Effect of Zinc on Glucose Homeostasis

Summary

The purpose of this investigation is to evaluate the impact of zinc supplementation on fasting glucose levels, hemoglobin A1c (HbA1c), and other indices of glucose homeostasis in individuals with prediabetes. The investigators hypothesize that prediabetic subjects receiving zinc will demonstrate a greater decrease in HbA1c and blood glucose compared to prediabetic subjects receiving placebo. Specific Aim: Conduct a prospective, double-blind randomized clinical trial comparing the effects of 12 months of zinc supplementation (zinc gluconate 30 milligram \[mg\] per day) versus placebo on glucose homeostasis. Based upon expected effect size and power calculations, and anticipating a 20% drop-out rate, the investigators will study 200 prediabetic subjects (100 per group) using a 1:1 randomization design. HbA1c, fasting plasma glucose, and other measures will be obtained at 0, 6, and 12 months and will be compared between zinc supplementation and placebo groups.

Eligibility

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.

Conditions3

Locations1 site

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