OBJECTIVES: Preclinically, curcumin has been shown to protect against glucocorticoid-induced insulin resistance. We evaluated the effect of curcumin administered with prednisolone in healthy overweight or obese men.

METHODS: In a double-blind, parallel-group trial, 24 overweight/obese non-diabetic men were randomised to one of three intervention groups A) prednisolone placebo+curcumin placebo, B) prednisolone (50 mg/day)+curcumin placebo or C) prednisolone and curcumin (400 mg/day). Curcumin or curcumin placebo treatment started one day prior to 10-day prednisolone or prednisolone placebo treatment. The primary endpoint was change in prednisolone-induced insulin resistance assessed by homeostatic model assessment of insulin resistance (HOMA2-IR). Other endpoints included anthropometric measurements, magnetic resonance spectroscopy-assessed hepatic fat content, blood pressure, circulating metabolic markers and continuous glucose monitoring measures.

RESULTS: Baseline characteristics (mean ± SD): age 44.2 ± 13.7 years, body mass index 30.1 ± 3.5 kg/m2, glycated haemoglobin A1c 33.3 ± 3.2 mmol/mol, HOMA2-IR 1.10 ± 0.45 and fasting plasma glucose 5.2 ± 0.4 mmol/L. Prednisolone significantly increased HOMA2-IR (estimated treatment difference 0.36 [95% CI 0.16; 0.57]). Co-treatment with curcumin had no effect on HOMA2-IR (estimated treatment difference 0.08 [95% CI -0.13; 0.39]). Prednisolone increased glycated haemoglobin A1c, insulin, C-peptide, glucagon, blood pressure, mean interstitial glucose, time spent in hyperglycaemia and glucose variability, but no protective effect of curcumin on any of these measures was observed.

CONCLUSIONS: In this double-blind, placebo-controlled parallel-group study involving 24 overweight or obese men randomised to one of three treatment arms, curcumin treatment had no protective effect on prednisolone-induced insulin resistance or other gluco-metabolic perturbations.