NCT05835037 · University of Maryland, Baltimore
Effect of Zinc on Glucose Homeostasis
What this study is about
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.
View original scientific description
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.
Who can participate
This study lists these criteria on ClinicalTrials.gov. A study coordinator reviews eligibility during screening — this page does not determine whether you qualify.
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
- 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.
Where
- Lancaster, Pennsylvania
Frequently asked questions
What is a clinical trial?
A clinical trial is a research study that tests new medical treatments, drugs, devices, or procedures to determine their safety and effectiveness. Trials are carefully designed and monitored to protect participants while advancing medical knowledge.
Is it safe to participate?
Clinical trials follow strict safety guidelines and ethical standards. Trials must be reviewed and approved, and participants are closely monitored by medical professionals throughout the study. You can withdraw at any time if you choose.
Will I be compensated?
Many clinical trials offer compensation for your time, travel expenses, and inconvenience. The specific compensation varies by study and will be discussed during the screening process. All study-related medical care is typically provided at no cost to participants.
Will I receive a placebo instead of treatment?
When effective treatment exists, participants typically receive either the standard treatment plus the study intervention, or the standard treatment plus placebo. You would not be denied effective care. Placebos are primarily used when no proven treatment is available, or in addition to standard care. Your trial consent form will clearly explain what treatments you may receive.
Can I leave a trial if I change my mind?
Absolutely. Participation in clinical trials is completely voluntary. You have the right to withdraw from the study at any time, for any reason, without penalty or loss of benefits to which you are otherwise entitled.
How long does a clinical trial last?
Trial duration varies widely depending on the study design and purpose. Some trials last just a few weeks, while others may continue for months or years. The study coordinator will provide specific timeline information during your screening call.
Data: ClinicalTrials.gov · synced Jul 10, 2026 · Source of record for eligibility and locations