Introduction This study investigated the status of serum ischaemia-modified albumin (IMA) levels in the development of diabetic foot ulcer (DFU) in patients with diabetes mellitus (DM) and in predicting ulcer formation and ulcer grading. Materials and method Thirty patients with DM, 30 with DFU and 30 healthy controls were included in the study. All participants' demographic characteristics and serum IMA, C-reactive protein (CRP), erythrocyte sedimentation rate (ESR) and white blood cell (WBC) levels and DFU infection grades were recorded. Results Nine (30%) patients with DFU were grade 2 according to the grading of International Working Group of the Diabetic Foot, 14 (46.7%) were grade 3 and seven (23.3%) were grade 4. Significant, powerful and positive correlation was determined between serum IMA and albumin-adjusted IMA levels and degrees of DFU (r = 0.878 and r = 0.846, P < .001 for both). Serum IMA levels in the DFU group were significantly higher than in the DM and control groups (P < .001). The optimal cut-off values for IMA in predicting DFU was 23.5 ng/mL (sensitivity 96%, specificity 87% and AUC = 0.97, P < .001). Additionally, at a cut-off value of 20.6 ng/mL, serum albumin-adjusted IMA differentiated cases of DFU from healthy individuals with 90% sensitivity and 83% specificity (AUC = 0.95, P < .001) Serum IMA levels exhibited significant, positive correlation with CRP, ESR, WBC, fasting plasma glucose and HbA1c (r = 0.575, r = 0.592, r = 0.597, r = 0.68 and r = 0.74, respectively, P < .001). Serum albumin levels were significantly negatively correlated with IMA, CRP, ESR and WBC values (r = -0.49, r = -0.56, r = -0.62 and r = -0.53, respectively, P < .001). Conclusion Our study findings indicate that together with CRP, ESH, WBC and albumin, increased IMA levels in patients with DM can be useful in the early prevention of DFU development and in predicting the severity of DFU infection.