| ObjectiveMechanisms of diabetic nephrpathy are very complicated. Different stages of type 2 diabetes can bring about different changes of clinical indexes of glomeruli and nephric tubule, thus inducing different morbidity and complications. Therefore, it is important to explore the relations among clinical indexes of renal function in different stages of diabetic nephropathy and in different complications. The factors affecting renal function of type 2 diabetes were analyzed in this study, and this would provide theoretical basis for clinical diagnosis and treatment of diabetic nephropathy.Methods1) Patients, who were hospitalized in Endocrine and Metabolic Department of Xijing Hospital, Fourth Military Medical University from 2003 to 2007, were all diagnosed of type 2 diabetes mellitus, according to the WHO diagnosis and classification of diabetes diagnosis standard defined in 1999. After hospitalization, they took on a check-up for observing 99mTC-DTPA glomerular filtration rates. Qualified patients received the intensive insulin treatment.Patients with pyelonephritis, other kidney disease, acute diabetes complications, congestive heart failure, chronic nephritis and the use of growth promoting excretion drug during the treatment were excluded. 171 patients were collected, including 109 males and 62 females. The basic data of these cases were as follows: the ages were (58.8±11.1) years, the durations of type 2 diabetes were (9.1±8.9) years, ranging from 1 months to 30 years.2) Indicators were observed as follows: case history of diabetes, age, systolic blood pressure (SBP), diastolic blood pressure (DBP), glomerular filtration rate (GFR), total cholesterol (TC), triglycerides (TG), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), serum creatinine (Scr), blood urea nitrogen (BUN), fasting blood glucose (FBG), 2 hours postprandial hyperglycemia (BG2h), bloodβ2-microglobulin (B-β2-MG), urinaryβ2-microglobulin (U-β2-MG), urinary albumin (U-Alb), urinaryα1-microglobulin (U-α1-MG), and uric acid (UA).3) Protocols: Patients were divided into three groups according to different GFR levels: 10 cases in group A (GFR<30mL/min), 43 cases in group B (30mL/min≤GFR<60mL/min) and 118 cases in group C (GFR≥60mL/min). Patients were redivided into two groups according to different Scr levels: There were 134 cases in normal Scr group (Scr≤125umol/L) and 37 cases in elevated Scr group (Scr>125umol/L). According to the clinical diagnostic criteria, 62 cases were included in diabetic group, 62 cases were included in diabetic patients with hypertension group and other 47 cases were included in diabetic patients with hypertension and hyperlipidemia group.4) Correlation analysis, multivariate regression analysis, analysis of variance (ANOVA) and the principal component analysis were applied to evaluate the statistical significance of differences among the different groups in this study.Results1. Analysis of factors correlated with glomerular filtration rate in type 2 diabetes.1) The correlation analysis indicated that the diabetic duration, the ages, the SBP, the BUN, the Scr, the UA, the B-β2-MG and the U-IgG were negatively correlated with GFR (P<0.01), while the U-A1b andU-α1-MG, were negatively correlated with GFR (P<0.05).2) All clinical data had no relationship with GFR in group A (GFR≤30mL/min), while BUN, Scr, BG2h, U-A1b and U-α1-MG were negatively correlated with GFR in group B(30mL/min < GFR <60mL/min). In group C(GFR≥60mL/min), UA was negatively correlated with GFR(P<0.05), FBG was positively correlated with GFR(P<0.05).3) Stepwise multivariable regression analysis showed that the Scr(t=-3.568, P<0.01)and UA(t=-2.483, P<0.01)were independent correlation factors of GFR in all patients, while diabetic courses and the level of UA were independently correlated with GFR in normal Scr group. 2. Analysis of factors correlated with renal tubule function in type 2 diabetes.1) Correlation analysis showed that the U-β2-microglobulin significantly related with U-A1b, U-IgG, U-α1-MG, SBP and Scr (P<0.01).2) In the diabetic group, the U-β2-microglobulin was significantly correlated with TC, HDL-C, Scr and BUN (P<0.05). In diabetic patients with hypertension group, the U-β2-microglobulin was significantly correlated with SBP (P<0.01); the U-β2-microglobulin was significantly correlated with TC, LDL-C and Scr (P<0.05). In diabetic patients with hypertension and hyperlipidemia group, the U-β2-microglobulin had no relationship with the all of the clinical data.3. Analysis of factors principal constituent with kidney function in type 2 diabetes.1) In principal component analysis, analysis of variance of all indicators showed that variational levels of U-A1b, U-β2-MG, U-IgG, U-α1-MG and TG were much higher than other indicators (>85%). And the variational levels of SBP, DBP, BG2h, FBG and UA were lower relatively (<30%). The degree of variation in Scr, DM, BUN, B-β2-MG, TC, HDL-C, LDL–C and GFR was between 30% and 70%.2) Principal component analysis from 18 clinical indicators extracted 10 unrelated factors showed that the total contribution rates were more than 85 percent (to 85.671%). The contribution rate of C1 principal components was up to 22.09. C1 included Scr, BUN and U-IgG. The indexes (Scr, BUN and U-IgG) had high factor loading.ConclusionsThese data showed that renal function decline in diabetic patients was related with various factors.1) In different stages of diabetic nephropathy, the correlation factors affecting the GFR were different. In all of the internalizing objects, Scr and UA were independent correlation factors with the decline of GFR in type 2 diabetes, while the correlation factors with the changing of renal function in DN were obviously different according to the different levels of Scr or UA.2) Based on the level of urineβ2-MG, presenting renal tubule function, the correlation analysis showed that renal tubule function was affected by the levels of blood pressure and blood lipid. At the same time, urineβ2-MG had the same changing tendency with other renal function correlation indexes. This indicated that the renal tubule function was one of important components in diabetic nephropathy in diabetes. As for the changing relationship between the influencing factors and others renal function indexes, were needed to further research.3) Scr was a favorable indicator which could evaluate renal function in the view of the variation, relevance and principal components of loading factor. Of course, it did not mean that Scr could replace other indicators. In fact, each indicator could contain its own independent and specific information. Therefore, we should analyze according to the actual situation.
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