Circulating adipocyte-derived exosomal MicroRNAs associated with decreased insulin resistance after gastric bypass

OBJECTIVE

Exosomes from obese adipose contain dysregulated microRNAs linked to insulin signaling, as compared with lean controls, providing a direct connection between adiposity and insulin resistance. This study tested the hypotheses that gastric bypass surgery and its subsequent weight loss would normalize adipocyte-derived exosomal microRNAs associated with insulin signaling and the associated metabolome related to glucose homeostasis.

METHODS

African American female subjects with obesity (N = 6; age: 38.5 ± 6.8 years; BMI: 51.2 ± 8.8 kg/m² ) were tested before and 1 year after surgery. Insulin resistance (HOMA), serum metabolomics, and global microRNA profiles of circulating adipocyte-derived exosomes were evaluated via ANCOVA and correlational analyses.

RESULTS

One year postsurgery, patients showed decreased BMI (-18.6 ± 5.1 kg/m² ; P < 0.001), ameliorated insulin resistance (HOMA: 1.94 ± 0.6 presurgery, 0.49 ± 0.1 postsurgery; P < 0.001), and altered metabolites including branched chain amino acids (BCAA). Biological pathway analysis of predicted mRNA targets of 168 surgery-responsive microRNAs (P < 0.05) identified the insulin signaling pathway (P = 1.27E-10; 52/138 elements), among others, in the data set. The insulin signaling pathway was also a target of 10 microRNAs correlated to changes in HOMA (P < 0.05; r > 0.4), and 48 microRNAs correlated to changes in BCAA levels.

CONCLUSIONS

These data indicate that circulating adipocyte-derived exosomes are modified following gastric bypass surgery and correlate to improved postsurgery insulin resistance.

Comparative effectiveness of Roux-en-Y gastric bypass and sleeve gastrectomy in super obese patients

BACKGROUND

The disproportionate increase in the super obese (SO) is a hidden component of the current obesity pandemic. Data on the safety and efficacy of bariatric procedures in this specific patient population are limited. Our aim is to assess the comparative effectiveness of the two most common bariatric procedures in the SO.

METHODS

Using the Bariatric Outcomes Longitudinal Database from 2007 to 2012, we compared SO patients (BMI ≥ 50) undergoing laparoscopic Roux-en-Y gastric bypass (RYGB) or sleeve gastrectomy (SG). Stepwise logistic regression modeling was used to calculate a propensity score to adjust for patient demographics and comorbidities.

RESULTS

We identified 50,987 SO patients who underwent RYGB (N = 42,119) or SG (N = 8868). There was no difference in adjusted overall 30-day complication rate comparing RYGB and SG patients (11.5 vs. 11.1 %, p = 0.250). RYGB patients had higher adjusted rates of 30-day mortality (0.3 vs. 0.2 %, p = 0.042), reoperation (4.0 vs. 2.4 %, p < 0.001), and readmission (6.9 vs. 5.5 %, p < 0.001) compared to SG patients. The percent of total weight loss (%TWL) was significantly higher for RYGB patients compared to SG at 3 months (14.1 vs. 13.1 %, p < 0.001), 6 months (25.2 vs. 22.4 %, p < 0.001), and 12 months (34.5 vs. 29.7 %, p < 0.001). RYGB patients had increased resolution of all measured comorbidities: diabetes mellitus (61.6 vs. 50.8 %, p < 0.001), hypertension (43.1 vs. 34.5 %, p < 0.001), gastroesophageal reflux disease (53.9 vs. 32.5 %, p < 0.001), hyperlipidemia (39.7 vs. 32.5 %, p < 0.001), and obstructive sleep apnea (42.8 vs. 40.6 %, p = 0.058) at 12 months compared to SG patients.

CONCLUSIONS

There are significant differences in comorbidity improvement and resolution as well as weight loss between RYGB and SG in the SO population. There was no difference in overall 30-day complications, but more RYGB patients required readmission and reoperation. However, RYGB was considerably more effective in controlling obesity-related comorbidities. Our results favor performance of RYGB in SO patients of appropriate risk.

Surgery for type 2 diabetes: the case for Roux-en-Y gastric bypass

The Roux-en-Y gastric bypass (RYGB) has traditionally been the most common bariatric procedure. Long-term data on the efficacy of RYGB demonstrate a long-lasting benefit in weight loss and control of the metabolic syndrome. Although observations of type 2 diabetes (T2D) resolution after RYGB have been reported for 3 decades, it was not until recently that multiple randomized trials comparing RYGB to medical therapy verified the same thing: RYGB leads to significantly greater diabetes control and remission. Even though T2D can relapse, there remains a significant overall benefit of bariatric surgery regarding the downstream effects of T2D: cardiovascular risk and micro- and macrovascular complications. Limited data are available on the comparative effectiveness of RYGB and sleeve gastrectomy in improving glucose homeostasis, but studies including both surgical procedures suggest that the benefit of RYGB in T2D may be more profound. Although further research is needed to examine closely any differences between these 2 procedures, multiple studies underscore the unprecedented value of bariatric surgery for the control and remission of T2D.

Bariatric Surgery in Patients with Dialysis-Dependent Renal Failure

BACKGROUND

Laparoscopic procedures for the treatment of morbid obesity are commonly offered to patients with comorbidities previously thought to carry prohibitive operative risk. In this study, we reviewed characteristics and perioperative outcomes of patients with dialysis-dependent renal failure (DDRF) who underwent laparoscopic bariatric procedures.

METHODS

The American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database from 2006 to 2011 was reviewed. Preoperative characteristics and 30-day outcome data of patients who underwent three common laparoscopic procedures were analyzed using ANOVA and Pearson chi-squared tests.

RESULTS

One hundred thirty-eight patients (52.5 % female) with DDRF and a median body mass index (BMI) of 45.5 kg/m(2) were identified; 33.8 % (n = 47) underwent laparoscopic banding (LAGB), 48.9 % (n = 68) laparoscopic Roux-en-Y gastric bypass (RYGB), and 16.5 % (n = 23) laparoscopic sleeve gastrectomy (LSG). No differences were found among groups in age, prevalence of American Society of Anesthesiology IV classification, BMI, weight, gender, prevalence of diabetes, and vascular or neurologic comorbidities. Total operation time and length of hospital stay were significantly different between groups. Mortality was 0.7 %, and overall morbidity was 5.8 %. The case mix reflected a decrease in LAGB procedures from 45.5 to 23.3 % from 2006-2009 to 2010-2011 and an increase in LSG procedures from 9.1 to 24.7 % (p < 0.006).

CONCLUSIONS

When performed in selected DDRF patients, bariatric surgery is safe. An increase in LSG with a concurrent decline in LAGB procedures was demonstrated over the period of the study.

Synchronous Ventral Hernia Repair in Patients Undergoing Bariatric Surgery

BACKGROUND

Obesity predisposes patients to abdominal wall hernias. Patients undergoing bariatric surgery are not uncommonly found to have ventral hernias. Synchronous ventral hernia repair (S-VHR) has been reported in 2-5% of patients undergoing bariatric surgery. Studies reporting on the outcomes of S-VHR are limited by sample size. The aim of this study was to assess the effect of S-VHR on surgical site infection (SSI) rate.

METHODS

The American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database from 2010 to 2011 was queried using Current Procedural Terminology codes for bariatric surgery. Data on patient demographics, comorbidities, procedural events, and postoperative occurrences were analyzed. Thirty-day mortality and morbidity were assessed. Comparisons between laparoscopic Roux-en-Y gastric bypass (RYGB) and sleeve gastrectomy (SG) were performed.

RESULTS

We identified 17,117 patients who underwent RYGB or SG. S-VHR was performed in 503 (2.94%) patients. S-VHR was independently associated with SSI (odds ratios (OR) 1.65, 95% confidence interval (CI) 1.06-2.58), but not overall morbidity (OR 1.33, 95% CI 0.96-1.86). Four hundred thirty-three patients with RYGB and 70 with SG had S-VHR. Serious morbidity (3.5 vs. 5.7%, p = 0.32) and overall morbidity (8.3 vs. 8.6%, p = 0.942) were similar. After controlling for baseline comorbidities, there was no significant effect of procedure type on SSI (OR 0.38, 95% CI 0.05-2.91).

CONCLUSIONS

S-VHR is associated with an increase in SSI but not overall morbidity. There is no significant difference in the SSI rate between RYGB and SG. Larger studies are needed to definitively assess a potential difference in the wound infection rate between RYGB and SG.

A History of Bariatric Surgery: The Maturation of a Medical Discipline

This article examines the progression of bariatric surgery since its creation more than 60 years ago with a focus on the effect of surgery on weight loss, comorbidity reduction, and safety. The success has been remarkable. It is possible to cure severe obesity, type 2 diabetes, and hyperlipidemia in addition to the many other manifestations of the metabolic syndrome with remarkable safety. Equally important are the opportunities for research afforded by the surgery and its outcomes. Until better treatments become available, bariatric surgery is the therapy of choice for patients with morbid obesity for weight control and comorbidity improvement.

Change in Pain and Physical Function Following Bariatric Surgery for Severe Obesity

IMPORTANCE

The variability and durability of improvements in pain and physical function following Roux-en-Y gastric bypass (RYGB) or laparoscopic adjustable gastric banding (LAGB) are not well described.

OBJECTIVES

To report changes in pain and physical function in the first 3 years following bariatric surgery, and to identify factors associated with improvement.

DESIGN, SETTING, AND PARTICIPANTS

The Longitudinal Assessment of Bariatric Surgery-2 is an observational cohort study at 10 US hospitals. Adults with severe obesity undergoing bariatric surgery were recruited between February 2005 and February 2009. Research assessments were conducted prior to surgery and annually thereafter. Three-year follow-up through October 2012 is reported.

EXPOSURES

Bariatric surgery as clinical care.

MAIN OUTCOMES AND MEASURES

Primary outcomes were clinically meaningful presurgery to postsurgery improvements in pain and function using scores from the Medical Outcomes Study 36-Item Short-Form Health Survey (SF-36) (ie, improvement of ≥5 points on the norm-based score [range, 0-100]) and 400-meter walk time (ie, improvement of ≥24 seconds) using established thresholds. The secondary outcome was clinically meaningful improvement using the Western Ontario McMaster Osteoarthritis Index (ie, improvement of ≥9.7 pain points and ≥9.3 function points on the transformed score [range, 0-100]).

RESULTS

Of 2458 participants, 2221 completed baseline and follow-up assessments (1743 [78.5%] were women; median age was 47 years; median body mass index [BMI] was 45.9; 70.4% underwent RYGB; 25.0% underwent LAGB). At year 1, clinically meaningful improvements were shown in 57.6% (95% CI, 55.3%-59.9%) of participants for bodily pain, 76.5% (95% CI, 74.6%-78.5%) for physical function, and 59.5% (95% CI, 56.4%-62.7%) for walk time. Additionally, among participants with severe knee or disability (633), or hip pain or disability (500) at baseline, approximately three-fourths experienced joint-specific improvements in knee pain (77.1% [95% CI, 73.5%-80.7%]) and in hip function (79.2% [95% CI, 75.3%-83.1%]). Between year 1 and year 3, rates of improvement significantly decreased to 48.6% (95% CI, 46.0%-51.1%) for bodily pain and to 70.2% (95% CI, 67.8%-72.5%) for physical function, but improvement rates for walk time, knee and hip pain, and knee and hip function did not (P for all ≥.05). Younger age, male sex, higher income, lower BMI, and fewer depressive symptoms presurgery; no diabetes and no venous edema with ulcerations postsurgery (either no history or remission); and presurgery-to-postsurgery reductions in weight and depressive symptoms were associated with presurgery-to-postsurgery improvements in multiple outcomes at years 1, 2, and 3.

CONCLUSIONS AND RELEVANCE

Among a cohort of participants with severe obesity undergoing bariatric surgery, a large percentage experienced improvement, compared with baseline, in pain, physical function, and walk time over 3 years, but the percentage with improvement in pain and physical function decreased between year 1 and year 3.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT00465829.

Effects of meal size on the release of GLP-1 and PYY after Roux-en-Y gastric bypass surgery in obese subjects with or without type 2 diabetes

Changes in gastrointestinal peptide release may play an important role in improving glucose control and reducing body weight following Roux-en-Y gastric bypass (RYGB), but the impact of low caloric intake on gut peptide release post-surgery has not been well characterized. The purpose of this study was to assess the relationships between low caloric intake and gut peptide release and how they were altered by RYGB. Obese females including ten normoglycemic (ON) and ten with type 2 diabetes mellitus (T2DM) (OD) were studied before, 1 week, and 3 months after RYGB. Nine lean, normoglycemic women were studied for comparison. Subjects were given three separate mixed meal challenges (MMCs; 75, 150, and 300 kcal). Plasma glucagon-like peptide 1 (GLP-1) and peptide YY (PYY) were analyzed. Prior to surgery, only minimal increases in GLP-1 and PYY were observed in response to the MMCs. After surgery, the peak GLP-1 concentration was progressively elevated in response to increasing meal sizes. The meal sizes had a statistically significant impact on elevation of GLP-1 incremental areas under the curve (ΔAUC) in both ON and OD at 1 week and 3 months post-surgery visits (p < 0.05 for all comparisons). The PYY ∆AUC was also significantly increased in a meal size-dependent manner in both ON and OD at both post-surgery visits (p < 0.05 for all comparisons). Meal sizes as small as 75-300 kcal, which cause minimal stimulation in GLP-1 or PYY release in the subjects before RYGB, are sufficient to provide statistically significant, meal size-dependent increases in the peptides post-RYGB both acutely and after meaningful weight loss occurred.

Urinary Incontinence Before and After Bariatric Surgery

IMPORTANCE

Among women and men with severe obesity, evidence for improvement in urinary incontinence beyond the first year after bariatric surgery-induced weight loss is lacking.

OBJECTIVES

To examine change in urinary incontinence before and after bariatric surgery and to identify factors associated with improvement and remission among women and men in the first 3 years after bariatric surgery.

DESIGN, SETTING, AND PARTICIPANTS

The Longitudinal Assessment of Bariatric Surgery 2 is an observational cohort study at 10 US hospitals in 6 geographically diverse clinical centers. Participants were recruited between February 21, 2005, and February 17, 2009. Adults undergoing first-time bariatric surgical procedures as part of clinical care by participating surgeons between March 14, 2006, and April 24, 2009, were followed up for 3 years (through October 24, 2012).

INTERVENTION

Participants undergoing bariatric surgery completed research assessments before the procedure and annually thereafter.

MAIN OUTCOMES AND MEASURES

The frequency and type of urinary incontinence episodes in the past 3 months were assessed using a validated questionnaire. Prevalent urinary incontinence was defined as at least weekly urinary incontinence episodes, and remission was defined as change from prevalent urinary incontinence at baseline to less than weekly urinary incontinence episodes at follow-up.

RESULTS

Of 2458 participants, 1987 (80.8%) completed baseline and follow-up assessments. At baseline, the median age was 47 years (age range, 18-78 years), the median body mass index was 46 kg/m2 (range, 34-94 kg/m2), and 1565 of 1987 (78.8%) were women. Urinary incontinence was more prevalent among women (49.3%; 95% CI, 46.9%-51.9%) than men (21.8%; 95% CI, 18.2%-26.1%) (P < .001). After a mean 1-year weight loss of 29.5% (95% CI, 29.0%-30.1%) in women and 27.0% (95% CI, 25.9%-28.6%) in men, year 1 urinary incontinence prevalence was significantly lower among women (18.3%; 95% CI, 16.4%-20.4%) and men (9.8%; 95% CI, 7.2%-13.4%) (P < .001 for all). The 3-year prevalence was higher than the 1-year prevalence for both sexes (24.8%; 95% CI, 21.8%-26.5% among women and 12.2%; 95% CI, 9.0%-16.4% among men) but was substantially lower than baseline (P < .001 for all). Weight loss was independently related to urinary incontinence remission (relative risk, 1.08; 95% CI, 1.06-1.10 in women and 1.07; 95% CI, 1.02-1.13 in men) per 5% weight loss, as were younger age and the absence of a severe walking limitation.

CONCLUSIONS AND RELEVANCE

Among women and men with severe obesity, bariatric surgery was associated with substantially reduced urinary incontinence over 3 years. Improvement in urinary incontinence may be an important benefit of bariatric surgery.

Hyperinsulinemic syndrome: the metabolic syndrome is broader than you think

BACKGROUND

Type 2 diabetes mellitus (T2DM) is characterized by hyperinsulinemia. In 2011 we showed that gastric bypass (RYGB) corrects these high levels even though insulin resistance remains high, ie, the operation "dissociates" hyperinsulinemia from insulin resistance. RYGB produces reversal of T2DM along with other diseases associated with the metabolic syndrome. This observation led us to examine whether these illnesses also were characterized by hyperinsulinemia.

METHODS

A systematic review was performed to determine whether hyperinsulinemia was present in disorders associated with the metabolic syndrome. We reviewed 423 publications. 58 were selected because of appropriate documentation of insulin measurements. Comparisons were based on whether the studies reported patients as having increased versus normal insulin levels for each metabolic disorder.

RESULTS

The presence (+) or absence (-) of hyperinsulinemia was documented in these articles as follows: central obesity (4+ vs 0-), diabetes (5+ vs 0-), hypertension (9+ vs 1-), dyslipidemia (2+ vs 0-), renal failure (4+ vs 0-), nonalcoholic fatty liver disease (5+ vs 0-), polycystic ovary syndrome (7+ vs 1-), sleep apnea (7+ vs 0-), certain cancers (4+ vs 1-), atherosclerosis (4+ vs 0-), and cardiovascular disease (8+ vs 0-). Four articles examined insulin levels in the metabolic syndrome as a whole (4+ vs 0-).

CONCLUSION

These data document that disorders linked to the metabolic syndrome are associated with high levels of insulin, suggesting that these diseases share a common etiology that is expressed by high levels of insulin. This leads us to propose the concept of a "hyperinsulinemic syndrome" and question the safety of insulin as a chronic therapy for patients with T2DM.

The BMI: Is It Time to Scratch for a More Accurate Assessment of Metabolic Dysfunction?

The body mass index (BMI = Kg/M(2)) is not a valid measure for clinical decisions, especially whether a patient will benefit from bariatric surgery. The measure, as used, discriminates against the muscular, the aged, women, and racial groups such as Asians and African Americans. The requirement must be eliminated since it denies many patients the only currently available therapy. This chapter provides the bibliographic data to support this argument and should prove useful in convincing carriers that the BMI is an inaccurate and, too often, cruel guideline.

Early morbidity and mortality of laparoscopic sleeve gastrectomy and gastric bypass in the elderly: a NSQIP analysis

BACKGROUND

Even though the U.S. population is aging, outcomes of bariatric surgery in the elderly are not well defined. Current literature mostly evaluates the effects of gastric bypass (RYGB), with paucity of data on sleeve gastrectomy (SG). The objective of this study was to assess 30-day morbidity and mortality associated with laparoscopic SG in patients aged 65 years and over, in comparison to RYGB.

METHODS

The National Surgical Quality Improvement Program (NSQIP) database was queried for all patients aged 65 and over who underwent laparoscopic RYGB and SG between 2010 and 2011. Baseline characteristics and outcomes were compared. P value<.05 was considered significant. Odds ratios (OR) with 95% confidence interval (CI) were reported when applicable.

RESULTS

We identified 1005 patients. Mean body mass index was 44 ± 7. SG was performed in 155 patients (15.4%). The American Society of Anesthesiology physical classification of 3 or 4 was similar between the 2 groups (82.6% versus 86.7%, P = .173). Diabetes was more frequent in the RYGB group (43.2% versus 55.6%, P = .004). 30-day mortality (0.6% versus 0.6%, OR 1.1, 95% CI .11-9.49), serious morbidity (5.2% versus 5.6%, OR .91, 95% CI .42-0.96), and overall morbidity (9% versus 9.1%, OR 1.0, 95% CI .55-1.81) were similar.

CONCLUSION

In elderly patients undergoing laparoscopic bariatric surgery, SG is not associated with significantly different 30-day outcomes compared to RYGB. Both procedures are followed by acceptably low morbidity and mortality.

Weight change and health outcomes at 3 years after bariatric surgery among individuals with severe obesity

IMPORTANCE

Severe obesity (body mass index [BMI] ≥35) is associated with a broad range of health risks. Bariatric surgery induces weight loss and short-term health improvements, but little is known about long-term outcomes of these operations.

OBJECTIVE

To report 3-year change in weight and select health parameters after common bariatric surgical procedures.

DESIGN AND SETTING

The Longitudinal Assessment of Bariatric Surgery (LABS) Consortium is a multicenter observational cohort study at 10 US hospitals in 6 geographically diverse clinical centers. PARTICIPANTS AND EXPOSURE: Adults undergoing first-time bariatric surgical procedures as part of routine clinical care by participating surgeons were recruited between 2006 and 2009 and followed up until September 2012. Participants completed research assessments prior to surgery and 6 months, 12 months, and then annually after surgery.

MAIN OUTCOMES AND MEASURES

Three years after Roux-en-Y gastric bypass (RYGB) or laparoscopic adjustable gastric banding (LAGB), we assessed percent weight change from baseline and the percentage of participants with diabetes achieving hemoglobin A1c levels less than 6.5% or fasting plasma glucose values less than 126 mg/dL without pharmacologic therapy. Dyslipidemia and hypertension resolution at 3 years was also assessed.

RESULTS

At baseline, participants (N = 2458) were 18 to 78 years old, 79% were women, median BMI was 45.9 (IQR, 41.7-51.5), and median weight was 129 kg (IQR, 115-147). For their first bariatric surgical procedure, 1738 participants underwent RYGB, 610 LAGB, and 110 other procedures. At baseline, 774 (33%) had diabetes, 1252 (63%) dyslipidemia, and 1601 (68%) hypertension. Three years after surgery, median actual weight loss for RYGB participants was 41 kg (IQR, 31-52), corresponding to a percentage of baseline weight lost of 31.5% (IQR, 24.6%-38.4%). For LAGB participants, actual weight loss was 20 kg (IQR, 10-29), corresponding to 15.9% (IQR, 7.9%-23.0%). The majority of weight loss was evident 1 year after surgery for both procedures. Five distinct weight change trajectory groups were identified for each procedure. Among participants who had diabetes at baseline, 216 RYGB participants (67.5%) and 28 LAGB participants (28.6%) experienced partial remission at 3 years. The incidence of diabetes was 0.9% after RYGB and 3.2% after LAGB. Dyslipidemia resolved in 237 RYGB participants (61.9%) and 39 LAGB participants (27.1%); remission of hypertension occurred in 269 RYGB participants (38.2%) and 43 LAGB participants (17.4%).

CONCLUSIONS AND RELEVANCE

Among participants with severe obesity, there was substantial weight loss 3 years after bariatric surgery, with the majority experiencing maximum weight change during the first year. However, there was variability in the amount and trajectories of weight loss and in diabetes, blood pressure, and lipid outcomes.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT00465829.

New technologies for treating obesity

Obesity has become a national epidemic and a disease of global magnitude. The numbers of patients with obesity have grown exponentially in the last 10 years to the degree that the Centers for Disease Control and Prevention reports that one third of the US population is obese. The prevalence of diabetes has grown by more than 50% in that same time period. Unfortunately, the traditional therapies of diets, exercise, behavioral modification and medications have had little effect, especially in the severely obese. The introduction of bariatric surgery has changed the natural history of the super obese. Operative approaches now provide the most effective treatment of obesity but carry with them possible risks. Only 1% of patients who are estimated to benefit from bariatric surgery have undergone a procedure. The burgeoning field of endoluminal therapy has now allowed us to consider even more minimally invasive procedures to reach a larger patient population. This article will review the most recent advances in innovative technologies to treat the growing numbers of obese patients.

What distinguishes adipose tissue of severely obese humans who are insulin sensitive and resistant?

PURPOSE OF REVIEW

Despite a strong correlation between obesity and insulin resistance, 25% of severely obese (BMI >40) individuals are insulin sensitive. In this review, we will examine the factors in adipose tissue that distinguish the two groups, as well as reasons for believing the insulin-sensitive group will be less disease prone.

RECENT FINDINGS

Obesity has been linked to the metabolic syndrome with an increase in visceral (intra-abdominal) compared to subcutaneous fat. Recent studies in which adipose tissue of insulin-sensitive and insulin-resistant patients with severe obesity were compared indicate that the insulin-resistant group is also distinguished by increases in oxidative stress and decreases in AMP-activated protein kinase (AMPK) activity. In contrast, changes in the expression of genes for SIRT1, inflammatory cytokines, mitochondrial biogenesis and function, and the two α-isoforms of AMPK showed more depot variation. Studies of how these and other changes in adipose tissue respond to bariatric surgery are still in their infancy.

SUMMARY

Available data suggest that increases in oxidative stress, decreases in AMPK activity and SIRT1 gene expression, depot-specific changes in inflammatory, mitochondrial and other genes distinguish adipose tissue of insulin resistant from insulin-sensitive individuals with severe obesity.

GLP-1 response to a mixed meal: what happens 10 years after Roux-en-Y gastric bypass (RYGB)?

BACKGROUND

Oral meal consumption increases glucagon-like peptide 1 (GLP-1) release which maintains euglycemia by increasing insulin secretion. This effect is exaggerated during short-term follow-up of Roux-en-y gastric bypass (RYGB). We examined the durability of this effect in patient with type 2 diabetes (T2DM) >10 years after RYGB.

METHODS

GLP-1 response to a mixed meal in the 10-year post-RYGB group (n = 5) was compared to lean (n = 9), obese (n = 6), and type 2 diabetic (n = 10) controls using a cross-sectional study design. Analysis of variance (ANOVA) was used to evaluate GLP-1 response to mixed meal consumption from 0 to 300 min, 0-20 min, 20-60 min, and 60-300 min, respectively. Weight, insulin resistance, and T2DM were also assessed.

RESULTS

GLP-1 response 0-300 min in the 10-year post-RYGB showed a statistically significant overall difference (p =  0.01) compared to controls. Furthermore, GLP-1 response 0-20 min in the 10-year post-RYGB group showed a very rapid statistically significant rise (p = 0.035) to a peak of 40 pM. GLP-1 response between 20 and 60 min showed a rapid statistically significant (p = 0.041) decline in GLP-1 response from ~40 pM to 10 pM. GLP-1 response in the 10-year post-RYGB group from 60 to 300 min showed no statistically significant difference from controls. BMI, HOMA, and fasting serum glucose before and >10 years after RYGB changed from 59.9 → 40.4, 8.7 → 0.88, and 155.2 → 87.6 mg/dl, respectively, and were statistically significant (p < 0.05).

CONCLUSIONS

An exaggerated GLP-1 response was noted 10 years after RYGB, strongly suggesting a durability of this effect. This phenomenon may play a key role in maintaining type 2 diabetes remission and weight loss after RYGB.

Can technical factors explain the volume-outcome relationship in gastric bypass surgery?

BACKGROUND

The existence of a relationship between surgeon volume and patient outcome has been reported for different complex surgical operations. This relationship has also been confirmed for patients undergoing Roux-en-Y gastric bypass (RYGB) in the Longitudinal Assessment of Bariatric Surgery (LABS) study. Despite multiple studies demonstrating volume-outcome relationships, fewer studies investigate the causes of this relationship.

OBJECTIVE

The purpose of the present study is to understand possible explanations for the volume-outcome relationship in LABS.

METHODS

LABS includes a 10-center, prospective study examining 30-day outcomes after bariatric surgery. The relationship between surgeon annual RYGB volume and incidence of a composite endpoint (CE) has been published previously. Technical aspects of RYGB surgery were compared between high and low volume surgeons. The previously published model was adjusted for select technical factors.

RESULTS

High-volume surgeons (>100 RYGBs/yr) were more likely to perform a linear stapled gastrojejunostomy, use fibrin sealant, and place a drain at the gastrojejunostomy compared with low-volume surgeons (<25 RYGBs/yr), and less likely to perform an intraoperative leak test. After adjusting for the newly identified technical factors, the relative risk of CE was .93 per 10 RYGB/yr increase in volume, compared with .90 for clinical risk adjustment alone.

CONCLUSION

High-volume surgeons exhibited certain differences in technique compared with low-volume surgeons. After adjusting for these differences, the strength of the volume-outcome relationship previously found was reduced only slightly, suggesting that other factors are also involved.

Distribution of 10-year and lifetime predicted risk for cardiovascular disease prior to surgery in the longitudinal assessment of bariatric surgery-2 study

Primary prevention guidelines recommend calculation of lifetime cardiovascular disease (CVD) predicted risk in patients who may not meet criteria for high short-term (10-year) Adult Treatment Panel III risk for coronary heart disease (CHD). Extreme obesity and bariatric surgery are more common in women who often have low short-term predicted CHD risk. The distribution and correlates of lifetime CVD predicted risk, however, have not yet been evaluated in bariatric surgical candidates. Using established 10-year (Adult Treatment Panel III) CHD and lifetime CVD risk prediction algorithms and presurgery risk factors, participants from the Longitudinal Assessment of Bariatric Surgery-2 study without prevalent CVD (n = 2,070) were stratified into 3 groups: low 10-year (<10%)/low lifetime (<39%) predicted risk, low 10-year (<10%)/high lifetime (≥39%) predicted risk, and high 10-year (≥10%) predicted risk or diagnosed diabetes. Participants were predominantly white (86%) and women (80%) with a median age of 45 years and median body mass index of 45.6 kg/m(2). High 10-year CHD predicted risk was common (36.5%) and associated with diabetes, male gender, and older age, but not with higher body mass index or high-sensitivity C-reactive protein. Most participants (76%) with low 10-year predicted risk had high lifetime CVD predicted risk, which was associated with dyslipidemia and hypertension but not with body mass index, waist circumference, high-density lipoprotein cholesterol, or high-sensitivity C-reactive protein. In conclusion, bariatric surgical candidates without diabetes or existing CVD are likely to have low short-term, but high lifetime CVD predicted risk. Current data support the need for long-term monitoring and treatment of increased CVD risk factors in bariatric surgical patients to maximize lifetime CVD risk decrease (clinical trial registration, Long-term Effects of Bariatric Surgery, indentifier NCT00465829, available at: http://www.clinicaltrials.gov/ct2/results?term=NCT00465829).

Prevalence of alcohol use disorders before and after bariatric surgery

CONTEXT

Anecdotal reports suggest bariatric surgery may increase the risk of alcohol use disorder (AUD), but prospective data are lacking.

OBJECTIVE

To determine the prevalence of preoperative and postoperative AUD, and independent predictors of postoperative AUD.

DESIGN, SETTING, AND PARTICIPANTS

A prospective cohort study (Longitudinal Assessment of Bariatric Surgery-2) of adults who underwent bariatric surgery at 10 US hospitals. Of 2458 participants, 1945 (78.8% female; 87.0% white; median age, 47 years; median body mass index, 45.8) completed preoperative and postoperative (at 1 year and/or 2 years) assessments between 2006 and 2011.

MAIN OUTCOME MEASURE

Past year AUD symptoms determined with the Alcohol Use Disorders Identification Test (indication of alcohol-related harm, alcohol dependence symptoms, or score ≥8).

RESULTS

The prevalence of AUD symptoms did not significantly differ from 1 year before to 1 year after bariatric surgery (7.6% vs 7.3%; P = .98), but was significantly higher in the second postoperative year (9.6%; P = .01). The following preoperative variables were independently related to an increased odds of AUD after bariatric surgery: male sex (adjusted odds ratio [AOR], 2.14 [95% CI, 1.51-3.01]; P < .001), younger age (age per 10 years younger with preoperative AUD: AOR, 1.31 [95% CI, 1.03-1.68], P = .03; age per 10 years younger without preoperative AUD: AOR, 1.95 [95% CI, 1.65-2.30], P < .001), smoking (AOR, 2.58 [95% CI, 1.19-5.58]; P = .02), regular alcohol consumption (≥ 2 drinks/week: AOR, 6.37 [95% CI, 4.17-9.72]; P < .001), AUD (eg, at age 45, AOR, 11.14 [95% CI, 7.71-16.10]; P < .001), recreational drug use (AOR, 2.38 [95% CI, 1.37-4.14]; P = .01), lower sense of belonging (12-item Interpersonal Support Evaluation List score per 1 point lower: AOR, 1.09 [95% CI, 1.04-1.15]; P = .01), and undergoing a Roux-en-Y gastric bypass procedure (AOR, 2.07 [95% CI, 1.40-3.08]; P < .001; reference category: laparoscopic adjustable gastric band procedure).

CONCLUSION

In this cohort, the prevalence of AUD was greater in the second postoperative year than the year prior to surgery or in the first postoperative year and was associated with male sex and younger age, numerous preoperative variables (smoking, regular alcohol consumption, AUD, recreational drug use, and lower interpersonal support) and undergoing a Roux-en-Y gastric bypass procedure.

Surgical treatment of metabolic syndrome

This article explores the surprising finding that bariatric surgery can produce full and durable remission of the metabolic syndrome as well as other comorbidities of obesity including type II diabetes, hypertension, polycystic ovary syndrome, gastroesophageal reflux disease, nonalcoholic steatotic hepatitis, adult asthma and improvement in weight-bearing arthropathy. Such an outcome was previously deemed impossible. One effect of the surgery is the correction of hyperinsulinemia, a common denominator in the various expressions of the metabolic syndrome. Basal insulin levels return to normal levels within a matter of days following surgery, allowing a return of the first phase of insulin secretion. This effect is 'dose related' to the extent of the reduction of contact between food and the gut. The resolution of the spectrum of diseases that comprise the metabolic syndrome following bariatric surgery suggests that hyperinsulinemia may be the common cause that is corrected by lowering contact between food and the gut. If this concept is true, then the cause of the syndrome, including diabetes, could be a diabetogenic signal from the gut that forces the islets to produce excessive and harmful levels of insulin, or the cause could be the removal of a signal that blocks excessive insulin secretion. If either of these mechanisms is proven correct, the current treatment of diabetes with long-term insulin administration deserves review.

Massive weight loss-induced mechanical plasticity in obese gait

We examined the hypothesis that metabolic surgery-induced massive weight loss causes mass-driven and behavioral adaptations in the kinematics and kinetics of obese gait. Gait analyses were performed at three time points over ∼1 yr in initially morbidly obese (mass: 125.7 kg; body mass index: 43.2 kg/m(2)) but otherwise healthy adults. Ten obese adults lost 27.1% ± 5.1 (34.0 ± 9.4 kg) weight by the first follow-up at 7.0 mo (±0.7) and 6.5 ± 4.2% (8.2 ± 6.0 kg) more by the second follow-up at 12.8 mo (±0.9), with a total weight loss of 33.6 ± 8.1% (42.2 ± 14.1 kg; P = 0.001). Subjects walked at a self-selected and a standard 1.5 m/s speed at the three time points and were also compared with an age- and gender-matched comparison group at the second follow-up. Weight loss increased swing time, stride length, gait speed, hip range of motion, maximal knee flexion, and ankle plantarflexion. Weight loss of 27% led to 3.9% increase in gait speed. An additional 6.5% weight loss led to an additional 7.3% increase in gait speed. Sagittal plane normalized knee torque increased and absolute ankle and frontal plane knee torques decreased after weight loss. We conclude that large weight loss produced mechanical plasticity by modifying ankle and knee torques and gait behavior. There may be a weight loss threshold of 30 kg limiting changes in gait kinematics. Implications for exercise prescription are also discussed.

Roux-en-Y gastric bypass corrects hyperinsulinemia implications for the remission of type 2 diabetes

CONTEXT

Roux-en-Y gastric bypass (RYGB) has been shown to induce rapid and durable reversal of type 2 diabetes.

OBJECTIVE

The aim of the study was to investigate a possible mechanism for the remission of type 2 diabetes after RYGB.

DESIGN

A cross-sectional, nonrandomized, controlled study was conducted. Surgery patients were studied before RYGB and 1 wk and 3 months after surgery.

SETTING

This study was conducted at East Carolina University.

SUBJECTS

Subjects were recruited into three groups: 1) lean controls with no surgery [body mass index (BMI) < 25 kg/m²; n = 9], 2) severely obese type 2 diabetic patients (BMI > 35 kg/m²; n = 9), and 3) severely obese nondiabetic patients (BMI > 35 kg/m²; n = 9).

INTERVENTION

Intervention was RYGB.

RESULTS

One week after RYGB, diabetes was resolved despite continued insulin resistance (insulin sensitivity index was approximately 50% of lean controls) and reduced insulin secretion during an iv glucose tolerance test (acute insulin response to glucose was approximately 50% of lean controls). Fasting insulin decreased and was no different from lean control despite continued elevated glucose in the type 2 diabetic patients compared with lean.

CONCLUSIONS

After RYGB, fasting insulin decreases to levels like those of lean control subjects and diabetes is reversed (fasting blood glucose < 125 mg/dl). This leads us to propose that 1) exclusion of food from the foregut corrects hyperinsulinemia and 2) fasting insulin is dissociated from the influence of fasting glucose, insulin resistance, and BMI. The mechanisms for reversal of diabetes in the face of reduced insulin remain a paradox.

The surgical treatment of type two diabetes mellitus

Since the discovery that gastric bypass surgery leads to the rapid reversal of type 2 diabetes mellitus in morbidly obese patients, researchers have been searching for possible mechanisms to explain the result. The significance of bariatric surgery is twofold. It offers hope and successful therapy to the severely obese; those with T2DM, sleep apnea, or polycystic ovary disease; and others plagued by the comorbidities of the metabolic syndrome. This article examines four surgical procedures and their outcomes.