OBJECTIVEThe metabolic effects of low-dose prednisolone and optimal management of glucocorticoid-induced diabetes are poorly characterized. The aims were to investigate the acute effects of low-dose prednisolone on carbohydrate metabolism and whether long-term low-dose prednisolone administration increases visceral adiposity, amplifying metabolic perturbations.RESEARCH DESIGN AND METHODSSubjects with inflammatory rheumatologic disease without diabetes mellitus were recruited. Nine subjects (age, 59 ± 11 years) not using oral glucocorticoids were studied before and after a 7- to 10-day course of oral prednisolone 6 mg daily. Baseline data were compared with 12 subjects (age, 61 ± 8 years) using continuous long-term prednisolone (6.3 ± 2.2 mg/day). Basal endogenous glucose production (EGP) was estimated by 6,6-2H2 glucose infusion, insulin sensitivity was estimated by two-step hyperinsulinemic-euglycemic clamp, insulin secretion was estimated by intravenous glucose tolerance test, and adipose tissue areas were estimated by computed tomography.RESULTSPrednisolone acutely increased basal EGP (2.44 ± 0.46 to 2.65 ± 0.35 mg/min/kg; P = 0.05) and reduced insulin suppression of EGP (79 ± 7 to 67 ± 14%; P = 0.03), peripheral glucose disposal (8.2 ± 2.4 to 7.0 ± 1.6 mg/kg/min; P = 0.01), and first-phase (5.9 ± 2.0 to 3.9 ± 1.6 mU/mmol; P = 0.01) and second-phase (4.6 ± 1.7 to 3.6 ± 1.4 mU/mmol; P = 0.02) insulin secretion. Long-term prednisolone users had attenuated insulin suppression of EGP (66 ± 14 vs. 79 ± 7%; P = 0.03) and nonoxidative glucose disposal (44 ± 24 vs. 62 ± 8%; P = 0.02) compared with nonglucocorticoid users, whereas basal EGP, insulin secretion, and adipose tissue areas were not significantly different.CONCLUSIONSLow-dose prednisolone acutely perturbs all aspects of carbohydrate metabolism. Long-term low-dose prednisolone induces hepatic insulin resistance and reduces peripheral nonoxidative glucose disposal. We conclude that hepatic and peripheral insulin sensitivity should be targeted by glucose-lowering therapy for glucocorticoid-induced diabetes.

There is discordance between a reduced fasting and increased post-glucose load glucose concentration in rheumatological patients on long-term prednisolone. Therefore fasting glucose has poor sensitivity to screen for diabetes in prednisolone-treated patients. Treatment of prednisolone-induced hyperglycaemia should be directed at the postprandial period. Trial registration. Australian New Zealand Clinical Trials Registry, http://www.anzctr.org.au/, ACTRN12607000540415.

Endothelial dysfunction may contribute to the increased cardiovascular mortality associated with higher glucocorticoid doses. This may be a direct glucocorticoid effect, not mediated by insulin resistance. ACTH-deficient patients should thus be prescribed the lowest safe glucocorticoid replacement dose.