Every now and then a diabetic pet just doesn’t seem to make sense. On paper it all seems so simple. You give insulin which should lower the pet’s blood glucose level for some period of time until it rises again. After all, insulin drives energy into cells. After an insulin injection we expect the blood glucose to go down, but sometimes it does not. Sometimes a pet doesn’t seem to respond to insulin at all. Sometimes, you get a Somogyi Swing.
When Pet Blood Glucose Numbers Don’t Make Sense
First, let’s talk about blood glucose curves. Human diabetics don’t run blood glucose curves on themselves. Human diabetics can dose themselves and know what they are going to eat, if they are going to eat, and how they react to various types of foods. They dose themselves appropriately for what they are about to ingest. Each day is a little different, and they adjust their insulin based on what they eat and when they eat.
Since animals can’t poke themselves with insulin, their human caretakers try to improve the pet’s diabetic control by having a consistent routine. Usually this means equally portioned meals and insulin doses every 12 hours. We figure that the pet will likely react the same way from one dose to another if we are feeding equally portioned meals. These meals are usually the same kind of food at each meal. This is the whole idea behind blood glucose curves. Again, humans don’t run curves on themselves because they are in control of what they eat and give themselves insulin injections accordingly.
How Do You Run a Blood Glucose Curve?
You first check the blood glucose right before a regularly scheduled insulin injection and meal. You then check the blood glucose every 2 hours until the next regularly scheduled insulin injection and meal. If the blood glucose goes lower than 150 mg/dl, we check it hourly until it starts to rise again.
A blood glucose curve tells us two things for pets:
- A curve tells us how low the blood glucose goes after a particular dose of insulin.
- A curve tells us how long a particular insulin lasts in a particular pet after a particular dose in that pet. Remember that each pet is unique in how it absorbs and metabolizes insulin. Some pets respond better to one insulin than another. It’s all very individual.
So, we expect that there will be a point a few hours after the insulin injection when the glucose hits the lowest point for that dose. We call that point where it “bottoms out” the “nadir”. We use the nadir to decide if we should increase the insulin dose, decrease the insulin dose, or leave the dose alone. We want the nadir to be somewhere around 100 mg/dl. What if that doesn’t happen? What if the glucose doesn’t drop at all? Sometimes it might even go up. That’s when we start to wonder if we might be experiencing the ‘Somogyi Swing’.
What is a ‘Somogyi Swing’?
The Somogyi Swing occurs if the dose of insulin is more than a pet needs. If the blood glucose dives down to hypoglycemia, the pet’s liver will likely react to save the day! The liver can turn stored glycogen into glucose. When the liver does this heroic gluconeogenesis, making glucose out of stored glycogen, we may then see a high blood glucose for hours or days thereafter. Truly, it can seem to make no sense whatsoever. Somogyi Swing can be a stinker to identify. Seriously, it is very very hard to recognize. We may wonder if the pet isn’t absorbing the insulin or if a pet isn’t responding to the insulin. We may wonder if the human is injecting the pet correctly. Or, we may consider dropping the insulin dose to see if we have a case of Somogyi Swing.
Of course, you should always chat with your veterinarian, who has examined your pet, before making dosing changes. If we suspect the Somogyi Swing, we back off on the insulin dosage and monitor over the next week and run a curve 5 to 7 days later.
Sometimes when folks first get the diagnosis of diabetes in their beloved pet they want to get the perfect dose as soon as possible! In their zeal to help Fluffy, they may increase the dosage of insulin too rapidly and bypass the actual appropriate dose for the pet. This Somogyi Swing phenomenon is why I advise folks to start slowly and sneak up on the dose. When I adjust the insulin dosage, I increase it by small increments. Whenever I change the insulin dosage I have the family run a blood glucose curve again in 5 to 7 days to see how that change has affected the glucose levels.
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NOTE: Consult your veterinarian first to make sure my recommendations fit your pets special health needs.