Table 2.
Characteristics of the included study.
| Study | Location | Comparisons | Eligible criteria of DKD/DN | Case [n (female%, age)] | Control [n(female%, age)] | Matched factors | Sequencing platform (Region) | Database | Outcomes | Modified NOS score |
|---|---|---|---|---|---|---|---|---|---|---|
| Tao 2019 (20) | Guangdong, China | DN vs. T2DM vs. HC | Biopsy-proven DN, eGFR ≥ 60 mL/min/1.73 m2 and UACR ≥ 30 mg/g | 14 (36%), 52.93 ± 9.98 | T2DM: 14 (36%), 53.29 ± 9.00; HC: 14 (36%), 52.86 ± 9.91 |
Age, sex, BMI | Illumina MiSeq (V3-V4) | RDP, Silva | α-diversity; β-diversity; microbial composition; clinical correlation | 7 |
| Bao 2019 (21) | Sichuan, China | DKD vs. T2DM vs. HC | DM complicated with massive proteinuria; or with DR and CKD; microalbuminuria in T1DM of more than 10 years | 25 (36%), 63.7 ± 13.3 | T2DM: 30 (54%), 62 ± 13.3; HC: 30 (47%), 60.2 ± 9.7 |
Age, sex | Illumina TruSeqTM (V4) | Greengenes | α-diversity; β-diversity; microbial composition | 7 |
| Winther 2020 (22) | Copenhagen, Denmark | T1DKD vs. HC | T1DM with eGFR ≥ 15 mL/min/1.73 m2 and excluded non-diabetic kidney disease | 161 (42%), 60 ± 10 | 50 (44%), 59 ± 13 | Age, sex, BMI | Illumina HiSeq2500 (V4) | Dada2 R package | α-diversity; β-diversity; microbial composition; clinical correlation | 7 |
| Yu 2020 (23) | Henan, China | DKD vs. MN | Diabetes more than 5 years with UACR ≥ 30 mg/g and presence of DR | 129 (36%), 56 (49, 65) | 142 (36%), 49 (43, 56) | Sex | Illumina MiSeq (V3-V4) | RDP, Silva | α-diversity; β-diversity; microbial composition | 6 |
| Feng 2020 (24) | Sichuan, China | DKD vs. T2DM vs. HC | Clinically diagnosed DKD and not on dialysis | 57 (41%), 55.23 ± 11.21 | T2DM: 68 (47%), 54.36 ± 11.12; HC: 36 (42%), 54.84 ± 11.17 |
Age, sex | Illumina HiSeq 2500 (V3) | NR | β-diversity; microbial composition | 6 |
| Chen 2021 (25) | Beijing, China | DKD vs. DM vs. HC | DKD with UAER ≥ 30 mg/24h or UACR ≥ 30 mg/g | 60 (32%), 60.53 ± 9.62 | DM: 20 (40%), 55.2 ± 14.77; HC: 20 (60%), 55.15 ± 13.77 |
Age, BMI, diet | Illumina MiSeq (V3-V4) | RDP, Silva | α-diversity; microbial composition; clinical correlation | 6 |
| Du 2021 (26) | Tianjin, China | DKD vs. HC | DN stage 3 or 4, without detailed criteria, not uremia | 43 (26%), 60.86 ± 5.69 | 37 (33%), 61.78 ± 6.40 | Age, sex, BMI | Illumina MiSeq (V3-V4) | RDP, Silva | α-diversity; β-diversity; microbial composition | 6 |
| Sun 2021 (27) | Shandong, China | DKD vs. NDKD vs. HC | Clinically diagnosed DKD | 25 (36%), 62.52 ± 13.61 | NDKD: 40 (23%), 53.98 ± 13.81; HC:24 (34%), 56 ± 9 |
Age, sex | Illumina MiSeq (V3-V4) | RDP, Silva | α-diversity; β-diversity; microbial composition | 6 |
| Song 2021 (28) | Inner Mongolia, China | DKD vs. T2DM vs. HC | Diagnosed DKD | 20 (40%), 58.2 ± 9.4 | T2DM: 20 (50%), 54.1 ± 13.5 HC: 20 (55%), 50.2 ± 12.6 |
Age, sex | Ilumina, NovaSeq PE250 (V4) | Dada2 R package | α-diversity; β-diversity; microbial composition; clinical correlation | 6 |
| Zhang 2021 (29) | Henan, China | DKD/DN vs. HC | Proteinuria or renal impairment caused by diabetes, and other kidney diseases were excluded, meeting one of the following conditions: UACR ≥ 30mg/g or UAER ≥ 30mg/24h or eGFR ≤ 60mL/min/1.73 m2 or biopsy-proven DN | 180 (38%), 55.27 (26-87) | 179 (42%), 52.05 (39-69) | SCr | Illumina MiSeq (V3-V4) | RDP | α-diversity; β-diversity; microbial composition; clinical correlation | 6 |
| Chu 2021 (30) | Zhejiang, China | T2DKD vs. T2DM vs. HC | DKD with UACR ≥ 30 - 300mg/g or UAER 20-200 ug/min | 47 (45%), 69.06 ± 11.23 | T2DM: 53 (42%), 68.47 ± 10.82 HC: 42 (43%), 67.11 ± 9.26 |
Age, sex | Ilumina HiSeq (V4) | NCBI-BLAST | α-diversity; microbial composition | 6 |
| Xin 2021 (31) | Shanxi, China | DN vs. HC | Biopsy-proven DN | 20 (50%), 55.1 ± 13.83 | 20 (50%), 50.9 ± 9.49 | Age, sex | Ilumina Novaseq6000 (NR) | HUMAnN3 | α-diversity; β-diversity; microbial composition; clinical correlation | 7 |
| Cai 2022 (32) | Zhejiang, China | DKD vs. T2DM vs. HC | DKD diagnosed clinically: UAER >300 mg/24h and presence of DR, and excluded other kidney diseases | 31 (26%), 61.35 ± 10.04 | T2DM: 32 (32%), 56.34 ± 10.79; HC: 34 (65%), 56.12 ± 8.11 |
Age | Ion S5TM (V3-V4) | Ion 530TM Chip | α-diversity; β-diversity; microbial composition | 6 |
| He 2022 (33) | Shanxi, China | DKD vs. T2DM | Diagnosed DKD stage 3 or4, presenting normal renal function and UACR > 30 mg/g, renal impairment due to other causes was excluded. | 10 (10%), 56.00 ± 14.97 | 10 (20%), 64.90 ± 7.37 | Age, sex, BMI | Illumina HiSeq4000 (NR) | Non-Redundant | β-diversity; microbial composition; clinical correlation | 7 |
| Yang 2022 (34) | Guizhou, China | DKD vs. T2DM vs. HC | T2DM with ACR > 265 mg/g or UAER > 300 mg/24h; and/or DR with ACR 22 (male, 31 female) - 265 mg/g; or UAER 30 - 300 mg/24h and/or eGFR < 60 min/mL. | 8 (50%), 58.75 ± 7.40 | T2DM: 9 (56%), 57.67 ± 4.61; HC: 8 (50%), 57.13 ± 2.8 |
Age, sex, BMI | Illumina MiSeq (V3-V4) | Greengenes | α-diversity; β-diversity; microbial composition | 7 |
DKD, diabetic kidney disease; DN, diabetic nephropathy; T2DM, type 2 diabetes mellitus; HC, healthy controls; eGFR, estimated glomerular filtration rate; UACR, urinary albumin-creatinine ratio; UAER, urinary albumin excretion rate; NOS, Newcastle-Ottawa Scale; DR, diabetes retinopathy; CKD, chronic kidney disease; BMI, body mass index; SCr, serum creatinine; NR, not reported; RDP, ribosomal database project.