Funded in part by Nestlé Purina Company.

Corticosteroids, particularly glucocorticoids, can result in decreased glucose tolerance and diabetes in cats. Insulin sensitivity is associated with insulin resistance and feline diabetes mellitus. This study evaluated the diabetogenic effects of prednisolone and dexamethasone at equally potent therapeutic dosages. Cats were treated with daily prednisolone (n = 7) and dexamethasone (n = 7) for 56 days. Serum fructosamine and urine glucose levels were measured on days 0, 28, and 56. The arginine stimulation test was performed on day 0, and the intravenous glucose tolerance test (IVGTT) was performed on day 2; the tests were repeated on days 56 (IVGTT) and 58 (arginine stimulation test). Fructosamine concentrations did not significantly differ between the 2 groups on day 0 or 28; a trend toward higher fructosamine concentrations was identified in dexamethasone-treated cats. Glucosuria was significantly greater on day 56 in dexamethasone-treated cats; no cats demonstrated glucosuria at the beginning of the study. Dexamethasone-treated cats demonstrated greater decreases in insulin sensitivity and lower compensatory increases in insulin secretion over time than prednisolone-treated cats. These data collectively suggested that dexamethasone is more diabetogenic than prednisolone at equally potent doses.

Commentary: Steroids are widespread in clinical veterinary practice and are routinely used in cats. It is prudent to avoid the most diabetogenic medications in cats, and these results urge further research in larger feline populations. They also suggest that clinical veterinarians should consider prednisolone as a therapeutic alternative to dexamethasone.

A pilot study comparing the diabetogenic effects of dexamethasone and prednisolone in cats. Lowe AD, Graves TK, Campbell KL, Schaeffer DJ. JAAHA 45:215-224, 2009.