Diabetic Renal Disease in Patients with Type 2 Diabetes Mellitus

The relationship between advanced glycation end products, metabolic metrics, HbA1c, and diabetic nephropathy

Background

In this cross-sectional study, we aim to investigate the value of non-invasive advanced glycation end products (AGEs) detection in the early screening of diabetic nephropathy(DN) among individuals with type 2 diabetes mellitus and assess whether metabolic parameters and glycated hemoglobin A1c (HbA1c) can moderate this relationship.

Methods

A total of 912 T2DM patients were enrolled. The urinary albumin-to-creatinine ratio (UACR) was measured in morning urine samples to assess DN. AGEs were non-invasively measured through skin autofluorescence. Recognizing the role of age in both AGEs and DN, AGEage was calculated as AGEs × age/100 for related analyses.

Results

The overall prevalence of DN in the present study was 37.2%. Elevated AGEage(χ2 = 61.06) was associated with a higher prevalence of DN. Multivariable linear regression demonstrated that AGEage was positively associated with UACR levels(β = 0.154, 95% CI: 0.126, 0.306, P<0.001). In the moderation analysis, glycated hemoglobin A1c (HbA1c) affected the correlation between AGEage and UACR. Body mass index (BMI) and triglyceride glucose-body mass index (TyG-BMI) also affect the correlation between AGEage and UACR, there were significant interactions between AGEage, HbA1c, BMI, TyG-BMI, and UACR.

Conclusions

Complex associations and interactions were observed between AGEs, metabolic metrics, HbA1c, and DN. Implementing comprehensive interventions can potentially benefit the prevention of DN in T2DM patients.

Long non-coding RNA ASncmtRNA-2 is upregulated in diabetic kidneys and high glucose-treated mesangial cells

Diabetic nephropathy (DN) is one of the most frequent complications associated with type I and II diabetes mellitus. Kidneys from patients with DN are characterized by mesangial matrix expansion and increased thickness of the glomerular basement membrane, which are induced by reactive oxygen species (ROS) production. Previous studies have been conducted to investigate this; however, the detailed mechanism of DN progression remains to be elucidated. The present study evaluated the expression of antisense mitochondrial non-coding RNA-2 (ASncmtRNA-2) in an experimental DN model and cultured human mesangial cells. When mice that exhibited genetic type II diabetes developed DN, ASncmtRNA-2 expression was significantly increased (P=0.017) and was positively correlated with pro-fibrotic factor transforming growth factor β1 (TGFβ1) expression and its downstream gene, fibronectin. Inhibition of ROS through administration of the nitric oxide synthase inhibitor, NG-nitro-L-Arginine methylester (L-NAME), significantly reduced (P=0.022) the upregulation of ASncmtRNA-2 in DN. In cultured human renal mesangial cells (HRMCs), ASncmtRNA-2 was upregulated by high glucose stimuli in a time-dependent manner. Glucose-induced upregulation of ASncmtRNA-2 was also reduced by co-incubation of HRMCs with L-NAME. Notably, specific short hairpin RNA against ASncmtRNA-2 significantly downregulated the expression of TGFβ1 in HRMCs. The present study suggests that ASncmtRNA-2 is upregulated by ROS and may promote glomerular fibrosis in DN via positively regulating the expression of pro-fibrotic factors. These findings may provide novel potential therapeutic and preventative treatments for DN.

Low-protein diet improves blood and urinary glucose levels and renal manifestations of diabetes in C57BLKS-db/db mice

PURPOSE

Dietary protein content is related clinically to the development of diabetic nephropathy. Here, we investigated how dietary protein content (12-24 % energy) within the range used by humans affected renal manifestations including the expressions of genes involved in the renin-angiotensin (RA) system in control and diabetic mice. Moreover, we examined the effects of dietary protein content on HbA1c and urinary glucose.

METHODS

Control (CT) and leptin receptor-deficient obese (db) mice, 5 weeks old, were fed the diets below. Under ad libitum conditions, mice were fed 12, 18, and 24 % energy from protein (L-, M-, and H-diets) for 8 weeks. Under pair-feeding conditions, db mice were supplied H-diet (db-Hp) to the equivalent energy to that consumed by db-L mice. Renal manifestations and values related to glucose and insulin were examined biochemically and pathologically.

RESULTS

Under ad libitum conditions, db mice consumed food and water dose dependently of the dietary protein content, although they were consumed similarly by CT mice. CT-L mice showed lower urinary albumin and kidney weight, in association with lower mRNA levels of angiotensinogen and renin, than CT-H mice. Under pair-feeding conditions, db-L mice showed a lower ratio of kidney/body weight, HbA1(C), and urinary glucose, and a higher β-cell distribution rate in the pancreas than db-Hp mice.

CONCLUSIONS

Low-protein intake in the range used by humans may relieve renal manifestations through the suppressed expression of genes in the renal RA system of CT mice. On the other hand, in db mice, low-protein intake improved hyperglycemia and the renal manifestations of diabetes.

Olmesartan medoxomil: current status of its use in monotherapy

Olmesartan medoxomil is an angiotensin II receptor antagonist. In pooled analyses of seven randomized, double-blind trials, 8 weeks’ treatment with olmesartan medoxomil was significantly more effective than placebo in terms of the response rate, proportion of patients achieving target blood pressure (BP) and mean change from baseline in diastolic (DBP) and systolic blood pressure (SBP). Olmesartan medoxomil had a fast onset of action, with significant between-group differences evident from 2 weeks onwards. The drug was well tolerated with a similar adverse event profile to placebo. In patients with type 2 diabetes, olmesartan medoxomil reduced renal vascular resistance, increased renal perfusion, and reduced oxidative stress. In several large, randomized, double-blind trials, olmesartan medoxomil 20 mg has been shown to be significantly more effective, in terms of primary endpoints, than recommended doses of losartan, valsartan, irbesartan, or candesartan cilexetil, and to provide better 24 h BP protection. Olmesartan medoxomil was at least as effective as amlodipine, felodipine and atenolol, and significantly more effective than captopril. The efficacy of olmesartan medoxomil in reducing cardiovascular risk beyond BP reduction is currently being investigated in trials involving patients at high risk due to atherosclerosis or type 2 diabetes.

Protective effects of keishibukuryogan on the kidney of spontaneously diabetic WBN/Kob rats

Keishibukuryogan, one of the traditional herbal formulations, is used clinically to improve blood circulation. It consists of the following five crude drugs: Cinnamomi Cortex, Poria, Moutan Cortex, Persicae Semen and Paeoniae Radix. In this study, the effects of keishibukuryogan against renal damage in spontaneously diabetic WBN/Kob rats were examined. Oral administration of keishibukuryogan significantly attenuated urinary protein excretion and serum creatinine levels. It did not affect body weight loss and blood glucose levels, but it suppressed renal and hepatic weights of WBN/Kob rats. Keishibukuryogan also reduced fibronectin and transforming growth factor beta(1) (TGF-beta(1)) protein expression in the renal cortex. Furthermore, lipid peroxidation levels in both kidney and liver were significantly lower than those of untreated control WBN/Kob rats. Urinary excretion of 8-hydroxy-deoxyguanosine was suppressed by keishibukuryogan treatment. These results suggest that keishibukuryogan reduces oxidative stress by hyperglycemia, and that it protects renal function and suppresses fibronectin deposition induced by TGF-beta(1) production in WBN/Kob rats.

Soy protein and isoflavones influence adiposity and development of metabolic syndrome in the obese male ZDF rat

BACKGROUND/AIMS

Previously, we demonstrated that soy protein ameliorates the diabetic phenotype in several rodent models of obesity and metabolic syndrome (MS). This study was designed to further elucidate factors related to adiposity, glycemic control, and renal function in male Zucker Diabetic Fatty (ZDF/Lepr(fa)) rats.

METHODS

Animals were randomly assigned to one of four diets: control, casein (C); low isoflavone (LIS) soy protein; high isoflavone (HIS) soy protein, or casein + rosiglitazone (CR) for 11 weeks. At sacrifice, physiological, biochemical, and molecular parameters were determined.

RESULTS

Body weight and total adiposity were higher in LIS and CR diet groups despite lower food intake. Additionally, these animals exhibited differential regulation of adipose-specific proteins (PPAR-gamma and GLUT4) and enzyme activity (FAS and GPDH). HIS-fed animals had reduced total and liver adiposity. Glycemic control was prolonged in both soy-based and rosiglitazone (RGZ) groups. Renal dysfunction was significantly reduced in soy-fed and RGZ-treated rodents as demonstrated by lower levels of proteinuria and dilated tubules with proteinaceous casts.

CONCLUSION

Collectively, these data provide evidence that soy protein with low or high isoflavone content may have therapeutic significance in reducing severity of diabetes, MS, and renal disease as demonstrated in this preclinical model.

Relationship between urinary albumin and serum soluble fms-like tyrosine kinase 1 (sFlt-1) in normal pregnancy

OBJECTIVE

To investigate if the circulating level of soluble fms-like tyrosine kinase 1 (sFlt-1) and vascular endothelial growth factor (VEGF) correlates with urinary albumin excretion in normal pregnancy.

STUDY DESIGN

Serum specimens and 24h urine collections were requested from normal pregnant women at 28-30 weeks of gestation and the following laboratory tests were performed: serum creatinine, urinary protein, urinary albumin and creatinine clearance. For the present study, 117 normal pregnant women were selected as subjects. Subjects' serum was tested to determine sFlt-1 and VEGF concentrations by ELISA. The correlation between sFlt-1 or VEGF concentrations in the serum and renal laboratory variables were analyzed. Simple regression was used to evaluate the correlations.

RESULTS

A significant association was noted between serum sFlt-1 concentration and urinary albumin excretion (r=0.68; P<.0001). Similarly, a significant association was noted between serum VEGF concentration and urinary albumin excretion (r=-0.39; P<.0001). Other urinary variables showed no correlations with either sFlt-1 or VEGF.

CONCLUSION

Even in normal pregnancy, albumin excretion is affected by an increase in placentally derived sFlt-1. If the sFlt-1 level is kept within normal range, only glomerular endothelial cells are affected and this phenomenon does not spread to the endothelial cells of a whole body.

Losartan in diabetic nephropathy

Losartan is an orally active, selective, nonpeptide, angiotensin II AT(1) receptor antagonist. Losartan 50 or 100 mg/day was significantly more effective than placebo in reducing the incidence of a doubling of serum creatinine, end-stage renal disease (ESRD) or death (43.5% vs 47.1%, p = 0.02) in a pivotal, well designed trial (Reduction of Endpoints in Non insulin dependent diabetes mellitus with the Angiotensin II Antagonist Losartan [RENAAL] study) in 1513 patients with type 2 diabetes mellitus and proteinuria. Losartan also significantly reduced the incidence of doubling of serum creatinine level (p = 0.006), ESRD (p = 0.002), ESRD or death (p = 0.01) and doubling of serum creatinine and ESRD (p = 0.01) compared with placebo in the RENAAL trial. There were similar incidences of overall mortality and morbidity and mortality from cardiovascular causes between treatment groups. In addition, data from several nonblind and double-blind studies indicates that losartan effectively reduces the mean albumin excretion rate. Two double-blind studies show that losartan has similar effects to enalapril on kidney function. Data from 4058 patients (3300 with essential hypertension) who have received losartan (10-150 mg/day) in clinical trials indicate it is well tolerated. In the RENAAL study 17.2% and 21.7% of losartan and placebo recipients discontinued treatment because of adverse events, but causality was not determined.