Type 2 diabetes mellitus and microvascular complications 1 year after Roux-en-Y gastric bypass: a case-control study

The effect of bariatric surgery on diabetes related foot complications among patients with type 2 diabetes: A systematic review

BACKGROUND

Bariatric surgery leads to considerable weight loss and improved glycaemic control and seems to have a favourable impact on diabetes related foot complications (DFC).

OBJECTIVES

To assess the effect of bariatric surgery on diabetes related foot complications in patients with type 2 diabetes and determine whether DFC symptoms are improved after bariatric surgery.

METHODS

We searched MEDLINE, Embase and Cochrane Central Register of Controlled Trials. The primary outcome was the presence of DFC after bariatric surgery. The secondary outcome was the improvement of DFC after bariatric surgery among patients who already had DFC before surgery.

RESULTS

There were nine studies showing the presence of DFC post bariatric surgery and six detailing the changes in DFC post bariatric surgery. Bariatric surgery was not associated with a lower risk of developing or worsening DFC compared to conventional medical treatment based on 4 randomised control trials (IR 0.87, 95 % CI, 0.26, 2.98), while from observational studies was associated with 51 % lower risk of DFC (IR 0.49, 95 % CI, 0.31, 0.77). Bariatric surgery was associated with improvement in diabetic neuropathy assessment parameters including toe tuning fork score, self-reported neuropathy symptoms, neuropathy symptom score, and neuropathy symptom profile.

CONCLUSION

Bariatric surgery led to a greater reduction in developing or worsening DFC among patients with type 2 diabetes compared to medical treatment in observational studies, but not among RCTs. Bariatric surgery was associated with improvements in diabetic neuropathy related assessment parameters and symptoms. Bariatric surgery could be a promising treatment for patients with type 2 diabetes who are at high risk of DFC.

Remission of corneal and peripheral neuropathy after bariatric surgery in people with diabetes

PURPOSE

Diabetic peripheral neuropathy can be detected using non-invasive in vivo confocal microscopy of the cornea (IVCM) and such abnormalities may precede the development of clinical neuropathy. The current study aimed to assess any progression or remission of corneal and peripheral neuropathy in patients with type 2 diabetes undergoing bariatric surgery.

METHODS

People with known type 2 diabetes for at least five years and listed for bariatric surgery were recruited. Participants were assessed before, and 12, 26, and 52 weeks following bariatric surgery. IVCM and corneal sensitivity measurements were performed. A modified total neuropathy score (mTNS) was obtained from neuropathy questionnaire, clinical assessment and biothesiometry.

RESULTS

Twenty-nine participants (M:F, 11:18) with mean BMI of 44.7 ± 6.4 kg/m2, and 11 ± 7.6 years duration of diabetes, were assessed. Corneal sub-basal nerve fibre length (CNFL), displayed an increase from a baseline mean of 12.20 ± 1.00 to 17.48 ± 0.92 mm/mm2 at 52 weeks (p < 0.0001). Corneal sensitivity threshold displayed a decrease over time, thus corneal sensitivity improved, falling from a mean of 1.11 ±0 .15 to 0.62 ± 0.11 (mBAR) (p < 0.0001). Clinical neuropathy scores demonstrated significant improvements from baseline, displaying a decrease in average mTNS score from 3.29 ± 0.68 to 0.76 ± 0.30 (p < 0.0001). A significant inverse relationship was shown between CNFL and sensitivity (β coefficient = -0.047, p < 0.001), and CNFL and mTNS (β coefficient = -0.178, p < 0.001).

CONCLUSION

Bariatric surgery led to an improvement in metabolic control of diabetes and weight loss, along with improvement in corneal nerve microstructure, corneal sensitivity, and neuropathic symptoms, suggesting a reversal of both small and large fibre neuropathy.

Obesity-Related Glomerulopathy: Clinical Management

Obesity-related glomerulopathy (ORG) and other obesity-associated kidney diseases pose a major challenge to the treating nephrologist. We review the benefits of weight loss and optimal management of ORG and kidney disease in the setting of obesity. Therapeutic strategies in ORG were limited mainly in the past to weight loss through lifestyle interventions and bariatric surgery, antihypertensive treatment, and renin-angiotensin-aldosterone system blockade. Current approaches to obtain the desired weight loss include novel pharmacologic therapies that have been approved for the treatment of diabetes while offering kidney protection, such as sodium-glucose cotransporter-2 inhibitors and glucagon-like peptide-1-receptor agonists. This review focuses on the nephroprotective role of the renin-angiotensin-aldosterone system blockade and of these new pharmacologic agents, and on the renal effects of bariatric surgery in chronic kidney disease.

Improvement of Renal Function After Bariatric Surgery: a Systematic Review and Meta-analysis

BACKGROUND/OBJECTIVE

The effect of bariatric surgery in renal function varies and the postoperative benefit time point remains unclear. We aim to assess the changes of renal function after bariatric surgery (BS) in different postoperative periods and subgroups.

METHODS

We searched the databases of PubMed and Cochrane from inception to December 14, 2020. Articles included in the study were drawn from all recipients of BS that provided assessments of renal function pre and post-surgery. Meta-analysis was performed to compare glomerular filtration rate (GFR), serum creatinine, albumin-to-creatinine ratio (ACR), and albuminuria before and after BS.

RESULTS

The study included 49 articles involving 8515 patients. Compared with pre-operative renal function, the overall analysis showed that bariatric surgery significantly reduced serum creatinine levels, ACR, and albuminuria. There was significant increase of GFR in the CKD subgroup, yet a noticeable decrease in the hyperfiltration subgroup. The most significant improvement in GFR was seen 6-12 months after BS, while ACR dropped most dramatically 12-24 months after BS.

CONCLUSIONS

Bariatric surgery can improve renal function in obese patients with kidney dysfunction, especially 1 year after surgery.

Outcomes of Diabetic Retinopathy Post-Bariatric Surgery in Patients with Type 2 Diabetes Mellitus

Bariatric surgery is an emerging therapeutic approach for obese type 2 diabetes mellitus (T2DM) patients, with proven benefits for achieving target glucose control and even remission of diabetes. However, the effect of bariatric surgery upon diabetic retinopathy is still a subject of debate as some studies show a positive effect while others raise concerns about potential early worsening effects. We performed a systematic review, on PubMed, Science Direct, and Web of Science databases regarding the onset and progression of diabetic retinopathy in obese T2DM patients who underwent weight-loss surgical procedures. A total of 6375 T2DM patients were analyzed. Most cases remained stable after bariatric surgery (89.6%). New onset of diabetic retinopathy (DR) was documented in 290 out of 5972 patients (4.8%). In cases with DR at baseline, progression was documented in 50 out of 403 (12.4%) and regression in 90 (22.3%). Preoperative careful preparation of hemoglobin A1c (HbA1c), blood pressure, and lipidemia should be provided to minimize the expectation of DR worsening. Ophthalmologic follow-up should be continued regularly in the postoperative period even in the case of diabetic remission. Further randomized trials are needed to better understand the organ-specific risk factors for progression and provide personalized counseling for T2DM patients planned for bariatric surgery.

Corneal Keratocyte Density and Corneal Nerves Are Reduced in Patients With Severe Obesity and Improve After Bariatric Surgery

Purpose

Obesity is associated with peripheral neuropathy, which bariatric surgery may ameliorate. The aim of this study was to assess whether corneal confocal microscopy can show a change in corneal nerve morphology and keratocyte density in subjects with severe obesity after bariatric surgery.

Methods

Twenty obese patients with diabetes (n = 13) and without diabetes (n = 7) underwent assessment of hemoglobin A1c (HbA1c), lipids, IL-6, highly sensitive C-reactive protein (hsCRP), and corneal confocal microscopy before and 12 months after bariatric surgery. Corneal nerve fiber density (CNFD), corneal nerve branch density (CNBD), corneal nerve fiber length (CNFL), and keratocyte density (KD) from the anterior, middle, and posterior stroma were quantified. Twenty-two controls underwent assessment at baseline only.

Results

CNFL (P < 0.001), CNBD (P < 0.05), and anterior (P < 0.001), middle (P < 0.001), and posterior (P < 0.001) keratocyte densities were significantly lower in obese patients compared to controls, and anterior keratocyte density (AKD) correlated with CNFL. Twelve months after bariatric surgery, there were significant improvements in body mass index (BMI; P < 0.001), HDL cholesterol (P < 0.05), hsCRP (P < 0.001), and IL-6 (P < 0.01). There were significant increases in CNFD (P < 0.05), CNBD (P < 0.05), CNFL (P < 0.05), and anterior (P < 0.05) and middle (P < 0.001) keratocyte densities. The increase in AKD correlated with a decrease in BMI (r = -0.55, P < 0.05) and triglycerides (r = -0.85, P < 0.001). There were no significant correlations between the change in keratocyte densities and corneal nerve fiber or other neuropathy measures.

Conclusions

Corneal confocal microscopy demonstrates early small fiber damage and reduced keratocyte density in obese patients. Bariatric surgery leads to weight reduction and improvement in lipids and inflammation and an improvement in keratocyte density and corneal nerve regeneration.

The Impact of Bariatric Surgery on Diabetic Retinopathy: A Systematic Review and Meta-Analysis

OBJECTIVE

While bariatric surgery induces remission of type 2 diabetes mellitus and reduces other microvascular complications, its impact on diabetic retinopathy (DR) is unclear. Some trials suggest early worsening of DR postsurgery because of rapid improvements in hyperglycemia. This meta-analysis sought to estimate the impact of bariatric surgery on DR for obese patients compared with medical treatment.

DESIGN

Systematic review and meta-analysis.

METHODS

The Medline, Embase, and PubMed Central databases were searched to March 2020. Primary studies comparing DR in patients undergoing bariatric surgery with those undergoing medical management were included. Results were meta-analyzed using a random-effects model. Primary outcomes included prevalence of all DR and sight-threatening DR after surgery. Secondary outcomes included worsening of DR within and beyond 12 months.

RESULTS

Overall, 14 studies comprised of 110,300 surgical patients and 252,289 control subjects were included. Surgical patients had a statistically significantly lower postoperative prevalence of all DR (relative risk [RR] 0.17 [95% confidence interval {CI} 0.13-0.22]) and sight-threatening DR (RR 0.47 [95% CI 0.27-0.82]). Early worsening of DR and progression to sight-threatening DR had occurred more often in those with more severe DR initially. However, beyond 12 months, bariatric surgery resulted in significantly fewer patients with worsened DR (RR 0.29 [95% CI 0.16-0.54]). The overall risk of bias was low; estimates of relative effects had low to moderate certainty of evidence.

CONCLUSION

While bariatric surgery was associated with fewer cases of all and sight-threatening DR, early worsening was more severe in patients with existing sight-threatening DR. These findings argue for frequent monitoring during the first postoperative year.

Effect of Bariatric Surgery on Diagnosed Chronic Kidney Disease and Cardiovascular Events in Patients with Insulin-treated Type 2 Diabetes: a Retrospective Cohort Study from a Large UK Primary Care Database

Aims

To compare the effect of bariatric surgery on renal, chronic kidney disease (CKD) and cardiovascular (CV) outcomes among obese patients with insulin-treated type 2 diabetes (T2D) with and without microalbuminuria (i.e., uACR > 3.0 mg/mmol).

Methods

A retrospective cohort study was conducted among 11,125 active patients with T2D from The Health Improvement Network (THIN) database. Propensity score matching (up to 1:6 ratio) was used to identify patients who underwent bariatric surgery (N = 131) with a non-bariatric cohort (N = 579). Follow-up was undertaken for 10 years (6487 person-years) to compare differences in risk of cardiovascular events and in renal outcomes.

Results

For the matched cohort at baseline: mean age 52 ± 13 years (60% female); weight 116 ± 25 kg, body mass index (BMI) 41 ± 9kg/m², estimated glomerular filtration rate (eGFR); 70.4 ± 20 mL/min/1.73 m², and median albumin-creatinine ratio (uACR) 2.0 mg/mmol (interquartile range (IQR): 0.9–5.2 mg/mmol). Bariatric surgery was associated with a 54% reduction in developing CKD compared to their matched non-bariatric cohort (adjusted hazard ratio [aHR]: 0.46; 95%CI: 0.24–0.85, P = 0.02). Among patients with microalbuminuria at baseline, bariatric surgery was protective against CKD (aHR: 0.42, 95%CI: 0.18–0.99, P = 0.050). eGFR was significantly increased from baseline favouring the bariatric group during 75% of the follow-up time (calculated mean difference between groups: 4.1 mL/min/1.73 m²; P < 0.05), especially at 5-year point (74.2 vs 67.8 mL/min/1.73 m²; P < 0.001). However, no significant change was observed with non-fatal CVD episodes (aHR: 0.36, 95%CI: 0.11–1.13, P = 0.079). Albumin levels were significantly reduced throughout the 2 years following the surgery (3.9 vs 4.1 g/dL, P < 0.001). uACR and total protein levels had little or no statistical association to the intervention.

Conclusion

Bariatric surgery may protect patients with diabetes with or without microalbuminuria against the risk of CKD and with a modest protective effect on non-fatal CVD risk. Bariatric surgery is also associated with improvements in overall renal outcomes such as eGFR.

The Effect of Bariatric Surgery versus Intensive Medical Care on Prevention of Microalbuminuria in Patients with Type 2 Diabetes: 3 Year Experience of a Prospective Study

BACKGROUND: Bariatric surgery could improve diabetic kidney disease; however, the effect of surgery versus medical therapy on renal out comes needs further evaluation. AIM: The aim of the study was to investigate the effect of sleeve-gastrectomy versus intensive medical therapy on the prevention of albuminuria in patients with Type 2 diabetes mellitus (T2DM). METHODS: This is a prospective study of 33 patients with T2DM undergoing sleeve gastrectomy matched for age, sex, and duration of diabetes to 64 medically treated patients. Urinary albumin/creatinine ratio (uACR) was assessed before and 3–year after intervention. RESULTS: At baseline, there was no significant difference between surgical and medical group regarding body mass index (BMI), blood pressure, Hemoglobin A1c (HbA1c), or uACR. After 3 years of interventions the mean BMI (kg/m2) and HbA1c (%) became significantly lower in the surgical group compared to medical group. Although mean uACR (g/mg) increased after interventions compared to its levels before interventions in both surgical (11.7 ± 4.8 vs.18.2 ± 5.9) g/mg and medical (13.4 ± 4.5 vs.17.1 ± 6) g/mg groups, albuminuria developed in only three surgical patients and two medical patients (p > 0.05). CONCLUSION: Although bariatric surgery is associated with more reduction in body weight and better glycemic control than intensive medical therapy, sleeve-gastrectomy may not be superior to intensive medical care in prevention of microalbuminuria in patients with T2DM.

Improvements in Diabetic Neuropathy and Nephropathy After Bariatric Surgery: a Prospective Cohort Study

PURPOSE

There are limited data on the impact of bariatric surgery on microvascular complications of type 2 diabetes (T2D), particularly diabetic neuropathy. We assessed microvascular complications (especially neuropathy) in obese patients with T2D before and 12 months after bariatric surgery.

MATERIALS AND METHODS

This was a prospective observational cohort study. Measurements of neuropathy symptom profile (NSP), neuropathy disability score (NDS), vibration (VPT), cold (CPT) and warm (WPT) perception thresholds, nerve conduction studies (NCS) and corneal confocal microscopy (CCM) to quantify corneal nerve fibre density (CNFD), branch density (CNBD) and fibre length (CNFL); urinary albumin/creatinine ratio (uACR), estimated glomerular filtration rate (eGFRcyst-creat) and retinal grading were taken.

RESULTS

Twenty-six (62% female; median age 52 years) obese patients with T2D were recruited. Body mass index (BMI) (47.2 to 34.5 kg/m2; p < 0.001) decreased post-operatively. There were improvements in CNFD (27.1 to 29.2/mm2; p = 0.005), CNBD (63.4 to 77.8/mm2; p = 0.008), CNFL (20.0 to 20.2/mm2; p = 0.001), NSP (3 to 0/38; p < 0.001) and eGFRcyst-creat (128 to 120 ml/min; p = 0.015) post-bariatric surgery. Changes in (Δ) triglycerides were independently associated with ΔCNFL (β = - 0.53; p = 0.024) and Δsystolic blood pressure (β = 0.62;p = 0.017), and %excess BMI loss (β = - 0.004; p = 0.018) were associated with ΔeGFRcyst-creat. There was no significant change in NDS, VPT, CPT, WPT, NCS, uACR or retinopathy status. Glomerular hyperfiltration resolved in 42% of the 12 patients with this condition pre-operatively.

CONCLUSION

Bariatric surgery results in improvements in small nerve fibres and glomerular hyperfiltration in obese people with T2D, which were associated with weight loss, triglycerides and systolic blood pressure, but with no change in retinopathy or uACR at 12 months.

The effects of metabolic surgery on microvascular complications in obese patients with type 2 diabetes: a meta-analysis

BACKGROUND

Metabolic surgery is a standard treatment for obesity with type 2 diabetes (T2D), although the effects of metabolic surgery on the incidence rate of microvascular complications remain controversial.

OBJECTIVES

We aimed to evaluate the effect of metabolic surgery versus nonsurgical treatments on the incidence rate of microvascular complications in obesity with T2D.

SETTING

A meta-analysis of published studies.

METHODS

We searched PubMed, Web of Science, and the Cochrane Library to identify clinical studies assessing the effect of metabolic surgery on the incidence rate of microvascular diabetic complications compared with that of nonsurgical treatments. We extracted the primary outcomes, including the incidence rate of microvascular complications after metabolic surgery.

RESULTS

A total of 32,756 participants from 12 studies were identified. Metabolic surgery reduced the incidence rate of microvascular complications (odds ratios [OR], .34; 95% confidence intervals [CI], .30-.39; P < .001) compared with that of nonsurgical treatments in obesity with T2D. Moreover, metabolic surgery also reduced the incidence of diabetic nephropathy (OR, .39; 95% CI, .30-.50; P < .001), diabetic retinopathy (OR, .52; 95% CI, .42-.65; P < .001) and diabetic neuropathy (OR, .27; 95% CI, .22-.34; P < .001) compared with nonsurgical treatments in obesity with T2D.

CONCLUSION

Metabolic surgery was superior to nonsurgical treatments in reducing the incidence of microvascular complications in obesity with T2D. Prospective studies, preferably randomized controlled trials, with evaluations of different types of metabolic surgery are warranted to provide guidelines for treatment preferences in obesity with T2D.

Bariatric Surgery Induces Retinal Thickening Without Affecting the Retinal Nerve Fiber Layer Independent of Diabetic Status

PURPOSE

Obese patients have neurodegeneration of the optic nerve demonstrated by decreased peripapillary nerve fiber layer. Whether bariatric surgery reverses this neurodegenerative process has not been explored. We aimed to evaluate the impact of bariatric surgery in the structure of the retina and optic nerve.

METHODS

Multicentric observational study. Obese patients scheduled for bariatric surgery were consecutively recruited and included in the study and evaluated before and 6-12 months after the intervention. The retinal structure was evaluated as retinal thickness in the different retinal layers in the foveal, perifoveal, and parafoveal regions using optical coherence tomography. Choroidal thickness and optic nerve retinal nerve fiber layer thickness were also evaluated.

RESULTS

Eighty eyes from 40 participants were included. Globally, we found a significant thickening of the retina after bariatric surgery (foveal: 273.5 (21.5) μm vs 280.0 (28.8) μm, p < 0.001; parafoveal 332.4 ± 17.8 μm vs 336.6 ± 15.9 μm, p = 0.003; perifoveal: 293.4 ± 13.8 μm vs 295.7 ± 14.9 μm; p = 0.001), whereas no significant differences were found for the ganglion cell layer, choroid, or peripapillary nerve fiber layer thickness. The retinal thickening was confined to inner retinal layers and was independent of the diabetic status of the patients. After multivariate adjustment, HbA1c variation, preoperative C-peptide, preoperative hypertension, preoperative OSA, and preoperative LDL and TG levels seem to be clinical predictors of retinal thickening.

CONCLUSIONS

We found a significant thickening of the retina after bariatric surgery that was independent of the diabetic status. The thickening was confined to inner retinal layers and may represent and improve perfusion. The peripapillary nerve fiber layer remained unchanged after the surgery.

Metabolic and cardiovascular outcomes of bariatric surgery

PURPOSE OF REVIEW

Bariatric surgery is an effective therapy for morbid obesity that also improves weight-related metabolic parameters and reduces morbidity and mortality. The purpose of this review is to consolidate our current understanding of metabolic, macrovascular and microvascular benefits of bariatric surgery and to provide an update.

RECENT FINDINGS

Early resolution of insulin resistance and type 2 diabetes mellitus (T2DM) varies by type of bariatric surgery and appears to be mediated by changes in secretion of gut hormones, metabolism of bile acids, expression of glucose transporters and the gut microbiome. Dyslipidaemia, atherosclerosis, microvascular complications of obesity and diabetes, systemic and tissue-level inflammation show evidence of regression and hypertension improves significantly after bariatric surgery.

SUMMARY

Bariatric surgery leads to improvements in obesity-related metabolic comorbidities such as dyslipidaemia, HDL functionality, hypertension, T2DM, insulin resistance and inflammation. It slows the atherosclerotic process and reduces cardiovascular and all-cause mortality. Recent data have demonstrated regression of the microvascular complications of obesity and diabetes including the regeneration of small nerve fibres. The magnitude of change in short-term metabolic effects depends on the surgical procedure whilst longer term effects are related to the amount of sustained excess weight loss.

Renal and Cardiovascular Outcomes After Weight Loss From Gastric Bypass Surgery in Type 2 Diabetes: Cardiorenal Risk Reductions Exceed Atherosclerotic Benefits

OBJECTIVE

We examined detailed renal and cardiovascular (CV) outcomes after gastric bypass (GBP) surgery in people with obesity and type 2 diabetes mellitus (T2DM), across several renal function categories, in a nationwide cohort study.

RESEARCH DESIGN AND METHODS

We linked data from the National Diabetes Register and the Scandinavian Obesity Surgery Register with four national databases holding information on socioeconomic variables, medications, hospitalizations, and causes of death and matched 5,321 individuals with T2DM who had undergone GBP with 5,321 who had not (age 18-65 years, mean BMI >40 kg/m², mean follow-up >4.5 years). The risks of postoperative outcomes were assessed with Cox regression models.

RESULTS

During the first years postsurgery, there were small reductions in creatinine and albuminuria and stable estimated glomerular filtration rate (eGFR) in the GBP group. The incidence rates of most outcomes relating to renal function, CV disease, and mortality were lower after GBP, being particularly marked for heart failure (hazard ratio [HR] 0.33 [95% CI 0.24, 0.46]) and CV mortality (HR 0.36 [(95% CI 0.22, 0.58]). The risk of a composite of severe renal disease or halved eGFR was 0.56 (95% CI 0.44, 0.71), whereas nonfatal CV risk was lowered less (HR 0.82 [95% CI 0.70, 0.97]) after GBP. Risks for key outcomes were generally lower after GBP in all eGFR strata, including in individuals with eGFR <30 mL/min/1.73 m².

CONCLUSIONS

Our data suggest robust benefits for renal outcomes, heart failure, and CV mortality after GBP in individuals with obesity and T2DM. These results suggest that marked weight loss yields important benefits, particularly on the cardiorenal axis (including slowing progression to end-stage renal disease), whatever the baseline renal function status.

The Effect of Metabolic Surgery on the Complications of Diabetes: What Are the Unanswered Questions?

It is now established that metabolic surgery (also known as bariatric surgery or obesity surgery) is an effective treatment for type 2 diabetes. Data from several randomized controlled trials have shown that surgery, when used as an adjunct to best medical therapy, is superior to medical therapy alone in achieving glycaemic and metabolic treatment targets in diabetes care. This has resulting in metabolic surgery being recommended as a treatment option for obesity-associated type 2 diabetes in national and international diabetes care guidelines. While the superior glycaemic effect of surgery is clear, the effect of surgery on the complications of diabetes is not fully understood. There are observational and epidemiological data that indicate a preventative effect in cohorts who do not have complications at baseline, as well as a positive effect on those with established diabetic kidney disease. However, there is a dearth of randomized controlled studies that specifically examine the effect of surgery on the complications of diabetes. Therefore, we should remain cautious in some cases, especially in those with retinopathy or neuropathy, as there is potential for deterioration of disease post-operatively. Further study is needed on this important topic. A lot is known, but there remain several unanswered questions. This article summarizes what we know about the effect of metabolic surgery on the complications of diabetes, poses some unanswered questions, and suggests how we could answer them.

How Ethical Is Our Current Delivery of Care to Patients with Severe and Complicated Obesity?

Despite overwhelming evidence that bariatric interventions reduce morbidity and mortality and are cost-effective, access for affected patients is limited. We sought to describe the extent to which health policy makers and publically funded health services have an ethical obligation to provide bariatric care. We conducted a narrative review of the literature pertaining to the efficacy, safety, and cost-effectiveness of bariatric surgical interventions, in the context of the core principles of medical ethics. We found that in relation to autonomy (i.e., the right to self-determination), beneficence, non-maleficence, and justice (i.e., the obligation to provide fair and equitable treatment to all patients), the current provision of bariatric surgical care fell short of meeting internationally recognized medical ethical standards. These findings have important implications for government policy and healthcare resource allocation. Respecting the individual’s right of self-determination, to do good, prevent harm, and provide equity in access to services is paramount, even when that individual is obese.

Novel Insights into Sensorimotor and Cardiovascular Autonomic Neuropathy from Recent-Onset Diabetes and Population-Based Cohorts

The most prevalent chronic complications of diabetes are diabetic neuropathies, among which distal sensorimotor polyneuropathy (DSPN) and cardiovascular autonomic neuropathy (CAN) are the best studied. Their major clinical sequelae such as foot ulcers, neuropathic pain, and orthostatic hypotension are associated with lower quality of life and increased risk of mortality. Here we discuss the recent insights into DSPN and CAN focusing on two prospective cohorts; that is, the German Diabetes Study (GDS) including recent-onset diabetes patients and the population-based Cooperative Health Research in the Region of Augsburg, Germany (KORA) surveys. The insights from these studies investigating novel tools for early detection and prediction of (pre)diabetic neuropathy as well as biomarkers of oxidative stress and inflammation should ultimately culminate in improving the health care of patients affected by this serious condition.

Emerging Biomarkers, Tools, and Treatments for Diabetic Polyneuropathy

Diabetic neuropathy, with its major clinical sequels, notably neuropathic pain, foot ulcers, and autonomic dysfunction, is associated with substantial morbidity, increased risk of mortality, and reduced quality of life. Despite its major clinical impact, diabetic neuropathy remains underdiagnosed and undertreated. Moreover, the evidence supporting a benefit for causal treatment is weak at least in patients with type 2 diabetes, and current pharmacotherapy is largely limited to symptomatic treatment options. Thus, a better understanding of the underlying pathophysiology is mandatory for translation into new diagnostic and treatment approaches. Improved knowledge about pathogenic pathways implicated in the development of diabetic neuropathy could lead to novel diagnostic techniques that have the potential of improving the early detection of neuropathy in diabetes and prediabetes to eventually embark on new treatment strategies. In this review, we first provide an overview on the current clinical aspects and illustrate the pathogenetic concepts of (pre)diabetic neuropathy. We then describe the biomarkers emerging from these concepts and novel diagnostic tools and appraise their utility in the early detection and prediction of predominantly distal sensorimotor polyneuropathy. Finally, we discuss the evidence for and limitations of the current and novel therapy options with particular emphasis on lifestyle modification and pathogenesis-derived treatment approaches. Altogether, recent years have brought forth a multitude of emerging biomarkers reflecting different pathogenic pathways such as oxidative stress and inflammation and diagnostic tools for an early detection and prediction of (pre)diabetic neuropathy. Ultimately, these insights should culminate in improving our therapeutic armamentarium against this common and debilitating or even life-threatening condition.

Measurement of glomerular filtration rate in patients undergoing obesity surgery

BACKGROUND

Most studies on obesity surgery have measured renal function using the estimated GFR. However, due to the reduction of muscle mass, and therefore creatinine that accompanies weight loss, such measures can falsely suggest an improvement in renal function. To balance the risks of surgery versus any potential benefits on renal function, we need to be able to determine renal function using valid and reliable methodologies. In this pilot study we aimed to measure renal function in patients with CKD undergoing obesity surgery using the gold standard ⁵¹Cr-EDTA GFR clearance methodology which is independent of measures of muscle mass.

METHODS

Nine consecutive obese patients with CKD underwent obesity surgery. Their renal function was assessed using ⁵¹Cr-EDTA GFR, cystatin C and serum creatinine as well as using eGFR equations including MDRD CKD Epi, Cockcroft Gault and CKD Epi cystatin before and 12 months after surgery.

RESULTS

Renal function using the ⁵¹Cr-EDTA measured GFR did not change significantly after surgery. Similar results were obtained when Cystatin C, CKD Epi cystatin, CKD Epi cystatin creatinine and adjusted Cockcroft Gault Creatinine clearance methods were used. In contrast there were either trends or significant improvements in renal function measured using the MDRD and CKD Epi equations.

CONCLUSIONS

In this pilot study using the gold standard ⁵¹Cr-EDTA method we found stabilisation in renal function after obesity surgery. Until further definitive data emerge it is critical to balance the risk and benefits of surgery, especially if renal function may not improve as often as previously suggested.

TRIAL REGISTRATION

ClinicalTrials.gov NCT01507350 . Registered June 2011.

Microvascular Outcomes in Patients With Diabetes After Bariatric Surgery Versus Usual Care: A Matched Cohort Study

Background

Bariatric surgery improves glycemic control in patients with type 2 diabetes mellitus (T2DM), but less is known about microvascular outcomes.

Objective

To investigate the relationship between bariatric surgery and incident microvascular complications of T2DM.

Design

Retrospective matched cohort study from 2005 to 2011 with follow-up through September 2015.

Setting

4 integrated health systems in the United States.

Participants

Patients aged 19 to 79 years with T2DM who had bariatric surgery (n = 4024) were matched on age, sex, body mass index, hemoglobin A1c level, insulin use, diabetes duration, and intensity of health care use up to 3 nonsurgical participants (n = 11 059).

Intervention

Bariatric procedures (76% gastric bypass, 17% sleeve gastrectomy, and 7% adjustable gastric banding) compared with usual care.

Measurements

Adjusted Cox regression analysis investigated time to incident microvascular disease, defined as first occurrence of diabetic retinopathy, neuropathy, or nephropathy.

Results

Median follow-up was 4.3 years for both surgical and nonsurgical patients. Bariatric surgery was associated with significantly lower risk for incident microvascular disease at 5 years (16.9% for surgical vs. 34.7% for nonsurgical patients; adjusted hazard ratio [HR], 0.41 [95% CI, 0.34 to 0.48]). Bariatric surgery was associated with lower cumulative incidence at 5 years of diabetic neuropathy (7.2% for surgical vs. 21.4% for nonsurgical patients; HR, 0.37 [CI, 0.30 to 0.47]), nephropathy (4.9% for surgical vs. 10.0% for nonsurgical patients; HR, 0.41 [CI, 0.29 to 0.58]), and retinopathy (7.2% for surgical vs. 11.2% for nonsurgical patients; HR, 0.55 [CI, 0.42 to 0.73]).

Limitation

Electronic health record databases could misclassify microvascular disease status for some patients.

Conclusion

In this large, multicenter study of adults with T2DM, bariatric surgery was associated with lower overall incidence of microvascular disease (including lower risk for neuropathy, nephropathy, and retinopathy) than usual care.

Primary Funding Source

National Institute of Diabetes and Digestive and Kidney Diseases.

Sudomotor function testing by electrochemical skin conductance: does it really measure sudomotor function?

OBJECTIVE

Electrochemical skin conductance (ESC) is a non-invasive test of sweat function developed as a potential marker of small fiber neuropathy. Here we systematically review the evolution of this device and the data obtained from studies of ESC across different diseases.

METHODS

Electronic databases, including MEDLINE, and Google Scholar were searched through to February 2018. The search strategy included the following terms: "electrochemical skin conductance," "EZSCAN," and "Sudoscan." The data values provided by each paper were extracted, where available, and input into tabular and figure data for direct comparison.

RESULTS

Thirty-seven studies were included this systematic review. ESC did not change by age or gender, and there was significant variability in ESC values between diseases, some of which exceeded control values. Longitudinal studies of disease demonstrated changes in ESC that were not biologically plausible. Of the 37 studies assessed, 25 received support from the device manufacturer. The extracted data did not agree with other published normative values. Prior studies do not support claims that ESC is a measure of small fiber sensory function or autonomic function.

CONCLUSIONS

Although many papers report significant differences in ESC values between disease and control subjects, the compiled data assessed in this review raises questions about the technique. Many of the published results violate biologic plausibility. A single funding source with a vested interest in the study outcomes has supported most of the studies. Normative values are inconsistent across publications, and large combined data sets do not support a high sensitivity and specificity. Finally, there is insufficient evidence supporting the claim that Sudoscan tests sudomotor or sensory nerve fiber function.

Roux-en-Y gastric bypass is an effective bridge to kidney transplantation: Results from a single center

Body mass index (BMI) > 35-40 kg/m² is often a contraindication, while Roux-en-Y gastric bypass (RYGB) is performed to enable kidney transplantation. This single-center retrospective study evaluated pre- and post-transplant outcomes of 31 morbidly obese patients with end-stage renal disease having RYGB before kidney transplantation between July 2009 and June 2014. Fourteen RYGB patients were subsequently transplanted. Nineteen recipients not having GB with a BMI ≥ 36 kg/m² at transplantation were used as historical controls. Mean BMI (±SE) before RYGB was 43.5 ± 0.7 kg/m² (range: 35.4-50.5 kg/m² ); 87.1% (27/31) achieved a BMI < 35 kg/m² . The percentage having improved diabetes/hypertension control was 29.0% (9/31); 25.8% (8/31) had complications (mostly minor) after RYGB. Among transplanted patients, blacks/Hispanics comprised 78.6% (11/14) and 84.2% (16/19) of RYGB and controls; 57.1% (8/14) and 63.2% (12/19) had a (mostly long-standing) pretransplant history of diabetes. While biopsy-proven acute rejection (BPAR) occurred significantly higher among RYGB vs control patients (6/14 vs 3/19, P = .03), patients developing T-cell BPAR were also significantly more likely to have a tacrolimus (TAC) trough level < 4.0 ng/mL within 3 weeks of T-cell BPAR (P = .0007). In Cox's model, the impact of having a TAC level < 4.0 ng/mg remained significant (P = .007) while the effect of RYGB was no longer significant (P = .13). Infections, graft, and patient survival were not significantly different. Despite obvious effectiveness in achieving weight loss, RYGB will need more careful post-transplant monitoring given the observed higher BPAR rate.

Incidence of end-stage renal disease following bariatric surgery in the Swedish Obese Subjects Study

Background

Obesity is a major public health problem leading to co-morbidities such as diabetes, hypertension and kidney failure. Bariatric surgery results in pronounced and maintained weight loss and prevention of obesity-related diseases and their complications. Most studies of bariatric surgery on kidney disease show improvements after surgery. However, long-term studies analyzing hard end-points are lacking. Here we report on the long-term effects of bariatric surgery compared to usual obesity care on incidence of end-stage renal disease (ESRD) alone and in combination with chronic kidney disease stage 4 (CKD4/ESRD).

Methods

4047 patients were included in the Swedish Obese Subjects (SOS) study. Inclusion criteria were age 37–60 years and BMI≥34 in men and BMI≥38 in women. Patients in the bariatric surgery group (N=2010) underwent banding (18%), vertical banded gastroplasty (69%) or gastric bypass (13%); controls (N=2037) received usual obesity care. In this analysis, patients were followed up for a median time of 18 years. The incidence of ESRD and CKD4 was obtained by crosschecking the SOS database with the Swedish National Patient Register.

Results

During follow-up, ESRD occurred in 13 patients in the surgery group and in 26 patients in the control group (adjusted hazard ratio (HR) = 0.27; 95% CI 0.12 – 0.60; p=0.001). The number of CKD4/ESRD events was 23 in the surgery group and 39 in the control group (adjusted HR = 0.33; 95% CI 0.18 – 0.62; p<0.001). In both analyses, bariatric surgery had a more favorable effect in patients with baseline serum insulin levels above median compared to those with lower insulin levels (interaction p=0.010). Treatment benefit of bariatric surgery was also greater in patients with macroalbuminuria at baseline compared to those without macroalbuminuria (interaction p<0.001).

Conclusions

Our study showed for the first time that bariatric surgery is associated with a long-term protection against ESRD and CKD4/ESRD.

Obesity surgery makes patients healthier and more functional: real world results from the United Kingdom National Bariatric Surgery Registry

BACKGROUND

The National Bariatric Surgery Registry (NBSR) is the largest bespoke database in the field in the United Kingdom.

OBJECTIVES

Our aim was to analyze the NBSR to determine whether the effects of obesity surgery on associated co-morbidities observed in small randomized controlled clinical trials could be replicated in a "real life" setting within U.K. healthcare.

SETTING

United Kingdom.

METHODS

All NBSR entries for operations between 2000 and 2015 with associated demographic and co-morbidity data were analyzed retrospectively.

RESULTS

A total of 50,782 entries were analyzed. The patients were predominantly female (78%) and white European with a mean age of 45 ± 11 years and a mean body mass index of 48 ± 8 kg/m². Over 5 years of follow-up, statistically significant reductions in the prevalence of type 2 diabetes, hypertension, dyslipidemia, sleep apnea, asthma, functional impairment, arthritis, and gastroesophageal reflux disease were observed. The "remission" of these co-morbidities was evident 1 year postoperatively and reached a plateau 2 to 5 years after surgery. Obesity surgery was particularly effective on functional impairment and diabetes, almost doubling the proportion of patients able to climb 3 flights of stairs and halving the proportion of patients with diabetes related hyperglycemia compared with preoperatively. Surgery was safe with a morbidity of 3.1% and in-hospital mortality of .07% and a reduced median inpatient stay of 2 days, despite an increasingly sick patient population.

CONCLUSIONS

Obesity surgery in the U.K. results not only in weight loss, but also in substantial improvements in obesity-related co-morbidities. Appropriate support and funding will help improve the quality of the NBSR data set even further, thus enabling its use to inform healthcare policy.

Monitoring of Diabetic Retinopathy in relation to Bariatric Surgery: a Prospective Observational Study

BACKGROUND

To investigate the need for closer perioperative monitoring of diabetic retinopathy in patients with type 2 diabetes undergoing bariatric surgery.

METHODS

Prospective observational clinical study of 56 patients with type 2 diabetes undergoing bariatric surgery. The patients were examined with 7-field fundus images and optical coherence tomography scans 2 weeks before and 1, 3, 6 and 12 months after bariatric surgery. Worsening was defined as a two-step change in the Wisconsin Epidemiologic Study of Diabetic Retinopathy scale or appearance or worsening of macular edema. Postoperative changes were analyzed in a mixed model.

RESULTS

Six patients (11 %) had any worsening at any visit, and three (5 %) persisted at 1 year. Of the 24 patients with preoperative retinopathy, 4-13 % worsened and 9-22 % improved, with significant overall improvement at 6 months (p = 0.01). Only one (3%) of the 32 patients without preoperative diabetic retinopathy had a transient worsening at 6 months. No patients developed macular edema, but the whole cohort had a minor increase in center point foveal thickness that peaked 6 months postoperatively. The patients were required to have good glucose control preoperatively where HbA1c was 6.4 ± 1.9 %.

CONCLUSIONS

Diabetic retinopathy was clinically stable after bariatric surgery, and none of the observed changes would have resulted in a changed screening interval at our center. This supports adherence to regular diabetic retinopathy screening guidelines following bariatric surgery in well-controlled patients. A clinically negligible but statistically significant foveal thickening 6 months postoperatively warrants further study.

Meta-analysis of metabolic surgery versus medical treatment for microvascular complications in patients with type 2 diabetes mellitus

Background

This study aimed to examine the effect of metabolic surgery on pre-existing and future microvascular complications in patients with type 2 diabetes mellitus (T2DM) in comparison with medical treatment. Although metabolic surgery is the most effective treatment for obese patients with T2DM regarding glycaemic control, it is unclear whether the incidence or severity of microvascular complications is reduced.

Methods

A systematic literature search was performed in MEDLINE, Embase, Web of Science and the Cochrane Central Register of Controlled Trials (CENTRAL) with no language restrictions, looking for RCTs, case–control trials and cohort studies that assessed the effect of metabolic surgery on the incidence of microvascular diabetic complications compared with medical treatment as control. The study was registered in the International prospective register of systematic reviews (CRD42016042994).

Results

The literature search yielded 1559 articles. Ten studies (3 RCTs, 7 controlled clinical trials) investigating 17 532 patients were included. Metabolic surgery reduced the incidence of microvascular complications (odds ratio 0·26, 95 per cent c.i. 0·16 to 0·42; P &lt; 0·001) compared with medical treatment. Pre-existing diabetic nephropathy was strongly improved by metabolic surgery versus medical treatment (odds ratio 15·41, 1·28 to 185·46; P = 0·03).

Conclusion

In patients with T2DM, metabolic surgery prevented the development of microvascular complications better than medical treatment. Metabolic surgery improved pre-existing diabetic nephropathy compared with medical treatment.

Bariatric Surgery for Obesity

In this review, the authors discuss the indications for and the published outcomes of commonly performed bariatric procedures, including weight loss, perioperative morbidity and mortality, late complications, as well as the impact of bariatric surgery on comorbidities, cardiovascular risk, and mortality. They also briefly discuss the mechanisms by which bariatric/metabolic surgery causes such significant weight loss and health gain.

Roles of increased glycaemic variability, GLP-1 and glucagon in hypoglycaemia after Roux-en-Y gastric bypass

OBJECTIVE

Roux-en-Y gastric bypass (RYGB) surgery is currently the most effective treatment for diabetes and obesity. An increasingly recognized and highly disabling complication of RYGB is postprandial hypoglycaemia (PPH). The pathophysiology of PPH remains unclear with multiple mechanisms suggested including nesidioblastosis, altered insulin clearance and increased glucagon-like peptide-1 (GLP-1) secretion. Whilst many PPH patients respond to dietary modification, some have severely disabling symptoms. Multiple treatments are proposed, including dietary modification, GLP-1 antagonism, GLP-1 analogues and even surgical reversal, with none showing a more decided advantage over the others. A greater understanding of the pathophysiology of PPH could guide the development of new therapeutic strategies.

METHODS

We studied a cohort of PPH patients at the Imperial Weight Center. We performed continuous glucose monitoring to characterize their altered glycaemic variability. We also performed a mixed meal test (MMT) and measured gut hormone concentrations.

RESULTS

We found increased glycaemic variability in our cohort of PPH patients, specifically a higher mean amplitude glucose excursion (MAGE) score of 4.9. We observed significantly greater and earlier increases in insulin, GLP-1 and glucagon in patients who had hypoglycaemia in response to an MMT (MMT Hypo) relative to those that did not (MMT Non-Hypo). No significant differences in oxyntomodulin, GIP or peptide YY secretion were seen between these two groups.

CONCLUSION

An early peak in GLP-1 and glucagon may together trigger an exaggerated insulinotropic response to eating and consequent hypoglycaemia in patients with PPH.

Early worsening of diabetic retinopathy after rapid improvement of blood glucose control in patients with diabetes

AIM

To review the frequency, importance of and risk factors for "early worsening of diabetic retinopathy" (EWDR) after rapid improvement of blood glucose in patients with diabetes.

METHODS

This was a systematic review of key references (PubMed 1980-2016) and the current international recommendations for the above-mentioned topics.

RESULTS

EWDR has been described during intensive treatment (IT) in patients with uncontrolled type 1 or 2 diabetes, and after pancreas transplantation or bariatric surgery. EWDR arises in 10-20% of patients within 3-6 months after abrupt improvement of glucose control, and in nearly two times that proportion in patients with advanced baseline diabetic retinopathy (DR). While EWDR is often transient and predominantly driven by the development of cotton-wool spots and intraretinal microvascular abnormalities in patients with no or minimal DR, it can lead to irreversible retinal damage in patients with advanced DR before IT. Its identified risk factors include higher baseline levels and larger magnitudes of reduction of HbA_1c, longer diabetes durations and previous severity of DR.

CONCLUSION

Intensive diabetes treatment inducing a rapid fall in glucose should prompt vigilance and caution, particularly in patients with long-term and uncontrolled diabetes and DR prior to IT. Careful retinal examination should be performed in all patients before initiating IT; however, in patients with severe non-proliferative or proliferative DR, panretinal photocoagulation therapy should be performed promptly. During the year following IT, quarterly eye monitoring is required in patients at high risk of EWDR (long-term uncontrolled diabetes, previous advanced DR), whereas follow-up every 6 months can be applied in patients with short-term diabetes and no/minimal DR before IT. To date, there is no evidence that controlling the speed or magnitude of HbA_1c decreases will reduce the risk of EWDR in patients with diabetes.

The role of bariatric surgery to treat diabetes: current challenges and perspectives

Bariatric surgery is emerging as a powerful weapon against severe obesity and type 2 diabetes mellitus (T2DM). Given its role in metabolic regulation, the gastrointestinal tract constitutes a meaningful target to treat T2DM, especially in light of accumulating evidence that surgery with gastrointestinal manipulations may result in T2DM remission (metabolic surgery). The major mechanisms mediating the weight loss-independent effects of bariatric surgery comprise effects on tissue-specific insulin sensitivity, β-cell function and incretin responses, changes in bile acid composition and flow, modifications of gut microbiota, intestinal glucose metabolism and increased brown adipose tissue metabolic activity. Shorter T2DM duration, better preoperative glycemic control and profound weight loss, have been associated with higher rates of T2DM remission and lower risk of relapse. In the short and medium term, a significant amount of weight is lost, T2DM may completely regress, and cardiometabolic risk factors are dramatically improved. In the long term, metabolic surgery may achieve durable weight loss, prevent T2DM and cancer, improve overall glycemic control while leading to significant rates of T2DM remission, and reduce total and cause-specific mortality. The gradient of efficacy for weight loss and T2DM remission comparing the four established surgical procedures is biliopancreatic diversion >Roux-en-Y gastric bypass >sleeve gastrectomy >laparoscopic adjustable gastric banding. According to recently released guidelines, bariatric surgery should be recommended in diabetic patients with class III obesity, regardless of their level of glycemic control, and patients with class II obesity with inadequately controlled T2DM despite lifestyle and optimal medical therapy. Surgery should also be considered in patients with class I obesity and inadequately controlled hyperglycemia despite optimal medical treatment.

Does bariatric surgery prevent progression of diabetic retinopathy?

PurposeTo assess the changes in diabetic retinopathy (DR) in type 2 diabetes (T2DM) patients post bariatric surgery and report on the risk factors that may be associated with it.Patients and methodsRetrospective observational study of T2DM patients who underwent bariatric surgery in a UK specialist bariatric unit between 2009 and 2015. Preoperative and postoperative weight, HbA1c, and annual DR screening results were collected from medical records. Patients with preoperative retinal screening and at least one postoperative retinal screening were eligible for analysis. Multivariate analysis was used to explore significant clinical predictors on postoperative worsening in DR.ResultsA total of 102 patients were eligible for analysis and were followed up for 4 years. Preoperatively, 68% of patients had no DR compared to 30% with background retinopathy, 1% pre-proliferative retinopathy, and 1% proliferative retinopathy. In the first postoperative visit, 19% of patients developed new DR compared to 70% stable and 11% improved. These proportions remained similar for each postoperative visit over time. Young age, male gender, high preoperative HbA1c, and presence of preoperative retinopathy were the significant predictors of worsening postoperatively.ConclusionBariatric surgery does not prevent progression of DR. Young male patients with pre-existing DR and poor preoperative glycaemic control are most at risk of progression. All diabetic patients should attend regular DR screening post bariatric surgery to allow early detection of potentially sight-threatening changes, particularly among those with identifiable risk factors. Future prospective studies with prolonged follow-up are required to clarify the duration of risk.

Bariatric surgery and diabetic retinopathy: a systematic review and meta-analysis of controlled clinical studies

BACKGROUND

Uncontrolled studies have indicated appearance or progression of diabetic retinopathy in obese diabetic patients after bariatric surgery. The aim of this systematic review and meta-analysis was to compare the rate of appearance, as well as progression or regression of diabetic retinopathy in studies comparing medical and surgical treatment of obese type 2 diabetes.

METHODS AND FINDINGS

Intervention effect (new cases of retinopathy, and cases with any change of diabetic retinopathy score) was expressed as odds ratio (OR), with 95% confidence intervals (CIs); change of diabetic retinopathy score was expressed as standardized mean difference (SMD), with 95% CIs. Meta-analyses were performed by a random-effects model according to DerSimonian and Laird. Heterogeneity was assessed through Q and I2 statistics for each comparison, and potential sources of heterogeneity were discussed where appropriate. Appropriate methodology [preferred reporting items for systematic reviews and meta-analyses (PRISMA) statement] was used. Seven studies were analyzed, and incident cases of retinopathy were fewer with bariatric surgery than with medical treatment; change of retinopathy score (three studies) was not different, while only two studies were available on numbers of patients showing progression or regression of retinopathy. Heterogeneity was not significant, and publication bias was not present.

CONCLUSIONS

Bariatric surgery seems to prevent new cases of diabetic retinopathy, but available studies are not sufficient to support progression or regression of retinopathy. Further studies are needed to draw firm conclusions on the effect of bariatric surgery on diabetic retinopathy.

Presentation, pathology and prognosis of renal disease in type 2 diabetes

OBJECTIVE

Non-diabetic renal disease (NDRD) is common in patients with type 2 diabetes (T2D), but the relationship between its presentation and prognosis is unknown.

RESEARCH DESIGN AND METHODS

In a retrospective cohort study, we compared renal and patient survival among 263 patients with T2D who had native renal biopsies between 2002 and 2008 from three Auckland hospitals in New Zealand. The presence of diabetic nephropathy (DN), NDRD or mixed (DN and NDRD) was determined from biopsy. We examined clinical associations according to NDRD etiologies and mode of presentation-acute (defined by acute kidney injury (AKI)) or non-acute. Patients were followed until end-stage renal disease, death or December 2015. Survival was compared using Log-rank test.

RESULTS

94 (36%) patients had DN, 72 (27%) had NDRD, and 97 (37%) had mixed pathologies. Obesity-related focal segmental glomerulosclerosis was the most common NDRD (46%) in patients with non-acute presentations, whereas interstitial nephritis or immune-complex glomerulonephritides were the most prevalent in those with acute presentations (60%). DN was commonly associated with AKI (p<0.001). The prevalence of DN increased with diabetes duration (p<0.001), but NDRD was still found in 55% of subjects with ≥14 years T2D. NDRD was strongly associated with the absence of retinopathy (p<0.001). Renal survival was best in the NDRD group (p<0.001). Among those with DN, renal prognosis was worse in those with more advanced DN lesions and those with an acute presentation (p<0.001). The proportion of all-cause mortality was similar in all three groups, but overall survival was poorest in the DN group (p=0.025).

CONCLUSIONS

Renal disease in patients with T2D is heterogeneous. The renal prognosis differs markedly according to histopathological diagnosis and mode of presentation.

Thickening of inner retinal layers in the parafovea after bariatric surgery in patients with type 2 diabetes

PURPOSE

Bariatric surgery dramatically improves the metabolic profile in patients with type 2 diabetes (T2D). We have previously reported a thickening of the retina after bariatric surgery and aimed to investigate these subclinical changes in retinal thickness and vessel calibres in more detail.

METHODS

We examined 51 patients with T2D 2 weeks before and 1, 3, 6 and 12 months after bariatric surgery. Retinal thickness was measured with optical coherence tomography and automated segmentation in the fovea, parafovea and perifovea in each retinal layer. Retinal vessels were semiautomatically measured in a zone 0.5-1 disc diameters from the optic disc.

RESULTS

The total macula thickened with a peak after 6 months in both univariate (2.7 ± 0.4 μm, p < 0.001) and multivariate analysis (2.2 ± 0.7 μm, p = 0.001). The thickening was most prominent in the parafoveal ring 1-3 mm from the centre and in the retinal nerve fibre layer and outer nuclear layer. A fall in HbA_1c (p = 0.01) and longer duration of diabetes (p = 0.01) were associated with more thickening. The central retinal artery equivalent widened 22.1 μm (±8.9, p = 0.01) in the multivariate analysis 12 months postoperatively. A reduction in blood pressure was associated with less widening of the arterioles (p = 0.01).

CONCLUSION

Patients with T2D had thickening of the retina after gastric bypass surgery with a peak 6 months postoperatively. The thickening was most pronounced in the retinal nerve fibre layer and the outer nuclear layer of the parafovea. In multivariate analysis, the central retinal artery equivalent increased at 12 months.

Effects of Bariatric Surgery on Renal Function in Obese Patients: A Systematic Review and Meta Analysis

Background

Obesity is an independent risk factor of development and progression of chronic kidney disease (CKD). Data on the benefits of bariatric surgery in obese patients with impaired kidney function have been conflicting.

Objective

To explore whether there is improvement in glomerular filtration rate (GFR), proteinuria or albuminuria after bariatric surgery.

Methods

We comprehensively searched the databases of MEDLINE, Embase, web of science and Cochrane for randomized, controlled trials and observational studies that examined bariatric surgery in obese subjects with impaired kidney function. Outcomes included the pre- and post-bariatric surgery GFR, proteinuria and albuminuria. In obese patients with hyperfiltration, we draw conclusions from studies using measured GFR (inulin or iothalamate clearance) unadjusted for BSA only. Study quality was evaluated using the Newcastle-Ottawa Scale.

Results

32 observational studies met our inclusion criteria, and 30 studies were included in the meta-analysis. No matter in dichotomous data or in dichotomous data, there were statistically significant reduction in hyperfiltration, albuminuria and proteinuria after bariatric surgery.

Limitations

The main limitation of this meta-analysis is the lack of randomized controlled trials (RCTs). Another limitation is the lack of long-term follow-up.

Conclusions

Bariatric surgery could prevent further decline in renal function by reducing proteinuria, albuminuria and improving glomerular hyperfiltration in obese patients with impaired renal function. However, whether bariatric surgery reverses CKD or delays ESRD progression is still in question, large, randomized prospective studies with a longer follow-up are needed.

Mechanisms underpinning remission of albuminuria following bariatric surgery

PURPOSE OF REVIEW

Albuminuria is a biomarker of renal injury commonly used to monitor progression of diabetic kidney disease. The appearance of excess albumin in the urine reflects alterations in the structure and permeability of the glomerular filtration barrier. The present article summarizes the clinical evidence base for remission of albuminuria after bariatric surgery. It furthermore focuses on how beneficial impacts on glomerular podocyte structure and function may explain this phenomenon.

RECENT FINDINGS

A coherent clinical evidence base is emerging demonstrating remission of albuminuria following bariatric surgery in patients with obesity and diabetes. The impaired metabolic milieu in diabetic kidney disease drives podocyte dedifferentiation and death through glucotoxic, lipotoxic proinflammatory, and pressure-related stress. Improvements in these parameters after surgery correlate with improvements in albuminuria and preclinical studies provide mechanistic data that support the existence of cause-effect relationship.

SUMMARY

The benefits of bariatric surgery extend beyond weight loss in diabetes to encompass beneficial effects on diabetic renal injury. Attenuation of the toxic metabolic milieu that the podocyte is exposed to postbariatric surgery suggests that the restitution of podocyte health is a key cellular event underpinning remission of albuminuria.

The Effect of Bariatric Surgery on Diabetic Retinopathy: Good, Bad, or Both?

Bariatric surgery, initially intended as a weight-loss procedure, is superior to standard lifestyle intervention and pharmacological therapy for type 2 diabetes in obese individuals. Intensive medical management of hyperglycemia is associated with improved microvascular outcomes. Whether or not the reduction in hyperglycemia observed after bariatric surgery translates to improved microvascular outcomes is yet to be determined. There is substantial heterogeneity in the data relating to the impact of bariatric surgery on diabetic retinopathy (DR), the most common microvascular complication of diabetes. This review aims to collate the recent data on retinal outcomes after bariatric surgery. This comprehensive evaluation revealed that the majority of DR cases remain stable after surgery. However, risk of progression of pre-existing DR and the development of new DR is not eliminated by surgery. Instances of regression of DR are also noted. Potential risk factors for deterioration include severity of DR at the time of surgery and the magnitude of glycated hemoglobin reduction. Concerns also exist over the detrimental effects of postprandial hypoglycemia after surgery. In vivo studies evaluating the chronology of DR development and the impact of bariatric surgery could provide clarity on the situation. For now, however, the effect of bariatric surgery on DR remains inconclusive.