Whenever I counsel people about diabetes in animals, I always advise consulting a veterinarian before adjusting their pet’s insulin dosage. Unfortunately, I met one client who ignored this advice. Every day, the diligent woman checked her cat’s urine for glucose and pricked his ear to get an exact blood level. Since the blood level was higher than she wanted and there was glucose in his urine, she increased the dose of insulin by a unit expecting the higher dose to control the glucose level. When the levels were still too high at the next check, the frustrated woman increased the insulin even more. Unfortunately, she did not understand the Somogyi response until it was too late for her cat. She found him lying in his litter box, in a coma.
Diabetes in animals is like diabetes in people. The pet needs insulin injections to control their level of blood sugar. If too much insulin is given, the blood sugar levels drop too low (hypoglycemia). To counteract this life-threatening situation, the body releases hormones – primarily epinephrine and glucagon. These break down glycogen reserves into glucose for release into the blood stream. This phenomenon of the blood sugar dropping too low, below 80 mg/dl and then skyrocketing to over 300 mgl/dl is known as the Somogyi response. It is also called rebound hyperglycemia or insulin-induced hyperglycemia.
Unfortunately for the cat in the story above, the owner always retested his urine and blood during the “rebound” hyperglycemia, not during the life-threatening hypoglycemia. She saw the high blood sugar results and gave more insulin because she did not understand what was really happening in her cat – the high dose of insulin bottomed out his blood sugar and then his body rebounded with its glycogen reserves.
Therefore, I want to warn all caretakers of diabetic animals to check with your veterinarian before changing your pet’s insulin dose. It is counterintuitive but a high blood glucose level might mask the fact that the pet needs less, not more insulin.