Patients and study design
The clinical data of patients with type 2 diabetes complicated with proteinuria who received renal biopsy from January 2013 to September 2019 in two Hospitals of Xuzhou (Xuzhou Medical University Affiliated Hospital and Xuzhou Central Hospital) were retrospectively collected. The inclusion criteria were as follows: a. T2DM was diagnosed according to the 2013 American Diabetes Association (ADA) criteria ; b.proteinuria was diagnosed when the urinary albumin to creatinine ratio (UACR) > 30 mg/g; c. renal biopsy (male or female) age > 18 years old with clear pathological results. The exclusion criteria were as follows: a. incomplete data or unclear medical history; b. combined with other acute complications of diabetes mellitus; c. Those who had taken fibrates triglyceride lowering drugs within 3 months before renal biopsy; d. Complicated with serious infection of other systems, failure of important organs, systemic immune system diseases and malignant tumors; e. proteinuria appeared before diagnosis of type 2 diabetes; f. The pathological manifestation was DKD combined with NDKD. According to the pathological results of renal biopsy, they were divided into DKD group (25 cases) and NDKD group (34 cases). This study was approved by the ethics committee of the Affiliated Hospital of Xuzhou Medical University (ethics No.: XYFY2021-KL073-01). All enrolled patients who participated in the biopsy of kidney biopsy signed written informed consent.
From October 2019 to October 2021, 37 patients with type 2 diabetes complicated with proteinuria were selected from the Department of Nephrology, four hospitals in Xuzhou (Affiliated Hospital of Xuzhou Medical University, Xuzhou Central Hospital, Xuzhou First People's Hospital and Xuzhou Traditional Chinese Medicine Hospital). According to the previous retrospective study, the cut-off point value of TG/Cys-C ratio for the diagnosis and prediction of DKD was 2.43. Taking the ratio ≥ 2.43and < 2.43 as the defined values, the subjects were divided into two groups. The TG/Cys-C ratio of 29 patients was less than 2.43, including 20 males and 9 females; The age ranged from 26 to 69 years, with an average of (50.00 ± 11.33) years. TG/Cys-C ratio ≥ 2.43 in 8 patients, 6 males and 2 females; The age ranged from 38 to 70 years, with an average of (53.63 ± 10.25) years. There was no significant difference between the two groups in terms of gender and age, and the two groups were comparable. The inclusion criteria were as follows: a. age ≥ 18 years; b. T2DM was diagnosed according to the 2022 American Diabetes Association (ADA) criteria ; c. Urinary albumin to creatinine ratio (UACR) > 30 mg/g; d. Underwent ultrasound-guided renal biopsy. The exclusion criteria were as follows: a. With acute complications such as diabetic ketoacidosis; b. Those who had taken fibrates triglyceride lowering drugs within 3 months before enrollment; c. Patients with severe infection of other systems, failure of important organs, diseases of systemic immune system and malignant tumors; d. Type 2 diabetes mellitus was diagnosed as CKD before diagnosis; e. Those who refuse to participate in the experiment. This study was approved by the ethics committee of the Affiliated Hospital of Xuzhou Medical University (ethics No.: XYFY2019-KL149). All enrolled patients who participated in the biopsy of kidney biopsy signed written informed consent.
Review research indicators
General information was collected
The clinical data of all patients from January 2013 to September 2019 were collected, including age, gender, duration of diabetes (the time from the first diagnosis to the time of renal biopsy), whether diabetic retinopathy was found, whether smoking and drinking history, height, weight, systolic blood pressure and diastolic blood pressure were calculated, and body mass index (BMI) was calculated. The blood test indexes of renal biopsy patients were collected, including hemoglobin, fasting blood glucose, albumin, cholesterol, triglyceride, uric acid, creatinine, glomerular filtration rate (eGFR), high-density lipoprotein-c, low-density lipoprotein-c, Cystatin C, glycosylated hemoglobin, fibrinogen (FIB), routine urine chemistry and urinary sediment quantification, and total 24-h urinary protein.TG/Cys-C ratio was calculated, and eGFR was estimated by kidney disease diet improvement (MDRD) formula : eGFR[ml/(min*1.73m2)] = 30,849 × (Scr)^-1.154 × (age)^-0.203 × (0.742female). The pathological report of renal puncture was provided by Nanjing Jinyu medical laboratory.
Experimental data collection
Develop unified and detailed forms, recording the gender, age, duration of diabetes, height and weight, Body Mass Index (BMI), BMI = body weight (kg)/height (m)2, measuring seat blood pressure, recording systolic and diastolic blood pressure (mmHg).
All subjects were fasted for 8-10 h, and they should avoid drinking one day in advance and eating high-fat protein diet. 10 ml blood was collected from the median vein of the cubital fossa of the forearm on an empty stomach the next morning (vigorous activities and brisk walking should be avoided 15 min before blood drawing). After standing at room temperature for 30 min, 3 ml was centrifuged at 1000 rpm for 5 min, the lower blood cells were removed, the upper serum was taken, the triglyceride level was detected by GPO-POD colorimetry, the serum cystatin C level was detected by immunoturbidimetric method, the creatinine level was detected by creatine oxidase method, and the glycosylated hemoglobin was detected by high performance liquid chromatography. TG/Cys-C ratio was calculated and eGFR was estimated: it was calculated by kidney disease diet improvement (MDRD) formula .
All subjects underwent 24-h quantitative detection of urinary protein: empty the bladder at 8 a.m. on the same day, then count the time, collect all urine until 8 a.m. on the next day in a clean container, accurately measure the total amount of urine, record it, stir it evenly, and take 100 ~ 200 ml for examination. In order to prevent deterioration of urination, preservatives (such as 1 ml of 40% formaldehyde solution) can be added to the bedpan during urine collection. The total amount of urinary protein was detected by turbidimetry.
All subjects underwent fundus photography: fundus photography was performed with VISUCAM S224 fundus camera. Two doctors of deputy director of Ophthalmology and above were evaluated.
All subjects were examined by ultrasound-guided fine needle renal biopsy: the ultrasonic instrument was Philips EPIQ7 ultrasonic diagnostic instrument, and the probe model was C5-1; The puncture needle shall be American automatic bard biopsy gun, 16 g × 16 cm, the length of biopsy tissue strip was 22 mm. The position, size (long × thick × width) and thickness of renal parenchyma of both kidneys were routinely examined before renal puncture, thickness of renal parenchyma, unit: cm; Laboratory examination of liver and kidney function, coagulation function, platelet count, blood pressure, preoperative discontinuation of anticoagulants. Empty bladder, puncture position: lie prone, abdominal pillow or cushion, fix the position, conduct ultrasonic positioning, routine disinfection and towel laying, after 2% lidocaine anesthesia, use 16G puncture needle under the guidance of ultrasound, enter the needle to the front edge of the capsule of the lower pole of the kidney, pull the trigger, and take out the tissue strip for biopsy. Continuous compression puncture for 6–8 h after operation. All pathological examinations were sent to Nanjing Jinyu Medical Laboratory for pathological diagnosis. Light microscope (HE, PAS, PASM, Masson staining), electron microscope and fluorescence immunopathological examination were performed respectively, which were analyzed by two experienced pathologists.
SPSS 20.0 statistical software was used to analyze the data. Through the normality test, the data conforming to the normal distribution are expressed in, and the independent sample t-test is used for the comparison between groups. Those that do not conform to the normal distribution are represented by M (Q1, Q3), and Mann Whitney U test is used for inter group comparison. The number of cases (%) was used for classification and counting data, and the comparison between groups was used χ2 test or Fisher test. Logistic regression analysis was used to analyze the related factors of DKD in patients with type 2 diabetes and proteinuria. The diagnostic value of TG/Cys-C ratio in patients with DKD was evaluated by receiver operating characteristic (ROC) curve, and the cut-off point value was selected. The difference was statistically significant (P < 0.05).