Effect of Zinc on Glucose Homeostasis

Inclusion Criteria: Amish men or women who are 18 to 80 years old Prediabetes (HgbA1c = 5.7-6.4% or fasting glucose levels 100-125 mg/dL) Exclusion Criteria: Pregnant Currently breastfeeding History of severe gastrointestinal disorders or upper gastrointestinal surgery Has hemochromatosis, cancer, liver disease, kidney disease, cardiovascular disease, or other coexisting malignancy Hemoglobin < 12.5 g/dl (male) or < 11 g/dl (female) Severe hypertension (blood pressure > 160/95 mm Hg) Has a creatinine greater than 2.0 mg/dl, aspartate aminotransferase (AST) or alanine transaminase (ALT) greater than 2 times the upper limit of normal, hematocrit (Hct) less than 32%, or thyroid-stimulating hormone (TSH) less than 0.4 or greater than 5.5 milli-international units (mIU) per liter. At the discretion of the study physician or PI, taking medications that affect the outcomes of the study including, but not limited to, corticosteroids, anti-psychotic agents, protease inhibitors, oral contraceptives, estrogens, niacin, and some classes of antidepressants, statins, and antihypertensive medications Zinc hypersensitivity Use of denture adhesive containing zinc Taking other medications or zinc-containing supplements and is unwilling or cannot safely, in the opinion of the study physician, discontinue their use at least 2 weeks prior to protocol initiation Any other condition that would, in the opinion of the investigator, place them at an unacceptable risk or render them unable to meet the requirements of the protocol.