Table 1.
Characteristics of the included studies.
| Study | Region-State | Object | Case (N, age) | Control (N, age) | Inclusion criteria of DKD | Analysis methods | Gender (male/female) | Sample storage |
|---|---|---|---|---|---|---|---|---|
| Sibei Tao et al. 2019 (33) | Sichuan, China | DN vs. T2D vs. HC vs. HH | DN 14, 52.93 ± 9.98 T2D 14, 53.29 ± 9.00 |
HC 14, 52.86 ± 9.91 HH 14, 44.29 ± 17.31 |
eGFR≧60mL/min/1.73 m2 and UACR≧30mg/g |
16sRNA microbial profiling approach | DN, 9/5 T2D, 9/5 HC, 9/5 HH, 4/10 |
Stored at -80°C |
| Bao Xuguang et al. 2019 (26) | Guangzhou, China | DKD vs. T2D vs. HC | DKD 25, 63.7 ± 13.3 T2D 30, 63.7 ± 13.3 |
HC 30, 60.2 ± 9.7 | Massive proteinuria with diabetes or DR with any stage of CKD or microalbuminuria in T1D with a course of more than 10 years | High-throughput sequencing technology | DKD, 16/9 T2D, 14/16 HC, 14/16 |
Stored at -80°C |
| Feng Chunnian et al. 2020 (27) | Sichuan, China | DKD vs. T2D vs. HC | DKD 57, 55.23 ± 11.21 T2D 68, 54.36 ± 11.12 |
HC 36, 54.36 ± 11.12 | Not on dialysis | High-throughput sequencing technology | DKD, 34/23 T2D, 36/32 HC, 21/15 |
Stored at -80°C |
| Li Lei et al. 2021 (32) | Zhejiang, China | DKD vs. T2D vs. HC | DKD 20, 66.92 ± 9.27 T2D 20, 66.24 ± 10.24 |
HC 30, 67.41 ± 9.47 | UAER >20μg/min | Bacterial culture | DKD, 11/9 T2D, 10/10 HC, 15/15 |
Stored at 4°C |
| Li Lei et al. 2020 (37) | Zhejiang, China | DKD vs. T2D vs. HC | DKD 25, 60∼96 T2D 21, 60∼96 |
HC 25, 60∼96 | Massive proteinuria or DR with microalbuminuria | Bacterial culture | DKD, N/A T2D, N/A HC, N/A |
Stored at -80°C |
| Lin Hao et al. 2020 (39) | Fujian, China | DKD vs. T2D vs. HC | DKD 68, 56.30 ± 4.26 T2D 72, 56.25 ± 4.32 |
HC 70, 55.24 ± 5.38 | N/A | Bacterial culture | DKD, 40/28 T2D, 41/31 HC, 40/30 |
Stored at -80°C |
| Song Dandan et al. 2021 (40) | Inner Mongolia, China | DKD vs. T2D vs. HC | DKD 20, 58.2 ± 9.4 T2D 20, 54.1 ± 13.5 |
HC 20, 50.2 ± 12.6 | eGFR: 22.4 ± 14.4mL/min/1.73 m2; SCr: 512.9 ± 364.6μmol/L |
16S rRNA gene sequencing analysis | DKD, 12/8 T2D, 10/10 HC, 9/11 |
Stored at-80°C |
| Chun Huan et al. 2021 (41) | Zhejiang, China | DKD vs. T2D vs. HC | DKD 42, 69.06 ± 11.23 T2D 53, 68.47 ± 10.82 |
HC 42, 67.11 ± 9.26 | UAER: 20~200μg/min; 24h UAER: 30~300mg/24h |
16S rRNA gene sequencing analysis | DKD, 26/21 T2D, 31/22 HC, 24/18 |
Stored at-80°C |
| Sun Ya xian et al. 2016 (42) | Liaoning, China | DKD vs. T2D vs. HC | DKD 29, 59.17 ± 5.51 T2D 23, 55.87 ± 6.46 |
HC 20, 50.10 ± 5.19 | ACR: 30~299mg/g | PCR-DEEG | DKD, 19/10 T2D, 11/12 HC, 5/15 |
Stored at-80°C |
| Li Ya et al. 2019 (36) | Guizhou, China | DKD vs. T2D vs. HC | DKD 10, N/A T2D 5, N/A |
HC 5, N/A | ACR≧2.5 mg/mmol(male), ACR≧3.5 mg//mmol (famale), or 24h UALB ≧30 mg/24 h; and eGFR >15 mL/min/1.73 m2 |
16S rRNA gene amplicon sequencing | DKD N/A, T2D, N/A HC, N/A |
Stored at -80°C |
| Xin Xiaohong et al. 2021 (25) | Shanxi, China | DN vs HC | DN 20, 55.1 ± 13.83 | HC 20, 50.9 ± 9.49 | SCr: 103 ± 17.72μmol/L | Metagenomic sequencing | DN, 10/10 HC, 10/10 |
N/A |
| Xi Du et al. 2021 (28) | Tianjin, China | DKD vs. HC | DKD 43, 60.86 ± 5.69 | HC 37, 61.78 ± 6.40 | Stage 3 or 4 of DKD | 16S ribosomal DNA gene sequencing | DKD, 32/11 HC, 25/12 |
Stored at -80°C |
| Mohammed A. I. Al-Obaide et al. 2017 (34) | the United States of America | DKD vs. HC | DKD 20, 64.4 ± 2.3 | HC 20, 54.3 ± 3.2 | GFR < 30 mL/min/1.72 m2 and not on dialysis | 16S rRNA gene sequencing analysis | DKD, N/A HC, N/A |
DNA extraction within 24 h |
| Maria V. Salguero et al. 2019 (17) | the United States of America | DKD vs. HC | DKD 20, 62.8 ± 3.6 | HC 20, 58.5 ± 4.1 | Stages 4 and 5 of CKD, not on dialysis; GFR < 30 ml/min/1.72 m2 |
16S rRNA gene sequencing analysis | DKD, 9/11 HC, 11/9 |
DNA extraction within 24 h |
| Gratiela P. Gradisteanu et al. 2019 (38) | Romania | DKD vs. HC | DKD 9, N/A | HC 5, N/A | N/A | 16 rDNA qRT-PCR | DKD, N/A HC, N/A |
Freezing at -20°C |
| Signe A. Winther et al. 2020 (35) | Denmark | DKD (T1D: Nor, Mic, Mac) vs. HC | T1D 161, 60 ± 10 | HC 50, 59 ± 13 | UACR≧30mg/g | 16S rRNA gene amplicon sequencing | T1D, 94/67 HC, 28/22 |
Stored at -80°C |
DKD, diabetic kidney disease; HC, healthy controls; T2D, type 2 diabetes; HH, household contacts; DN, diabetic nephropathy confirmed by renal biopsy; T1D, type 1 diabetes; Nor, normoalbuminuria; Mic, microalbuminuria; Mac, macroalbuminuria; PCR, polymerase chain reaction; DEEG, denaturing gradient gel electrophoresis; DR, diabetic retinopathy; CKD, chronic kidney disease; eGFR, estimated glomerular filtration rate; UAER, urinary albumin excretion rates; UACR, urine albumin creatinine ratio; ACR, urine albumin-to-creatinine ratio; SCr, serum creatinine; GFR, the glomerular filtration rate; N/A, not available.