Glucose concentrations after insulin‐induced hypoglycemia and glycemic variability in healthy and diabetic cats

Background Little information is available about posthypoglycemic hyperglycemia (PHH) in diabetic cats, and a causal link between hypoglycemia and subsequent hyperglycemia is not clear. Fluctuations in blood glucose concentrations might only represent high glycemic variability. Hypothesis Insulin induces PHH in healthy cats, and PHH is associated with poorly regulated diabetes and increased glycemic variability in diabetic cats. Animals Six healthy cats, 133 diabetic cats. Methods Insulin (protamine‐zinc and degludec; 0.1‐0.3 IU/kg) administered to healthy cats. Blood glucose curves were generated with portable glucose meter to determine the percentage of curves with PHH. Data from insulin‐treated diabetic cats with blood glucose curves showing hypoglycemia included data of cats with and without PHH. Post‐hypoglycemic hyperglycemia was defined as blood glucose concentrations 15 mmol/L within 12 hours. Glycemic variability was calculated as the standard deviation of the blood glucose concentrations. Results In healthy cats, all insulin doses caused hypoglycemia but PHH was not observed; glycemic variability did not differ between insulin preparations. Among diabetic cats with hypoglycemia, 33 (25%) had PHH. Compared with cats without PHH, their daily insulin dose was higher (1.09 ± 0.55 versus 0.65 ± 0.56 IU/kg; P