Intensive 50-week evaluation of glipizide administration in 50 cats with previously untreated diabetes mellitus

Objective - To evaluate use of the oral hypoglycemic drug glipizide in diabetic cats. Design - Prospective study. Animals - 50 cats with recently diagnosed but untreated diabetes mellitus. Procedure - Each cat received glipizide (5 mg, q 12 h) for 16 weeks. Medication was not given during the subsequent 16 weeks; then glipizide treatment was repeated. Each cat was evaluated prior to treatment and at 2, 4, 8, 12, and 16 weeks during each of the 3 phases: blood samples for serum glucose and insulin determinations were obtained every 2 hours, from 8 AM to 6 PM. A preprandial blood glycosylated hemoglobin percentage was determined for the first sample obtained at each visit. Results - During the first 22 weeks of the study, diabetes worsened in 28 of the 50 cats, which then were disqualified from the study and treated with insulin. Of the remaining 22 cats that improved clinically, 7 had corresponding metabolic improvement in each diabetes-related parameter assessed and did not become hypoglycemic. Six of the 22 cats became hypoglycemic. Glipizide was discontinued, and diabetes did not recur. Serum glucose concentration did not improve in 6. Three cats had metabolic and clinical improvement during initial glipizide treatment, but had recurrence of the disease during repeated treatment; glipizide was discontinued and insulin was administered. None of the 50 treated cats died, and observed morbidity was mild and transient. Transient anorexia and vomiting were observed in 8 cats, and 4 became transiently icteric with abnormal liver enzyme activities. Clinical Implications - Trial use of glipizide is feasible in diabetic cats of owners who are unable or unwilling to administer insulin.