What best explains elevated serum glucose levels in a client receiving corticosteroids for pneumonia?

Elevated serum glucose levels in a client receiving corticosteroids can be primarily attributed to the direct impact that corticosteroids have on glucose metabolism. Corticosteroids stimulate gluconeogenesis, which is the process by which the liver generates glucose from non-carbohydrate sources, essentially increasing the overall glucose production in the body. They also promote insulin resistance, meaning that the body's cells become less responsive to insulin, leading to impaired glucose uptake. This combination results in higher serum glucose concentrations.

While other factors such as poor nutrition and the body’s stress response to pneumonia may influence glucose levels, the direct pharmacological effect of corticosteroids on glucose metabolism is the most significant reason for the elevation in serum glucose levels in this scenario. Thus, understanding the role of corticosteroids in affecting glucose regulation is essential for managing patients on this medication.