zones A and B (clinically acceptable) using the PBGM and the hexokinase method as a reference, respectively. The ISO15197:2013 criteria were not met. There was no difference in the accuracy of the device among days (P = 0.74); however, there was a difference between the hydration status (P = 0.019) and blood glucose ranges (hypoglycemic, euglycemic, and hyperglycemic; P < 0.0001), in which it was less precise in measuring the blood glucose range in hypoglycemic dogs. Therefore, it can be concluded that in spite of the fact that the device did not meet the ISO 15197:2013 criteria, the FGMS evaluated presents good clinical precision and can be a valuable tool in treating dogs with diabetic DKA.

Efficacy and Safety of Intramuscular Insulin Lispro vs. Continuous Intravenous Regular Insulin for the Treatment of Dogs With Diabetic Ketoacidosis

The use of rapid-acting insulin analogs as routes of administration other than IV has never been described for the treatment of dogs with diabetic ketoacidosis (DKA). This study aims to compare the efficacy and safety of a new protocol based on IM administration of insulin lispro with that of low-dose IV continuous rate infusion of regular insulin in the treatment of canine DKA. Client-owned dogs with naturally occurring DKA were included. Dogs treated with IM insulin lispro (Group L, n = 11) received 0.25 U/kg. The goal was to achieve a drop of at least 10% in blood glucose between 1 h and the next. If this goal was not achieved, the insulin dose was repeated hourly; otherwise, the insulin dose was not repeated up to a maximum of 3 h, after which the insulin dose was repeated anyway. When blood glucose was ≤250 mg/dL, the insulin dose was reduced to 0.125 U/kg IM every 3 h. Cases receiving IV continuous rate infusion of regular insulin (Group R, n = 13) were treated according to a previously published protocol. The median time to resolution of ketosis was significantly shorter in Group L (12 h; range, 4–27 h) compared to Group R (23 h; 10–46 h; P = 0.04). The median times to resolution of acidemia and ketoacidosis were 13 h (4–35 h) and 17.5 h (4–35 h) in Group L, and 22 h (9–80 h) and 23.5 h (10–80 h) in Group R, respectively. These differences were not significant (P = 0.06 and P = 0.09, respectively). The median length of hospitalization did not differ significantly between groups (P = 0.67). There were no differences in the frequency and severity of adverse events (hypoglycemia, hypokaliemia, and hypophosphatemia) between groups. The new protocol based on IM administration of insulin lispro preliminarily appears effective and safe for treatment of canine DKA.

Changes in serum cortisol and blood glucose concentrations in anesthetized, pain-free dogs administered fentanyl

OBJECTIVE

To evaluate whether fentanyl administered at analgesic doses in pain-free anesthetized dogs increases the serum cortisol or blood glucose concentrations and is associated with postanesthetic dysphoria.

STUDY DESIGN

Experimental, blinded, randomized crossover.

ANIMALS

A group of six adult research dogs.

METHODS

Each dog was anesthetized twice and was administered fentanyl or saline with a 15-day wash-out period. Treatment allocation was randomly assigned via a closed envelope technique. Cortisol and glucose concentrations were measured on arrival in the research room (T_PRE), induction of general anesthesia (T_IND), extubation (T_EXT) and 1 hour after extubation (T_POST). Dogs were premedicated with methadone (0.1 mg kg^-1) and carprofen (4 mg kg^-1) intravenously (IV), anesthesia induced with propofol (4-6 mg kg^-1) IV and maintained with isoflurane in oxygen. Standard anesthesia monitoring was performed throughout the experiment. Fentanyl (5 μg kg^-1 over 90 seconds followed by 7.5 μg kg^-1 hour ^-1) or an equivalent amount in mL of saline solution were administered IV for 60 minutes. T_PRE behavior scores and recovery scores were evaluated using descriptive 4-point scales. Data from serum cortisol and blood glucose concentrations were analyzed with a Split Plot on time test, whereas recovery scores were analyzed using a Wilcox match-pairs signed rank test. Statistical significance was set at p < 0.05.

RESULTS

There were no significant increases in serum cortisol and blood glucose concentrations over time, and there were no differences between treatments. None of the dogs developed postanesthetic dysphoria with either treatment.

CONCLUSIONS AND CLINICAL RELEVANCE

Fentanyl, administered at analgesic doses to healthy, pain-free, anesthetized dogs, was not associated with significant changes in serum cortisol or glucose concentrations in the studied population.

Evaluation of newly developed veterinary portable blood glucose meter with hematocrit correction in dogs and cats

This study evaluated the accuracy of a newly developed veterinary portable blood glucose meter (PBGM) with hematocrit correction in dogs and cats. Sixty-one dogs and 31 cats were used for the current study. Blood samples were obtained from each dog and cat one to six times. Acceptable results were obtained in error grid analysis between PBGM and reference method values (glucose oxidation methods) in both dogs and cats. Bland–Altman plot analysis revealed a mean difference between the PBGM value and reference method value of −1.975 mg/dl (bias) in dogs and 1.339 mg/dl (bias) in cats. Hematocrit values did not affect the results of the veterinary PBGM. Therefore, this veterinary PBGM is clinically useful in dogs and cats.

Evaluation of portable blood glucose meters using canine and feline pooled blood samples

This study evaluated the accuracy and reproducibility of a human portable blood glucose meter (PBGM) for canine and feline whole blood. Reference plasma glucose values (RPGV) were concurrently measured using glucose oxidation methods. Fifteen healthy dogs and 6 healthy cats were used for blood sampling. Blood glucose concentrations and hematocrits were adjusted using pooled blood samples for our targeted values. A positive correlation between the PBGM and RPGV was found for both dogs (y = 0.877, x = -24.38, r = 0.9982, n = 73) and cats (y = 1.048, x = -27.06, r = 0.9984, n = 69). Acceptable results were obtained in error grid analysis between PBGM and RPGV in both dogs and cats; 100% of these results were within zones A and B. Following ISO recommendations, a PBGM is considered accurate if 95% of the measurements are within ± 15 mg/dl of the RPGV when the glucose concentration is <100 mg/dl and within ±15% when it is ≥100 mg/dl; however, small numbers of samples were observed inside the acceptable limits for both dogs (11%, 8 of 73 dogs) and cats (39%, 27 of 69 cats). Blood samples with high hematocrits induced lower whole blood glucose values measured by the PBGM than RPGV under hypoglycemic, normoglycemic, and hyperglycemic conditions in both dogs and cats. Therefore, this device is not clinically useful in dogs and cats. New PBGMs which automatically compensate for the hematocrit should be developed in veterinary practice.

Accuracy of a Flash Glucose Monitoring System in Diabetic Dogs

Background

A novel flash glucose monitoring system (FGMS) (FreeStyle Libre, Abbott, UK) was recently developed for humans. It continuously measures the interstitial glucose (IG) concentrations for 14 days.

Objectives

To assess the clinical and analytical accuracy of the FGMS in diabetic dogs.

Animals

Ten client‐owned diabetic dogs on insulin treatment.

Methods

Prospective and observational study. The FGMS was placed on the neck for up to 14 days. During the 1st–2nd, 6–7th, and 13–14th days from application, the IG measurements were compared with the plasma (EDTA) glucose (PG) concentrations analyzed by a reference hexokinase based method.

Results

The application and the use of the FGMS were apparently painless, easy, and well tolerated by all dogs. Mild erythema at the site of the application was found in 5/10 dogs at the end of the wearing period. A good correlation between IG and PG concentrations (rho = 0.94; P < .001) was found. The FGMS was 93, 99, and 99% accurate at low, normal, and high blood glucose concentrations. Mean ± standard deviation difference from the reference method was 2.3 ± 46.8 mg/dL.

Conclusion and clinical importance

The FGMS is easy to use and is accurate for IG glucose measurement in diabetic dogs.

Study of the pathogenesis and treatment of diabetes mellitus through animal models

Most research in diabetes mellitus (DM) has been conducted in animals, and their replacement is currently a chimera. As compared to when they started to be used by modern science in the 17th century, a very high number of animal models of diabetes is now available, and they provide new insights into almost every aspect of diabetes. Approaches combining human, in vitro, and animal studies are probably the best strategy to improve our understanding of the underlying mechanisms of diabetes, and the choice of the best model to achieve such objective is crucial. Traditionally classified based on pathogenesis as spontaneous or induced models, each has its own advantages and disadvantages. The most common animal models of diabetes are described, and in addition to non-obese diabetic mice, biobreeding diabetes-prone (BB-DP) rats, streptozotocin-induced models, or high-fat diet-induced diabetic C57Bl/6J mice, new valuable models, such as dogs and cats with spontaneous diabetes, are described.