Which medication added to a client's regimen may contribute to increased hyperglycemia in a patient with diabetes mellitus?

Prednisone is a corticosteroid that can significantly impact blood glucose levels. This medication is known to promote gluconeogenesis, the process by which glucose is produced from non-carbohydrate sources in the liver. By increasing glucose production and potentially decreasing insulin sensitivity, prednisone can lead to elevated blood glucose levels, making it difficult for people with diabetes to maintain their target glycemic control.

In the context of diabetes management, understanding the effects of various medications is crucial. While other medications may have side effects, they do not generally contribute to increased hyperglycemia in the same way that corticosteroids like prednisone do. For example, phenelzine is a monoamine oxidase inhibitor used primarily for depression, but it does not have a direct impact on blood glucose levels. Atenolol, a beta-blocker, can influence insulin response and blood glucose, but it is less likely to cause significant hyperglycemia compared to corticosteroids. Allopurinol, used to treat gout, primarily affects uric acid levels and does not impact blood sugar directly.

Therefore, when considering medications that might complicate diabetes management by causing hyperglycemia, prednisone stands out due to its well-documented effects on glucose metabolism.