The cardiac benefits of gastrointestinal hormones have been of interest in recent years. The aim of this study was to explore the myocardial and renal effects of the gastrointestinal hormone secretin in the GUTBAT trial (NCT03290846). A placebo-controlled crossover study was conducted on 15 healthy males in fasting conditions, where subjects were blinded to the intervention. Myocardial glucose uptake was measured with [¹⁸F]2-fluoro-2-deoxy-D-glucose ([¹⁸F]FDG) positron emission tomography. Kidney function was measured with [¹⁸F]FDG renal clearance and estimated glomerular filtration rate (eGFR). Secretin increased myocardial glucose uptake compared to placebo (secretin vs. placebo, mean + standard deviation, 15.5 ± 7.4 vs. 9.7 ± 4.9 μmol/100g/min, 95% confidence interval (CI) [2.2, 9.4], p=0.004). Secretin also increased [¹⁸F]FDG renal clearance (44.5 ± 5.4 vs. 39.5 ± 8.5 ml/min, 95%CI[1.9, 8.1], p=0.004) and eGFR was significantly increased from baseline after secretin, compared to placebo (17.8 ± 9.8 vs. 6.0 ± 5.2 Δml/min/1.73m², 95%CI[6.0, 17.6], p=0.001). Our results implicate that secretin increases heart work and renal filtration, making it an interesting drug candidate for future studies in heart and kidney failure.