Fructosamine and glycosylated haemoglobin (GHb) are two glycated proteins commonly used for monitoring diabetics.
These two proteins are markers of mean blood glucose concentration, with their concentration being proportional to the blood glucose concentration. The concentration of these proteins is not affected by stress; they are ideal for monitoring diabetic animals, particularily cats.
The bonding of glucose to proteins produces fructosamines. A single fructosamine measurement indicates the average glucose concentration over the previous 2-3 weeks, based on the half-life of the plasma proteins.
The majority of diabetic animals will not always have optimal control of blood glucose thus fructosamine concentrations are unlikely to lie entirely within the reference range. Single fructosamine measurements should be interpreted in the light of clinical signs of diabetes, body weight and blood glucose concentration. In general, the closer the fructosamine concentration is to the reference range for healthy dogs and cats, the better the glycemic control.
Fructosamine reference ranges
|Normal non-diabetic dog||225-365|
|Newly diagnosed diabetic dog||320-850|
|Treated diabetic dogs:|
(Reference: Feldman EC, Nelson RW (2004) Canine diabetes mellitus. In Canine and Feline Endocrinology and Reproduction. 3rd edition. Saunders, St Louis, USA p. 510)
|Normal non-diabetic cat||190-365|
|Newly diagnosed diabetic cat||350-730|
|Treated diabetic cats:|
(Reference: Feldman EC, Nelson RW (2004) Feline diabetes mellitus. In Canine and Feline Endocrinology and Reproduction. 3rd edition. Saunders, St Louis, USA p. 563)
|Advantages of measuring fructosamine||Limitations of fructosamine measurements|
|Distinguishes hyperglycaemic, non-diabetic animals from diabetics with chronic hyperglycaemia||Unable to detect short-term or transient abnormalities in the blood glucose concentration, e.g. hypoglycaemia.|
|Does not appear to be influenced by transient (stress) hyperglycaemia||Hyperthyroid cats with diabetes mellitus may have decreased fructosamine concentrations, despite having normal serum protein concentrations due to an increase in the protein turnover rate (decreased protein half-life) due to increased thyroid hormone concentrations.|
|Useful in confirming diagnosis in cats||Increase in hyperproteinaemia (e.g. dehydration).|
|Useful in evaluating longer-term control and owner compliance with insulin treatment||Dogs with hypoalbuminaemia also have a decreased fructosamine concentration (false negative).|
In practice fructosamine is often used as an aid to the diagnosis and monitoring of diabetic cats.