In this VETgirl online veterinary CE blog, Amy Newfield, CVT, VTS (ECC) reviews blood glucose monitoring, and what you need to know as a veterinary technician.

Let’s talk blood glucose. One low reading can kill a patient, but too many high readings can cause issues as well.

What is Blood Glucose?
Glucose comes from the Greek word for “sweet” and is a type of sugar the body gets from foods the pet eats throughout the day. The body uses this blood glucose (BG) sugar as an energy source in all metabolic functions like walking, playing and even sleeping.

How is it Made?
The pancreas is an organ that is a mixed gland (endocrine and exocrine parts). The exocrine secretions enter the duodenum through the pancreatic duct. The endocrine secretions are formed in tissue found within the exocrine tissue known as the islets of Langerhans. The three hormones secreted from the islets of Langerhans are insulin, glucagon and somatostatin.

Insulin is secreted in response to high blood glucose levels in the body. Ultimately the insulin helps to lower the blood glucose by increasing the uptake of glucose into the cells and storing the excessive glucose as glycogen in the liver for later use. It is also responsible for breaking down fat and storing it as adipose tissue. Glucagon is secreted in response to low blood glucose levels. It helps to raise the blood glucose by converting the stored glycogen in the liver back to glucose. Somatostatin helps to regulate blood glucose levels in conjunction with insulin and glucagon as well as helps to decrease gut motility and secretion of digestive juices.

An insult to the pancreas occurs causing a degeneration in the islet cells. The insult could be from an acute or chronic onset of pancreatitis, neoplasm or may be idiopathic. The end result is that there is a change in the level of the hormone insulin, the failure of the cells of the body to be able to respond to insulin and/or the increase of glucagon resulting in hyperglycemia or hypoglycemia.

How to Measure a Blood Glucose
The general normal range for both dogs and cats for a blood glucose is 80-120 mg/dL (4.4-6.7 mmol.L). Various diseases and illnesses can cause it to be high or low. You must get a blood sample in order to obtain a blood glucose. The sample size is just a drop. Therefore you do not need to violate a large vessel or major vein. Too many times I see veterinary staff using a 1.0 cc syringe or even an insulin syringe and drawing blood from the cephalic, femoral or saphenous veins. Save those veins for more important things like large blood draws or intravenous catheters! Instead use a 20g or 22g needle and prick the pinna of the ear or the lower lip. I have found cats do better with ears and dogs do better with the chin or lower lip. After you make a quick prick of the skin apply gentle pressure around it to “squeeze” out a drop of blood if it doesn’t automatically flow freely. Have your blood glucose machine ready to go, strip in and hold the strip in the machine up to the drop of blood. This is how people take their BG measurements. They prick their finger and hold the machine with the strip in it up to the drop of blood.

Another newer way of obtaining a blood glucose is through using the Freestlye Libre sensor. This is a sensor that is attached to a dog or cat into their subcutaneous layer of their skin. It can stay on the pet for 14 days and allows the owner to get continuous BG readings on their pet. Some veterinary clinics will put a little skin glue on the sensor before injecting it, but others do not. The sensor is usually attached to the pet’s thoracic cavity after the fur is shaved and the area cleaned and dried with an alcohol swab. Both dogs and cat do not really seem too bothered by the sensor placement. The sensor is then connected to an online app from the company and the monitoring can begin! This is the most consistent way to monitor BG levels in the dog and cats.

Reducing the Fear
I had a cat that was a transient diabetic. The best way to manage her was by taking blood glucose readings from her at home where she was less stressed. I took the time to systematically desensitize her to the experience (and this was before Freestyle Libre!). I would pinch my ear with my finger and the give her the best slinkiest cat treat ever which for her was tuna! Pinch and tuna for days until she would get a pinch, not react and look to me for a treat. Then I got ready with my 20g needle and did the fastest stab of the pinna of the ear and treated her right away! She was great and from that point forward I could do all the BG checks at home! We can teach our owners these techniques so they can get their own readings at home, where pets are happier and more comfortable. Both the pet and the owner would rather not have to come into the hospital. It also allows for much better control of the pet at home!

PS. Be aware of the limitations of a handheld glucometer if your patient is very anemic (e.g, FeLV, IMHA, chronic anemic of illness) or hemoconcentrated, as you will get an inaccurate result. You can listen to the study HERE:

  1. I was always taught to only use cat/dog specific glucometers (alpha trak)? We had a client bring in their human one and compared it with the alpha trak and got significantly different values. Wouldn’t this be the case with the Freestyle as well?

    • The AlphaTrak is FDA approved for vet med. Most are SIMILAR but as the patient has BG values that are very abnormal, they are usually less reliable, IMO.

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