Glycated haemoglobin and serum fructosamine concentrations in sick, non-diabetic dogs receiving oral prednisolone

Glucocorticoids have been associated with an increased risk of developing diabetes mellitus (DM) in dogs. Glycated haemoglobin (HbA1c) and serum fructosamine have been scarcely studied in dogs receiving glucocorticoid therapy. The aim of this study was to evaluate HbA1c and fructosamine in non-diabetic dogs receiving oral prednisolone. This was a cross-sectional study including non-diabetic dogs receiving oral prednisolone for 2 weeks or more for a diverse range of diseases. Aliquots of blood samples collected for diagnostic purposes were used. HbA1c was measured using a previously validated capillary electrophoresis assay. Fructosamine was measured using the nitroblue tetrazolium assay. Forty-three adult dogs were included. The dogs received oral prednisolone (0.1‒2.3 mg/kg daily) for a median duration of 8 weeks (range: 2‒52 weeks). The median (range) glucose, fructosamine and HbA1c were 5.3 (2.6‒9.2) mmol/L, 265 (128‒388) µmol/L and 1.6% (0.8‒2.7%), respectively. Glucose increased in nine of the 43 dogs (16.2%), while fructosamine increased in eight of the 33 dogs in which it was tested (24.2%). HbA1c did not increase in any of the 40 dogs in which it was tested. The cross-sectional study design is a limitation, as more conclusions could be drawn in a longitudinal study. HbA1c does not appear to be increased in sick, non-diabetic dogs receiving oral prednisolone for 2 weeks or more at the doses used in our study, whereas increases in serum fructosamine are not uncommon.