Blood Glucose Curves in Diabetic Dogs and Cats
- A useful tool in the initial stabilisation and monitoring of diabetic animals.
- Give the most accurate assessment on which to base changes in insulin therapy.
- Vital in investigating the unstable diabetic.
- Help to determine insulin effectiveness and the maximum and minimum blood glucose concentrations and when these occur.
- An ideal tool for differentiating the problems of short duration of action and the Somogyi effect. See Problems.
When using a glucose curve, 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).
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: many animals eat better at home and can be fed prior to bringing to the surgery.
- Administer the insulin yourself
- 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.
- Be careful not to take too many large blood samples in 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:
- 6 and 10-12 mmol/l (90 and 180-216 mg/dl) in dogs
- 6 and 14-16 mmol/l (90 and 252-288 mg/dl) in cats
for most of the interval between insulin injections.