What effect is most likely observed in patients on long-term glucocorticoid therapy?

Patients on long-term glucocorticoid therapy are most likely to experience hyperglycemia. Glucocorticoids, such as prednisone, have a significant impact on glucose metabolism as they can induce insulin resistance and stimulate gluconeogenesis in the liver. This leads to an increase in blood sugar levels, commonly resulting in hyperglycemia.

Long-term use of these medications can also promote fat redistribution and lead to conditions such as Cushing's syndrome, characterized by elevated glucose levels among other symptoms. Monitoring of blood sugar levels is crucial for patients receiving prolonged glucocorticoid therapy to manage and prevent complications like diabetes.

The other choices reflect effects that are generally contrary to those produced by glucocorticoids. For instance, instead of increasing muscle mass, glucocorticoids tend to cause muscle wasting. Weight gain rather than decline is commonly observed as these medications can increase appetite and redistribute fat. Lastly, glucocorticoid therapy is associated with decreased bone density over time due to inhibition of osteoblast function and increased risk of osteoporosis, rather than an increase in bone density.