Development and validation of equations estimating glomerular filtration rates in Chinese patients with type 2 diabetes

Associations of serum amino acids related to urea cycle with risk of chronic kidney disease in Chinese with type 2 diabetes

OBJECTIVE

Serum levels of amino acids related to urea cycle are associated with risk of type 2 diabetes mellitus (T2DM). Our study aimed to explore whether serum levels of amino acids related to urea cycle, i.e., arginine, citrulline, and ornithine, are also associated with increased risk of chronic kidney disease (CKD) in T2DM.

METHODS

We extracted medical records of 1032 consecutive patients with T2DM from the Electronic Administrative System of Liaoning Medical University First Affiliated Hospital (LMUFAH) system from May 2015 to August 2016. Of them, 855 patients with completed data available were used in the analysis. CKD was defined as estimated glomerular filtration rate (eGFR) <60 mL/min/1.73 m². Serum amino acids were measured by mass spectrometry (MS) technology. Binary logistic regression was performed to obtain odds ratios (ORs) and their 95% confidence intervals (CIs).

RESULTS

52.3% of the 855 T2DM patients were male, and 143 had CKD. In univariable analysis, high serum citrulline, high ratio of arginine to ornithine, and low ratio of ornithine to citrulline were associated with markedly increased risk of CKD (OR of top vs. bottom tertile: 2.87, 95%CI, 1.79-4.62 & 1.98, 95%CI,1.25-3.14 & 2.56, 95%CI, 1.61-4.07, respectively). In multivariable analysis, the ORs of citrulline and ornithine/citrulline ratio for CKD remained significant (OR of top vs. bottom tertile: 2.22, 95%CI, 1.29-3.82 & 2.24, 1.29-3.87, respectively).

CONCLUSIONS

In Chinese patients with T2DM, high citrulline and low ornithine/citrulline ratio were associated with increased risk of CKD.

Chronic Kidney Disease in the Transgender, Nonbinary, or Gender Diverse Person

Nephrologists are increasingly providing care to transgender, nonbinary, and gender diverse (TNBGD) individuals with chronic kidney disease. This narrative review discusses the care of TNBGD individuals from a nephrology perspective. TNBGD individuals are under-represented in the nephrology literature. TNBGD individuals are at an increased risk of adverse outcomes compared with the cisgender population including mental health, cardiovascular disease, malignancy, sexually transmitted infections, and mortality. Gender-affirming hormone therapy (GAHT) with estradiol in transfeminine individuals potentially increases the risk of venous thromboembolism and cardiovascular disease. GAHT with testosterone in transmasculine individuals potentially increases the risk of erythrocytosis and requires careful monitoring. GAHT modifies body composition and lean muscle mass, which in turn influence creatinine generation and excretion, which may impact the performance of estimated glomerular filtration rate (GFR) equations and the estimation of 24-hour urine values from spot urine albumin/protein to creatinine ratios. There are limited studies regarding TNBGD individuals with chronic kidney disease. Additional research is needed to evaluate the effects of GAHT on GFR and biomarkers of kidney function and the performance of the estimated GFR equation in TNBGD populations.

Development and validation of a more accurate estimating equation for glomerular filtration rate in a Chinese population

Previously published equations to estimate glomerular filtration rate (GFR) have limited accuracy in Asian populations. We aimed to develop and validate a more accurate equation for estimated GFR (eGFR) in the Chinese population, using data from 8571 adults who were referred for direct measurement of GFR by renal dynamic imaging (mGFR) at 3 representative hospitals in China. Patients from the Third Xiangya Hospital were included in our development (n=1730) and internal validation sets (n=1042) and patients from the other hospitals comprised the external validation set (n=5799). We excluded patients who were prescribed medications known to influence the tubular secretion of creatinine, patients on dialysis, kidney transplant recipients, and patients with missing creatinine values or with creatinine >700 μmol/l. We derived a novel eGFR equation by linear regression analysis and compared the performance to 12 creatinine-based eGFR equations, including previously published equations for use in Chinese or Asian populations. In the development and internal validation sets, the novel Xiangya equation had high accuracy (accuracy within 30% [P30], 79.21% and 84.33%, respectively), low bias (mean difference between mGFR and eGFR, -1.97 and -1.85 ml/min per 1.73 m², respectively), and high precision (interquartile range of the differences, 21.13 and 18.88 ml/min per 1.73 m², respectively). In external validation, the Xiangya equation had the highest P30 among all eGFR equations, with P30 ≤ 75% for the other 12 equations. This novel equation provides more accurate GFR estimates in Chinese adults and could replace existing eGFR equations for use in the Chinese population.

Abdominal adiposity contributes to adverse glycemic control and albuminuria in Chinese type 2 diabetic patients: A cross-sectional study

BACKGROUND

Abdominal adipose tissue plays an important role in the development of type 2 diabetes. However, few data have suggested its role in the prognosis of diabetes. This study aimed to investigate the association between waist-hip ratio (WHR), glycemic control, and early nephropathy in Chinese type 2 diabetic patients.

METHODS

A cross-sectional study was conducted in 1709 previously- and newly-diagnosed diabetic patients nested in a cohort study consisting of 10 375 participants aged ≥40 years in Shanghai, China. General characteristics through questionnaire, anthropometric measures, and biochemical results were recorded. Statistical analysis was performed by SPSS v20.0.

RESULTS

Each quartile increase in WHR was significantly associated with a fasting plasma glucose (FPG) ≥ 126 mg/dl [OR (95% CI):1.18 (1.06-1.30)], an HbA1c ≥ 7.0% [1.21 (1.08-1.35)], and a HOMA-IR ≥ 2.5 [1.30 (1.16-1.46)] after multivariable adjustments. WHR was not associated with a 2h PG ≥ 200mg/dl [1.13 (0.97-1.31)]. The risk for increased albuminuria (UACR ≥10.18mg/g) was also significantly associated with higher WHR after adjustment for HbA1c [1.14 (1.02-1.27)]. However, no significant relationship was seen between WHR and an estimated glomerular filtration rate < 90 ml/min per 1.73 m² . Interactions of sex, or physical activity with WHR in association with glycemic control and increased albuminuria were found (P values for interaction <0.05).

CONCLUSIONS

These data demonstrated an independent role of abdominal adipose tissue in glycemic control and renal complications of type 2 diabetes. Interventions aiming to reduce abdominal adipose tissue may have additional benefits.

High body mass index reduces glomerular filtration rate decline in type II diabetes mellitus patients with stage 3 or 4 chronic kidney disease

Whether high body mass index (BMI) has an effect on progressive diabetic nephropathy in type II diabetes mellitus (DM) patients with chronic kidney disease (CKD) stage 3 or 4 remains unclear. This prospective study aimed to investigate the relationship between BMI and progression of renal function deterioration in type II DM patients with CKD stage 3 or 4.A total of 105 type II DM patients with CKD stage 3 or 4 participated in this 24-month prospective observational study. Patients were divided into 3 groups according to BMI as follows: normal group, BMI of 18.5-22.9 kg/m; overweight group, BMI of 23-24.9 kg/m; and obese group, BMI of ≥25 kg/m. The primary end point was a 2-fold elevation in serum creatinine levels (measured twice with a 1-month interval) from baseline values, need for long-term dialysis, or death during the 24-month observation period.In the linear regression analysis with the stepwise method, each 1 kg/m increase in BMI led to an increase of 0.32 mL min × 1.73 m in the estimated glomerular filtration rate (95% confidence interval, CI, 0.01-0.62; P = 0.04) during the 24-month study period. Moreover, multivariate Cox regression analysis showed that compared with the obese group, the normal BMI group (hazard ratio = 2.76, 95% CI : 1.27-6; P = 0.01) achieved the primary outcome after adjusting for other factors.In this 24-month prospective observational study, we showed that BMI of ≥25 kg/m was a protective factor for renal function deterioration in type II DM patients with CKD stage 3 or 4.

Using mathematical algorithms to modify glomerular filtration rate estimation equations

BACKGROUND

The equations provide a rapid and low-cost method of evaluating glomerular filtration rate (GFR). Previous studies indicated that the Modification of Diet in Renal Disease (MDRD), Chronic Kidney Disease-Epidemiology (CKD-EPI) and MacIsaac equations need further modification for application in Chinese population. Thus, this study was designed to modify the three equations, and compare the diagnostic accuracy of the equations modified before and after.

METHODOLOGY

With the use of (99 m)Tc-DTPA renal dynamic imaging as the reference GFR (rGFR), the MDRD, CKD-EPI and MacIsaac equations were modified by two mathematical algorithms: the hill-climbing and the simulated-annealing algorithms.

RESULTS

A total of 703 Chinese subjects were recruited, with the average rGFR 77.14±25.93 ml/min. The entire modification process was based on a random sample of 80% of subjects in each GFR level as a training sample set, the rest of 20% of subjects as a validation sample set. After modification, the three equations performed significant improvement in slop, intercept, correlated coefficient, root mean square error (RMSE), total deviation index (TDI), and the proportion of estimated GFR (eGFR) within 10% and 30% deviation of rGFR (P10 and P30). Of the three modified equations, the modified CKD-EPI equation showed the best accuracy.

CONCLUSIONS

Mathematical algorithms could be a considerable tool to modify the GFR equations. Accuracy of all the three modified equations was significantly improved in which the modified CKD-EPI equation could be the optimal one.

Environmental lead exposure accelerates progressive diabetic nephropathy in type II diabetic patients

Whether environmental lead exposure has a long-term effect on progressive diabetic nephropathy in type II diabetic patients remains unclear. A total of 107 type II diabetic patients with stage 3 diabetic nephropathy (estimated glomerular filtration rate (eGFR) range, 30-60 mL/min/1.73 m(2)) with normal body lead burden (BLB) (<600  μ g/72 hr in EDTA mobilization tests) and no history of exposure to lead were prospectively followed for 2 years. Patients were divided into high-normal BLB (>80  μ g) and low-normal BLB (<80  μ g) groups. The primary outcome was a 2-fold increase in the initial creatinine levels, long-term dialysis, or death. The secondary outcome was a change in eGFR over time. Forty-five patients reached the primary outcome within 2 years. Although there were no differences in baseline data and renal function, progressive nephropathy was slower in the low-normal BLB group than that in the high-normal BLB group. During the study period, we demonstrated that each 100  μ g increment in BLB and each 10  μ g increment in blood lead levels could decrease GFR by 2.2 mL/min/1.72 m(2) and 3.0 mL/min/1.72 m(2) (P = 0.005), respectively, as estimated by generalized equations. Moreover, BLB was associated with increased risk of achieving primary outcome. Environmental exposure to lead may have a long-term effect on progressive diabetic nephropathy in type II diabetic patients.

Effect of chelation therapy on progressive diabetic nephropathy in patients with type 2 diabetes and high-normal body lead burdens

BACKGROUND

A previous study in type 2 diabetic patients with high-normal body lead burdens showed that EDTA chelation therapy for 3 months slows progressive diabetic nephropathy during a 12-month follow-up. The effect of a longer course of therapy on kidney function decrease over a longer follow-up is not known.

STUDY DESIGN

A 12-month run-in phase, then a randomized single-blind study with a 27-month intervention.

SETTING & PARTICIPANTS

University medical center; 50 patients (serum creatinine, 1.5-3.9 mg/dL) with high-normal body lead burden (≥80-<600 μg) were randomly assigned to the treatment and control groups.

INTERVENTION

The treatment group received weekly chelation therapy for 3 months to reduce their body lead burden to <60 μg and then as needed for 24 months to maintain this level. The control group received placebo for 3 months and then weekly for 5 weeks at 6-month intervals for 24 months.

OUTCOMES

The primary end point was change in estimated glomerular filtration rate (eGFR) over time. A secondary end point was a 2-fold increase in baseline serum creatinine level or the requirement for renal replacement therapy.

MEASUREMENTS

Body lead burdens were assessed by EDTA mobilization tests and eGFR was calculated using the equation for Chinese patients with type 2 diabetes.

RESULTS

Mean baseline eGFRs in the treatment and control groups were similar. After 3 months of chelation therapy, the change in eGFR in the treatment group (+1.0 ± 4.8 mL/min/1.73 m(2)) differed significantly from that in the control group (-1.5 ± 4.8 mL/min/1.73 m(2); P = 0.04). In the subsequent 24-month intervention, the yearly rate of decrease in eGFR (5.6 ± 5.0 mL/min/1.73 m(2) per year) in the treatment group was slower than that (9.2 ± 3.6 mL/min/1.73 m(2) per year; P = 0.04) in the control group. 17 (68%) control-group patients and 9 (36%) treatment-group patients achieved the secondary end point.

LIMITATIONS

Small sample size, not double blind.

CONCLUSIONS

A 27-month course of EDTA chelation therapy retards the progression of diabetic nephropathy in type 2 diabetic patients with high-normal body lead burdens.

A randomized-controlled trial to investigate the effects of rivoglitazone, a novel PPAR gamma agonist on glucose-lipid control in type 2 diabetes

AIM

To examine the efficacy, safety and tolerability of rivoglitazone, a novel thiazolidinedione (TZD), and explore its effects on glucose and lipid control compared to placebo and pioglitazone in Chinese type 2 diabetic patients who are treatment naÏve or treated with a single oral blood glucose-lowering drug.

METHODS

This was a double-blind, randomized, placebo- and active-controlled study. A total of 287 Chinese type 2 diabetic patients with suboptimal glycaemic control (defined as HbA1c ≥6.5 to <10% and fasting plasma glucose ≥7 to ≤15 mmol/l) were enrolled. One hundred and seventy-four eligible patients were randomized into one of the five treatment arms for 12 weeks: placebo, pioglitazone 30 mg daily, rivoglitazone of dose 0.5, 1.0 or 1.5 mg daily. In a full set analysis, we used analysis of covariance to compare the primary endpoint defined as change in HbA1c from baseline to week 12/last observation carried forward in the rivoglitazone group at each dose level with the placebo group.

RESULTS

Changes in HbA1c were -0.11% in the 0.5-mg group; -0.22% in the 1-mg group and -0.17% in the 1.5-mg rivoglitazone group; -0.06% in the 30-mg pioglitazone group and 0.61% in the placebo group. Compared to placebo, changes were significant in all active treatment groups (all p < 0.05). Increase in high-density lipoprotein cholesterol and decrease in triglyceride were observed in the rivoglitazone 1 and 1.5 mg groups, respectively, compared to placebo from baseline to week 12 (p < 0.05). Drug-related oedema was reported in eight patients (7.7%) in all rivoglitazone groups compared to six patients (16.2%) in the pioglitazone group and one patient (3.0%) in the placebo group.

CONCLUSIONS

Rivoglitazone is an efficacious, safe and well-tolerated TZD which improved glycaemic control in Chinese type 2 diabetic patients up to 3 months.