Serum zinc, copper, and the Zn/Cu ratio across the glycemic spectrum: evidence from an automated clinical chemistry platform.

OBJECTIVES

The zinc-to-copper ratio (Zn/Cu) integrates the opposing redox and metabolic roles of zinc and copper and may offer additional value for stratifying glycemic risk in clinical practice. This study evaluated serum zinc, copper, and the Zn/Cu ratio across the glycemic spectrum using a routine automated chemistry analyzer.

DESIGN AND

METHODS

In this cross-sectional study, 217 adults were categorized into control (n = 78), impaired fasting glucose (n = 60), insulin resistance (n = 48), and type 2 diabetes mellitus (T2DM; n = 31) groups based on fasting plasma glucose, hemoglobin A1c (HbA1c), and homeostatic model assessment of insulin resistance (HOMA-IR), using American Diabetes Association thresholds. Serum zinc and copper were measured on an ARCHITECT c16000 analyzer with validated colorimetric assays, and the Zn/Cu ratio was calculated. Group comparisons used ANOVA; correlations with glycemic indices were assessed using Pearson's r and multivariable linear regression adjusted for age and sex. Discrimination of T2DM was evaluated via receiver operator characteristic analysis.

RESULTS

Serum copper increased and the Zn/Cu ratio decreased progressively from control to T2DM (p = 0.0148 and p = 0.0135, respectively), while zinc levels did not differ significantly between groups. Zn/Cu showed negative correlations with fasting glucose, insulin, HbA1c, and HOMA-IR, and was independently associated with lower HOMA-IR in regression models (β =  - 6.81; 95% CI: -11.16 to - 2.46). Zn/Cu discriminated T2DM with an area under the curve of 0.675.

CONCLUSIONS

The Zn/Cu ratio, derived from routine clinical chemistry assays, reflects glycemic dysregulation and insulin resistance. It may serve as a low-cost, pragmatic adjunct to standard markers such as fasting glucose and HbA1c in clinical laboratories.