Useful Tests in the Diagnosis and Management of Diabetes Mellitus

Fructosamine

What is it?

Fructosamine is the common name for glycated-protein complexes that form in the blood when hyperglycaemia is present. The amount of fructosamine present is proportional to the blood glucose concentration over the life span of the protein (1-2 weeks).

What is it used for?

Measurement of fructosamine has shown to be very useful in differentiating true diabetes from transient hyperglycaemia resulting from stress. It is also useful in the management of diabetic dogs by providing a guide to longer-term glycaemic control.

Why?

Both blood and urine glucose are subject to many variables and their measurement indicates only the glycaemic state at that point in time. Fructosamine provides a longer-term view of average blood glucose levels and is not affected by these variables.

When?

• Cats: when hyperglycaemia and/or glycosuria are detected.
• Dogs: where diabetes is initially diagnosed to provide a baseline value or where hyperglycaemia or glycosuria are present.

Following the diagnosis of diabetes, samples should be taken initially every 2-3 weeks to confirm the establishment of good control. Stable diabetics should be checked 3 times per year.

What sample is required?

0.5 ml serum or 1 ml clotted blood.

Cost?

£9.30 (analysis run daily).

Serial Blood Glucose Testing

What is it?

A series of blood glucose samples taken over 24 hours. Shortened tests over a working day can miss hyperglycaemia or overswings occurring overnight (a minimum of a 2-3 hour post-prandial sample should be taken after the evening meal if overnight sampling is not possible).

What is it used for?

To assess insulin responsiveness, peak activity, duration and extent of glycaemic control over a 24-hour period. It is the test of choice for identification of the Somogyi phenomenon (insulin induced hypoglycaemia inducing a rebound hyperglycaemia).

When?

Test should be used early in therapy to optimise dosage and timing of feeding or where glycaemic control is unstable or deteriorating.

How?

Taking 8 blood samples in 24 hours can be associated with significant stress leading to elevations of blood glucose. Intravenous catheter placement facilitates sampling and leads to more accurate results. Full details are given in our protocol for this test together with a table to aid data collection. Interpretation of the curve is supplied with the test results where this table is supplied with the samples.

What sample is required?

1 ml fluoride oxalate at 2-3 hour intervals.

Cost?

£2.75 per sample if less than 5 samples, £2.00 per sample for 5 or more samples.