There were no significant differences in age and gender among the three groups (P > 0.05).There were no statistically significant differences in DBP, BMI, CHOL, TG, and LDL levels among the three groups (P > 0.05) (Table 1).
Table 1
Comparison of general clinical data among the three groups
Groups | NC (n = 34) | T2DM (n = 38) | T2DN (n = 34) | F | P |
BMI, kg/m2 | 26.19 ± 1.28 | 26.32 ± 1.31 | 26.27 ± 1.24 | 0.094 | 0.911 |
SBP, mmHg | 117.82 ± 12.06 | 130.61 ± 12.44a | 142.55 ± 14.78ab | 33.11 | < 0.001 |
DBP, mmHg | 80.48 ± 9.16 | 83.26 ± 9.36 | 85.19 ± 10.08 | 2.098 | 0.128 |
HbA1c (%) | 5.3 ± 0.51 | 10.45 ± 2.65a | 10.27 ± 2.77a | 58.55 | < 0.001 |
FBG, mmol/L | 4.63 ± 0.52 | 9.98 ± 4.63a | 10.69 ± 4.27a | 27.710 | < 0.001 |
CHOL, mmol/L | 4.35 ± 0.66 | 4.82 ± 1.08 | 4.83 ± 1.14 | 2.670 | 0.074 |
TG, mmol/L | 1.29 ± 0.54 | 1.3 ± 0.61 | 1.33 ± 0.56 | 0.045 | 0.956 |
LDL, mmol/L | 2.17 ± 0.43 | 2.33 ± 0.61 | 2.41 ± 0.69 | 1.474 | 0.234 |
aCompared with NC: P < 0.05, |
bCompared with T2DM: P < 0.05 |
Abbreviations: BMI, body mass index; SBP, systolic blood pressure; DBP, diastolic blood pressure; HbA1c (%), glycosylated hemoglobin; FBG, mmol/L, fasting blood glucose; CHOL, mmol/L, cholesterol; TG, mmol/L, triglycerides; LDL, mmol/L, low density lipoproteins. |
There were significant differences in SBP, HbA1c, and FBG between the NC and the other two groups (P < 0.05). However, there was no statistical difference in the general clinical data between the T2DM and T2DN groups (P > 0.05). As renal damage increased in patients, urine orosomucoid levels gradually increased as well (P < 0.05) (Table 2).
Table 2
Comparison of urinary orosomucoid, RBP, MAL, and eGFR levels among the three groups
Groups | NC (n = 34) | T2DM (n = 38) | T2DN (n = 34) | F | P |
Orosomucoid, mg/L | 9.45 ± 2.03 | 18.35 ± 4.04a | 29.46 ± 6.13 ab | 177.82 | < 0.001 |
RBP, mg/L | 0.26 ± 0.07 | 0.31 ± 0.09 | 0.95 ± 0.28 ab | 172.56 | < 0.001 |
eGFR, mL/min/1.73 m2 | 108.08 ± 13.73 | 102.17 ± 10.12 | 94.92 ± 10.57ab | 11.11 | < 0.001 |
MAL, mg/24 h | 10.22 ± 6.42 | 12.13 ± 7.83 | 199.65 ± 49.72ab | 492.19 | < 0.001 |
aCompared with NC group: P < 0.05 |
bCompared with T2DM group: P < 0.05 |
Abbreviations, RBF, renal blood flow; eGFR, estimated glomerular filtration rate; MAL, microalbumin. |
Urine RBP and MAL levels in the T2DN group were significantly higher than those in the NC and T2DN groups (P < 0.001). The eGFR levels in the T2DN group were significantly lower than in the NC and T2DM groups (P < 0.001). There were no significant differences in RBP, eGFR, and MAL levels between the NC and T2DM groups (P > 0.05).
For the NC group and the T2DM group, the dependent variable was whether T2DM had occurred (Yes = 1, No = 0), and the independent variables were the four variables with differences between the two groups, shown in Tables 1 and 2, including SBP, HbA1c, FBG, and orosomucoid. A binary logistic regression model was established and used to determine the influence of these four variables on T2DM (Table 3), and all were shown to be risk factors (all OR > 1, p < 0.05).
Table 3
Binary logistic regression analysis of the factors associated with type 2 diabetes mellitus
Variable | Regression coefficient (B) | Significance level (P) | Odds ratio (OR) | 95% CI of the OR |
Lower limit | Upper limit |
SBP, mmHg | 0.106 | 0.000 | 1.112 | 1.056 | 1.170 |
HbA1c (%) | 2.133 | 0.001 | 8.438 | 2.320 | 30.688 |
FBG, mmol/L | 1.022 | 0.000 | 2.779 | 1.663 | 4.646 |
Orosomucoid, mg/L | 0.964 | 0.001 | 2.621 | 1.521 | 4.516 |
Abbreviations: SBP, systolic blood pressure; HbA1c, glycosylated hemoglobin; FBG, fasting blood glucose.; OR, odds ration; CI, confidence interval. |
For the T2DM group and the T2DN group, the dependent variable was whether T2DN had occurred (Yes = 1, No = 0), and the independent variables were the five variables with differences between the two groups shown in Tables 1 and 2. A binary logistic regression model was established for analysis (Table 4).
Table 4
Binary logistic regression analysis of the factors associated with Type 2 diabetic nephropathy
Variable | Regression coefficient (B) | Significance level (P) | Odds ratio (OR) | 95% CI of the OR |
Lower limit | Upper limit |
SBP, mmHg | 0.089 | 0.000 | 1.093 | 1.045 | 1.143 |
Orosomucoid, mg/L | 0.626 | 0.000 | 1.871 | 1.360 | 2.574 |
RBP, mg/L | 0.241 | 0.023 | 13.305 | 9.079 | 26.000 |
eGFR, mL/min/1.73 m2 | -0.054 | 0.021 | 0.948 | 0.905 | 0.992 |
MAL, mg/24 h | 0.892 | 0.000 | 2.441 | 1.070 | 3.149 |
Abbreviations: RBF, renal blood flow; eGFR, estimated glomerular filtration rate; MAL, microalbumin; SBP, systolic blood pressure; OR, odds ration; CI, confidence interval. |
Of the five factors that were included in the regression model (p < 0.05), SBP, orosomucoid, RBP, and MAL were all determined to be risk factors (OR > 1) and eGFR was shown to be a protective factor (OR = 0.948 > 1). Correlation analysis showed that in the T2DN group, urinary orosomucoid level was significantly positively correlated with RBP (r = 0.489) and MAL (r = 0.513). RBP and MAL were significantly positively correlated with a correlation coefficient of 0.468. eGFR and urine orosomucoid, RBP, and MAL were significantly negatively correlated (r = -0.577, -0.474, and − 0.466, respectively).
ROC curve analysis was used to assess the diagnostic points and diagnostic value of orosomucoid and that of RBP to predict DN. Figure 1 and Table 5 show the areas under the ROC curves for orosomucoid and RBP with the respective standard error values.
Table 5
Areas under the two ROC curves for predicting diabetic nephropathy
Variable | Area under the ROC curve | Standard error | P | 95% confidence interval |
-LR | +LR |
Orosomucoid | 0.953 | 0.021 | 0.00 | 0.875 | 0.989 |
RBP | 0.970 | 0.022 | 0.00 | 0.900 | 0.996 |
Abbreviations: RBP, renal blood flow; ROC, receiver operating characteristic; -LR, negative likelihood ratio; ་LR, positive likelihood ratio. |
The diagnostic value of DN had improved; however, no statistical significance was observed (Z = 0.598, P = 0.550 > 0.05). The diagnostic point of orosomucoid was 22.43, sensitivity was 0.941, specificity was 0.842, and Youden index was 0.783. The diagnostic point of RBP was 0.53, sensitivity was 0.942, specificity was 1.000, and Youden index was 0.941.