SAT-621 - Effect of Zinc Supplementation on Glycemic Control in Adult Patients with Type 2 Diabetes Mellitus: A Systematic Review and Meta-Analysis

Background:
Type 2 diabetes mellitus (T2DM) is a chronic metabolic disorder associated with persistent hyperglycemia and insulin resistance, leading to substantial morbidity and mortality worldwide. Zinc is an essential trace element involved in insulin synthesis, secretion, and signaling, and altered zinc homeostasis has been implicated in poor glycemic control among patients with diabetes. Although zinc supplementation has been explored as an adjunctive therapy, its overall impact on glycemic and insulin-related parameters remains incompletely defined. This systematic review and meta-analysis aimed to comprehensively evaluate the effect of zinc supplementation on glycemic control in adult patients with T2DM.

Methods:
A systematic search of major electronic databases was conducted to identify randomized and comparative clinical studies assessing zinc supplementation versus placebo or standard care in adults with diabetes. Seventeen studies comprising 1,116 patients were included, with 559 patients receiving zinc supplementation and 557 serving as controls. Outcomes assessed included fasting blood glucose (FBG), glycated hemoglobin (HbA1c), homeostatic model assessment of insulin resistance (HOMA-IR), and serum insulin levels. Subgroup analyses were performed for patients with explicitly diagnosed T2DM and those with diabetes not otherwise specified. Pooled mean differences (MDs) with 95% confidence intervals (CIs) were calculated using meta-analytic models.

Results:
Zinc supplementation significantly reduced FBG in patients with T2DM (MD −23.23 mg/dL; 95% CI −29.58 to −16.89), in non-specified diabetes populations (MD −28.20 mg/dL; 95% CI −43.98 to −12.42), and overall (MD −24.72 mg/dL; 95% CI −31.56 to −17.87). HbA1c levels were also significantly reduced in the T2DM subgroup (MD −0.38%; 95% CI −0.68 to −0.07), non-specified diabetes subgroup (MD −0.57%; 95% CI −0.96 to −0.17), and overall (MD −0.41%; 95% CI −0.64 to −0.17). Zinc supplementation significantly improved insulin resistance overall (HOMA-IR MD −1.65; 95% CI −2.62 to −0.68), with a pronounced effect in non-specified diabetes populations. Changes in serum insulin levels were inconsistent and not significant overall.

Conclusion:
Zinc supplementation significantly improves glycemic control by lowering fasting blood glucose, HbA1c, and insulin resistance in adult patients with type 2 diabetes mellitus. These findings support zinc as a safe, low-cost, and effective adjunct to conventional antidiabetic therapy. Future large-scale, well-designed randomized trials are needed to establish optimal dosing strategies and long-term metabolic benefits.

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