A Double Blind Randomised Placebo-controlled Trial to Assess the Role of Iron Repletion in Glucose Homeostasis.

Inclusion Criteria: * Premenopausal women. * Negative pregnancy test. * Adequate contraception during the study period and for 1 month following study completion. * Overt or relative iron deficiency at screening defined as follows: Serum ferritin \<50 ng/mL AND transferrin saturation \<20%, OR Serum ferritin \<30 ng/mL. \- Serum C-reactive protein: \<5 mg/L if not on oral contraception, OR \<20 mg/L if use of oral contraception * Intolerance to oral iron formulations, or lack of efficacy of oral iron formulations. * Minimum total score of 5 on the Visual analogic scale of fatigue. * Normal levels of vitamin B12 and folic acid at screening. * Availability and willingness to complete all study visits and procedures per protocol. * Ability to sign an informed consent. Exclusion Criteria: * Age \<18 years. * Menopause (defined as an amenorrhea of at least 12 months). * Irregularly menstruating women (menstrual cycle outside a range of 24-38 days in duration) or experiencing overt metrorrhagia (simple spotting not being an exclusion criteria). * Body mass index \<18.5 kg/m2 or \>30 kg/m2. * Diabetes, defined as subjects with HbA1c ≥ 6.5 % and/or with fasting blood glucose levels ≥ 7 mmol/l and/or with a history of diabetes and/or by the use of anti-diabetic drugs. * Hb level \<117 g/L or known haemoglobinopathy or haemochromatosis. * Blood transfusion within the last 12 weeks. * Intake of iron preparations 4 weeks prior to screening. * Known hypersensitivity to FCM or to any…