Blood Samples as a Monitoring Tool

Blood samples can be taken to measure blood glucose concentrations.

Measuring blood glucose

1. Collect a venous blood sample from a peripheral vein into a suitable tube.

2. Collect a drop of capillary blood from the ear (pinna), or sometimes a carpal pad or a footpad, and analyse this using a hand-held blood glucose meter (glucometers).

  • Readings may vary by as much as 15% from samples submitted to the laboratory.
  • Hand-held glucometers are reasonably accurate.

If a reading seems unusual or does not match the clinical signs, a second reading should be taken or another method used to confirm the blood glucose concentration.

3. A number of new methods are being tested. These include continuous, less invasive methods of glucose testing, such as using a glucose sensor placed under the skin to record several hundred blood glucose concentrations over a two- to three-day period. This type of device has been tested in diabetic cats.

More information

See Publications:

  • Wess G, Reusch C (2000). Capillary blood sampling from the ear of dogs and cats and use of portable meters to measure glucose concentration.
  • Casella M, Wess G, Reusch CE (2002). Measurement of capillary blood glucose concentrations by pet owners: a new tool in the management of diabetes mellitus. J Am Anim Hosp Assoc. 2002 May-Jun; 38(3): 239-45

Single blood glucose measurements

A single blood sample for glucose measurement can be taken at the time that the blood glucose nadir (lowest concentration is expected). This is particularly used after a dose increase to check that the new dose is not producing hypoglycaemia. The time to blood glucose nadir is different in each animal. Thus, taking a single sample between 6 and 10 hours after insulin administration is not always going to be appropriate. It is not advisable to use single blood glucose measurements as a method of monitoring the efficacy of the insulin dose.

A more accurate way of monitoring the efficacy of treatment is to produce a blood glucose curve.

Blood Samples to monitor Diabetic Dogs and Cats

Single blood glucose measurements are thus most appropriate in animals where the time of blood glucose nadir has been established.