Incretins, diabetes, and bariatric surgery: a review

Data assimilation on mechanistic models of glucose metabolism predicts glycemic states in adolescents following bariatric surgery

Type 2 diabetes mellitus is a complex and under-treated disorder closely intertwined with obesity. Adolescents with severe obesity and type 2 diabetes have a more aggressive disease compared to adults, with a rapid decline in pancreatic β cell function and increased incidence of comorbidities. Given the relative paucity of pharmacotherapies, bariatric surgery has become increasingly used as a therapeutic option. However, subsets of this population have sub-optimal outcomes with either inadequate weight loss or little improvement in disease. Predicting which patients will benefit from surgery is a difficult task and detailed physiological characteristics of patients who do not respond to treatment are generally unknown. Identifying physiological predictors of surgical response therefore has the potential to reveal both novel phenotypes of disease as well as therapeutic targets. We leverage data assimilation paired with mechanistic models of glucose metabolism to estimate pre-operative physiological states of bariatric surgery patients, thereby identifying latent phenotypes of impaired glucose metabolism. Specifically, maximal insulin secretion capacity, σ, and insulin sensitivity, S_I, differentiate aberrations in glucose metabolism underlying an individual's disease. Using multivariable logistic regression, we combine clinical data with data assimilation to predict post-operative glycemic outcomes at 12 months. Models using data assimilation sans insulin had comparable performance to models using oral glucose tolerance test glucose and insulin. Our best performing models used data assimilation and had an area under the receiver operating characteristic curve of 0.77 (95% confidence interval 0.7665, 0.7734) and mean average precision of 0.6258 (0.6206, 0.6311). We show that data assimilation extracts knowledge from mechanistic models of glucose metabolism to infer future glycemic states from limited clinical data. This method can provide a pathway to predict long-term, post-surgical glycemic states by estimating the contributions of insulin resistance and limitations of insulin secretion to pre-operative glucose metabolism.

Effects of Exercise Mode on Improving Cardiovascular Function and Cardiorespiratory Fitness After Bariatric Surgery: A Narrative Review

ABSTRACT

Obesity affects 600 million people globally and increases the risk of developing cardiovascular disease, stroke, diabetes, and cancer. Bariatric surgery is an increasingly popular therapeutic intervention for morbid obesity to induce rapid weight loss and reduce obesity-related comorbidities. However, some bariatric surgery patients, after what is considered a successful surgical procedure, continue to manifest obesity-related health issues, including weight gain, reduced physical function, persistent elevations in blood pressure, and reduced cardiorespiratory fitness. Cardiorespiratory fitness is a strong predictor of mortality and several health outcomes and could be improved by an appropriate exercise prescription after bariatric surgery. This review provides a broad overview of exercise training for patients after bariatric surgery and discusses cardiorespiratory fitness and other potential physiological adaptations in response to exercise training.

Role of Gastrointestinal Hormones as a Predictive Factor for Long-Term Diabetes Remission: Randomized Trial Comparing Metabolic Gastric Bypass, Sleeve Gastrectomy, and Greater Curvature Plication

PURPOSE

Long-term studies comparing the mechanisms of different bariatric techniques for T2DM remission are scarce. We aimed to compare type 2 diabetes (T2DM) remission after a gastric bypass with a 200-cm biliopancreatic limb (mRYGB), sleeve gastrectomy (SG), and greater curvature plication (GCP), and to assess if the initial secretion of gastrointestinal hormones may predict metabolic outcomes at 5 years.

MATERIAL AND METHODS

Forty-five patients with mean BMI of 39.4(1.9)kg/m² and T2DM with HbA_1c of 7.7(1.9)% were randomized to mRYGB, SG, or GCP. Anthropometric and biochemical parameters, fasting concentrations of PYY, ghrelin, glucagon, and AUC of GLP-1 after SMT were determined prior to and at months 1 and 12 after surgery. At 5-year follow-up, anthropometrical and biochemical parameters were determined.

RESULTS

Total weight loss percentage (TWL%) at year 1 and GLP-1 AUC at months 1 and 12 were higher in the mRYGB than in the SG and GCP. TWL% remained greater at 5 years in mRYGB group - 27.32 (7.8) vs. SG - 18.00 (10.6) and GCP - 14.83 (7.8), p = 0.001. At 5 years, complete T2DM remission was observed in 46.7% after mRYGB vs. 20.0% after SG and 6.6% after GCP, p < 0.001. In the multivariate analysis, shorter T2DM duration (OR 0.186), p = 0.008, and the GLP-1 AUC at 1 month (OR 7.229), p = 0.023, were prognostic factors for complete T2DM remission at 5-year follow-up.

CONCLUSIONS

Long-term T2DM remission is mostly achieved with hypoabsortive techniques such as mRYGB. Increased secretion of GLP-1 after surgery and shorter disease duration were the main predictors of T2DM remission at 5 years.

NDRG1 Activity in Fat Depots Is Associated With Type 2 Diabetes and Impaired Incretin Profile in Patients With Morbid Obesity

OBJECTIVE

We aimed to investigate insulin-, mTOR- and SGK1-dependent signaling basal states in morbidly obese patients' fat. We analyzed the correlation between the signaling activity, carbohydrate metabolism, and incretin profiles of patients.

METHODS

The omental and subcutaneous fat was obtained in patients with obesity. The omental study included 16 patients with normal glucose tolerance (NGT) and 17 patients with type 2 diabetes mellitus (T2DM); the subcutaneous study included 9 NGT patients and 12 T2DM patients. Insulin resistance was evaluated using the hyperinsulinemic euglycemic clamp test and HOMA-IR index. The oral glucose tolerance test (OGTT) for NGT patients and mixed meal tolerance test (MMTT) for T2DM patients were performed. The levels of incretins (GLP-1, GIP, oxyntomodulin) and glucagon were measured during the tests. Signaling was analyzed by Western blotting in adipose tissue biopsies.

RESULTS

We have shown equal levels of basal phosphorylation of insulin- and mTOR-dependent signaling in omental fat depot in NGT and T2DM obese patients. Nevertheless, pNDRG1-T346 was decreased in omental fat of T2DM patients. Correlation analysis has shown an inverse correlation of pNDRG1-T346 in omental fat and diabetic phenotype (HbA1c, impaired incretin profile (AUC GLP-1, glucagon)). Moreover, pNDRG1-T346 in subcutaneous fat correlated with impaired incretin levels among obese patients (inverse correlation with AUC glucagon and AUC GIP).

CONCLUSIONS

According to results of the present study, we hypothesize that phosphorylation of pNDRG1-T346 can be related to impairment in incretin hormone processing. pNDRG1-T346 in adipose tissue may serve as a marker of diabetes-associated impairments of the systemic incretin profile and insulin sensitivity.

Low AS160 and high SGK basal phosphorylation associates with impaired incretin profile and type 2 diabetes in adipose tissue of obese patients

OBJECTIVE

To compare basal insulin and mTOR signaling in subcutaneous fat of obese T2DM vs. obese subjects with normal glucose tolerance (NGT), and correlate it with clinical parameters of carbohydrate metabolism and incretin secretion profiles.

METHODS

Recruited were 22 patients with long (>10 years) and morbid (BMI > 35 kg/m²) obesity, 12 of which had NGT and 10 had T2DM. Hyperinsulinemic-euglycemic clamp test and HOMA-IR were used to measure insulin resistance. Blood samples taken at 0, 30 and 120 min of food load test were used to assess incretin profile, insulin and glucose levels. Amount of total and visceral fat was determined by bioelectrical impedance analysis. Subcutaneous fat biopsies were obtained during bariatric surgery for all patients and analyzed by western blots.

RESULTS

As assessed by western blots of insulin receptor substrate (IRS), Akt, Raptor, Rictor, mTOR and S6K1, the basal insulin signaling and mTORC activities were comparable in NGT and T2DM groups, whereas phosphorylation of AS160 was significantly lower and that of serum and glucocorticoid-induced kinase (SGK) was significantly higher in T2DM group. Various correlations were found between the degree of insulin resistance and amount of visceral fat, changes in incretin profile, glucose metabolic parameters and phosphorylation level of AS160, incretin secretion profile and phosphorylated levels of AS160 or SGK1.

CONCLUSION

Altered phosphorylation of AS160 and SGK1 is associated with obese T2DM phenotype.

Predictive Value of Gut Peptides in T2D Remission: Randomized Controlled Trial Comparing Metabolic Gastric Bypass, Sleeve Gastrectomy and Greater Curvature Plication

BACKGROUND

Our aim was to determine the predictive value of gut hormone changes for the improvement of type 2 diabetes (T2D) following metabolic Roux-en-Y gastric bypass (mRYGB), sleeve gastrectomy (SG), and greater curvature plication (GCP) in a randomized controlled trial. Contradictory results have been obtained regarding the role of gastrointestinal hormones (in particular GLP-1) in beneficial metabolic bariatric surgery outcomes.

METHODS

Forty-five patients with T2D (mean BMI 39.4 ± 1.9 kg/m²) were randomly assigned to mRYGB, SG, or GCP. Anthropometric and biochemical parameters, fasting concentrations of PYY, ghrelin, glucagon, and area under the curve (AUC) of GLP-1 after a standard meal test were determined prior to and at months 1 and 12 after surgery.

RESULTS

Twelve months after surgery, total weight loss percentage was higher and HbA1c lower in the mRYGB group than in the SG and GCP groups (-35.2 ± 8.1 and 5.1 ± 0.6% vs. -27.8 ± 5.4 and 6.2 ± 0.8% vs. -20.5 ± 6.8 and 6.6 ± 1.3%; p = 0.007 and p < 0.001, respectively). Moreover, GLP-1 AUC at months 1 and 12 was greater and T2D remission was higher in mRYGB (80 vs. 53.3 vs. 20%, p < 0.001). Insulin treatment (odds ratio (OR) 0.025, p = 0.018) and the increase in GLP-1 AUC from baseline to month 1 (OR 1.021, p = 0.013) were associated with T2D remission.

CONCLUSIONS

mRYGB achieves a superior rate of weight loss and T2D remission at month 12. Enhanced GLP-1 secretion 1 month after surgery was a determinant of glucose metabolism improvement. Registration number ( http://www.clinicaltrials.gov ): NCT14104758.

Outcomes of One Anastomosis Gastric Bypass in 472 Diabetic Patients

BACKGROUND

The positive impact of Roux-en-Y gastric bypass (RYGB) on metabolic syndrome and glycemic control has been proven in obese patients. One anastomosis gastric bypass (OAGB) is a simple, effective and easy to learn procedure. OAGB provides encouraging results for the treatment of diabetes obese patients, but does it have the ability to be an alternative procedure to RYGB in the treatment of these patients? The aim of this study is to evaluate the outcomes of OAGB on diabetic obese patients at the bariatric centre of our university hospital. By extension, we evaluated the possibility of BMI and the preoperative antidiabetic medication usage to be predictive factors for postoperative diabetes resolution.

METHODS

This is a retrospective single-centre study of 472 diabetic patients who underwent OAGB from November 2009 to December 2015. All patients were followed-up for at least 1 year, and up to 3 years, where available. Weight, HbA1c, and anti-diabetic medications were recorded at baseline, 3, 6, 12, 24 and 36 months.

RESULTS

A total of 472 patients have been followed-up for 1 year and 361 for 3 years. The mean BMI decreased from 46.8 ± 7.2 to 29.5 ± 2.8 kg/m² and HbA1c from 9.6 ± 1.3 to 5.7 ± 1.5% at the 12-month follow-up. At the 3-year follow-up, the mean BMI was 32.1 ± 3.3 and HbA1c mean was 5.8 ± 0.9%. Diabetes remission was achieved by 84.1% of patients.

CONCLUSIONS

OAGB can be an excellent alternative to RYGB for the treatment of diabetes and obesity. Pre-operative medications may be used to predict postoperative diabetes remission, but not BMI.

Morbidity and mortality associated with obesity

Obesity and its repercussions constitute an important source of morbidity, impaired quality of life and its complications can have a major bearing on life expectancy. The present article summarizes the most important co-morbidities of obesity and their prevalence. Furthermore, it describes classification and grading systems that can be used to assess the individual and combined impact of co-morbid conditions on mortality risk. The literature was screened for assessment tools that can be deployed in the quantification of morbidity and mortality risk in individual patients. Thirteen specific domains have been identified that account for morbidity and mortality in obesity. Cardiovascular disease (CVD) and cancer account for the greatest mortality risk associated with obesity. The King's Criteria and Edmonton Obesity Staging System (EOSS) were identified as useful tools for the detection and monitoring of individual patient mortality risk in obesity care. The stark facts on the complications of obesity should be capitalized on to improve patient management and knowledge and referred to in the wider dissemination of public health messages aimed at improving primary prevention.

Glucose-Dependent Insulinotropic Peptide Level Is Associated with the Development of Type 2 Diabetes Mellitus

BACKGROUND

Incretin hormone levels as a predictor of type 2 diabetes mellitus have not been fully investigated. Therefore, we measured incretin hormone levels to examine the relationship between circulating incretin hormones, diabetes, and future diabetes development in this study.

METHODS

A nested case-control study was conducted in a Korean cohort. The study included the following two groups: the control group (n=149), the incident diabetes group (n=65). Fasting total glucagon-like peptide-1 (GLP-1) and total glucose-dependent insulinotropic peptide (GIP) levels were measured and compared between these groups.

RESULTS

Fasting total GIP levels were higher in the incident diabetes group than in the control group (32.64±22.68 pmol/L vs. 25.54±18.37 pmol/L, P=0.034). There was no statistically significant difference in fasting total GLP-1 levels between groups (1.14±1.43 pmol/L vs. 1.39±2.13 pmol/L, P=0.199). In multivariate analysis, fasting total GIP levels were associated with an increased risk of diabetes (odds ratio, 1.005; P=0.012) independent of other risk factors.

CONCLUSION

Fasting total GIP levels may be a risk factor for the development of type 2 diabetes mellitus. This association persisted even after adjusting for other metabolic parameters such as elevated fasting glucose, hemoglobin A1c, and obesity in the pre-diabetic period.

Short-term outcomes of laparoscopic single anastomosis gastric bypass (LSAGB) for the treatment of type 2 diabetes in lower BMI (<30 kg/m(2)) patients

BACKGROUND

Bariatric surgery is an efficient procedure for remission of type 2 diabetes (T2DM) in morbid obesity. However, in Asian countries, mean body mass index (BMI) of T2DM patients is about 25 kg/m(2). Various data on patients undergoing gastric bypass surgery showed that control of T2DM after surgery occurs rapidly and somewhat independent to weight loss. We hypothesized that in non-obese patients with T2DM, the glycemic control would be achieved as a consequence of gastric bypass surgery.

METHODS

From September 2009, the 172 patients have had laparoscopic single anastomosis gastric bypass (LSAGB) surgery. Among them, 107 patients have been followed up more than 1 year. We analyzed the dataset of these patients. Values related to diabetes were measured before and 1, 2, and 3 years after the surgery.

RESULTS

The mean BMI decreased during the first year after the surgery but plateaued after that. The mean glycosylated hemoglobin level decreased continuously. The mean fasting and postglucose loading plasma glucose level also decreased.

CONCLUSION

After LSAGB surgery in non-obese T2DM patients, the control of T2DM was possible safely and effectively. However, longer follow-up with matched control group is essential.

Metabolic Mechanisms in Obesity and Type 2 Diabetes: Insights from Bariatric/Metabolic Surgery

Obesity and the related diabetes epidemics represent a real concern worldwide. Bariatric/metabolic surgery emerged in last years as a valuable therapeutic option for obesity and related diseases, including type 2 diabetes mellitus (T2DM). The complicated network of mechanisms involved in obesity and T2DM have not completely defined yet. There is still a debate on which would be the first metabolic defect leading to metabolic deterioration: insulin resistance or hyperinsulinemia? Insight into the metabolic effects of bariatric/metabolic surgery has revealed that, beyond weight loss and food restriction, other mechanisms can be activated by the rearrangements of the gastrointestinal tract, such as the incretinic/anti-incretinic system, changes in bile acid composition and flow, and modifications of gut microbiota; all of them possibly involved in the remission of T2DM. The complete elucidation of these mechanisms will lead to a better understanding of the pathogenesis of this disease. Our aim was to review some of the metabolic mechanisms involved in the development of T2DM in obese patients as well as in the remission of this condition in patients submitted to bariatric/metabolic surgery.

Expression of glucose-dependent insulinotropic polypeptide and its receptor in the rat major salivary glands

Glucose-dependent insulinotropic polypeptide receptors (GIPR) are expressed throughout the body. The expression of its ligand, glucose-dependent insulinotropic polypeptide (GIP) however, has only been reported in a limited numbers of organs. Although the rat submandibular salivary gland (SMG) has been found to express GIP, its biological role is still not understood. Moreover, nothing is known about the expression of GIP in other types of salivary glands, i.e. the parotid (PG) and sublingual (SLG) glands. We detected the expression of GIP mRNA in the rat PG, SMG and SLG. Immunohistochemical analyses revealed that GIP and GIPR were expressed only in the ductal area of all types of major salivary glands, and no immunostaining was found in the acini area. We also found GIP expression in the rat SMG to be age dependent, with 8-week-old rats showing 2-3-fold higher than those of 9- and 11-week-old rats, respectively. This is the first study to indicate both GIP and GIPR expression in the rat major salivary glands, as well as its variation in the rat SMG during the growth period. These findings are crucial for a better understanding of the physiological function of GIP in rat major salivary gland.

Endoscopic duodenal-jejunal bypass liner rapidly improves type 2 diabetes

BACKGROUND

Bariatric procedures excluding the proximal small intestine improve glycemic control in type 2 diabetes within days. To gain insight into the mediators involved, we investigated factors regulating glucose homeostasis in patients with type 2 diabetes treated with the novel endoscopic duodenal-jejunal bypass liner (DJBL).

METHODS

Seventeen obese patients (BMI 30-50 kg/m(2)) with type 2 diabetes received the DJBL for 24 weeks. Body weight and type 2 diabetes parameters, including HbA1c and plasma levels of glucose, insulin, glucagon-like peptide-1 (GLP-1), glucose-dependent insulinotropic polypeptide (GIP), and glucagon, were analyzed after a standard meal before, during, and 1 week after DJBL treatment.

RESULTS

At 24 weeks after implantation, patients had lost 12.7 ± 1.3 kg (p < 0.01), while HbA1c had improved from 8.4 ± 0.2 to 7.0 ± 0.2 % (p < 0.01). Both fasting glucose levels and the postprandial glucose response were decreased at 1 week after implantation and remained decreased at 24 weeks (baseline vs. week 1 vs. week 24: 11.6 ± 0.5 vs. 9.0 ± 0.5 vs. 8.6 ± 0.5 mmol/L and 1,999 ± 85 vs. 1,536 ± 51 vs. 1,538 ± 72 mmol/L/min, both p < 0.01). In parallel, the glucagon response decreased (23,762 ± 4,732 vs. 15,989 ± 3,193 vs. 13,1207 ± 1,946 pg/mL/min, p < 0.05) and the GLP-1 response increased (4,440 ± 249 vs. 6,407 ± 480 vs. 6,008 ± 429 pmol/L/min, p < 0.01). The GIP response was decreased at week 24 (baseline-115,272 ± 10,971 vs. week 24-88,499 ± 10,971 pg/mL/min, p < 0.05). Insulin levels did not change significantly. Glycemic control was still improved 1 week after explantation.

CONCLUSIONS

The data indicate DJBL to be a promising treatment for obesity and type 2 diabetes, causing rapid improvement of glycemic control paralleled by changes in gut hormones.

Incretin levels 1 month after laparoscopic single anastomosis gastric bypass surgery in non-morbid obese type 2 diabetes patients

PURPOSE

Bariatric surgery is an efficient procedure for the remission of type 2 diabetes (T2DM) from morbid obesity. However, in Asian countries, the mean body mass index (BMI) of T2DM patients is about 25 kg/m(2). Various data on patients undergoing gastric bypass surgery suggest that the control of T2DM after surgery occurs rapidly. We hypothesized that even in nonobese patients with T2DM, the levels of incretin and insulin changed along with the improvement of T2DM as a consequence of the gastric bypass.

MATERIALS AND METHODS

From March to December 2011, 12 nonobese patients (mean BMI; 26.2 kg/m(2)) with poorly-controlled [mean glycated hemoglobin (HbA1C); 9.5%] diabetes underwent gastric bypass surgery. Values related to diabetes, including incretin [gastric inhibitory peptide (GIP) and glucagon-like peptide-1 (GLP-1)] levels were measured before and 1 month after surgery. All values were measured in response to a 75 g oral glucose tolerance test (OGTT).

RESULTS

On average, the BMI decreased by 2.1 ± 0.7 kg/m(2). Mean HbA1C level decreased by 1.6 ± 2%. Oral glucose-stimulated insulin levels increased and GLP-1 levels also increased significantly. Oral glucose-stimulated GIP levels decreased sharply.

CONCLUSION

Soon after gastric bypass in nonobese T2DM patients, control of T2DM is achieved. The incretin release after oral glucose is improved. This could be a consequence of changes of the enteroinsular axis, particularly in the incretins.

Mechanisms behind the immediate effects of Roux-en-Y gastric bypass surgery on type 2 diabetes

Background

The most common bariatric surgery, Roux-en-Y gastric bypass, leads to glycemia normalization in most patients long before there is any appreciable weight loss. This effect is too large to be attributed purely to caloric restriction, so a number of other mechanisms have been proposed. The most popular hypothesis is enhanced production of an incretin, active glucagon-like peptide-1 (GLP-1), in the lower intestine. We therefore set out to test this hypothesis with a model which is simple enough to be robust and credible.

Method

Our method involves (1) setting up a set of time-dependent equations for the concentrations of the most relevant species, (2) considering an “adiabatic” (or quasi-equilibrium) state in which the concentrations are slowly varying compared to reaction rates (and which in the present case is a postprandial state), and (3) solving for the dependent concentrations (of e.g. insulin and glucose) as an independent concentration (of e.g. GLP-1) is varied.

Results

Even in the most favorable scenario, with maximal values for (i) the increase in active GLP-1 concentration and (ii) the effect of GLP-1 on insulin production, enhancement of GLP-1 alone cannot account for the observations. I.e., the largest possible decrease in glucose predicted by the model is smaller than reported decreases, and the model predicts no decrease whatsoever in glucose ×insulin, in contrast to large observed decreases in homeostatic model assessment insulin resistance (HOMA-IR). On the other hand, both effects can be accounted for if the surgery leads to a substantial increase in some substance that opens an alternative insulin-independent pathway for glucose transport into muscle cells, which perhaps uses the same intracellular pool of GLUT-4 that is employed in an established insulin-independent pathway stimulated by muscle contraction during exercise.

Conclusions

Glycemia normalization following Roux-en-Y gastric bypass is undoubtedly caused by a variety of mechanisms, which may include caloric restriction, enhanced GLP-1, and perhaps others proposed in earlier papers on this subject. However, the present results suggest that another possible mechanism should be added to the list of candidates: enhanced production in the lower intestine of a substance which opens an alternative insulin-independent pathway for glucose transport.

Endoscopic duodenal-jejunal bypass liner rapidly improves type 2 diabetes

BACKGROUND

Bariatric procedures excluding the proximal small intestine improve glycemic control in type 2 diabetes within days. To gain insight into the mediators involved, we investigated factors regulating glucose homeostasis in patients with type 2 diabetes treated with the novel endoscopic duodenal-jejunal bypass liner (DJBL).

METHODS

Seventeen obese patients (BMI 30-50 kg/m(2)) with type 2 diabetes received the DJBL for 24 weeks. Body weight and type 2 diabetes parameters, including HbA1c and plasma levels of glucose, insulin, glucagon-like peptide-1 (GLP-1), glucose-dependent insulinotropic polypeptide (GIP), and glucagon, were analyzed after a standard meal before, during, and 1 week after DJBL treatment.

RESULTS

At 24 weeks after implantation, patients had lost 12.7 ± 1.3 kg (p < 0.01), while HbA1c had improved from 8.4 ± 0.2 to 7.0 ± 0.2 % (p < 0.01). Both fasting glucose levels and the postprandial glucose response were decreased at 1 week after implantation and remained decreased at 24 weeks (baseline vs. week 1 vs. week 24: 11.6 ± 0.5 vs. 9.0 ± 0.5 vs. 8.6 ± 0.5 mmol/L and 1,999 ± 85 vs. 1,536 ± 51 vs. 1,538 ± 72 mmol/L/min, both p < 0.01). In parallel, the glucagon response decreased (23,762 ± 4,732 vs. 15,989 ± 3,193 vs. 13,1207 ± 1,946 pg/mL/min, p < 0.05) and the GLP-1 response increased (4,440 ± 249 vs. 6,407 ± 480 vs. 6,008 ± 429 pmol/L/min, p < 0.01). The GIP response was decreased at week 24 (baseline-115,272 ± 10,971 vs. week 24-88,499 ± 10,971 pg/mL/min, p < 0.05). Insulin levels did not change significantly. Glycemic control was still improved 1 week after explantation.

CONCLUSIONS

The data indicate DJBL to be a promising treatment for obesity and type 2 diabetes, causing rapid improvement of glycemic control paralleled by changes in gut hormones.

Isolated duodenal exclusion increases energy expenditure and improves glucose homeostasis in diet-induced obese rats

Roux-en-Y gastric bypass (RYGB) in rodent models reduces food intake (FI), increases resting energy expenditure (EE), and improves glycemic control. We have shown that mimicking the duodenal component of RYGB by implantation of a 10-cm endoluminal sleeve device (ELS-10) induces weight loss and improves glycemic control in diet-induced obese (DIO) rats. We sought to determine the mechanisms and structural requirements of these effects. We examined the effects of ELS-10 devices implanted in male DIO rats on body weight, food intake (FI), meal patterns, total and resting EE, and multiple parameters of glucose homeostasis, comparing them with sham-operated (SO) rats and with SO rats weight matched to the ELS-10-treated group. To determine the extent of duodenal exclusion required to influence metabolic outcomes, we compared the effects of implanting 10-, 4-, or 1-cm ELS devices. ELS-10 rats exhibited 13% higher total and 9% higher resting EE than SO controls. ELS-10 rats also exhibited enhanced postprandial GLP-1 secretion and improved glucose tolerance and insulin sensitivity out of proportion to the effects of weight loss alone. Implantation of 4- or 1-cm ELS devices had no effect on EE and limited effects on glucose homeostasis. Complete duodenal exclusion with ELS-10 induces weight loss by decreasing FI and increasing EE and improves glycemic control through weight loss-independent mechanisms. Thus signals originating in the proximal small intestine appear to exert a direct influence on the physiological regulation of EE and glucose homeostasis. Their selective manipulation could provide effective new therapies for obesity and diabetes that mimic the benefits of RYGB.

[Bariatric surgery for the treatment of type 2 diabetes mellitus]

Weight loss can improve metabolic control in patients with type 2 diabetes mellitus but the results of conventional therapy in this respect have been discouraging. Besides achieving significant and sustained weight loss, bariatric surgery can improve or resolve type 2 diabetes mellitus in the majority of patients. Anatomical modifications and changes in the secretion of intestinal hormones can explain the superiority of malabsorptive techniques. Currently, bariatric surgery offers a therapeutic alternative for type 2 diabetes patients with severe obesity and poor metabolic control under conventional therapy. Ongoing research will provide insights regarding the effect of intestinal hormones, new surgery techniques and the possible benefits of bariatric surgery in non-obese patients.

Metabolic laparoscopic gastric bypass for obese patients with type 2 diabetes

BACKGROUND

Bariatric surgery has been proposed as the most effective treatment for patients with type 2 diabetes mellitus (T2DM) and body mass index (BMI) above 35 kg/m(2). The purpose of our study was to access remission rate and improvement of metabolic control of T2DM after gastric bypass.

METHODS

A prospective study was carried out on 94 diabetic patients, who underwent gastric bypass with a 200-cm biliopancreatic limb. Characteristics evaluated included weight, BMI, percentage of excess BMI lost (% EBMIL), fasting glucose, HbA1c, and lipid profile up to 36 months after surgery, as well as anti-diabetic treatment before and after surgery.

RESULTS

At the time of surgery, patients had a mean BMI of 44.3 ± 0.65 kg/m(2) and length of T2DM diagnosis of 6.2 ± 0.98 years and HbA1c of 6.6 ± 0.21%. After a mean time of follow-up of 2.6 ± 0.13 years, the weight loss was significant from 3 months onwards after surgery, reaching its peak at 24 months with a BMI of 32.1 ± 0.9 kg/m(2) and corresponding % EBMIL of 69.0 ± 2.84%. Remission rates of diabetes were 87.91% at 6 months, 92.68% at 12 months, 92.85% at 24 months, and 100% at 36 months of follow-up.

CONCLUSIONS

Gastric bypass in obese patients is associated with a high remission rate of diabetes and improvement of the metabolic control. Although confirmation with randomized controlled studies is needed, these results suggest that this type of surgery might be particularly indicated for obese diabetic patients with good pancreatic reserve.

Molecular insights from bariatric surgery

Bariatric surgical procedures have become important therapeutic options for treatment of morbid obesity in both adults and adolescents co-morbidities of obesity such as glucose intolerance, type 2 diabetes (T2DM), metabolic syndrome, steatohepatitis, hyperlipidemia and cardiovascular disease. These co-morbidities of obesity have significant impacts on the overall quality of life of the individual and our society at large. Roux-en-Y gastric bypass (RYGB) and the relatively newer procedures of gastric banding (GB) and vertical sleeve gastrectomy (VSG) have proven to be efficacious in achieving rapid weight loss and reversing the comorbidities of obesity. Unfortunately, bariatric procedures are not without risks including micronutrient deficiency, failure to maintain lost weight, and mortality. Further, the resolution of T2DM has long been understood to precede weight loss, and this finding provides important clues about the physiologic underpinnings of the observation. In order to design more effective, safe, and widely available therapeutics for obesity, important and highly relevant questions need to be addressed regarding mechanisms behind the weight-loss-independent benefits of bariatric surgical procedures. This review will provide an overview of the molecular changes occurring across all biological systems after bariatric surgery including the changes in hepatic, adipocyte and gut derived signals after surgery. We will also discuss existing literature regarding the weight-loss-independent metabolic benefits including improvement in insulin sensitivity and central nervous system integration of these signals.

Early and mid-term outcomes of single-stage laparoscopic sleeve gastrectomy

BACKGROUND

This is the largest single-centre series of single-stage laparoscopic sleeve gastrectomy (LSG) reporting on perioperative outcomes, weight loss, comorbidity resolution including urological outcomes and results in the super obese. Review of prospectively collected data for patients who underwent LSG from March 2007-August 2009.

METHODS

There were 253 patients with a mean age of 44 years (SD, 9) and a mean preoperative body mass index (BMI) of 50 kg/m(2) (SD, 7). There were 17 (7%) major complications and no deaths. The mean follow-up was 9 months. One hundred and seventy-one patients with a mean follow-up of 12 months had a mean postoperative weight loss of 41 kg (SD, 16) and mean excess BMI (meBMI) loss of 59% (SD, 22).

RESULTS

One hundred fourteen patients were super obese (BMI, >50 kg/m(2)). The mean weight loss was 45 kg (SD, 18), and the meBMI lost was 49% (SD, 21). Super-obese patients experienced more complications (p = 0.02) and lost less eBMI (49% vs. 61%; p < 0.01). Fifty-three patients (46%) remained morbidly obese (BMI, >40 kg/m(2)) postoperatively. Hypertension and diabetes improved or resolved in 73 (79%) and 73 (90%) patients, respectively. Stress urinary incontinence was reported preoperatively in 60 (32%) females, and complete resolution or improvement was reported in 54 (90%) patients.

CONCLUSIONS

LSG provides satisfactory weight loss and resolution of comorbidities in the short- and medium-term with inferior, though acceptable, results in the super obese.

Morbid obesity in pediatric diabetes mellitus: surgical options and outcomes

The current obesity epidemic has led to a dramatic increase in insulin resistance and type 2 diabetes mellitus among adolescents, along with other obesity-related comorbidities, such as hypertension, hyperlipidemia, obstructive sleep apnea, psychosocial impairment and nonalcoholic fatty liver disease. Medical treatment of severe obesity is effective in only a small percentage of adolescent patients. In light of the potentially life-threatening complications of obesity, bariatric surgery can be considered a treatment option for adolescent patients with morbid obesity. Indications for surgery rely on both BMI and comorbidity criteria, as well as the ability of the adolescents and their family to understand and comply with perioperative protocols. The long-term effects of bariatric surgery in adolescents are not known; therefore, participation in prospective outcome studies is important. The risk associated with bariatric surgery in adolescents seems to be similar to that observed in adult patients in the short term. Data suggest that bypass procedures successfully reverse or improve abnormal glucose metabolism in the majority of patients and may be more effective in adolescents than adults. This improvement in glucose metabolism occurs before marked weight loss in patients undergoing bypass procedures, suggesting a direct effect on the hormonal control of glucose metabolism.

A review of weight loss following Roux-en-Y gastric bypass vs restrictive bariatric surgery: impact on adiponectin and insulin

BACKGROUND

Bariatric surgery is a common procedure often used to ameliorate comorbidities associated with obesity, including type 2 diabetes. Substantial weight loss leads to alterations in inflammation and insulin sensitivity as well as numerous metabolic and physiologic pathways. Several inflammatory markers have been evaluated, yet adiponectin, an anti-inflammatory adipokine, has not been fully investigated. Adiponectin may play a key role as a mediator between obesity and inflammation, as lower blood levels are more commonly associated with obesity and type 2 diabetes and because adiponectin lessens insulin resistance. This review evaluates outcome variables from patients who underwent Roux-en-Y gastric bypass (RYGB) or restrictive bariatric surgery to compare and contrast any differential surgical impacts on weight loss, adiponectin, and insulin.

METHODS

A systematic literature review was conducted using a PubMed search. Published studies from 1999 to 2009 that measured blood levels of adiponectin and insulin in bariatric surgery patients prior to and at least 6 months after surgery were included.

RESULTS

Eighteen studies met inclusion criteria for evaluation. RYGB surgery compared to restrictive surgery led to significantly greater weight loss and improvements in adiponectin and insulin sensitivity. Despite significant weight loss, many patients did not achieve "healthy" body mass index or normalization of inflammatory markers.

CONCLUSIONS

While RYGB surgery appears to more favorably influence body weight and inflammatory markers, data are insufficient to fully understand the impact of bariatric surgery on changes in adiponectin and insulin and related health implications. Long-term research is needed to more thoroughly evaluate inflammatory outcomes following these two bariatric surgery procedures.

Serum markers of bone turnover are increased at six and 18 months after Roux-en-Y bariatric surgery: correlation with the reduction in leptin

OBJECTIVE

The aim of the study was to examine serum markers of bone turnover at 6 and 18 months after Roux-en-Y gastric bypass surgery.

PARTICIPANTS

Ten women and 10 men [body mass index (BMI), 50.2 +/- 8.4 kg/m(2)] were studied at 6 months; 10 women and nine men (BMI, 47.2 +/- 6.6 kg/m(2)) were studied at 18 months after surgery.

MAIN OUTCOME MEASURES

Serum osteocalcin, bone specific alkaline phosphatase (BAP), N-telopeptide of type 1 collagen (NTX), PTH, 25-hydroxy vitamin D, and leptin were measured.

RESULTS

BMI was reduced 32.7 +/- 6.2% at 6 months after surgery. Serum osteocalcin (6.9 +/- 2.4 to 10.9 +/- 2.6 ng/ml; P < 0.0001), BAP (14.2 +/- 3.7 to 16.4 +/- 4.5 ng/ml; P = 0.04), and NTX (10.9 +/- 1.7 to 19.6 +/- 5.3 nm bone collagen equivalents; P < 0.0001) were increased. Calcium, phosphate, and PTH were unchanged, but 25-hydroxy vitamin D increased (16.0 +/- 8.9 vs. 26.9 +/- 10.6 ng/ml; P <0.0001). The increase in NTX correlated with reduction in serum leptin (r = 0.58; P = 0.007). BMI was reduced 40.9 +/- 7.5% at 18 months after surgery. Serum BAP (17.6 +/- 5.3 to 22.2 +/- 7.8 ng/ml; P = 0.0017) and NTX (10.8 +/- 2.7 to 16.9 +/- 5.5 nm bone collagen equivalents; P < 0.0001) were increased. Calcium, phosphate, and PTH were unchanged, but 25-hydroxy vitamin D increased (17.7 +/- 7.6 to 25.6 +/- 6.8 ng/ml; P < 0.0001). The increase in NTX correlated with reduction in BMI (r = 0.58; P = 0.009) and leptin (r = 0.45; P = 0.04) and the increase in serum 25-hydroxy vitamin D (r = 0.43; P = 0.05). In multiple regression (adjusted model R(2) 0.263; P = 0.013), reduction in leptin was a significant predictor of increase in NTX (P = 0.016), but changes in BMI and 25-hydroxy vitamin D were not.

CONCLUSIONS

Weight loss after bariatric surgery is associated with long-term increase in serum markers of bone turnover. The increase in NTX is related to the decrease in leptin, which may signal caloric restriction to the skeleton.

Improvement in peripheral glucose uptake after gastric bypass surgery is observed only after substantial weight loss has occurred and correlates with the magnitude of weight lost

INTRODUCTION

Altered gut and pancreatic hormone secretion may bolster resolution of insulin resistance after Roux-en-Y gastric bypass (RYGB), but the independent effects of weight loss and hormonal secretion on peripheral glucose disposal are unknown.

METHODS

Two groups of nondiabetic morbidly obese patients were studied: RYGB followed by standardized caloric restriction (RYGB, n = 12) or caloric restriction alone (diet, n = 10). Metabolic evaluations (euglycemic-hyperinsulinemic clamp, meal tolerance test) were done at baseline and 14 days (both groups) and 6 months after RYGB.

RESULTS

At baseline, body composition, fasting insulin, and glucose and peripheral glucose disposal did not differ between groups. At 14 days, excess weight loss (EWL) was similar (RYGB, 12.7% vs. diet, 10.9%; p = 0.12), fasting insulin and glucose decreased to a similar extent, and RYGB subjects had altered postmeal patterns of gut and pancreatic hormone secretion. However, peripheral glucose uptake (M value) was unchanged in both groups. Six months after RYGB, EWL was 49.7%. The changes in fasting glucose and insulin levels and gut hormone secretion persisted. M values improved significantly, and changes in M values correlated with the % EWL (r = 0.68, p = 0.02).

CONCLUSIONS

Improvement in peripheral glucose uptake following RYGB was observed only after substantial weight loss had occurred and correlated with the magnitude of weight lost.

Apelin levels are increased in morbidly obese subjects with type 2 diabetes mellitus

BACKGROUND

The physiological role of apelin in obesity and diabetes remains unclear. Although apelin has been studied in persons with different conditions, no studies have yet examined the joint influence of obesity and diabetes on apelin levels. We measured the changes in apelin levels in morbidly obese subjects, with and without diabetes, and in the inverse situation of improvement in carbohydrate metabolism as a result of bariatric surgery.

METHODS

The study was undertaken in 54 morbidly obese persons, 16 of whom had type 2 diabetes mellitus, before and 7 months after undergoing bariatric surgery, and in 12 healthy, nonobese persons. Measurements were made of apelin levels and insulin sensitivity by an intravenous glucose tolerance test.

RESULTS

The apelin levels in the morbidly obese patients prior to surgery were significantly higher than those of the controls only when the morbidly obese subjects were diabetic (P < 0.005). Apelin levels correlated significantly in the morbidly obese patients with serum triglycerides (r = 0.292, P = 0.032) and glucose (r = 0.337, P = 0.039). Bariatric surgery resulted in a significant decrease in apelin levels only in the morbidly obese subjects with impaired fasting glucose or diabetes. The change in apelin levels correlated significantly in the morbidly obese patients with the changes in serum glucose (r = 0.338, P = 0.038) and insulin sensitivity (r = -0.417, P = 0.043).

CONCLUSIONS

This study demonstrates that obesity is not the main determinant of the rise in apelin levels. The association between apelin levels and glucose concentrations and insulin sensitivity provides evidence that apelin may play a role in the pathogenesis of diabetes.

Do Incretins play a role in the remission of type 2 diabetes after gastric bypass surgery: What are the evidence?

Gastric bypass surgery (GBP), in addition to weight loss, results in dramatic remission of type 2 diabetes (T2DM). The mechanisms by which this remission occurs are unclear. Besides weight loss and caloric restriction, the changes in gut hormones that occur after GBP are increasingly gaining recognition as key players in glucose control. Incretins are gut peptides that stimulate insulin secretion postprandially; the levels of these hormones, particularly glucagon-like peptide-1, increase after GBP in response to nutrient stimulation. Whether these changes are causal to changes in glucose homeostasis remain to be determined. The purpose of this review is to assess the evidence on incretin changes and T2DM remission after GBP, and the possible mechanisms by which these changes occur. Our goals are to provide a thorough update on this field of research so that recommendations for future research and criteria for bariatric surgery can be evaluated.

Different effect of laparoscopic Roux-en-Y gastric bypass and open biliopancreatic diversion of Scopinaro on serum PYY and ghrelin levels

BACKGROUND

The impact of bariatric surgery on levels of peptide YY (PYY) and ghrelin is still under discussion. We undertook a simultaneous evaluation of the serum changes in PYY and ghrelin depending on the specific type of bariatric surgery.

METHODS

Total PYY and ghrelin were analyzed in 29 healthy persons and in morbidly obese persons undergoing open biliopancreatic diversion (BPD) of Scopinaro (n = 38) or laparoscopic Roux-en-Y gastric bypass (RYGB; n = 13).

RESULTS

RYGB resulted in a significantly greater loss of weight and body mass index than BPD. Both RYGB and BPD were associated with a significant increase in PYY, significantly greater for BDP (p = 0.001). Ghrelin rose significantly after RYGB (p = 0.022) but not after BPD. After surgery, PYY correlated positively with weight (r = 0.416, p = 0.009). Ghrelin did not correlate significantly with any of the variables studied. Analysis of variance showed that only the type of surgery contributed significantly to explain the variances in the PYY (p = 0.002) and ghrelin (p = 0.018).

CONCLUSIONS

BPD results in a greater increase in PYY and a lower weight loss than RYGB. However, only RYGB was associated with a significant increase in ghrelin. The differing weight loss according to the type of bariatric surgery does not seem to be explained by changes arising in PYY and ghrelin.

Management of type 2 diabetes in the obese patient: current concerns and emerging therapies

OBJECTIVES

The aims of this review are (1) to examine the pathophysiologic relationship between type 2 diabetes and obesity, (2) to provide an overview of current and emerging treatments for type 2 diabetes and their effects on body weight.

METHODS

A MEDLINE search was performed for literature published in the English language from 1966 to 2006. Abstracts and presentations from the American Diabetes Association Scientific Sessions (2002-2006) and the European Association for the Study of Diabetes Annual Meetings (1998-2006) were also searched for relevant studies. Preclinical and clinical data were selected for inclusion based on novelty and pertinence to treatment of the obese patient.

FINDINGS

Recent guidelines suggest that all patients with type 2 diabetes should initially receive metformin as well as lifestyle intervention, followed by rapid administration of other oral anti-diabetic agents or insulin if glycemic goals are not met or maintained. Many oral anti-diabetic drugs, and insulin, are associated with weight gain. New agents with anti-diabetic activity that may be advantageous in obese patients with type 2 diabetes have recently become available. These include injectable incretin mimetics, which reduce blood glucose while reducing body weight but commonly cause nausea and vomiting. A new class of oral agents, the dipeptidyl peptidase-4 inhibitors, is weight-neutral and largely devoid of gastrointestinal side-effects. The cannabinoid receptor antagonist rimonabant is the first of a new class of anti-obesity agents that reduces central obesity and improves multiple aspects of vascular risk.

CONCLUSION

New agents offer the prospect of improved glycemic control without weight gain. However, the ultimate roles of these agents in the treatment of obese patients with type 2 diabetes remain to be established.

Cost effectiveness of duloxetine in the treatment of diabetic peripheral neuropathic pain in the UK

OBJECTIVE

The objective of this analysis was to evaluate the cost-effectiveness of duloxetine when considered as an additional treatment option for UK-based patients suffering from diabetic peripheral neuropathic pain.

RESEARCH DESIGN AND METHODS

A decision-analytic model was used to represent the sequential management of patients with diabetic peripheral neuropathic pain. The standard UK treatment strategy was defined as first-line tricyclic antidepressants (amitriptyline), second-line anticonvulsants (gabapentin) and lastly an opioid-related treatment. The cost-effectiveness of duloxetine was evaluated as an additional first, second, third or fourth-line therapy over a 6-month treatment period for a cohort of 1000 patients. Treatment response was modelled based on changes from baseline pain severity using a standard 11-point pain scale (0-10); full response (>or= 50% change), partial response (30-49%) and no response (< 30%). The model was populated with efficacy and discontinuation data using indirect comparisons of treatment efficacy based on relative effects to a common placebo comparator.

RESULTS

The second-line use of duloxetine resulted in cost savings of pound 77,071 for every 1000 treated patients, with an additional 29 patients achieving a full pain response when compared to standard UK treatment. Additional quality-adjusted life years (QALYs) were achieved at 1.88 QALYs per 1000 patients.

CONCLUSIONS

This UK-based economic model suggests that second-line use of duloxetine is a beneficial and cost-effective treatment strategy for diabetic peripheral neuropathic pain.

Dietary fructans and serum triacylglycerols: a meta-analysis of randomized controlled trials

Convincing evidence indicates that the intake of inulin-type fructans, inulin and oligofructose, has beneficial effects on blood lipid changes in animals, although data in humans have been considered contradictory. We conducted a meta-analysis of available literature to quantify the effects in humans of dietary inulin-type fructans on serum triacylglycerols. Fifteen eligible randomized, controlled trials published from 1995 to 2005, for a total of 16 comparisons, were identified from the PubMed (National Library of Medicine, Bethesda, MD) and SCOPUS (Elsevier B.V., Amsterdam, NL) databases. Standardized mean effect sizes were calculated for net changes in serum triacylglycerol concentrations using random-effect model. The intake of inulin-type fructans was associated with significant decreases in serum triacylglycerols by 0.17 mmol/L (95%CI -0.33, -0.01; Z = 2.12, P = 0.04) or 7.5%. Given the limited number of studies, no specific effects for gender, amount fed, duration of the study, background diet, overweight, hyperlipidemia, or diabetes were further formally investigated, but, from the test for heterogeneity [chi(2) = 13.34, df = 15, (P = 0.55), I(2) = 0%], it appears that the effect of inulin-type fructans on circulating triacylglycerols is consistent across conditions. In conclusion, dietary inulin-type fructans significantly reduced serum triacylglycerols. The mechanisms, possibly related to colonic fermentation and/or incretin release from the distal gut, warrant further studies.

Entero-Endocrine Changes After Gastric Bypass in Diabetic and Nondiabetic Patients: A Preliminary Study

INTRODUCTION

Alterations in entero-endocrine signaling may play a role in improvements in satiety and glucose tolerance after Roux-en-Y gastric bypass (RYGB). We report our findings of gut hormone secretion in a cohort of diabetic and nondiabetic morbidly obese patients.

MATERIALS AND METHODS

Ten morbidly obese subjects who underwent uncomplicated RYGB were studied: 5 were diabetic and 9 were female. Nonfasting plasma levels of glucagon-like peptide-1 (GLP-1), insulin, desacyl ghrelin, active ghrelin, neuropeptide Y (NPY), and gastric inhibitory polypeptide (GIP) were determined preoperatively and 6 months postoperatively.

RESULTS

Mean patient age was 42 +/- 11 years, and the mean preoperative body mass index was 50 +/- 6 kg/m(2). At 6 months mean BMI fell to 33 +/- 5 kg/m(2) (P < 0.0001), and there were no differences between diabetics and nondiabetics with respect to amount of weight loss. In non-diabetics, compared to preoperative levels, there were significant increases in GLP-1 and desacyl-ghrelin in the nondiabetic patients (P = 0.046 and P = 0.016, respectively); no change in plasma insulin, active ghrelin, NPY, or GIP was demonstrated. In contrast, when compared to preoperative levels, there were no significant changes in entero-endocrine hormone levels in the diabetic cohort postoperatively.

CONCLUSIONS

At 6 months postoperation, RYGB significantly alters the hormone levels for GLP-1 and desacyl-ghrelin in morbidly obese nondiabetic patients. No significant change was noted in a matched cohort of diabetic patients. Weight loss was similar in diabetics and nondiabetics, suggesting that GLP-1 and ghrelin are not the only mechanisms producing weight loss after RYGB.

Incretin levels and effect are markedly enhanced 1 month after Roux-en-Y gastric bypass surgery in obese patients with type 2 diabetes

OBJECTIVE

Limited data on patients undergoing Roux-en-Y gastric bypass surgery (RY-GBP) suggest that an improvement in insulin secretion after surgery occurs rapidly and thus may not be wholly accounted for by weight loss. We hypothesized that in obese patients with type 2 diabetes the impaired levels and effect of incretins changed as a consequence of RY-GBP.

RESEARCH DESIGN AND METHODS

Incretin (gastric inhibitory peptide [GIP] and glucagon-like peptide-1 [GLP-1]) levels and their effect on insulin secretion were measured before and 1 month after RY-GBP in eight obese women with type 2 diabetes and in seven obese nondiabetic control subjects. The incretin effect was measured as the difference in insulin secretion (area under the curve [AUC]) in response to an oral glucose tolerance test (OGTT) and to an isoglycemic intravenous glucose test.

RESULTS

Fasting and stimulated levels of GLP-1 and GIP were not different between control subjects and patients with type 2 diabetes before the surgery. One month after RY-GBP, body weight decreased by 9.2 +/- 7.0 kg, oral glucose-stimulated GLP-1 (AUC) and GIP peak levels increased significantly by 24.3 +/- 7.9 pmol x l(-1) x min(-1) (P < 0.0001) and 131 +/- 85 pg/ml (P = 0.007), respectively. The blunted incretin effect markedly increased from 7.6 +/- 28.7 to 42.5 +/- 11.3 (P = 0.005) after RY-GBP, at which it time was not different from that for the control subjects (53.6 +/- 23.5%, P = 0.284).

CONCLUSIONS

These data suggest that early after RY-GBP, greater GLP-1 and GIP release could be a potential mediator of improved insulin secretion.

Gut-brain communication: how does it stand after bariatric surgery?

PURPOSE OF REVIEW

This article aims to critically review the literature, describing the possible implications of different bariatric surgery techniques in gastrointestinal peptides and their relation with the neural paths involved in the central regulation of appetite and satiety: the gut-brain axis.

RECENT FINDINGS

Bariatric surgery operations change orexigenic and anorexigenic gastrointestinal peptide levels. Forty-one studies were analyzed in order to understand the effects of different operations on the behavior of gut peptides (ghrelin, cholecystokinin, peptide YY, glucagon-like peptide-1, gastric inhibitory polypeptide, pancreatic polypeptide). The authors have tried to correlate these findings with weight loss/maintenance via different surgical techniques.

SUMMARY

The present line of research is recent and there is a lack of comparability between studies. There are different design approaches and study protocols, different laboratorial exams. Prospective long-term studies with larger samples are needed to clarify the effects of bariatric operations on the gut-brain axis.