Table 1.
Cross-sectional studies analyzing zinc serum levels and renal impairment progression in DKD. Abbreviations: CKD, Chronic kidney disease; Cu, Copper; DKD, Diabetic Kidney Disease; T1D, Type 1 diabetes mellitus; T2D, Type 2 diabetes mellitus; DKD, Diabetic Kidney Disease; DPN, Diabetic peripheral neuropathy; DR, Diabetic retinopathy; eGFR, estimated glomerular filtration rate; IFG, Impaired fasting glucose; IGT, Impaired glucose tolerance; PPM, part per million; Zn, Zinc.
| Study, year | Patients (n.) | Controls (n.) | Results |
|---|---|---|---|
| Jiancheng Xu et al. [64] 2013 |
189 patients with DM or prediabetes Age 20–65, mean age 55 IFG: (n = 12) IGT: (n = 15) T1D: (n = 25) T2D: (n = 137) DKD: (n = 24) DR: (n = 34) DPN: (n = 50) |
50 healthy patients | Plasma Zn (mg/L): Control group 0.81 (0.67–0.93) vs. IFG group 0.75 (0.70–0.84) (NS) vs. IGT 0.77 (0.67–0.87) (NS) vs. T1D 0.59 (0.53–0.75) (p = 0.056) vs. T2D 0.61 (0.51–0.75) (p < 0.001) Urinary Zn (mg/L): Control 0.20 (0.14–0.32) vs. IFG 0.32 (0.26–0.37) (NS) vs. IGT 0.27 (0.19–0.41) (NS) vs. T1D 0.86 (0.67–0.91) p < 0.001 vs. T2D 0.48 (0.38–0.57) p < 0.001 Plasma Zn (mg/L): T2D 0.73 (0.55–0.79) vs. DKD 0.59 (0.48–0.76) (NS) vs. DR 0.58 (0.46–0.63) p = 0.002 vs. DPN 0.63 (0.59–0.75) p = 0.08 Urinary Zn (mg/L): T2D 0.47 (0.28–0.53) vs. DKD 0.44 (0.30–0. 52) (NS) vs. DR 0.45 (0.25–0.52) (NS) vs. DPN 0.52 (0.44–0.63) (p < 0.001) |
| Al Timini et al. [65] 2014 |
300 T2D patients Age 43.5–71.6 Group II: Diabetic, normotensive (n = 145) Group III: Diabetic, hypertensive (n = 41) Group IV: Diabetic, normotensive with microalbuminuria (n = 62) Group V: Diabetic, hypertensive with microalbuminuria (n = 52) |
100 apparently healthy subjects Age 45.7–69.2 Group I: Nondiabetic, normotensive (n = 100) |
Urinary zinc/creatine (ug/g): 2.33 + 1.18 in patient groups vs. 1.01 + 0.57 in control (p value < 0.001) Serum zinc (ug/dL): 70.0 + 19.2 in patient groups vs. 86.2 + 15.2 in control (p value < 0.001) Group I: 86.2 + 15.2 Group II: 79.2 + 15.0 Group III: 77.9 + 17.2 Group IV: 56.8 + 13.8 Group V: 55.0 + 14.2 eGFR > 90 mL/min/1.73 m2: 107 (45.7%) had serum zinc levels < 70 ug/dL and 127 (54.3%) > 70 ug/dL (total 234) eGFR 60–89 mL/min/1.73 m2: 38 (76.0%) had serum zinc levels < 70 ug/dL and 12 (24.0%) > 70 ug/dL (total 50) eGFR 30–59 mL/min/1.73 m2: 14 (93.3%) had serum zinc levels < 70 ug/dL and 1 (6.7%) > 70 ug/dL (total 15) eGFR 15–29 mL/min/1.73 m2: 1 (100%) had serum zinc levels < 70 μg/dL and none > 70 μg/dL (total 1) |
| Lin et al. [66] 2018 |
148 T2D patients with CKD Age 62.4 ± 9.8 CKD Stage 1 eGFR > 90 mL/min/1.73 m2 (n = 25) CKD Stage 2 eGFR 60–89 mL/min/1.73 m2 (n = 49) CKD Stage 3a eGFR 45–69 mL/min/1.73 m2 (n = 40) CKD Stage 3b eGFR 30–44 mL/min/1.73 m2 (n = 34 |
No control group | Zinc (ppm) Stage 1: 1.0 ± 0.2 Stage 2: 0.9 ± 0.2 Stage 3a: 0.9 ± 0.2 Stage 3b: 0.8 ± 0.2 p = <0.001 |
| Takao et al. [67] 2021 |
651 patients with T2D Age 65 ± 9.7 DKD group (n = 220) No DKD group (n = 431) |
No control group | Cu (microg/dL): 97.0 ± 15.6 in no DKD group vs. 100.5 ± 15.5 in DKD group (p = 0.007) Zn (microg/dL): 85.4 ± 11.3 in no DKD group vs. 82.1 ± 11.6 in DKD group (p = 0.0005) Cu/Zn ratio: 1.155 ± 0.242 in no DKD group vs. 1.247 ± 0.265 in DKD group (p < 0.0001) The optimal Cu\Zn cut-off value for detecting DKD was 1.1648 |