James McGinty

Effect of Weight Loss by Gastric Bypass Surgery Versus Hypocaloric Diet on Glucose and Incretin Levels in Patients with Type 2 Diabetes

CONTEXTnGastric bypass surgery (GBP) results in rapid weight loss, improvement of type 2 diabetes (T2DM), and increase in incretins levels. Diet-induced weight loss also improves T2DM and may increase incretin levels.nnnOBJECTIVEnOur objective was to determine whether the magnitude of the change of the incretin levels and effect is greater after GBP compared with a low caloric diet, after equivalent weight loss.nnnDESIGN AND METHODSnObese women with T2DM studied before and 1 month after GBP (n = 9), or after a diet-induced equivalent weight loss (n = 10), were included in the study. Patients from both groups were matched for age, body weight, body mass index, diabetes duration and control, and amount of weight loss.nnnSETTINGnThis outpatient study was conducted at the General Clinical Research Center.nnnMAIN OUTCOME MEASURESnGlucose, insulin, proinsulin, glucagon, gastric inhibitory peptide (GIP), and glucagon-like peptide (GLP)-1 levels were measured after 50-g oral glucose. The incretin effect was measured as the difference in insulin levels in response to oral and to an isoglycemic iv glucose load.nnnRESULTSnAt baseline, none of the outcome variables (fasting and stimulated values) were different between the GBP and diet groups. Total GLP-1 levels after oral glucose markedly increased six times (peak:17 +/- 6 to 112 +/- 54 pmol/liter; P < 0.001), and the incretin effect increased five times (9.4 +/- 27.5 to 44.8 +/- 12.7%; P < 0.001) after GBP, but not after diet. Postprandial glucose levels (P = 0.001) decreased more after GBP.nnnCONCLUSIONSnThese data suggest that early after GBP, the greater GLP-1 and GIP release and improvement of incretin effect are related not to weight loss but rather to the surgical procedure. This could be responsible for better diabetes outcome after GBP.

Rise of Oxyntomodulin in Response to Oral Glucose after Gastric Bypass Surgery in Patients with Type 2 Diabetes

CONTEXTnThe mechanisms by which Roux-en-Y gastric bypass surgery (GBP) results in sustained weight loss and remission of type 2 diabetes are not fully understood.nnnOBJECTIVEnWe hypothesized that the anorexic hormone oxyntomodulin (OXM) might contribute to the marked weight reduction and the rapid improvement in glucose metabolism observed in morbidly obese diabetic patients after GBP.nnnMETHODSnTwenty obese women with type 2 diabetes were studied before and 1 month after GBP (n=10) or after a diet-induced equivalent weight loss (n=10). Patients from both groups were matched for age, body weight, body mass index, and diabetes duration and control. OXM concentrations were measured during a 50-g oral glucose challenge before and after weight loss.nnnRESULTSnAt baseline, OXM levels (fasting and stimulated values) were indistinguishable between the GBP and the diet group. However, OXM levels rose remarkably in response to an oral glucose load more than 2-fold (peak, 5.25+/-1.31 to13.8+/-16.2 pmol/liter; P=0.025) after GBP but not after diet. The peak of OXM after glucose was significantly correlated with glucagon-like peptide-1 and peptide YY3-36.nnnCONCLUSIONSnOur data suggest that the observed changes in OXM primarily occur in response to GBP and not as a consequence of weight loss. These changes were observed early after surgery and occurred in parallel with previously reported increases in incretins and peptide YY. We speculate that the combination of gut hormone changes is essential for the improved glucose homeostasis and may partially explain the success of this surgery on diabetes resolution and weight loss.

Superior Appetite Hormone Profile After Equivalent Weight Loss by Gastric Bypass Compared to Gastric Banding

The goal of this study was to understand the mechanisms of greater weight loss by gastric bypass (GBP) compared to gastric banding (GB) surgery. Obese weight‐ and age‐matched subjects were studied before (T0), after a 12 kg weight loss (T1) by GBP (n = 11) or GB (n = 9), and at 1 year after surgery (T2). peptide YY3–36 (PYY3–36), ghrelin, glucagon‐like peptide‐1 (GLP‐1), leptin, and amylin were measured after an oral glucose challenge. At T1, glucose‐stimulated GLP‐1 and PYY levels increased significantly after GBP but not GB. Ghrelin levels did not change significantly after either surgery. In spite of equivalent weight loss, leptin and amylin decreased after GBP, but not after GB. At T2, weight loss was greater after GBP than GB (P = 0.003). GLP‐1, PYY, and amylin levels did not significantly change from T1 to T2; leptin levels continued to decrease after GBP, but not after GB at T2. Surprisingly, ghrelin area under the curve (AUC) increased 1 year after GBP (P = 0.03). These data show that, at equivalent weight loss, favorable GLP‐1 and PYY changes occur after GBP, but not GB, and could explain the difference in weight loss at 1 year. Mechanisms other than weight loss may explain changes of leptin and amylin after GBP.

Limited recovery of β-cell function after gastric bypass despite clinical diabetes remission.

The mechanisms responsible for the remarkable remission of type 2 diabetes after Roux-en-Y gastric bypass (RYGBP) are still puzzling. To elucidate the role of the gut, we compared β-cell function assessed during an oral glucose tolerance test (OGTT) and an isoglycemic intravenous glucose clamp (iso-IVGC) in: 1) 16 severely obese patients with type 2 diabetes, up to 3 years post-RYGBP; 2) 11 severely obese normal glucose-tolerant control subjects; and 3) 7 lean control subjects. Diabetes remission was observed after RYGBP. β-Cell function during the OGTT, significantly blunted prior to RYGBP, normalized to levels of both control groups after RYGBP. In contrast, during the iso-IVGC, β-cell function improved minimally and remained significantly impaired compared with lean control subjects up to 3 years post-RYGBP. Presurgery, β-cell function, weight loss, and glucagon-like peptide 1 response were all predictors of postsurgery β-cell function, although weight loss appeared to be the strongest predictor. These data show that β-cell dysfunction persists after RYGBP, even in patients in clinical diabetes remission. This impairment can be rescued by oral glucose stimulation, suggesting that RYGBP leads to an important gastrointestinal effect, critical for improved β-cell function after surgery.

Accelerated Gastric Emptying but No Carbohydrate Malabsorption 1 Year After Gastric Bypass Surgery (GBP)

BackgroundFollowing gastric bypass surgery (GBP), there is a post-prandial rise of incretin and satiety gut peptides. The mechanisms of enhanced incretin release in response to nutrients after GBP is not elucidated and may be in relation to altered nutrient transit time and/or malabsorption.MethodsSeven morbidly obese subjects (BMIu2009=u200944.5u2009±u20092.8xa0kg/m2) were studied before and 1xa0year after GBP with a d-xylose test. After ingestion of 25xa0g of d-xylose in 200xa0mL of non-carbonated water, blood samples were collected at frequent time intervals to determine gastric emptying (time to appearance of d-xylose) and carbohydrate absorption using standard criteria.ResultsOne year after GBP, subjects lost 45.0u2009±u20099.7xa0kg and had a BMI of 27.1u2009±u20094.7xa0kg/m2. Gastric emptying was more rapid after GBP. The mean time to appearance of d-xylose in serum decreased from 18.6u2009±u20096.9xa0min prior to GBP to 7.9u2009±u20092.7xa0min after GBP (pu2009=u20090.006). There was no significant difference in absorption before (serum d-xylose concentrationsu2009=u200935.6u2009±u200912.6xa0mg/dL at 60xa0min and 33.9u2009±u20099.1xa0mg/dL at 180xa0min) or 1xa0year after GBP (serum d-xyloseu2009=u200931.5u2009±u200918.1xa0mg/dL at 60xa0min and 27.2u2009±u200911.9xa0mg/dL at 180xa0min).ConclusionsThese data confirm the acceleration of gastric emptying for liquid and the absence of carbohydrate malabsorption 1xa0year after GBP. Rapid gastric emptying may play a role in incretin response after GBP and the resulting improved glucose homeostasis.

Gastric bypass surgery, but not caloric restriction, decreases dipeptidyl peptidase 4 activity in obese patients with type 2 diabetes.

The mechanism by which incretins and their effect on insulin secretion increase markedly following gastric bypass (GBP) surgery is not fully elucidated. We hypothesized that a decrease in the activity of dipeptidyl peptidase‐4 (DPP‐4), the enzyme which inactivates incretins, may explain the rise in incretin levels post‐GBP. Fasting plasma DPP‐4 activity was measured after 10‐kg equivalent weight loss by GBP (n = 16) or by caloric restriction (CR,n = 14) in obese patients with type 2 diabetes. DPP‐4 activity decreased after GBP by 11.6% (p = 0.01), but not after CR. The increased peak glucagon‐like peptide‐1 (GLP‐1) and glucose‐dependent insulinotropic polypeptide (GIP) response to oral glucose after GBP did not correlate with DPP‐4 activity. The decrease in fasting plasma DPP‐4 activity after GBP occurred by a mechanism independent of weight loss and did not relate to change in incretin concentrations. Whether the change in DPP‐4 activity contributes to improved diabetes control after GBP remains therefore to be determined.

Surgical Residents' Perception of the 16-Hour Work Day Restriction: Concern for Negative Impact on Resident Education and Patient Care

BACKGROUNDnEffective July 1, 2011, the Accreditation Council for Graduate Medical Education (ACGME) instituted a 16-hour duty period limitation for postgraduate year I (PGY I) residents. Our aim was to assess the attitudes and perception of general surgery residents regarding the new duty hour limitation as well as the transfer of care process under the new guidelines.nnnSTUDY DESIGNnAn anonymous, web-based survey was conducted nationally 7 months after the institution of the 16-hour duty limitation.nnnRESULTSnA total of 464 completed surveys were analyzed. Overall, 75% of residents expressed dissatisfaction with the new duty hour limitation. PGY II to V residents reported a higher level of dissatisfaction compared with PGY I residents (87% vs 54%, p < 0.01). Eighty-nine percent of PGY II to V residents responded that there has been a shift of responsibilities from the PGY I class to PGY II to V residents, with 73% reporting increased fatigue as a result. Seventy-five percent of PGY I and 94% of PGY II to V residents expressed concerns about the adverse impact of the restrictions on the education of PGY I residents (p < 0.01). Residents at all PGY training levels reported encountering problems due to inadequate sign-outs (PGY I, 59%; PGY II to V, 85%; p < 0.01). Sixty-two percent of PGY I residents and 54% of PGY II to V residents believed that the new 16-hour duty restriction contributes to inadequate sign-outs (p = NS). Most PGY II to V residents (86%) believe there is a decreased level of patient ownership due to the work hour restrictions.nnnCONCLUSIONSnThe results of the survey suggest that the majority of general surgery residents are concerned over the potential negative impact of the duty limitation on resident education and patient care. Further research is needed to address these concerns.

The incidence of trocar-site hernia in minimally invasive bariatric surgery: A comparison of multi versus single-port laparoscopy

IntroductionSingle-port laparoscopy (SPL) employs a 1.5- to 2.5-cm incision at the umbilicus for the placement of a single working port. We hypothesized that the longer incision created by SPL compared with multiport laparoscopy may increase the incidence of trocar-site hernias. We examined our experience with SPL in bariatric operations.MethodsThere were 734 laparoscopic sleeve gastrectomy and laparoscopic adjustable gastric banding procedures performed at our institution between 2001 and 2011. Fifty-eight patients were lost to follow-up or had a short duration of follow-up (<1xa0month). Of the remaining 676 cases, 163 were performed via SPL. All laparoscopic wounds created by trocar size greater than 12xa0mm were closed with absorbable suture.ResultsPatient demographics of the SPL group and the multiport group were similar in terms of age, gender, and comorbidities. The average body mass index (BMI) of the SPL group was lower than the multiport group (43.5xa0±xa05.3 vs. 45.8xa0±xa07.7, pxa0<xa00.01). The mean follow-up for the SPL group was 11xa0months versus 24xa0months for the multiport group. There were three trocar-site hernias out of 513 cases in the multiport compared to one hernia out of 163 cases in the SPL group (0.6 vs. 0.6xa0%, pxa0=xa00.967). All trocar-site hernias occurred at the 15-mm port site. The median time to hernia occurrence for the multiport group was 13xa0months (range, 1–18). In the SPL group, the hernia occurred at 8xa0months. On multivariate analysis, age, BMI, SPL, procedure type, and the postoperative weight loss were not associated with the development of trocar-site hernias.ConclusionsSPL did not increase the rate of trocar-site hernia in this series. A low rate of trocar-site hernia can be achieved with the use of SPL in bariatric surgery.

Outcomes of Laparoscopic Roux-en-Y Gastric Bypass Versus Laparoscopic Adjustable Gastric Banding in Adolescents

BackgroundThe goal of this study is to compare the outcomes of laparoscopic adjustable gastric banding (LAGB) and laparoscopic Roux-en-Y gastric bypass (LRYGB) in obese adolescents.MethodsWe performed a retrospective review of all adolescents between the ages of 15 and 19 who underwent LAGB or LRYGB at our university affiliated Bariatric Center of Excellence from 2002 to 2011. Postsurgical weight loss at 1, 3, 6, 12, 18, and 24xa0months was noted and expressed as percentage of excess weight loss (% EWL).ResultsThirty-two patients underwent LRYGB and 23 underwent LAGB. The LAGB group was younger (18.6u2009±u20090.6 versus 17.2u2009±u20091.5) than the LRYGB group. Other preoperative demographic factors including body mass index, gender, ethnicity, and comorbidities were similar between the two groups. The average % EWL was superior in the LRYGB group compared to the LAGB group at all time points studied (pu2009<u20090.05), although at 2-year follow-up, only 16xa0% (5/32) LRYGB and 30xa0% (7/23) LAGB patients were available for follow-up. Three patients with type II diabetes mellitus underwent LRYGB and all experienced remission of their diabetes. The number of complications requiring interventions was similar between the two groups.ConclusionsIn our study, adolescents undergoing LRYGB achieved superior weight loss compared to LAGB in the short-term follow-up. The complication rate for LAGB was similar compared to LRYGB. More studies are needed to monitor the long-term effects of these operations on adolescents before definitive recommendations can be made.

Effects of Gastrogastric Fistula Repair on Weight Loss and Gut Hormone Levels

BackgroundWeight regain after gastric bypass (GBP) can be associated with a gastrogastric fistula (GGF), in which a channel forms between the gastric pouch and gastric remnant, allowing nutrients to pass through the “old route” rather than bypassing the duodenum. To further understand the mechanisms by which GGF may lead to weight regain, we investigated gut hormone levels in GBP patients with a GGF, before and after repair.Materials and MethodsSeven post-GBP subjects diagnosed with GGF were studied before and 4xa0months after GGF repair. Another cohort of 22 GBP control subjects without GGF complication were studied before and 1xa0year post-GBP. All subjects underwent a 50-g oral glucose tolerance test and blood was collected from 0–120xa0min for glucose, insulin, ghrelin, PYY3-36, GIP, and GLP-1 levels.ResultsFour months after GGF repair subjects lost 6.0u2009±u20093.9xa0kg and had significantly increased postprandial PYY3-36 levels. After GGF repair, fasting and postprandial ghrelin levels decreased and were strongly correlated with weight loss. The insulin response to glucose also tended to be increased after GGF repair, however no concomitant increase in GLP-1 was observed. Compared to the post-GBP group, GLP-1 and PYY3-36 levels were significantly lower before GGF repair; however, after GGF repair, PYY3-36 levels were no longer lower than the post-GBP group.ConclusionsThese data utilize the GGF model to highlight the possible role of duodenal shunting as a mechanism of sustained weight loss after GBP, and lend support to the potential link between blunted satiety peptide release and weight regain.