Effect of Iron Reduction by Phlebotomy for Type 2 Diabetes

High tissue iron is a risk factor for diabetes even within the broad normal range of normal human values. In order to demonstrate the benefits of reducing iron on glucose homeostasis and to better define the parameters for larger clinical trials, the investigators will subject individuals with prediabetes (impaired glucose tolerance, IGT) or early type 2 diabetes to phlebotomy in order to reduce serum ferritin concentrations and determine the effect on glucose homeostasis as revealed by oral and frequently sampled intravenous glucose tolerance testing.