Acute mesenteric ischaemia (AMI) is a life-threatening disease with a mortality rate around 60%. This high mortality rate is largely caused by diagnostic delay, which means there is a pressing need for a reliable biomarker. In clinical practice, serum lactate measurement is often used for the diagnosis of AMI. To assess the diagnostic value of serum lactate, we performed a literature search. Lactate has two different isomers. The well-known L-lactate, produced by anaerobic glycolysis, and the more unknown D-lactate which is only produced by intestinal bacteria. In this review, we present and evaluate the current literature on the diagnostic value of the measurement of both lactate isomers. Furthermore, we suggest another biomarker which might have the potential to serve as a useful diagnostic test in the future.