Fig. 1Receiver operating characteristic curve of glucose parameters for predicting the renal tubulopathy in subjects with diabetes with normal renal function and normoalbuminuria. GA, glycated albumin; HbA1c, glycosylated hemoglobin; CI, confidence interval.
Table 1Baseline characteristics of study subjects according to urinary NAG levels
Characteristic |
All |
Normal urinary NAG (≤5.8 U/g Cr) |
High urinary NAG (>5.8 U/g Cr) |
P value |
Number |
1,061 |
431 |
630 |
|
Demographic |
|
|
|
|
Age, yr |
60.14±11.37 |
57.42±11.31 |
62.00±11.03 |
<0.001 |
Male sex |
593 (55.61) |
268 (62.3) |
325 (51.6) |
0.002 |
BMI, kg/m2
|
25.03±3.68 |
25.39±3.39 |
24.78±3.85 |
0.009 |
Current smoker |
162 (15.27) |
70 (16.3) |
92 (14.6) |
0.487 |
Diabetes duration, yr |
8.33±7.56 |
6.94±6.78 |
9.28±7.91 |
<0.001 |
Systolic blood pressure, mm Hg |
123.79±15.09 |
124.68±14.80 |
123.18±15.27 |
0.115 |
Diastolic blood pressure, mm Hg |
76.22±20.51 |
77.15±11.36 |
75.57±24.92 |
0.220 |
Glucometabolic parameter |
|
|
|
|
Fasting glucose, mg/dL |
137.93±40.91 |
133.15±32.96 |
141.20±45.31 |
0.001 |
Stimulated glucose, mg/dL |
195.07±61.05 |
181.10±50.78 |
202.87±64.85 |
<0.001 |
δ Glucose, mg/dL |
56.63±43.64 |
49.80±39.96 |
60.44±43.64 |
0.001 |
HbA1c, % |
7.26±1.27 |
7.04±1.05 |
7.41±1.38 |
<0.001 |
Glycated albumin, % |
18.75±5.44 |
17.42±4.18 |
19.65±5.99 |
<0.001 |
Glycated albumin to HbA1c |
2.55±0.43 |
2.45±0.36 |
2.62±0.47 |
<0.001 |
Fasting C-peptide, ng/mL |
2.27±1.03 |
2.33±1.01 |
2.23±1.04 |
0.128 |
Stimulated C-peptide, ng/mL |
5.16±2.29 |
5.52±2.39 |
4.95±2.21 |
0.002 |
δ C-peptide, ng/mL |
2.83±1.81 |
3.13±1.94 |
2.67±1.71 |
0.001 |
HOMA-β |
42.07 (26.23–67.08) |
48.09 (31.71–74.74) |
39.09 (23.74–63.93) |
<0.001 |
HOMA-IR |
2.59 (1.63–4.21) |
2.67 (1.71–4.18) |
2.58 (1.57–4.24) |
0.299 |
Nephropathic indice |
|
|
|
|
eGFR, mL/min/1.73 m2
|
91.17±15.33 |
90.98±14.97 |
91.30±15.59 |
0.736 |
Urinary NAG, U/g creatinine |
6.66 (4.44–10.47) |
3.99 (2.82–4.96) |
9.48 (7.38–13.51) |
<0.001 |
Urinary ACR, mg/g |
7.59 (4.54–12.47) |
6.16 (4.04–10.03) |
8.68 (5.31–14.65) |
<0.001 |
Biochemistry profile |
|
|
|
|
Albumin, mg/dL |
4.35±0.31 |
4.43±0.28 |
4.29±0.31 |
<0.001 |
Total cholesterol, mg/dL |
160.57±37.02 |
157.69±34.89 |
162.55±38.31 |
0.036 |
Triglyceride, mg/dL |
112 (80–158.25) |
113.5 (80–157) |
111 (80–159.75) |
0.977 |
HDL-C, mg/dL |
49.81±13.69 |
50.68±14.39 |
49.22±13.16 |
0.090 |
LDL-C, mg/dL |
79.07±33.19 |
74.24±31.73 |
82.38±33.79 |
<0.001 |
Antidiabetic drug |
|
|
|
|
Insulin |
132 (12.44) |
46 (10.7) |
86 (13.7) |
0.156 |
Metformin |
818 (77.10) |
325 (75.4) |
493 (78.3) |
0.298 |
DPP-4 inhibitor |
542 (51.08) |
206 (47.8) |
336 (53.3) |
0.080 |
Thiazolidinedione |
61 (5.7) |
13 (3) |
48 (7.6) |
0.002 |
Sulfonylurea |
340 (32.05) |
113 (26.2) |
227 (36) |
0.001 |
Diuretics |
57 (5.37) |
24 (5.6) |
33 (5.2) |
0.890 |
ACE inhibitor or ARB |
326 (30.73) |
141 (32.7) |
185 (29.4) |
0.278 |
Table 2Correlation between urinary NAG and demographic and glycometabolic parameters
Parameter |
Urinary NAG/Cr, U/g creatininea
|
r
|
P value |
Age, yr |
0.227 |
<0.001 |
Body mass index, kg/m2
|
−0.069 |
0.025 |
Fasting glucose, mg/dL |
0.124 |
<0.001 |
Stimulated glucose, mg/dL |
0.185 |
<0.001 |
Fasting C-peptide, ng/mL |
0.001 |
0.974 |
Stimulated C-peptide, ng/mL |
−0.115 |
0.002 |
δ C-peptide, nmol/L |
−0.153 |
<0.001 |
Glycated albumin, % |
0.259 |
<0.001 |
HbA1c, % |
0.197 |
<0.001 |
HOMA-βa
|
−0.060 |
0.098 |
HOMA-IRa
|
0.029 |
0.423 |
Urinary ACR, mg/ga
|
0.233 |
<0.001 |
eGFR, mL/min/1.73 m2
|
0.044 |
0.154 |
Table 3Multiple linear regression models for urinary NAG in type 2 diabetes mellitus
Variable |
Model 1a
|
Model 2b
|
Model 3c
|
STD β |
P value |
STD β |
P value |
STD β |
P value |
Glycated albumin, % |
0.276 |
<0.001 |
0.217 |
0.014 |
0.213 |
0.016 |
HbA1c, % |
−0.002 |
0.968 |
−0.135 |
0.096 |
−0.137 |
0.096 |
Fasting glucose, mg/dL |
- |
- |
−0.003 |
0.962 |
0.006 |
0.930 |
Stimulated glucose, mg/dL |
- |
- |
0.100 |
0.115 |
0.095 |
0.140 |
Stimulated C-peptide, ng/mL |
- |
- |
0.176 |
0.103 |
0.152 |
0.171 |
δ C-peptide, ng/mL |
- |
- |
−0.226 |
0.028 |
−0.206 |
0.050 |