Glycated haemoglobin in various pathological conditions: investigations based on a new, fully automated method

Establishment of a feline glycated hemoglobin reference interval for a novel dried-blood-spot assay and the effects of anemia on assay results

BACKGROUND

Glycated hemoglobin A1c (HbA1c) reflects long-term (months) glycemic control and has been previously investigated as a monitoring and diagnostic tool in diabetic cats. However, a standardized, reliable, and globally available test and reference intervals (RIs) have not been established. A novel dried-blood-spot card system (A1Care, Baycom Diagnostics) allows for easy collection and evaluation of HbA1c levels in feline patients.

OBJECTIVE

We aimed to establish an RI for HbA1c values in healthy adult cats using the A1Care (Baycom Diagnostics) dried-blood-spot card system.

METHODS

Forty-one healthy client-owned adult cats were enrolled in this study. The RI for HbA1c was calculated according to the recommendation of the American Society for Veterinary Clinical Pathology.

RESULTS

The A1Care HbA1c RI for cats was determined to be 1.9%-3.1%. In healthy cats, A1Care HbA1c values were positively correlated with age (Spearman rho = 0.4 [95% CI 0.1 to 0.6], P = 0.01). In 50% of anemic cats, the A1Care HbA1c value was above 3.1%. There was a weak negative correlation between the A1Care HbA1c value and PCV (Spearman rho = -0.4 [95% CI -0.6 to -0.1]).

CONCLUSIONS

This study established an RI for HbA1c in healthy adult cats similar to previously reported RIs. Future clinical studies are necessary to substantiate that this RI can differentiate diabetic from nondiabetic cats. Further long-term clinical studies will be valuable to determine if HbA1c values can be used as a screening test for prediabetes in cats.

The effect of age and sex on glycated hemoglobin in dogs

We investigated the effect of age and sex on canine glycated hemoglobin (HbA1c) using a validated capillary electrophoresis assay. Aliquots of EDTA blood samples collected for routine health checks were used. HbA1c was measured using the Capillarys 2 flex-piercing system (Sebia). We included 58 clinically and hematologically healthy, normoglycemic dogs (29 males, 29 females), allocated to 3 age groups: young (14 dogs <1-y-old), adult (31 dogs 1-7.9-y-old), and senior (13 dogs ≥8-y-old). The mean (± SD) HbA1c was not significantly different (p = 0.428) between the age groups (young: 1.68 ± 0.54%; adult: 1.59 ± 0.41%; senior: 1.80 ± 0.57%). The HbA1c was not significantly correlated with age (rho = 0.144, p = 0.280). The median (range) HbA1c was not significantly different (p = 0.391) between male [1.7% (0.5-2.5%)] and female [1.5% (1.0-2.7%)] dogs. Age and sex do not appear to affect canine HbA1c; however, a study of geriatric dogs would be needed to fully exclude an effect of age on HbA1c.

Effect of anaemia and erythrocyte indices on canine glycated haemoglobin

BACKGROUND

The major fraction of glycated haemoglobin (HbA1c) depends on blood glucose concentration and erythrocyte lifespan, and consequently erythrocyte indices may affect HbA1c; our objective was to study this effect in dogs.

METHODS

Blood samples from two (healthy and anaemic) age- and sex-matched, normoglycaemic populations were prospectively included. Advia 120 and Capillarys 2 flex-piercing were used for the haematological and HbA1c analyses, respectively.

RESULTS

Lower mean HbA1c was found in dogs with regenerative (n = 8, 0.88 ± 0.58%) and non-regenerative anaemia (n = 12, 1.36 ± 0.56%) compared to healthy ones (n = 40, 1.68 ± 0.48%); the difference was significant (p < 0.001) between the healthy dogs and those with regenerative anaemia. HbA1c was significantly correlated (p < 0.05) with red blood cell count (r = 0.506), haemoglobin (r = 0.474), haematocrit (r = 0.467), mean corpuscular volume (r = -0.289), mean corpuscular haemoglobin concentration (r = 0.284), red cell distribution width (r = -0.286) and reticulocytes (r_s = -0.542).

CONCLUSION

Anaemia, particularly if regenerative, can lower HbA1c. The significant correlation between HbA1c and erythrocyte indices likely reflects the effect of erythrocyte turnover on HbA1c.

Comparison of serum fructosamine and glycated hemoglobin values for assessment of glycemic control in dogs with diabetes mellitus

OBJECTIVE

To evaluate the performance of 2 assays for measurement of serum fructosamine (SF) and glycated hemoglobin (HbA1c) values in dogs and to compare the usefulness of the 2 glycated proteins for assessment of glycemic control in dogs with diabetes mellitus (DM).

SAMPLE

Blood samples from 40 healthy dogs, 13 diabetic dogs, and 23 anemic normoglycemic nondiabetic dogs and results of 200 assessments of glycemic control in 46 diabetic dogs.

PROCEDURES

Colorimetric and immunoturbidimetric methods were used for measurement of SF and HbA1c values, respectively. Linearity and precision were determined. The usefulness of SF and HbA1c values for assessment of glycemic control was evaluated with a clinical scoring method used as the reference standard. Cutoff values obtained from receiver operating characteristic curves were used to identify the percentage of dogs correctly categorized by means of SF and HbA1c values.

RESULTS

Mean intra-assay and interassay coefficients of variation were 3.8% and 2.5%, respectively, for the SF assay, and 1.2% and 1.8%, respectively, for the HbA1c assay. Excellent linearity (R² > 0.99) was obtained for both assays. Values for SF and HbA1c were inversely correlated (r = -0.40 and -0.33, respectively) with clinical score and correctly indicated glycemic control in 99 of 200 (50%) and 88 of 200 (44%) assessments, respectively.

CONCLUSIONS AND CLINICAL RELEVANCE

The SF and HbA1c assays were precise, had good linearity, and appeared to be suitable for routine use in veterinary medicine. However, they performed poorly for classifying glycemic control in diabetic dogs.

Evaluation of two point-of-care analysers for measurement of fructosamine or haemoglobin A1c in dogs

Measurement of glycosylated proteins such as fructosamine and haemoglobin A1c (HbA1c) can be used to assess glycaemic control in canine diabetic patients. Two point-of-care analysers, designed for human diabetics, were evaluated for use in dogs. Blood samples were collected from 50 normoglycaemic dogs, 100 diabetic patients and five dogs with insulinoma and tested using the In Charge fructosamine meter and the Haemaquant/Glycosal HbA1c meter. Readings were obtained in all cases except for 21 of 50 diabetics, which were above the upper limit of the In Charge meter. Diabetic dogs had higher fructosamine and HbA1c concentrations compared to controls. However, there was poor agreement between the In Charge meter readings and serum fructosamine concentrations, suggesting that there are problems associated with the use of this device in dogs. HbA1c concentrations showed a high degree of correlation with glycosylated haemoglobin measured at an external laboratory, suggesting that the Haemaquant/Glycosal meter warrants further evaluation for veterinary use.

Troubleshooting the diabetic small animal patient

Effective troubleshooting for a diabetic small animal patient starts with the initial diagnosis of diabetes. Preempting trouble with a thorough and complete history, physical examination, laboratory assessment, and extensive and thoughtful client education before discharge, are crucial first steps toward avoiding trouble altogether. As problems arise, careful consideration of the many variables that contribute to effective diabetic control is necessary. As monitoring strategies evolve and treatment options expand, the clinician's ability to accurately assess and adjust the glycemic control in his or her troubled diabetic patient improves. Common causes of trouble in diabetic patients are reviewed and various strategies for the diagnosis and management of these disorders are discussed in this article. Every effort was made to draw from recently published reports of clinical cases. Few diseases will tie together owner, patient, and therapy as intimately as diabetes mellitus, and few problems will be solved without fully considering all potential factors.

Effect of acute hyperglycaemia on the serum fructosamine and blood glycated haemoglobin concentrations in canine samples

The effect was studied of an acute and non-persistent hyperglycaemia on the serum fructosamine and blood glycated haemoglobin concentrations in canine samples. Five dogs were given glucose solution intravenously and blood samples were taken from each dog before and at 5, 15, 30, 60 and 120 min and 24 h after the infusion. There was an intense hyperglycaemia 5 min after the injection was given, but no statistically significant differences in the serum fructosamine and glycated haemoglobin were observed. It was concluded that an acute and transient hyperglycaemia does not cause significant changes in the glycated haemoglobin and fructosamine concentrations in healthy dogs.