Effects of Zinc Supplementation on Patients With Elevated Glycemic Status

The goal of this randomized, double-blind, placebo-controlled study included patients with elevated glycemic status is to investigate whether zinc supplementation (4mg per day) has beneficial effects on controlling blood glucose.

About 124 patients aged 18 years or older, had resided locally for at least one year, with elevated glycemic status will be enrolled in the study. Patients with elevated glycemic status are defined as meeting any of the following criteria:

1. Fasting blood glucose ≥ 6.1 mmol/L; 2. Glycated hemoglobin (HbA1c) ≥ 5.7%; 3. Oral glucose tolerance test (OGTT) 2-hour or postprandial blood glucose ≥ 7.8 mmol/L; 4. Patients with previously diagnosed type 2 diabetes with stable drug hypoglycemic treatment and blood glucose controlled well.

Eligible participants will be assigned by chance to one of two groups: (1) daily zinc supplementation: zinc-enriched yeast capsules (4 mg); (2) daily edible yeast placebo capsules (not zinc-enriched) (4mg). Randomization will be conducted.

At enrollment, baseline questionnaires are designed to collect data on sociodemographic factors, lifestyle habits, health status, and medical conditions. Participants in both groups will take one capsule that contained either Zinc-enriched yeast or edible yeast placebo each day until the end of the intervention period.

Participants will be followed up two times (3 months and 6 months post-intervention), and receive a single stage-specific dosage at any given follow-up time. During each follow-up visit, participants will complete a questionnaire survey, a 3-day 24-hour dietary recall, and undergo physical measurements. Blood, urine, and stool samples will also be obtained in the study center, fasting blood glucose, HbA1c and other biochemical indicators will also be detected at the same time.

The primary outcomes, including fasting blood glucose and HbA1c will be measured using blood samples. Secondary outcomes in this study include changes in blood lipids (such as total cholesterol, triglycerides, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol), trends in plasma zinc levels, inflammatory factors, oxidative stress indexes, other blood indicators and liver and kidney function indicators. Data will be collected and analyzed.

• Concentration of fasting plasma insulin (FPI) [Time frame: 0 week, 12th week, and 24th week in the intervention period]
• Concentration of plasma c-peptide [Time frame: 0 week, 12th week, and 24th week in the intervention period]
• Homeostatic model assessment of insulin resistance (HOMA-IR) [Time frame: 0 week, 12th week, and 24th week in the intervention period]
• Homeostatic model assessment of β-cell function (HOMA-β) [Time frame: 0 week, 12th week, and 24th week in the intervention period]
• Homeostatic model assessment of insulin sensitivity (HOMA-S) [Time frame: 0 week, 12th week, and 24th week in the intervention period]
• Concentration of blood lipids [Time frame: 0 week, 12th week, and 24th week in the intervention period]
• Concentration of C-reactive protein (CRP) [Time frame: 0 week, 12th week, and 24th week in the intervention period]
• Concentration of interleukin-6 (IL-6) [Time frame: 0 week, 12th week, and 24th week in the intervention period]
• Concentration of malondialdehyde (MDA) [Time frame: 0 week, 12th week, and 24th week in the intervention period]
• Activity of Cu-Zn superoxide dismutase (SOD) [Time frame: 0 week, 12th week, and 24th week in the intervention period]
• Concentration of homocysteine (HCY) [Time frame: 0 week, 12th week, and 24th week in the intervention period]
• Concentration of plasma albumin (ALB) [Time frame: 0 week, 12th week, and 24th week in the intervention period]