Effect of weight loss using formula diet on renal function in obese patients with diabetic nephropathy

Short-term changes after a weight reduction intervention in advanced diabetic nephropathy

BACKGROUND AND OBJECTIVES

Obesity precedes and is strongly linked to the development of type 2 diabetic nephropathy in most patients, yet little is known about the effects of weight reduction on this disease. This study aimed to establish proof of concept for the hypothesis that weight reduction ameliorates diabetic nephropathy.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Six obese individuals with advanced diabetic nephropathy (estimated GFR <40 ml/min per 1.73 m(2), urine albumin excretion >30 mg/d) currently taking a renin-aldosterone axis inhibitor underwent a 12-week very low calorie ketogenic weight reduction diet with encouragement of exercise between March and September 2012. Albuminuria and other parameters of kidney health were the main outcome measures.

RESULTS

There was a 12% reduction in weight (median 118.5 versus 104.3 kg, P=0.03). The intervention was associated with a 36% reduction in albuminuria that did not reach statistical significance (2124 versus 1366 mg/24 h, P=0.08) and significant reductions in the filtration markers serum creatinine (3.54 versus 3.13 mg/dl, P<0.05) and cystatin C (2.79 versus 2.46 mg/l, P<0.05). Improvements were also noted for the diabetes markers fasting glucose (166 versus 131 mg/dl, P<0.05), fasting insulin (26.9 versus 10.4 μU/ml, P<0.05), and insulin resistance (9.6 versus 4.2, P=0.03). Physical function, general health, and the number of diabetes medications also showed statistically significant signs of improvement.

CONCLUSIONS

After a short-term intensive weight reduction intervention in patients with advanced diabetic nephropathy, improvements were observed in markers of glomerular filtration, diabetes status, and risk factors for kidney disease progression, as well as other general indicators of health and well-being.

Weight-loss diets in people with type 2 diabetes and renal disease: a randomized controlled trial of the effect of different dietary protein amounts

BACKGROUND

Higher-protein weight-loss diets (defined as >25% of energy as protein) are not recommended for individuals with type 2 diabetes because of their potential adverse effect on renal function.

OBJECTIVE

We aimed to examine the effect of such diets on renal function over 12 mo in people with type 2 diabetes and early renal disease.

DESIGN

Overweight and obese people with type 2 diabetes were screened to identify those with an albumin:creatinine ratio from 3 to 30 mg/mmol. Seventy-six subjects were randomly assigned to either a moderate-protein weight-loss diet or a standard-protein weight-loss diet for 12 mo. The primary endpoint was the change in renal function as assessed by the isotope glomerular filtration rate (GFR), estimated GFR, and cystatin C. Forty-five subjects (moderate protein: n = 21; standard protein: n = 24) completed the study.

RESULTS

The mean (±SE) weight loss was not different between diets at 9.7 ± 13.4 kg for the moderate-protein diet and 6.6 ± 7.1 kg for the standard-protein diet. There were no changes in renal function or albuminuria or blood pressure, although glycated hemoglobin was lowered with both diets. Changes in renal function were related to the baseline estimated GFR. Patients with stage 1-3 renal disease (<120 mL · min(-1) · 1.73 m(-2); n = 33) had an improvement in renal function, whereas patients with hyperfiltration (>120 mL · min(-1) · 1.73 m(-2); n = 12) had a decrease in the GFR. After adjustment for weight loss, the baseline GFR remained a significant predictor of outcomes with no effect of dietary treatment. An average difference in protein intake between diets of 19 ± 6 g/d was achieved.

CONCLUSION

Weight loss improved renal function, but differences in dietary protein had no effect. This trial was registered at the Australian and New Zealand Clinical Trial Register as ACTRN12608000045314.

Obesity and kidney disease: potential mechanisms

Assessment of adiposity should include measurements of both body mass index and waist circumference. The prevalence of obesity, based on a body mass index of 30 kg/m(2) or greater, has increased substantially over the past 2 decades in Western societies. Obesity remains the number one preventable risk factor for chronic kidney disease because obesity largely mediates diabetes and hypertension, the 2 most common etiologies for end-stage kidney disease. However, obesity itself likely has independent effects on renal hemodynamics and individuals with a low number of nephrons are likely to be the most susceptible to these changes. Multiple mechanisms have been postulated whereby obesity directly impacts kidney disease including hyperfiltration, increased glomerular capillary wall tension, and podocyte stress. Weight loss reduces glomerular filtration rate and effective renal plasma flow along with proteinuria, but these changes are most notable after bariatric surgery in adults with morbid obesity. Aside from adiposity itself, the high caloric intake that leads to obesity also may heighten chronic kidney disease risk via the circuitous loop between Sirt1 and adiponectin and podocyte effacement. Sirt1 is a nicotinamide adenine dinucleotide+dependent deacteylase that is up-regulated in the setting of caloric restriction. Sirt1 expression modulates adiponectin levels that in turn appear to influence podocyte effacement. Clinical trials are needed to assess the benefits and risks of intentional weight loss on kidney disease measures and progression.

Association of a reduction in central obesity and phosphorus intake with changes in urinary albumin excretion: the PREMIER study

BACKGROUND

Excess adiposity and dietary factors may be important determinants of urinary albumin excretion (UAE).

STUDY DESIGN

Observational analysis of PREMIER, a randomized trial designed to lower blood pressure using behavioral interventions (counseling on weight loss, healthy diet, and exercise).

SETTING & PARTICIPANTS

481 participants with normal kidney function who provided adequate 24-hour urine collections at baseline and 6 months.

PREDICTORS

Change in waist circumference; 24-hour urine sodium, potassium, and phosphorus excretion; and protein intake estimated from urea nitrogen.

OUTCOMES & MEASUREMENTS

The primary outcome was change in log-transformed 24-hour UAE over 6 months.

RESULTS

After 6 months, the proportion of individuals with UAE ≥10 mg/d decreased from 18.7% to 12.7% (P < 0.001). Changes in mean waist circumference (-4.2 ± 6.6 [SD] cm), 24-hour excretion of sodium (-28.2 ± 71.7 mmol/d), potassium (+8.4 ± 27.8 mmol/d), phosphorus (-27.7 ± 314.1 mg/d), and protein intake (-1.7 ± 19.4 g/d) were observed. After adjustment for relevant covariates, the following variables were associated significantly with reduction in ln(UAE) in separate models: decrease in waist circumference (P = 0.001), decrease in 24-hour urine phosphorus excretion (P < 0.001), and decrease in protein intake (P = 0.01). In a multivariable model including these 3 predictors, decreases in waist circumference (P = 0.002) and 24-hour urine phosphorus excretion (P = 0.03), but not change in protein intake (P = 0.5), remained associated significantly with reduction in ln(UAE). These associations remained significant even after adjustment for changes in blood pressure and insulin resistance. Baseline UAE and metabolic syndrome modified the relationship of waist circumference with ln(UAE); specifically, individuals with higher UAE and baseline metabolic syndrome experienced greater reductions in ln(UAE) from decreases in waist circumference.

LIMITATIONS

Observational study with potential for confounding.

CONCLUSIONS

In adults with normal kidney function, decreases in waist circumference and 24-hour urine phosphorus excretion are associated with reductions in UAE. These findings support the rationale for clinical trials to determine whether reducing dietary phosphorus intake or waist circumference could prevent chronic kidney disease or slow its progression.

Weight loss for reduction of proteinuria in diabetic nephropathy: Comparison with angiotensin-converting enzyme inhibitor therapy

Reduction of weight in obese type 2 diabetes mellitus (T2DM) individuals is emerging as a significant strategy in the reduction of proteinuria in diabetic nephropathy along with control of hyperglycemia, hypertension, and dyslipidemia. The objective was to evaluate the reduction in 24-h proteinuria in T2DM patients with nephropathy by weight loss, with conventional therapy (angiotensin-converting enzyme [ACE] inhibitors) as the control arm. A prospective, randomized controlled trial was conducted between June 2010 and May 2011. T2DM patients with confirmed nephropathy by 24-h urinary protein estimation with a body mass index (BMI) of >25 kg/m² were studied. Patients who had nondiabetic nephropathy, uncontrolled hypertension (>125/75 mmHg) irrespective of antihypertensive drugs, excess weight due to edema or obesity due to other specific diseases, alcoholics, smokers, and patients who were on hemodialysis were excluded from the study. The patients were divided into three groups, namely, group A, patients on ACE inhibitor therapy; group B, patients on lifestyle modifications for weight loss; and group C, patients on an antiobesity drug (orlistat) and lifestyle modifications. At the end of 6 months, all the three groups were compared. Data were analyzed using software SPSS version 15.0. This study encompassed a total of 88 patients; 12 patients were dropped during the study period and 76 (group A: 22, group B: 23, and group C: 31) patients remained. The mean age of the patients was 58.36 ± 10.87 years (range: 30-70 years). At baseline, age, gender, mean BMI, waist-to-hip ratio (WHR), and 24-h proteinuria did not vary significantly among the three groups. At 6 months, the mean BMI significantly decreased in group C (P < 0.001) compared to that in the other two groups. Among the parameters BMI and WHR, the proportional form of BMI correlated well with the degree of reduction in proteinuria (r = 0.397, P = 0.01). Reduction in weight using lifestyle modifications and antiobesity drugs might improve renal function and proteinuria safely as observed in obese patients with diabetic nephropathy.

Dissecting the mechanisms of left ventricular diastolic dysfunction and inflammation in peritoneal dialysis patients

OBJECTIVE

Patients with symptoms of heart failure and preserved left ventricular (LV) systolic function are commonly encountered in clinical practice especially in peritoneal dialysis (PD) patients. We hypothesized that adiposity might influence LV diastolic function through systemic inflammation in this specific group.

METHODS

We designed a cross-sectional study in 173 prevalent PD patients. LV diastolic dysfunction was diagnosed by echocardiography. PD patient without LV diastolic dysfunction served as the control group. Serum inflammatory biomarkers were examined including tissue necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6). The location and amount of adipose tissue were assessed by computerized tomography (CT) at the level of the fourth lumbar vertebra.

RESULTS

Subjects with LV diastolic dysfunction had higher levels of the pro-inflammation cytokines and more visceral and peritoneal fat (all P<0.001) than control subjects. A significant correlation was found between visceral adipose tissue and pro-inflammatory cytokines (r = 0.70; P<0.001). Multivariable regression analysis found that the relationship between visceral adipose tissue and LV diastolic dysfunction became insignificant when either TNF-α or IL-6 were introduced into the model, although TNF-α and IL-6 were both significantly associated with LV diastolic dysfunction even after adjusting for visceral fat (OR = 1.51; 95% CI = 1.09-2.02; P = 0.033 and OR = 1.62; 95% CI = 1.09-1.82; P = 0.031, respectively).

CONCLUSIONS

Larger amounts of adipose tissue were associated with higher serum pro-inflammatory levels in PD patients, which might be related to the development of LV diastolic dysfunction. Modulating inflammatory reactions in PD patients can be a useful therapeutic approach for managing LV diastolic dysfunction.

The relationship between obesity and diabetic nephropathy in China

Background

The epidemic of diabetic nephropathy (DN) has been paralleled by rapid increases in both obesity and diabetes in China. The aim of this study was to investigate the natural history of DN and the association of obesity and renal function with diabetes.

Methods

In total, 264 patients with renal biopsy-confirmed DN were examined from 2002 to 2008 and followed up to June 2008 in our institute. Among these, 129 patients were classified into a Kidney Disease Outcomes Quality Initiative (K/DOQI) stage I subgroup. Weight status, clinico-histopathological features, the development of end-stage renal disease (ESRD) and increased proteinuria were evaluated at the baseline of biopsy and during the follow up. Lean, overweight and obese phenotypes were defined as body mass index (BMI) less than 25 kg/m², 25–28 kg/m², and more than 28 kg/m² over, respectively.

Results

In the patients with renal biopsy-confirmed DN, BMI was 25.5 ± 3.39 kg/m², with 122 (46.2%), 83 (31.4%) and 59 (22.3%) having lean, overweight and obese phenotypes, respectively. Mean proteinuria was 3.09 ± 2.32 g/24 h, serum creatinine was 2.02 ± 2.02 mg/dL, and creatinine clearance rate (Ccr) was 96.0 ± 54.0 mL/min/1.73 m². Compared with obese patients, lean patients had a lower Ccr, a higher percentage of anemia, more renal lesions and higher risk for ESRD (HR = 1.812, P = 0.048). The weight in obese patients decreased significantly after 27 months, and lean patients had a longer duration of diabetes than obese patients. Regarding patients at K/DOQI stage I, patients with DN showed similar duration of diabetes regardless of weight status. Minimal weight loss was recorded in obese patients during follow-up, and they exhibited greater glomerular hyperfiltration and higher risk for increased proteinuria (HR = 2.872, P = 0.014) than lean patients.

Conclusions

In China, obesity is common in DN patients undergoing biopsy. Initial high levels of proteinuria and subsequent weight loss are the major characteristics of the natural course of DN. Obesity contributed to increased proteinuria at an early stage, while the lean phenotype was associated with ESRD development, especially at the later stages.

Serum creatinine as a marker of muscle mass in chronic kidney disease: results of a cross-sectional study and review of literature

BACKGROUND

Higher muscle mass is associated with better outcomes and longevity in patients with chronic disease states. Imaging studies such as dual-energy X-ray absorptiometry (DEXA) are among the gold standard methods for assessing body fat and lean body mass (LBM), approximately half of which is comprised of skeletal muscle mass. Elaborate imaging devices, however, are not commonly available in routine clinical practice and therefore easily accessible and cost-effective, but reliable muscle mass biomarkers are needed. One such marker is serum creatinine, derived from muscle-based creatine, which is inexpensive and ubiquitously available, and it can serve as a biomarker of skeletal muscle mass in human subjects.

METHODS AND RESULTS

In 118 hemodialysis patients, we found that the 3-month averaged serum creatinine concentration correlated well with DEXA-measured LBM. The recent literature regarding serum creatinine as a surrogate of muscle mass is summarized, as is the literature concerning the use of other measures of muscle mass, such as plasma gelsolin and actin, and urinary creatinine excretion. We have also reviewed the role of dietary meat intake in serum creatinine variability along with several biomarkers of dietary meat intake (creatine, carnitine, carnosine, ophidine, anserine, 3-methyl-L-histidine and 1-methylhistidine).

CONCLUSION

In summary, none of these biomarkers was studied in CKD patients. We advance the hypothesis that in both health and disease, under steady state, serum creatinine can serve as a reliable muscle mass biomarker if appropriate adjustment for full or residual kidney function and dietary meat intake is undertaken.

Dendrobium moniliforme Attenuates High-Fat Diet-Induced Renal Damage in Mice through the Regulation of Lipid-Induced Oxidative Stress

Obesity is an important and preventable risk factor for renal disease. The administration of an antioxidant with a lipid-lowering effect is an important therapeutic approach for kidney disease in obese patients. The present study was conducted to examine whether methanolic extract of Dendrobium moniliforme (DM), one of the most famous traditional medicines used in many parts of the world, has an antioxidant effect in vitro and an ameliorative effect on high-fat diet (HFD)-induced alterations such as renal dysfunction and lipid accumulation in vivo. The 1,1-diphenyl-2-picrylhydrazyl radical scavenging activity of DM extract (IC50 = 29.6 μg/mL) was increased in a dose-dependent manner. The LLC-PK1 kidney cell damage induced by oxidative stress was significantly inhibited by the treatments with DM extract. In the animal study, DM extract (200 mg/kg) was orally administered every day for nine weeks to HFD-fed mice, and its effect was compared with that of metformin. The administration of DM extract decreased the elevated serum glucose, total cholesterol concentration and renal lipid accumulation in HFD-fed mice. It also ameliorated renal dysfunction biomarkers including serum creatinine and renal collagen IV deposition. Taken together, these results provide important evidence that DM extract exhibits a pleiotropic effect on obesity induced parameters and exerted a renoprotective effect in HFD-fed mice.

Effects of bariatric surgery on diabetic nephropathy after 5 years of follow-up

BACKGROUND

Studies have reported that the benefits of bariatric surgery extend beyond durable weight loss and include significant improvement in glycemic control. We hypothesized that improving diabetes control may have positive effects on end-organ complications of this disease, such as diabetic nephropathy (DN).

METHODS

We identified all patients with type 2 diabetes mellitus (T2DM) who underwent bariatric surgery at our institution and had completed a 5-year follow-up. Patients' current diabetes status (remission, improvement, or no change) was determined by biochemical analyses and medication review. The presence of DN, preoperatively and postoperatively, was determined by urinary albumin/creatinine ratio (uACR).

RESULTS

Fifty-two T2DM patients underwent bariatric surgery and had completed 5-year follow-up, including serial uACR measurements (25% male; age 51.2 ± 10.1 years). Preoperative body mass index (BMI) was 49 ± 8.7 kg/m(2), mean duration of T2DM was 8.6 years (range .3-39), and baseline HbA(1c) was 7.7% ± 1.4%. DN, as indicated by microalbuminuria (30-300 mg/g) or macroalbuminuria (>300 mg/g), was present in 37.6% preoperatively. Of these, DN resolved in 58.3% at a mean follow-up of 66 months (range 60-92 ). Among those with no evidence of DN preoperatively, albuminuria proceeded to develop 5 years later in only 25%. The 5-year remission and improvement rates for T2DM were 44% and 33%, respectively. Mean reductions in fasting glucose and glycosylated hemoglobin (HbA(1c)) were 36.6 mg/dL and 1.2%, respectively.

CONCLUSION

Bariatric surgery can induce a significant and sustainable improvement in T2DM and improve or halt the development of microvascular complications such as nephropathy. Considering that diabetes is often a progressive disease, these results are clinically important and warrant further investigation.

The effect of weight loss in obesity and chronic kidney disease

Several epidemiologic investigations have confirmed that obesity is a significant risk factor for the appearance of proteinuria and end-stage kidney disease in a normal population. Weight loss induced by low-calorie diets, physical exercise, or bariatric surgery is accompanied by an important antiproteinuric effect. Reduction in proteinuria is already observed after a few weeks from the onset of weight loss and it is evident even in patients with modest weight losses. Reduction in proteinuria by weight loss has been described in chronic proteinuric nephropathies of different etiologies. The mechanisms through which weight loss may reverse proteinuria are likely to be plural: better control of blood pressure, improvement of serum lipid profile, improvement of insulin sensitivity, better glycemic control in diabetes patients, decrease of circulating leptin levels, reversal of glomerular hyperfiltration, and decreased activation of the renin-angiotensin-aldosterone system.

Early improvement in albuminuria in non-diabetic patients after Roux-en-Y bariatric surgery

BACKGROUND

Obesity is a growing epidemic in the USA that has been shown to be associated with chronic kidney disease and albuminuria. Bariatric surgery is an effective means of achieving long-term weight loss and improvements in metabolic derangements including albumin excretion over the long term.

METHODS

We report changes in urinary albumin excretion levels in the early post-operative period for a euglycemic, predominantly Hispanic American cohort undergoing Roux-en-Y gastric bypass surgery.

RESULTS

Our cohort of 38 patients was largely female (89.5%) and predominantly Hispanic (76.3%) with a mean BMI of 46 ± 8.0 kg/m(2). Over half (53.3%) of the patients with significant preoperative albumin excretion in our cohort lowered their albumin excretion levels to <20 mg/g of creatinine. This early reduction in albumin excretion in our cohort correlated significantly with the level of albumin excretion preoperatively but not with the degree of weight loss experienced in this early post-operative period.

CONCLUSIONS

Improvements in microalbuminuria in the early post-operative period after Roux-en-Y surgery may result from an interplay between changes in gastrointestinal hormones, insulin sensitivity, blood pressure, and adipose tissue-and needs further study.

Management of obesity-induced kidney disease: a critical review of the literature

It is well established that obesity is a risk factor for the development of chronic kidney disease (CKD) and may promote the progression to end stage renal disease (ESRD). Therefore, it is strongly suggested that reduction of body weight can be an important intervention in order to reduce the prevalence of renal impairment. The current article describes extensively the already published trials which have studied the association between weight loss and kidney disease. The weight management programs include surgical and non-surgical interventions (low-calorie diet, aerobic exercise, drug-induced weight loss, combination treatment). The focus has been placed on the following renal function markers: albuminuria, proteinuria, glomerular filtration rate (GFR), and creatinine clearance. This review also aims to clarify challenges that clinicians have to deal with in everyday practice regarding the management of obesity-induced kidney disease (degree of weight loss, duration of the weight loss program, early initiation of the intervention).

Benefits of staple food restriction for Japanese obese patients with chronic kidney disease: a pilot study

OBJECTIVE

We conducted a pilot study to assess the effects of dietary intervention on metabolic risk factors and renal parameters in obese patients with chronic kidney disease (CKD).

METHODS

We studied 19 obese patients with CKD at our outpatient clinic. The diet selected for this study restricted only their staple food intake, with no change in the side dish component of their meals. We studied neither the lifestyles of the patients nor the activities that they were involved in. We examined changes in clinical and laboratory parameters at baseline and after consumption of the diet.

RESULTS

After 2 and 6 months of staple food restriction, changes in body weight were found to be -3.6% ± 3.9% and -3.4% ± 4.7%, respectively. Of the 19 patients, the body weights of 9 decreased by >3% (range: 3.4% to 17.1%) from baseline to follow-up at 6 months. After 6 months of following the diet, these 9 patients showed marked reductions in blood pressure, homeostasis model assessment insulin resistance, and triglycerides, when compared with the remaining 10 patients with stable body weights; however, for proteinuria and estimated glomerular filtration rate they reported having values similar to the 10 patients with stable body weights.

CONCLUSIONS

Weight reduction associated with a lowered insulin resistance was reported in obese patients with CKD after 6 months of staple food restriction; however, further studies need to be conducted to confirm the presence of other possible renal benefits.

Obesity-related glomerulopathy: body mass index and proteinuria

BACKGROUND AND OBJECTIVES

Obesity-related glomerulopathy (ORG) is an increasing cause of end-stage renal disease, but evidence concerning the effects of treatments is rather limited. This study was aimed at exploring the renoprotective effects of weight loss on patients with ORG.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

A total of 63 patients with renal biopsy-proven ORG had food and exercise intervention in the physician-supervised weight loss program and were divided into three groups on the basis of the percentage of weight change from baseline to follow-up: significant weight loss (>3% reduction in body mass index [BMI]), stable weight, or significant weight gain (>3% increase). Metabolic parameters and renal lesions were evaluated regularly for 2 years.

RESULTS

After 6 months, 27 patients lost weight by 8.29 +/- 4.00%, with a mean decrease in proteinuria of 35.3%, whereas 24 months later, 27 patients achieved a 9.20 +/- 3.78% reduction in BMI and a 51.33% reduction in urine protein secretion. The levels of serum triglyceride, serum uric acid, and BP were also decreased. Contrarily, in patients with increased BMI, urine protein was increased by 28.78%. Correlation analysis showed proteinuria was associated with BMI, serum triglyceride, and uric acid, and multivariate regression analysis indicated the changes in BMI were the only predictor of proteinuria (P < 0.01).

CONCLUSIONS

Weight loss intervention benefited remission of proteinuria in patients with ORG, whose function could not be replaced by conventional pharmacotherapy.

Urinary albumin excretion, HMW adiponectin, and insulin sensitivity in type 2 diabetic patients undergoing bariatric surgery

BACKGROUND

Microalbuminuria portends an increased risk for renal and cardiovascular diseases in diabetes. In this pilot study, we determined the effect of weight loss induced by different types of bariatric surgery on albuminuria in severely obese type 2 diabetic (T2DM) subjects.

METHODS

Fifteen consecutive T2DM patients (9M/6F, 51+/-14 years, body mass index (BMI) 49+/-9 kg/m2, HbA1c 7.2+/-1.1 percent) undergoing either Roux-en-Y gastric bypass (RYGB; N=9) or other types of bariatric surgery (N=6) underwent determination of urine albumin/creatinine ratio (UACR) and adipokine and insulin sensitivity during a mixed meal tolerance test performed 2 weeks prior to and 6 months following surgery.

RESULTS

Following RYGB, there was a significant decrease in BMI ((-4.74)+/-(-5.05) kg/m2), fasting glucose, cholesterol, and leptin levels. Insulin sensitivity (Matsuda index [12.05+/-3.81, p=0.003]) and high molecular weight (HMW) adiponectin increased significantly along with a significant reduction in UACR (median, 36 mg/g [7-94] vs. 27 mg/g [5.5-42.5], p=0.01). The reduction in UACR following RYGB was inversely correlated with the Matsuda index (r=-0.74), p=0.02) and HMW adiponectin (r=(-0.67), p=0.04). In contrast, despite reduction in BMI ((-4.11)+/-(-4.10) kg/m2) following other types of bariatric surgery (n=6), there was no significant improvement in insulin sensitivity (0.88+/-2.40, p=0.63), UACR, or HMW adiponectin levels.

CONCLUSIONS

RYGB in severely obese DM subjects is associated with a reduction in albuminuria that correlates to the improvement in insulin sensitivity and HMW adiponectin. The data point to a need for larger studies to confirm these findings and evaluate the micro-macrovascular benefits including renal parenchymal benefits of different types of bariatric surgery in T2DM.

Body weight control by a high-carbohydrate/low-fat diet slows the progression of diabetic kidney damage in an obese, hypertensive, type 2 diabetic rat model

Obesity is one of several factors implicated in the genesis of diabetic nephropathy (DN). Obese, hypertensive, type 2 diabetic rats SHR/NDmcr-cp were given, for 12 weeks, either a normal, middle-carbohydrate/middle-fat diet (MC/MF group) or a high-carbohydrate/low-fat diet (HC/LF group). Daily caloric intake was the same in both groups. Nevertheless, the HC/LF group gained less weight. Despite equivalent degrees of hypertension, hyperglycemia, hyperlipidemia, hyperinsulinemia, and even a poorer glycemic control, the HC/LF group had less severe renal histological abnormalities and a reduced intrarenal advanced glycation and oxidative stress. Mediators of the renoprotection, specifically linked to obesity and body weight control, include a reduced renal inflammation and TGF-beta expression, together with an enhanced level of adiponectin. Altogether, these data identify a specific role of body weight control by a high-carbohydrate/low-fat diet in the progression of DN. Body weight control thus impacts on local intrarenal advanced glycation and oxidative stress through inflammation and adiponectin levels.

Weight loss and proteinuria: systematic review of clinical trials and comparative cohorts

BACKGROUND

Obesity is a risk factor for the progression of chronic kidney disease (CKD). The impact of weight loss on proteinuria and renal function is less clear. We aimed to determine the effect of intentional weight loss on proteinuria and kidney function.

METHODS

Three bibliographic databases including Medline, Cochrane and SCUPOS as well as reference list of articles were searched. We included randomized and non-randomized controlled trials as well as single-arm trials published in English through May 2009 which examined urinary protein among obese or overweight adults before and after weight loss interventions including dietary restriction, exercise, anti-obesity medications and bariatric surgery. Study characteristics and methodological quality of trials were assessed.

RESULTS

Five hundred twenty-two subjects from five controlled and eight uncontrolled trials were included. Weight loss interventions were associated with decreased proteinuria and microalbuminuria by 1.7 g [95% confidence interval (95% CI), 0.7 to 2.6 g] and 14 mg (95% CI, 11 to 17 mg), respectively (P < 0.05). Meta-regression showed that, independent of decline in mean arterial pressure, each 1 kg weight loss was associated with 110 mg (95% CI, 60 to 160 mg, P < 0.001) decrease in proteinuria and 1.1 mg (95% CI, 0.5 to 2.4 mg, P = 0.011) decrease in microalbuminuria, respectively. The decrease was observed across different designs and methods of weight loss. Only bariatric surgery resulted in a significant decrease in creatinine clearance.

CONCLUSIONS

Weight loss is associated with decreased proteinuria and microalbuminuria. There were no data evaluating the durability of this decrease or the effect of weight loss on CKD progression.

Weight loss interventions in chronic kidney disease: a systematic review and meta-analysis

BACKGROUND AND OBJECTIVES

Obesity is an independent risk factor for development and progression of chronic kidney disease (CKD). We conducted a systematic review to assess the benefits of intentional weight loss in patients with non-dialysis-dependent CKD and glomerular hyperfiltration.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We searched MEDLINE, SCOPUS, and conference proceedings for randomized, controlled trials and observational studies that examined various surgical and nonsurgical interventions (diet, exercise, and/or antiobesity agents) in adult patients with CKD. Results were summarized using random-effects model.

RESULTS

Thirteen studies were included. In patients with CKD, body mass index (BMI) decreased significantly (weighted mean difference [WMD] -3.67 kg/m(2); 95% confidence interval [CI] -6.56 to -0.78) at the end of the study period with nonsurgical interventions. This was associated with a significant decrease in proteinuria (WMD -1.31 g/24 h; 95% CI -2.11 to -0.51) and systolic BP with no further decrease in GFR during a mean follow-up of 7.4 mo. In morbidly obese individuals (BMI >40 kg/m(2)) with glomerular hyperfiltration (GFR >125 ml/min), surgical interventions decreased BMI, which resulted in a decrease in GFR (WMD -25.56 ml/min; 95% CI -36.23 to -14.89), albuminuria, and systolic BP.

CONCLUSIONS

In smaller, short-duration studies in patients with CKD, nonsurgical weight loss interventions reduce proteinuria and BP and seem to prevent further decline in renal function. In morbidly obese individuals with glomerular hyperfiltration, surgical interventions normalize GFR and reduce BP and microalbuminuria. Larger, long-term studies to analyze renal outcomes such as development of ESRD are needed.

The Why WAIT program: improving clinical outcomes through weight management in type 2 diabetes

Targeting body weight, as an alternative model to targeting hemoglobin A(1c), is emerging as a viable and potentially cost-effective approach to diabetes management in clinical practice. Why WAIT (Weight Achievement and Intensive Treatment) is a 12-week multidisciplinary program for weight control and intensive diabetes management specifically designed for application in routine diabetes practice. The program, which is generally covered by insurance, is followed by continuous support aimed at long-term maintenance of weight loss and diabetes control. This model was effective in improving key metabolic abnormalities observed in diabetic patients. Eighty-two percent of participants achieved the target hemoglobin A(1c) of less than 7% on less diabetes medications. The achieved weight reduction after 12 weeks of intervention was maintained for an additional year. Future dissemination of this intervention model in routine clinical practice may require wider endorsement by third-party payers and support of governmental health care agencies to halt the progression of the epidemic of obesity and diabetes in the United States.

Oxidative stress and potential interventions to reduce oxidative stress in overweight and obesity

PURPOSE

Obesity may be a state of chronic oxidative stress. Oxidative stress may be the mechanism underlying the development of co-morbidities in obesity. This review provides a summary of the available evidence regarding systemic oxidative stress in young, older and clinical obese populations.

METHODS

Medline was searched for all available articles published between 1975 and 2006 that evaluated oxidative stress biomarkers in resting conditions or following various interventions in overweight and obese humans.

RESULTS

Obesity elevates oxidative stress in young, old and clinical populations as shown by elevations in lipid peroxidation (malondialdehyde, hydroperoxides, 4-hydroxynonenal, isoprostanes, conjugated dienes) or protein oxidation (8-hydroxy-deoxyguanosine). Lipid peroxidation is associated with several indices of adiposity and a low systemic antioxidant defence (i.e. antioxidant enzymes, tissue dietary antioxidants, glutathione). Oxidative stress may be exacerbated with acute exercise, advancing age or co-existing clinical conditions and may be corrected by improving antioxidant defences through fat volume reduction via surgery, pharmacological agents, exercise and/or dietary modification.

CONCLUSION

Oxidative stress is related to chronic disease in obesity, but is reversible with one or more interventions described above.

Bariatric surgery for morbid obesity: risks and benefits in chronic kidney disease patients

Obesity is one of the most preventable causes of morbidity and mortality of the 21st century. Chronic kidney disease (CKD) has been a largely overlooked consequence of obesity; however, accumulating evidence elucidates the association. Obesity is at the core, promoting a cascade of secondary pathologies including diabetes, dyslipidemia, inflammation, hypertension, and the metabolic syndrome; these comorbidities constitute great risk for CKD. With the diagnosis of CKD, there is an increased threat of cardiovascular disease and the attendant increase in morbidity and mortality rates. Substantial weight loss in the obese population can be effectively achieved and maintained through bariatric surgery, which confers major health benefits by producing resolution or improvement of obesity-related comorbidities. This surgical procedure presents an early hazard of acute on chronic kidney failure, which is offset by a potential improvement in the risk of CKD progression with anticipated improvement in hypertension, diabetes, and CKD risk factors. Future research is needed to describe the clinical course and risks and benefits of bariatric surgery in the CKD population.

Emerging global epidemic of obesity: the renal perspective

Obesity, as a core component of the metabolic syndrome, is among the top ten global health risks classified by the World Health Organization (WHO) as being strongly associated with the development and progression of chronic renal disease--a widely prevalent but often silent condition. Obesity carries elevated risks of cardiovascular morbidity and mortality besides having an array of metabolic complications. Maladaptive glomerular hemodynamics with increased intraglomerular pressure in association with vasoactive, fibrogenic substances released from adipocytes, in addition to cytokines and hormones, are the key factors in the causation of renal injury and the progression of nephron loss among obese subjects.