Increased blood urea nitrogen levels and compromised peripheral nerve function in patients with type 2 diabetes

Table 1 Clinical features of the recruited patients with type 2 diabetes, n (%)

Variables	Total	Quartiles of BUN levels				Test statistic	P for trend
		Q1	Q2	Q3	Q4
BUN (mmol/L) (range)	5.79 ± 1.64 (2.03-16.28)	3.94 ± 0.49 (2.03-4.56)	5.08 ± 0.31 (4.57-5.65)	6.16 ± 0.36 (5.66-6.86)	8.00 ± 1.17 (6.87-16.28)	-	-
n	585	147	147	146	145	-	-
Age (year)	54.7 ± 12.9	51.5 ± 13.6	51.6 ± 13.6	56.5 ± 11.3	59.0 ± 11.6	34.7791	< 0.001
Female	210 (35.9)	69 (46.9)	56 (38.1)	47 (32.2)	38 (26.2)	14.7012	< 0.001
BMI (kg/m2)	25.3 ± 3.9	25.8 ± 4.1	25.3 ± 3.8	25.1 ± 3.7	24.8 ± 3.8	5.2321	0.023
SBP (mmHg)	135 ± 19	137 ± 19	135 ± 20	135 ± 19	133 ± 17	4.0811	0.044
DBP (mmHg)	83 ± 12	85 ± 10	84 ± 14	83 ± 13	81 ± 10	10.3241	0.001
Diabetes duration (year)	5.0 (1.0-10.0)	3.0 (0.2-10.0)	4.0 (0.9-10.0)	6.0 (2.0-10.0)	8.0 (3.0-15.0)	5.6383	< 0.001
Hypoglycemic drugs
Insulin	265 (45.3)	55 (37.4)	64 (43.5)	58 (39.7)	88 (60.7)	12.7572	< 0.001
Secretagogues	55 (9.4)	13 (8.8)	17 (11.6)	9 (6.2)	16 (11.0)	0.0112	0.916
Metformin	302 (51.6)	88 (59.9)	77 (52.4)	80 (54.8)	57 (39.3)	10.2132	0.001
TZDs	94 (16.1)	22 (15.0)	21 (14.3)	24 (16.4)	27 (18.6)	0.9272	0.336
AGIs	21 (3.6)	5 (3.4)	6 (4.1)	4 (2.7)	6 (4.1)	0.0152	0.901
DPP-4Is	82 (14.0)	19 (12.9)	21 (14.3)	23 (15.8)	19 (13.1)	0.0252	0.874
SGLT-2Is	265 (45.3)	63 (42.9)	61 (41.5)	81 (55.5)	60 (41.4)	0.2772	0.599
GLP-1RAs	156 (26.7)	41 (27.9)	41 (27.9)	44 (30.1)	30 (20.7)	1.3832	0.240
Hypertension	235 (40.2)	54 (36.7)	63 (42.9)	62 (42.5)	56 (38.6)	0.0872	0.768
Statins uses	141 (24.1)	27 (18.4)	32 (21.8)	46 (31.5)	36 (24.8)	3.4042	0.065
ALT (U/L)	20 (14-31)	25 (14-41)	20 (14-31)	19 (15-28)	20 (13-28)	-2.3953	0.017
ALB (g/L)	39.2 ± 4.0	39.0 ± 3.6	39.7 ± 4.1	39.3 ± 4.1	38.7 ± 4.3	0.7381	0.391
TG (mmol/L)	1.65 (1.16-2.71)	1.95 (1.29-3.17)	1.60 (1.14-2.98)	1.65 (1.11-3.00)	1.48 (1.07-2.22)	-3.0193	0.003
TC (mmol/L)	4.59 ± 1.27	4.70 ± 1.01	4.67 ± 1.44	4.46 ± 1.25	4.52 ± 1.32	2.5001	0.114
UA (μmol/L)	323 ± 155	311 ± 100	337 ± 261	309 ± 89	333 ± 100	0.4221	0.516
CysC (mg/L)	0.73 (0.57-0.92)	0.66 (0.52-0.83)	0.71 (0.54-0.90)	0.76 (0.63-0.94)	0.85 (0.66-1.03)	5.0433	< 0.001
eGFR (mL/minute/1.73 m2)	113.23 ± 29.74	122.46 ± 33.15	116.43 ± 31.23	109.98 ± 24.00	103.68 ± 26.48	33.9621	< 0.001
ACR (mg/g/cr)	15.3 (8.5-42.5)	13.4 (8.0-33.9)	21.8 (9.8-50.7)	15.6 (7.8-45.4)	13.5 (7.3-39.2)	0.012 3	0.990
Fasting C-peptide (ng/mL)	1.67 ± 1.15	1.75 ± 1.21	1.56 ± 0.96	1.70 ± 1.12	1.69 ± 1.30	0.0071	0.934
Hemoglobin (g/L)	140 ± 18	138 ± 18	140 ± 19	142 ± 16	141 ± 17	2.6331	0.105
HbA1c (%)	8.35 ± 1.56	8.03 ± 1.47	8.19 ± 1.66	8.38 ± 1.49	8.41 ± 1.60	5.1971	0.023
Overall composite Z-score for latency	0.04 ± 0.66	-0.18 ± 0.56	0.01 ± 0.64	-0.01 ± 0.57	0.32 ± 0.77	38.9961	< 0.001
Overall composite Z-score for amplitude	-0.03 ± 0.58	0.18 ± 0.49	0.06 ± 0.59	-0.09 ± 0.55	-0.27 ± 0.61	50.9721	< 0.001
Overall composite Z-score for NCV	-0.03 ± 0.75	0.20 ± 0.64	-0.01 ± 0.77	0.01 ± 0.73	-0.31 ± 0.79	30.6361	< 0.001

¹Linear polynomial contrasts of analysis of variance (F value).

²Linear-by-linear association of χ² test (χ² value).

³Jonckheere-Terpstra test (Z value).

BUN: Blood urea nitrogen; BMI: Body mass index; SBP: Systolic blood pressure; DBP: Diastolic blood pressure; TZDs: Thiazolidinediones; AGIs: Α-glucosidase inhibitors; DPP-4Is: Dipeptidyl peptidase-4 inhibitors; SGLT-2Is: Sodium-glucose cotransporter 2 inhibitors; GLP-1RAs: Glucagon-like peptide 1 receptor agonists; ALT: Alanine aminotransferase; ALB: Albumin; TG: Triglyceride; TC: Total cholesterol; UA: Uric acid; CysC: Cystatin C; eGFR: Estimated glomerular filtration rate; ACR: Urinary albumin /creatinine ratio; HbA1c: Glycosylated hemoglobin A1c; NCV: Nerve conduction velocity.