Blood Glucose Curves in Diabetic Dogs and Cats

Blood glucose curves are a a useful tool in the stabilisation and monitoring of diabetic animals.They give an accurate assessment on which to base changes in insulin therapy and are vital in investigating the unstable diabetic. They help to determine insulin effectiveness and the maximum and minimum blood glucose concentrations and when these occur. They are an ideal tool for differentiating the problems of short duration of action and the Somogyi effect. See Problems.

Protocol for producing serial glucose curves

  • Hospitalise the animal
  • Follow the pet owner’s normal regime. This includes insulin injections, size, type and timing of meals and exercise routine.
  • Take a blood sample prior to insulin injection.
  • Administer the insulin.
  • Take a blood sample every two (to four) hours, if possible for 24 hours but at least until the concentration has crossed back above the renal threshold. More frequent blood sampling (e.g. hourly) may be required if Somogyi effect is suspected and difficult to identify. Be careful not to take too many large blood samples from small dogs and cats. Blood glucose concentrations are measured and plotted against time to produce a blood glucose curve

Spreadsheet to produce a blood glucose curve

The spreadsheet below enables glucose curves (in mmol/l) to be drawn and viewed easily. The graph is on the second page of the spreadsheet and appears as a scatter plot as it is then less likely that a Somogyi effect may be missed. There is also a conversion table for mg/dl and g/L.

Spreadsheet for serial glucose curve (mmol/l)

Interpreting blood glucose curves

The aim of treatment is to alleviate the clinical signs of diabetes mellitus. To achieve this, blood glucose concentrations must be kept below the renal threshold and hypoglycaemia must be avoided. Thus the goal is to maintain blood glucose concentrations roughly between::

5 and 10-12 mmol/l (90 and 180-216 mg/dl) in dogs

5 and 14-16 mmol/l (90 and 252-288 mg/dl) in cats

for most of the interval between insulin injections.

For once daily Caninsulin treatment to be considered effective in dogs the duration of the insulin action needs to be at least 20 hours.

For twice daily Caninsulin treatment to be considered effective, the duration of the insulin action has to be around 8-12 hours following each insulin injection.

Examples of blood glucose curves

Monitoring Blood Glucose Curves

Remember that, particularily in cats, stress can affect the results (the blood glucose concentrations at home will likely be different to those recorded in the surgery).