Arginine stimulation test does not predict diabetes remission in cats

Abstract

BACKGROUND: Cats with diabetes mellitus frequently achieve clinical remission, suggesting residual β-cell function. Responsiveness of β-cells to arginine persists the longest during diabetes progression, making the intravenous arginine stimulation test (IVAST) a useful tool to assess residual insulin and glucagon secretion. HYPOTHESIS: Diabetic cats with and without remission will have different arginine-induced insulin or glucagon response. ANIMALS: Seventeen cats with diabetes, 7 healthy cats. METHODS: Blood samples collected on admission and during subsequent IVAST. Glucose, insulin, and glucagon were measured. Response to IVAST was assessed by calculating the insulin and glucagon area under the curve (AUC) and the AUC glucagon-to-insulin ratio. Diabetic cats were treated with insulin and were followed for 18 weeks. Remission was defined as normoglycemia and disappearance of clinical signs of diabetes for ≥4 weeks, without requiring insulin. RESULTS: Seven diabetic cats (41%) achieved remission. On admission, blood glucose concentration was significantly lower in cats with remission (median, 389 mg/dL; range, 342-536 mg/dL) than in those without remission (median, 506 mg/dL; range, 266-738 mg/dL). After IVAST, diabetic cats with remission had higher AUC glucagon-to-insulin ratios (median, 61; range, 34-852) than did cats without remission (median, 26; range, 20-498); glucose, insulin, and glucagon AUCs were not different. Diabetic cats had lower insulin AUC than did healthy cats but comparable glucagon AUC. CONCLUSIONS AND CLINICAL IMPORTANCE: Diabetic cats with and without remission have similar arginine-stimulated insulin secretion on admission. Although cats with remission had lower blood glucose concentrations and higher AUC glucagon-to-insulin ratios, large overlap between groups prevents use of these parameters in clinical practice.