Overview

Glucocorticoids may precipitate hyperglycaemia and overt diabetes in patients not known to have pre-existing diabetes. At higher risk are patients who:

• have pre-existing risk factors for diabetes
• are taking high doses or prolonged courses of glucocorticoids.

The hyperglycaemic effect depends on the dose and duration of action of the glucocorticoid. Hyperglycaemia persists with ongoing use of glucocorticoids and can arise with any route of administration (oral, intra-articular, intramuscular, inhaled), though the effect with inhaled administration is not as pronounced.

The type and route of glucocorticoid used results in different timing and patterns of hyperglycaemia; for example:

• a morning dose of oral prednisolone causes a progressive increase in blood glucose concentrations during the day (peak effect after about 6 hours and continuing for about 12 hours) with a fall in concentrations during the late evening and overnight
• longer-acting glucocorticoids such as dexamethasone cause hyperglycaemia throughout the day
• intra-articular glucocorticoid injections can cause a significant rise in blood glucose concentrations, which can take several days to develop and peak.

In patients with pre-existing type 1 or type 2 diabetes, glucocorticoid treatment exacerbates hyperglycaemia, so the need to adjust diabetes management should be anticipated.