Background: the controversies concerning the influence of iron deficiency on glycaemic control parameters in patients with prediabetes prompted us to conduct this research. Objective: Our aim was to get a delicate estimation of these changes that may alter the management plan in this clinical situation. Patients and methods: a case control study included 197 Egyptian patients with prediabetes; 113 patients with iron deficiency versus 84 patients without iron deficiency (control group) during the period (May 2019 - October 2019). History, physical examination and laboratory tests of fasting and postprandial plasma glucose (FPG and PPPG), glycosylated haemoglobin (HBA1c), fructosamine, serum creatinine, ALT, AST, CBC, ferritin, serum iron and total iron binding capacity (TIBC) were done. Results: HBA1c was significantly higher in the iron deficiency group than the control group with non-significant difference between the studied groups regarding FPG and PPPG. HBA1c level was positively correlated with fructosamine, exclusively in the healthy group indicating the lack of credibility of HBA1c in iron deficient subjects with prediabetes. HBA1C level was inversely correlated with serum iron level in both study groups. Conclusion: there is discordance in glycaemic control parameters in patients with prediabetes and iron deficiency. Diagnosis of deranged glucose homeostasis in patients with co-existent iron deficiency and prediabetes should not be with HBA1c solely.