Diabetes mellitus, one of the most common chronic metabolic diseases worldwide, is characterised by high blood sugar and leads to many serious complications. 1 The complications caused by longterm high blood glucose include nephropathy, retinopathy and neurovascular complications. 2 One of the most serious conditions of diabetes-related neurovascular complications is foot ulcers. It was estimated that ~15% of people with type 2 diabetes would be affected by foot ulcers. 3 However, in 2015, the International Diabetes Federation reported that this rate was ~34%. 4 Diabetic foot ulcers lead to amputation at various levels, depending on severity, in ~20% of patients. Furthermore, diabetic foot ulcers increase the risk of death. Patients with diabetic foot ulcers have a 2.5-fold higher risk of death at 5 years than those without diabetic foot ulcers. 5 Unfortunately, despite significant improvements in diabetic foot care and treatment, the rate of amputation due to diabetic foot ulcers is increasing.One of the classifications of diabetic foot ulcers was developed by Wagner in the 1970s, in which ulcers were graded between 0 and 5. In this classification, only the depth of the ulcer, osteomyelitis and gangrene are evaluated, but the presence of ischaemia is not considered. 6,7 New classification systems have been developed after this classification; however, the Wagner classification is simple and very effective in predicting low extremity amputation. 8,9 Ischaemia in tissues due to the decreased blood flow in diabetic foot ulcers is not considered in the Wagner classification, making it difficult to determine the level of amputation. Therefore, a biomarker to help determine the level of ischaemia in these patients may be more effective in determining the degree of amputation. Classical