Relationship between HbA1c, fructosamine and clinical assessment of glycemic control in dogs

Abstract

Background: Serum fructosamine is a routine test used for clinical monitoring of diabetes mellitus (DM) but the usefulness of HbA1c for this purpose has not been extensively studied.

Hypothesis: The study aimed to compare the ability of blood HbA1c and serum fructosamine tests to correctly classify DM control determined using a clinically-based assessment.

Animals: 28 client-owned dogs with naturally-occurring diabetes mellitus.

Methods: Cross-sectional observational study. Ability of fructosamine and HbA1c tests to classify diabetes control in dogs was determined.

Results: Clinical assessment classified 50% of dogs as having good diabetic control and 82% as having acceptable diabetic control. Analysis using Cohen's kappa test showed that agreements between fructosamine and HbA1c results and the clinical assessment ranged from poor to fair. Fructosamine and HbA1c results from each dog showed a moderate correlation. Overall, the HbA1c test showed the best agreement with the clinical assessment when diabetes control was considered either acceptable or unacceptable, although the strength of agreement was considered fair (kappa = 0.27).

Conclusions and clinical importance: The HbA1c concentration was found to be more consistent with clinical evaluation of diabetes control than was the serum fructosamine concentration. The HbA1c level is a useful tool for assessment of glycemic status in diabetic dogs but should be used alongside other tests for outpatient monitoring of clinically stable diabetic dogs.

Fig 1. Relationships between classifications of glycemic control in study dogs by CST, blood HbA1c, and serum fructosamine.

Individual dogs are represented by colored squares. The color of each square indicates glycemic classification determined using the gold standard (CST) assessment: GOOD–green, FAIR–yellow, POOR–red. The position of each square on the graph is determined by the dog’s serum fructosamine concentration (x-axis) and blood HbA1c concentration (y-axis). Respective cut-offs and ranges for classification using fructosamine and HbA1c are indicated by the color-coded bars along each axis (GOOD–green, FAIR–yellow, POOR–red). The pale red area indicates dogs classified as having ACCEPTABLE control by the serum fructosamine test. The pale-yellow area indicates dogs classified as having ACCEPTABLE control by the blood HbA1c test. Dogs that fall into the area of overlap (pale orange) were classified as having ACCEPTABLE control by both tests. Blood HbA1c (%) and serum fructosamine (μmol/l) concentrations showed a significant correlation among the study group (n = 28 dogs). Pearson’s R = 0.578; p = 0.001.