Effects of prednisolone on energy and fat metabolism in patients with rheumatoid arthritis: tissue-specific insulin resistance with commonly used prednisolone doses.
OBJECTIVE
Glucocorticoids can cause postprandial hyperglycaemia, but the effects on postprandial energy and fat metabolism are uncertain. We investigated the effects of acute and chronic low-dose prednisolone on fasting and postprandial energy expenditure and substrate metabolism.


METHODS
An open interventional and cross-sectional study was undertaken.


METHODS
Eighteen patients who had not taken oral glucocorticoids for ≥6 months were studied before and after 7 days prednisolone (6 mg/day) to assess the acute effects of prednisolone. Baseline data from patients, not on glucocorticoids, were compared with 18 patients on long-term prednisolone (6·5 ± 1·8 mg/day for >6 months) to assess the chronic effects. Energy expenditure and substrate oxidation were measured using indirect calorimetry before and after a mixed meal. Adipocyte insulin resistance index and insulin-mediated suppression of NEFA were calculated from fasting and postprandial insulin and NEFA concentrations.


RESULTS
There were no significant differences in resting energy expenditure or diet-induced thermogenesis with prednisolone. Acute (-2·1 ± 6·2 vs -16·3 ± 4·8 mg/min, P = 0·01) and chronic (-1·4 ± 2·8 vs -16·3 ± 4·8 mg/min, P = 0·01) prednisolone attenuated postprandial suppression of fat oxidation. Chronic (31·6 ± 3·8 vs 17·0 ± 3·3, P = 0·007), but not acute, prednisolone increased adipocyte insulin resistance index. However, insulin-mediated suppression of NEFA was not significantly different after acute or chronic prednisolone.


CONCLUSIONS
Prednisolone does not alter energy expenditure. However, even at low doses, prednisolone exerts adverse effects on fat metabolism, which could exacerbate insulin resistance and increase cardiovascular risk. Attenuated postprandial suppression of fat oxidation, but not lipolysis, suggests that prednisolone causes greater insulin resistance in skeletal muscle than in adipocytes.
School of Medicine, Flinders University, Bedford Park, SA, Australia.|Southern Adelaide Diabetes and Endocrine Services, Repatriation General Hospital, Daw Park, SA, Australia.
Anjana
A
Radhakutty
Southern Adelaide Diabetes and Endocrine Services, Repatriation General Hospital, Daw Park, SA, Australia.
Brenda L
BL
Mangelsdorf
Southern Adelaide Diabetes and Endocrine Services, Repatriation General Hospital, Daw Park, SA, Australia.
Sophie M
SM
Drake
Diabetes & Metabolism Division, Garvan Institute of Medical Research, Darlinghurst, Sydney, NSW, Australia.
Dorit
D
Samocha-Bonet
Discipline of Medicine, The University of Adelaide, Adelaide, SA, Australia.
Leonie K
LK
Heilbronn
Department of Rheumatology, Repatriation General Hospital, Daw Park, SA, Australia.
Malcolm D
MD
Smith
School of Medicine, Flinders University, Bedford Park, SA, Australia.|Discipline of Medicine, The University of Adelaide, Adelaide, SA, Australia.
Campbell H
CH
Thompson
School of Medicine, Flinders University, Bedford Park, SA, Australia. morton.burt@sa.gov.au.|Southern Adelaide Diabetes and Endocrine Services, Repatriation General Hospital, Daw Park, SA, Australia. morton.burt@sa.gov.au.
Morton G
MG
Burt
D017667:Adipocytes / Q000187:drug effects / Q000378:metabolism; D000368:Aged; D001172:Arthritis, Rheumatoid / Q000188:drug therapy*; D002153:Calorimetry, Indirect; D004734:Energy Metabolism / Q000187:drug effects*; D005230:Fatty Acids, Nonesterified / Q000032:analysis; D005260:Female; D006801:Humans; D007333:Insulin Resistance; D050356:Lipid Metabolism / Q000187:drug effects*; D008066:Lipolysis; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000187:drug effects / Q000378:metabolism; D010084:Oxidation-Reduction; D011239:Prednisolone / Q000008:administration & dosage / Q000494:pharmacology*; D022722:Thermogenesis / Q000187:drug effects
D005230:Fatty Acids, Nonesterified; D011239:Prednisolone