In patients with diabetes receiving chronic haemodialysis, both very high and low glucose levels are associated with poor outcomes, including mortality. Conditions that are associated with an increased risk of hypoglycaemia in these patients include decreased gluconeogenesis in the remnant kidneys, deranged metabolic pathways, inadequate nutrition, decreased insulin clearance, glucose loss to the dialysate and diffusion of glucose into erythrocytes during haemodialysis. Haemodialysis-induced hypoglycaemia is common during treatments with glucose-free dialysate, which engenders a catabolic status similar to fasting; this state can also occur with 5.55 mmol/l glucose-containing dialysate. Haemodialysis-induced hypoglycaemia occurs more frequently in patients with diabetes than in those without. Insulin therapy and oral hypoglycaemic agents should, therefore, be used with caution in patients on dialysis. Several hours after completion of haemodialysis treatment a paradoxical rebound hyperglycaemia may occur via a similar mechanism as the Somogyi effect, together with insulin resistance. Appropriate glycaemic control tailored for patients on haemodialysis is needed to avoid haemodialysis-induced hypoglycaemia and other glycaemic disarrays. In this Review we summarize the pathophysiology and current management of glycaemic disarrays in patients on haemodialysis.