Gut dysbiosis, low-grade inflammation, and renal impairment severity in elderly diabetic nephropathy

Table 1 Comparison of baseline data between diabetic nephropathy group and control group, n (%)

Variables	DN group (n = 167)	Control group (n = 85)	t/χ2	P value
Age (year), mean ± SD	73.34 ± 6.10	69.81 ± 5.92	2.901	0.008
Gender			0.757	0.354
Male (example)	98 (58.68)	45 (52.94)
Female (example)	69 (41.32)	40 (47.06)
BMI (kg/m2), mean ± SD	24.20 ± 1.96	23.81 ± 2.10	1.458	0.146
Course of diabetes (years), mean ± SD	10.72 ± 3.18	8.95 ± 2.64	2.741	0.015
Smoking (example)	59 (35.33)	38 (44.71)	2.092	0.148
Drinking alcohol (example)	55 (32.93)	36 (42.35)	2.166	0.141
Systolic pressure (mmHg), mean ± SD	128.34 ± 7.31	126.51 ± 7.44	1.868	0.063
Diastolic pressure (mmHg), mean ± SD	78.54 ± 6.60	76.80 ± 6.92	1.946	0.053

BMI: Body mass index; DN: Diabetic nephropathy.

Table 2 Comparison of alpha diversity index of intestinal microbiota between diabetic nephropathy group and control group

Variables	DN group (n = 167)	Control group (n = 85)	t	P value
Chao	55.10 ± 8.56	68.85 ± 11.31	-10.789	0.000
Ace	57.26 ± 12.61	72.97 ± 16.26	-8.457	0.000
Simpson	0.34 ± 0.09	0.29 ± 0.07	4.402	0.000
Shannon	1.38 ± 0.18	1.48 ± 0.23	-3.745	0.000

DN: Diabetic nephropathy.

Table 3 Comparison of relative abundance of gut microbiota between diabetic nephropathy group and control group

Variables	DN group (n = 167)	Control group (n = 85)	t	P value
Bacteroides (%)	18.44 ± 3.64	21.76 ± 3.69	-6.811	0.000
Fusobacterium (%)	7.88 ± 2.13	4.00 ± 1.58	14.883	0.000
Blautia (%)	8.37 ± 1.12	8.59 ± 1.10	-1.487	0.138
Bifidobacterium (%)	2.09 ± 0.55	4.30 ± 0.88	-24.326	0.000
Prevotella (%)	3.42 ± 0.39	3.46 ± 0.46	-0.725	0.469
‌Alloprevotella (%)	2.59 ± 0.39	2.60 ± 0.42	-0.124	0.901
Lachnospira (%)‌	2.35 ± 0.49	2.52 ± 0.48	-2.697	0.007
Roseburia (%)	2.37 ± 0.44	2.29 ± 0.35	1.378	0.170
Butyricimonas (%)	5.46 ± 0.84	5.87 ± 0.39	-1.500	0.135
Escherichia-Shigella (%)	1.40 ± 0.30	1.44 ± 0.29	-1.085	0.279
Klebsiella (%)	4.22 ± 0.30	2.51 ± 0.33	42.544	0.000
Enterococcus (%)	3.91 ± 0.42	2.39 ± 0.19	31.516	0.000
Veillonella (%)	2.87 ± 0.57	2.23 ± 0.39	9.321	0.000
Megamonas (%)	2.33 ± 0.51	1.68 ± 0.29	10.766	0.000

DN: Diabetic nephropathy.

Table 4 Comparison of relative abundance of gut microbiota between diabetic nephropathy group and control group, and comparison of glucose and lipid metabolism indicators

Variables	DN group (n = 167)	Control group (n = 85)	t	P value
FBG (mmol/L)	8.14 ± 0.60	7.38 ± 0.61	9.290	0.000
PBG (mmol/L)	11.58 ± 1.39	10.39 ± 0.96	7.067	0.000
HbA1c (%)	10.68 ± 1.47	8.53 ± 0.86	12.435	0.000
FINS (pmol/mL)	36.96 ± 8.84	27.52 ± 4.99	9.136	0.000
HOMA-IR	13.39 ± 3.41	9.03 ± 1.79	11.019	0.000
TC (mmol/L)	6.58 ± 2.19	6.08 ± 1.33	1.889	0.060
TG (mmol/L)	2.47 ± 0.68	1.90 ± 0.41	7.182	0.000
LDL-C (mmol/L)	3.66 ± 0.75	3.11 ± 0.52	6.112	0.000
HDL-C (mmol/L)	0.61 ± 0.12	0.80 ± 0.14	-11.578	0.000
FFA (mmol/L)	0.85 ± 0.39	0.68 ± 0.31	3.620	0.000

DN: Diabetic nephropathy; FBG: Fasting blood glucose; PBG: Postprandial blood glucose; HbA1c: Glycated hemoglobin; FINS: Fasting insulin; HOMA-IR: Homeostasis model assessment of insulin resistance; TC: Total cholesterol; TG: Triglycerides; LDL-C: Low-density lipoprotein cholesterol; HDL-C: High-density lipoprotein cholesterol; FFA: Free fatty acids.

Table 5 Comparison of inflammatory indicators between diabetic nephropathy group and control group

Variables	DN group (n = 167)	Control group (n = 85)	t	P value
CRP (mg/L)	7.83 ± 2.39	3.75 ± 1.28	14.662	0.000
TNF-α (μg/L)	44.64 ± 8.96	27.52 ± 5.37	16.186	0.000
IL-6 (μg/L)	154.42 ± 31.61	83.29 ± 16.14	19.480	0.000
IL-1β (μg/L)	69.67 ± 19.14	27.06 ± 8.18	19.617	0.000

DN: Diabetic nephropathy; CRP: C-reactive protein; TNF-α: Tumor necrosis factor α; IL: Interleukin.

Table 6 Comparison of renal function indexes between diabetic nephropathy group and control group

Variables	DN group (n = 167)	Control group (n = 85)	t	P value
eGFR (mL/minute)	79.67 ± 8.77	115.22 ± 10.17	-27.163	0.000
Cys-C (mg/L)	5.98 ± 2.57	3.80 ± 0.98	7.554	0.000
Scr (μmol/L)	95.48 ± 16.27	66.81 ± 11.51	14.494	0.000
BUN (mmol/L)	8.60 ± 2.36	6.56 ± 1.71	7.108	0.000
ACR (mg/g)	289.93 ± 105.69	160.73 ± 33.62	10.982	0.000

DN: Diabetic nephropathy; eGFR: Estimated glomerular filtration rate; Cys-C: Cystatin C; Scr: Serum creatinine; BUN: Blood urea nitrogen; ACR: Albumin-to-creatinine ratio.

Table 7 The impact of gut microbiota structure on diabetic nephropathy occurrence

Variables	β	SE	Z	P	OR (95%CI)
Chao	-0.143	0.019	-7.440	0.000	0.866 (0.834-0.900)
Ace	-0.079	0.012	-6.668	0.000	0.927 (0.903-0.946)
Simpson	7.090	1.728	4.103	0.000	9.623 (4.570-17.138)
Shannon	-2.516	0.714	-3.522	0.000	0.081 (0.020-0.328)
Bacteroides	-0.295	0.049	-6.034	0.000	0.745 (0.677-0.819)
Fusobacterium	1.086	0.140	7.765	0.000	2.964 (2.253-3.899)
Bifidobacterium	-4.255	0.662	-6.427	0.000	0.014 (0.004-0.052)
Lachnospira	-3.789	0.508	-7.457	0.000	0.234 (0.038-0.763)
Klebsiella	9.569	3.291	3.211	0.000	14.404 (3.428-28.438)
Enterococcus	5.807	5.611	2.016	0.000	9.622 (2.273-16.725)
Veillonella	2.403	0.353	7.014	0.000	5.859 (2.942-9.669)
Megamonas	3.663	0.496	7.383	0.000	7.975 (4.739-13.062)

OR: Odds ratio; CI: Confidence interval.

Table 8 Comparison of changes in gut microbiota an index between the progressive group and the stable group

Variables	Progress group (n = 118)	Stable group (n = 134)	t	P value
Chao	4.21 ± 2.12	1.44 ± 1.89	11.006	0.000
Ace	4.51 ± 2.60	1.46 ± 2.16	10.146	0.000
Simpson	-0.21 ± 0.01	-0.01 ± 0.01	-9.722	0.000
Shannon	0.10 ± 0.04	0.03 ± 0.05	12.177	0.000

Table 9 Comparison of the relative abundance changes of gut microbiota between the progressive group and the stable group

Variables	Progress group (n = 118)	Stable group (n = 134)	t	P value
Bacteroides (%)	1.42 ± 0.67	0.39 ± 0.63	12.375	0.000
Fusobacterium (%)	0.45 ± 0.31	0.15 ± 0.24	8.417	0.000
Bifidobacterium (%)	0.19 ± 0.12	0.05 ± 0.11	9.923	0.000
Butyricimonas (%)	0.32 ± 0.16	0.11 ± 0.17	10.183	0.000
Klebsiella (%)	-0.23 ± 0.12	-0.06 ± 0.07	-9.859	0.000
Enterococcus (%)	-0.21 ± 0.12	-0.08 ± 0.11	-8.403	0.000
Veillonella (%)	-0.16 ± 0.09	-0.06 ± 0.07	-9.503	0.000
Megamonas (%)	-0.13 ± 0.08	-0.05 ± 0.07	-7.965	0.000

Table 10 Comparison of changes in glucose and lipid metabolism indicators between the progressive group and the stable group

Variables	Progress group (n = 118)	Stable group (n = 134)	t	P value
FBG (mmol/L)	-0.51 ± 0.22	-0.16 ± 0.24	-11.635	0.000
PBG (mmol/L)	-0.72 ± 0.35	-0.21 ± 0.38	-11.253	0.000
HbA1c (%)	-0.64 ± 0.30	-0.19 ± 0.35	-10.798	0.000
FINS (pmol/mL)	-4.62 ± 3.98	1.55 ± 3.87	-12.523	0.000
HOMA-IR	-2.44 ± 1.61	0.29 ± 1.51	-13.897	0.000
TC (mmol/L)	-0.73 ± 0.60	0.34 ± 0.71	-12.609	0.000
TG (mmol/L)	-0.34 ± 0.27	0.14 ± 0.24	-13.969	0.000
LDL-C (mmol/L)	-0.43 ± 0.32	0.07 ± 0.37	-11.596	0.000
HDL-C (mmol/L)	0.01 ± 0.07	0.06 ± 0.08	-6.113	0.000
FFA (mmol/L)	-0.12 ± 0.12	0.03 ± 0.11	-10.743	0.000

FBG: Fasting blood glucose; PBG: Postprandial blood glucose; HbA1c: Glycated hemoglobin; FINS: Fasting insulin; HOMA-IR: Homeostasis model assessment of insulin resistance; TC: Total cholesterol; TG: Triglycerides; LDL-C: Low-density lipoprotein cholesterol; HDL-C: High-density lipoprotein cholesterol; FFA: Free fatty acids.

Table 11 Comparison of inflammatory index changes between the progressive group and the stable group

Variables	Progress group (n = 118)	Stable group (n = 134)	t	P value
CRP (mg/L)	-1.15 ± 1.07	0.39 ± 1.02	-11.420	0.000
TNF-α (μg/L)	-6.30 ± 4.08	6.45 ± 6.44	-16.091	0.000
IL-6 (μg/L)	-28.69 ± 23.63	17.64 ± 25.37	-14.936	0.000
IL-1β (μg/L)	-7.74 ± 9.80	6.39 ± 5.84	-11.399	0.000

CRP: C-reactive protein; TNF-α: Tumor necrosis factor α; IL: Interleukin.

Table 12 Comparison of changes in renal function indicators between the progressive group and the stable group

Variables	Progress group (n = 118)	Stable group (n = 134)	t	P value
eGFR (mL/minute)	7.02 ± 1.10	2.65 ± 1.43	-13.235	0.000
Cys-C (mg/L)	-0.98 ± 0.86	0.44 ± 0.81	-14.554	0.000
Scr (μmol/L)	-13.13 ± 10.27	5.17 ± 9.65	-16.448	0.000
BUN (mmol/L)	-1.62 ± 1.19	0.83 ± 1.16	-13.621	0.000
ACR (mg/g)	-61.04 ± 53.67	24.66 ± 46.82	27.248	0.000

eGFR: Estimated glomerular filtration rate; Cys-C: Cystatin C; Scr: Serum creatinine; BUN: Blood urea nitrogen; ACR: Albumin-to-creatinine ratio.

Table 13 Results of logistic regression analysis on factors related to patient disease progression

Variables	β	SE	Z	P value	OR (95%CI)
Chao	0.308	0.147	4.393	0.036	1.361 (1.020-1.815)
Ace	0.285	0.133	4.622	0.032	1.330 (1.026-1.725)
Simpson	-0.768	2.231	5.145	0.023	1.495 (1.042-1.898)
Shannon	0.553	7.167	1.111	0.292	1.201 (0.872-1.405)
Bacteroides	1.831	0.503	13.245	0.000	6.240 (2.328-16.729)
Fusobacterium	1.098	1.222	0.807	0.369	2.998 (0.273-32.898)
Bifidobacterium	2.095	2.505	0.699	0.403	8.122 (0.006-11.422)
Lachnospira	3.383	1.969	2.952	0.086	29.449 (0.621-95.825)
Klebsiella	-4.635	2.492	3.458	0.063	0.001 (0.000-1.284)
Enterococcus	-7.111	2.794	6.478	0.011	0.001 (0.000-0.195)
Veillonella	-6.936	3.562	3.792	0.051	0.001 (0.000-1.046)
Megamonas	-4.320	3.937	1.204	0.273	0.013 (0.000-9.843)

OR: Odds ratio; CI: Confidence interval.