The purpose of this study is to investigate the correlation between HbA1c and iron status in Type 2 Diabetes mellitus patients with iron deficiency by intravenous substitution of iron.

T2DM patients with diagnosis of ID defined as follows:

• serum ferritin <150 ng/mL or TSAT <25% if Hb < 14 g/dL serum ferritin <100 ng/mL or TSAT <20% if Hb ≥ 14 g/dL and ≤ 15g/dL]
• HbA1c: ≥ 6.5 to < 8.5 %
• Age > 18 years
• Written informed consent has been obtained.

Exclusion Criteria:

• Continuous subcutaneous insulin infusion (CSII)
• thalassaemia
• Hb > 15 g/dL (> 9,31 mmol/L)
• Change of HbA1c of more than ±0,3 % within the last 3 months.
• known sensitivity to ferric carboxymaltose
• history of acquired iron overload
• History of erythropoietin stimulating agent, i.v. iron therapy, and/or blood transfusion in previous 12 weeks prior to randomisation
• History of oral iron therapy at doses ≥ 100 mg/day 1 week prior to randomisation. Note: Ongoing oral use of multivitamins containing iron < 75 mg/day is permitted.
• Body weight ≤ 40 kg
• CRP > 15 mg/L
• Chronic liver disease (including known active hepatitis) and/or screening alanine transaminase (ALAT) or aspartate transaminase (ASAT) > 3 x ULN (upper limit of the normal range).
• Subjects with known hepatitis B surface antigen positivity and/or Hepatitis C virus ribonucleic acid positivity.
• Vitamin B12 and/or serum folate deficiency. If deficiency corrected subject may be rescreened for inclusion.
• Subjects with known seropositivity to human immunodeficiency virus.
• Clinical evidence of current malignancy with exception of basal cell or squamous cell carcinoma of the skin, and cervical intraepithelial neoplasia.
• Currently receiving systemic chemotherapy and/or radiotherapy.
• Renal dialysis (previous, current or planned within the next 6 months).
• Renal function GFR < 30 mL/min/ 1.73m2 (severe)
• Unstable angina pectoris as judged by the Investigator; severe valvular or left ventricular outflow obstruction disease needing intervention; atrial fibrillation/flutter with a mean ventricular response rate at rest >100 beats per minute.
• Acute myocardial infarction or acute coronary syndrome, transient ischaemic attack or stroke within the last 3 months prior to randomisation.
• Coronary-artery bypass graft, percutaneous intervention (e.g., cardiac, cerebrovascular, aortic; diagnostic catheters are allowed) or major surgery, including thoracic and cardiac surgery, within the last 3 months prior to randomisation.
• Patients with a polyneuropathy without ischemia.
• Subject of child-bearing potential who is pregnant (e.g., positive human chorionic gonadotropin test) or is breast feeding.
• Any subject not willing to use adequate contraceptive precautions during the study and for up to 5 days after the last scheduled dose of study medication.
• Participation in other interventional trials
• Female subject of child-bearing potential who is pregnant (e.g., positive human chorionic gonadotropin test) or is breast feeding.
• Failure to use highly-effective contraceptive methods
• Persons with any kind of dependency on the investigator or employed by the sponsor or investigator