Normalization of Insulin Sensitivity in the Obese Patient after Stable Weight Reduction with Biliopancreatic Diversion

Total Antioxidant Capacity: Biochemical Aspects and Clinical Significance

Despite the physiological role of oxidant molecules, oxidative stress (OS) could underlie several human diseases. When the levels of antioxidants are too low or too high, OS occurs, leading to damage at the molecular, tissue and cellular levels. Therefore, antioxidant compounds could represent a way to modulate OS and/or to maintain proper redox balance. This review provides an overview of the methods available to assess total antioxidant capacity (TAC) in biological systems to elucidate the correct terminology and the pathophysiological roles. The clinical context is fundamental to obtain a correct interpretation of TAC. Hence, we discuss metabolic syndrome and infertility, two clinical conditions that involve OS, including the potential prognostic role of TAC evaluation in monitoring antioxidant supplementation. This approach would provide more personalised and precise therapy.

Obesity-related cognitive impairment: The role of endothelial dysfunction

Obesity is a global pandemic associated with macro- and microvascular endothelial dysfunction. Microvascular endothelial dysfunction has recently emerged as a significant risk factor for the development of cognitive impairment. In this review, we present evidence from clinical and preclinical studies supporting a role for obesity in cognitive impairment. Next, we discuss how obesity-related hyperinsulinemia/insulin resistance, systemic inflammation, and gut dysbiosis lead to cognitive impairment through induction of endothelial dysfunction and disruption of the blood brain barrier. Finally, we outline the potential clinical utility of dietary interventions, exercise, and bariatric surgery in circumventing the impacts of obesity on cognitive function.

Changes in Fat Mass InfluenceSREBP-1candUCP-2Gene Expression in Formerly Obese Subjects

OBJECTIVE

To investigate the effect of fat mass (FM) reduction on adipose tissue gene expression in terms of lipid synthesis [sterol regulatory binding protein 1c (SREBP-1c)] and lipid oxidation [uncoupling protein 2 (UCP-2)] 2 years after lipid malabsorption and to assess the influence of lipid malabsorption on fat-free mass (FFM) maintenance evaluating the expression of genes related to glycolysis [hexokinase (HKII)] and glucose storage [glycogen synthase (GS)].

RESEARCH METHOD AND PROCEDURES

SREBP-1c, UCP-2, HKII, and GS mRNA expression were studied by reverse transcriptase-competitive polymerase chain reaction in 10 massively obese subjects before and 2 years after bilio-pancreatic diversion (BPD). Body composition was assessed by isotopic dilution method and insulin sensitivity by euglycemic-hyperinsulinemic clamp.

RESULTS

FM decrease was approximately 60%, whereas FFM remained at normal physiological levels. In adipose tissue, SREBP-1c mRNA reduction (-39%, p < 0.005) was related only to FM changes after BPD, and UCP-2 decrease (-37%, p < 0.05) was dependent on free fatty acid (FFA) changes. No significant variations were observed in HKII and GS gene expression in skeletal muscle.

DISCUSSION

Lipid malabsorption induced by BPD altered the expression of genes involved in glucose and lipid metabolism, with different consequences on FM and FFM. The degree of FM loss seems to interfere with SREBP-1c gene suppression to preserve an adequate amount of fat storage, in accordance with the thrifty genotype hypothesis. The reduction of FFAs induced by BPD acts in inhibiting FFA transportation to the mitochondria (UCP-2), contributing to the decreased lipid oxidation inside the adipose tissue.

Effects and mechanism of duodenal-jejunal bypass and sleeve gastrectomy on GLUT2 and glucokinase in diabetic Goto-Kakizaki rats

Background

The study investigated the effects and mechanism of duodenal-jejunal bypass (DJB) and sleeve gastrectomy (SG) on the expression of liver GLUT2 and glucokinase (GCK) in diabetic rats.

Methods

Animal models of Goto–Kakizaki (GK) rats were established for the investigation of DJB and SG. Results of weight, food intake, fasting plasma glucose level, oral glucose tolerance test and insulin were compared. Liver tissues were harvested 8 weeks postoperatively. Reverse transcription-PCR and western blot were used to detect liver GLUT2 and GCK mRNA and protein expression after operation.

Results

Fasting plasma glucose levels of DJB group and SG group in GK rats were markedly declined at 3 days and l, 2, 4, 6, and 8 weeks postoperatively (P <0.01), whereas the levels of the sham-operated group only dropped at 3 days and 1 week postoperatively, and there were no significant differences 2 weeks postoperatively (P >0.05). In the liver of GK rats, GLUT2 mRNA level and protein expression after DJB were higher than those in sham-operated group and control group. GLUT2 mRNA level and protein expression after SG were significantly lower than those in control group (P <0.01). GCK mRNA and protein experienced similar expression change.

Conclusions

Both DJB and SG can decrease the plasma glucose levels of GK rats, whereas they have different effects on the expression of liver GLUT2 and GCK.

Bariatric surgery and T2DM improvement mechanisms: a mathematical model

Background

Consensus exists that several bariatric surgery procedures produce a rapid improvement of glucose homeostasis in obese diabetic patients, improvement apparently uncorrelated with the degree of eventual weight loss after surgery. Several hypotheses have been suggested to account for these results: among these, the anti-incretin, the ghrelin and the lower-intestinal dumping hypotheses have been discussed in the literature. Since no clear-cut experimental results are so far available to confirm or disprove any of these hypotheses, in the present work a mathematical model of the glucose-insulin-incretin system has been built, capable of expressing these three postulated mechanisms. The model has been populated with critically evaluated parameter values from the literature, and simulations under the three scenarios have been compared.

Results

The modeling results seem to indicate that the suppression of ghrelin release is unlikely to determine major changes in short-term glucose control. The possible existence of an anti-incretin hormone would be supported if an experimental increase of GIP concentrations were evident post-surgery. Given that, on the contrary, collected evidence suggests that GIP concentrations decrease post-surgery, the lower-intestinal dumping hypothesis would seem to describe the mechanism most likely to produce the observed normalization of Type 2 Diabetes Mellitus (T2DM) after bariatric surgery.

Conclusions

The proposed model can help discriminate among competing hypotheses in a context where definitive data are not available and mechanisms are still not clear.

Temporal changes in glucose and insulin homeostasis after biliopancreatic diversion and laparoscopic adjustable gastric banding

BACKGROUND

Obesity surgery is associated with improvement in type 2 diabetes mellitus. Our aim was to examine the effects of biliopancreatic diversion (BPD) and laparoscopic adjustable gastric banding (LAGB) on the body mass index, fasting insulin level, glucose level, and insulin resistance in morbidly obese subjects with type 2 diabetes mellitus. The setting was the Department of Surgery, Morriston Hospital (Swansea, Wales, United Kingdom).

METHODS

A total of 13 morbidly obese patients (7 BPD, 6 LAGB) underwent serial measurements of fasting glucose and insulin at baseline, immediately after surgery (days 1-7), and 1, 6, and 12 months postoperatively. The homeostasis model of assessment-insulin resistance was calculated.

RESULTS

In the BPD group, the glucose levels had normalized by day 3 (5.6 ± 1 mmol/L) and the difference was statistically significant at 6 and 12 months postoperatively (5 ± .7 and 4.4 ± .5 mmol/L, respectively). The insulin levels had improved from day 1, and the difference was statistically significant at days 2, 5, 6, and 7 (19 ± 9, 14.2 ± 7, 15.2 ± 8, and 17.4 ± 8 mU/L, respectively). All diabetes medications were stopped on the fourth postoperative day. In the LAGB group, no statistically significant changes were seen in the glucose levels. Statistically significant changes in insulin were seen on days 1 and 2 (19 ± 13 and 13 ± 6.5 mU/L, respectively). The homeostatic model of assessment-insulin resistance had improved in both groups (BPD, 1.6 ± 1.2, P < .01; and LAGB, 4.3 ± 1.4, P < .05).

CONCLUSION

BPD causes immediate remission of type 2 diabetes mellitus. Leptin might play an important role in the early improvement of insulin resistance in fasting states after BPD. In the LAGB group, glucose homeostasis improved, but the patients still required diabetes medications, although the dosages were reduced.

Resolution of diabetes mellitus by ileal transposition compared with biliopancreatic diversion in a nonobese animal model of type 2 diabetes

BACKGROUND

It has been demonstrated that biliopancreatic diversion (BPD) and ileal transposition (IT) effectively induce weight loss and long-term control of type 2 diabetes in morbidly obese individuals. It is unknown whether the control of diabetes is better after IT or after BPD. The objective of this study was to investigate the effects of IT and BPD on the control of diabetes in an animal model.

METHODS

We performed IT and BPD on 10- to 12-week-old Goto-Kakizaki rats with a spontaneous nonobese model of type 2 diabetes, and we performed a series of detection. The rats were observed for 24 weeks after surgery.

RESULTS

Animals who underwent IT and BPD demonstrated improved glucose tolerance, insulin sensitivity and the secretion of glucagon-like peptide-1 compared with the sham-operated animals. Furthermore, IT resulted in a shorter duration of surgery and better postoperative recovery than BPD.

CONCLUSION

This study provides strong evidence for the crucial role of the hindgut in the resolution of diabetes after duodenum-jejunum bypass or IT. We confirmed that IT was associated with better postoperative recovery than BPD and had a similar control of diabetes as BPD in nonobese animals with type 2 diabetes.

Bypass of the duodenum improves insulin resistance much more rapidly than sleeve gastrectomy

BACKGROUND

Obesity is very often accompanied by other diseases, with the most common type 2 diabetes mellitus and cardiovascular complications. Bariatric surgery is the most effective strategy for treating morbidly obese patients. We evaluated the metabolic changes that occur in the early stage after 2 types of bariatric surgery, biliopancreatic diversion of Scopinaro (BPD) and sleeve gastrectomy (SG), in morbidly obese patients.

METHODS

The study was undertaken in 31 nondiabetic morbidly obese patients (7 men and 24 women). Of the 31 patients, 18 underwent BPD and 13 underwent SG. All patients were examined before bariatric surgery (baseline) and at 15, 30, 45, and 90 days postoperatively.

RESULTS

Significant improvement occurred in the anthropometric variables after the 2 types of bariatric surgery, without significant differences between the 2 types of interventions. In patients undergoing BPD, the serum glucose, cholesterol, triglycerides, high-density lipoprotein cholesterol, and free fatty acids were significantly reduced. The changes that occurred in these biochemical variables after SG were not significant. Insulin resistance decreased significantly during the 90 days after surgery, with the greatest decrease at 15 days. However, in the patients who underwent SG, insulin resistance worsened at 15 days and later diminished.

CONCLUSION

The results of the present study have shown that the surgical technique that excludes the duodenum (i.e., BPD) has immediate postoperative changes in the degree of insulin resistance in morbidly obese patients compared to those techniques that do not exclude the duodenum (i.e., SG).

Alterations in the mitochondrial regulatory pathways constituted by the nuclear co-factors PGC-1alpha or PGC-1beta and mitofusin 2 in skeletal muscle in type 2 diabetes

Muscle mitochondrial metabolism is regulated by a number of factors, many of which are responsible for the transcription of nuclear genes encoding mitochondrial proteins such as PPARdelta, PGC-1alpha or PGC-1beta. Recent evidence indicates that proteins participating in mitochondrial dynamics also regulate mitochondrial metabolism. Thus, in cultured cells the mitochondrial fusion protein mitofusin 2 (Mfn2) stimulates respiration, substrate oxidation and the expression of subunits involved in respiratory complexes. Mitochondrial dysfunction has been reported in skeletal muscle of type 2 diabetic patients. Reduced mitochondrial mass and defective activity has been proposed to explain this dysfunction. Alterations in mitochondrial metabolism may be crucial to account for some of the pathophysiological traits that characterize type 2 diabetes. Skeletal muscle of type 2 diabetic patients shows reduced expression of PGC-1alpha, PGC-1beta, and Mfn2. In addition, a differential response to bilio-pancreatic diversion-induced weight loss in non-diabetic and type 2 diabetic patients has been reported. While non-diabetic morbidly obese subjects showed an increased expression of genes encoding Mfn2, PGC-1alpha, PGC-1beta, PPARdelta or SIRT1 in response to bariatric surgery-induced weight loss, no effect was detected in type 2 diabetic patients. These observations suggest the existence of a heritable component responsible for the abnormal control of the expression of genes encoding for modulators of mitochondrial biogenesis/metabolism, and which may participate in the development of the disease.

Sleeve gastrectomy provides a better control of diabetes by decreasing ghrelin in the diabetic Goto-Kakizaki rats

AIM

Sleeve gastrectomy (SG) and modified duodenal jejunal bypass (MDJB) were compared as procedures for glucose control. We aim to form the initial conclusions with respect to the possibility of (1) whether gastric fundus exclusion is essential for the control of diabetes and (2) application as a low morbidity procedure.

MATERIALS AND METHODS

SG and MDJB were performed on 10- to 12-week-old Goto-Kakizaki rats that spontaneously develop type 2 diabetes. Rats were observed for 36 weeks after surgery, and glucose, insulin, glucagons-like peptide-1 (GLP-1), glucose tolerate, insulin sensitivity, cholesterol, triglycerides, and free fatty acid levels were measured.

RESULTS

Apart from distinct weight loss of SG and MDJB after 1 month compared with sham-operated rats (P < 0.001), SG showed strikingly improved blood glucose levels and significantly decreased Ghrelin secretion (P < 0.001). Furthermore, SG resulted in a shorter operative time (P < 0.01) and postoperative recovery time (P < 0.01) than MDJB group.

CONCLUSIONS

SG shows better control in terms of glucose tolerance and other measurements. This study provides direct evidence that SG possesses better improvement of diabetes by reduction of Ghrelin.

Mitochondrial dynamics in mammalian health and disease

The meaning of the word mitochondrion (from the Greek mitos, meaning thread, and chondros, grain) illustrates that the heterogeneity of mitochondrial morphology has been known since the first descriptions of this organelle. Such a heterogeneous morphology is explained by the dynamic nature of mitochondria. Mitochondrial dynamics is a concept that includes the movement of mitochondria along the cytoskeleton, the regulation of mitochondrial architecture (morphology and distribution), and connectivity mediated by tethering and fusion/fission events. The relevance of these events in mitochondrial and cell physiology has been partially unraveled after the identification of the genes responsible for mitochondrial fusion and fission. Furthermore, during the last decade, it has been identified that mutations in two mitochondrial fusion genes (MFN2 and OPA1) cause prevalent neurodegenerative diseases (Charcot-Marie Tooth type 2A and Kjer disease/autosomal dominant optic atrophy). In addition, other diseases such as type 2 diabetes or vascular proliferative disorders show impaired MFN2 expression. Altogether, these findings have established mitochondrial dynamics as a consolidated area in cellular physiology. Here we review the most significant findings in the field of mitochondrial dynamics in mammalian cells and their implication in human pathologies.

Genes involved in mitochondrial biogenesis/function are induced in response to bilio-pancreatic diversion in morbidly obese individuals with normal glucose tolerance but not in type 2 diabetic patients

AIMS/HYPOTHESIS

The mechanisms allowing normalisation of insulin sensitivity and reversal of type 2 diabetes after bilio-pancreatic diversion (BPD) have not been elucidated. We studied whether the expression of genes relevant to mitochondrial biogenesis/function is induced in response to BPD and whether the response differs between morbidly obese patients with normal glucose tolerance (NGT) and patients with type 2 diabetes.

METHODS

The effect of stable weight reduction after BPD on metabolic variables and expression of nuclear genes encoding for mitochondrial proteins or regulators of mitochondrial function was investigated in skeletal muscle. Insulin sensitivity was assessed by euglycaemic-hyperinsulinaemic clamp and substrate oxidation by indirect calorimetry.

RESULTS

Both NGT and type 2 diabetic patients showed a net improvement of insulin sensitivity, with the latter also showing blood glucose normalisation. NGT patients had a large increase in glucose oxidation and substantial reduction in lipid oxidation. In contrast, type 2 diabetic patients had a blunted response to BPD in terms of glucose oxidation. NGT patients showed increased expression of genes encoding mitofusin 2, porin or citrate synthase; no significant changes were detected in diabetic patients. The expression of genes regulating mitochondrial activity (PGC-1beta [also known as PPARGC1B], PGC-1alpha [also known as PPARGC1A], PPARdelta [also known as PPARD], SIRT1) was induced only in NGT patients.

CONCLUSIONS/INTERPRETATION

These findings indicate that weight loss after BPD exerts a beneficial effect on insulin sensitivity via mechanisms that are independent of the expression of genes involved in mitochondrial biogenesis/activity. Furthermore, the observation that gene expression is not altered with weight loss in type 2 diabetic patients while it is induced in NGT patients suggests a heritable component.

Evaluation of antioxidant systems (coenzyme Q10 and total antioxidant capacity) in morbid obesity before and after biliopancreatic diversion

Biliopancreatic diversion (BPD) is a surgical procedure performed in patients with untreatable obesity and insulin resistance. The demonstrated metabolic and hormonal results of this procedure include the reversal of insulin resistance; an increase in diet-induced thermogenesis; and modifications of gut hormones, such as gastrin, enteroglucagon, neurotensin, and cholecystokinin. On the other hand, obesity is a condition of increased oxidative stress; however, few studies have investigated antioxidant systems in obese persons with BPD. To evaluate the metabolic status and antioxidant systems in such patients, we studied a group of 11 morbidly obese patients, aged 28 to 62 years, with a mean body mass index (BMI) of 54.71 +/- 2.52 kg/m(2), before and after successful BPD (mean post-BPD BMI, 44.68 +/- 1.51 kg/m(2)). A control group composed of 10 slightly overweight women, with a mean BMI of 28.5 +/- 0.72 kg/m(2), was also studied. Coenzyme Q(10) (CoQ(10)) levels (also normalized for cholesterol levels) and total antioxidant capacity in blood plasma were assessed in these populations. The most striking datum was the extremely low level of CoQ(10) in postoperative period (0.34 +/- 0.16 vs 0.66 +/- 0.09 mug/mL, P = .04); also, the data corrected for cholesterol levels presented the same pattern, with a more marked significance (152.46 +/- 11.13 vs 186.4 +/- 17.98 nmol/mmol, P = .001). This could be due to lipid malabsorption after surgery. In fact, the pre-BPD data present all the metabolic and hormonal characteristics of severe obesity; and after BPD, there was a net improvement in the metabolic parameters. The first pathophysiologic phenomenon seems to be lipid malabsorption that has been argued to be the cause of insulin resistance reversion. This metabolic interpretation is also confirmed by the absence of significant variations of total antioxidant capacity (57.5 +/- 5.3 vs 66 +/- 5.3). The mechanisms of these phenomena remain to be established. These data suggest the importance of correcting postsurgical metabolic complications, in these clinical populations, with CoQ(10) supplementation.

Ileal transposition controls diabetes as well as modified duodenal jejunal bypass with better lipid lowering in a nonobese rat model of type II diabetes by increasing GLP-1

OBJECTIVE

Modified duodenal jejunal bypass (MDJB) and ileal transposition (IT) were compared as surgeries for glucose control. Initial conclusions might be formed with respect to the possibility of (1) whether duodenal exclusion is essential for the control of diabetes and (2) application as a low morbid procedure.

SUMMARY BACKGROUND DATA

IT, MDJB, sham-IT, and sham-MDJB procedures were performed on 10- to 12-week-old Goto-Kakizaki (GK) rats, nonobese animals who spontaneously develop type 2 diabetes. Rats were observed for 24 weeks after surgery. Glucose, insulin, glucagon-like peptide-1 (GLP-1), glucose tolerance, insulin sensitivity, cholesterol, triglycerides, and free fatty acid levels were measured.

RESULTS

MDJB and IT rats, when compared with sham-operated rats, showed reduced blood-glucose levels (P < 0.001); but IT- and MDJB did not differ from one another (P < 0.05). Compared with sham-operated rats, IT- and MDJB rats showed increased GLP-1 secretion (P < 0.01), with a more rapid and higher secretion in IT operated than in MDJB rats (P < 0.05). After 6 months, sham-operated rats weighed more than IT or MDJB rats (P < 0.01), but the weights of IT- and MDJB rats were similar to one another (P > 0.05). In terms of both operative time (P < 0.001) and postoperative recovery time (P < 0.001), MDJB took longer than did IT.

CONCLUSION

In nonobese spontaneously diabetic rats, IT is equivalent to MDJB in terms of glucose control and weight secondary to significant increases of GLP-1. IT is faster to perform and yields a shorter recovery period than does MDJB.

Predictors of weight loss and reversal of comorbidities in malabsorptive bariatric surgery

BACKGROUND

Cardiovascular and metabolic comorbidities are dramatically increased in severe obesity, a condition highly resistant to nonsurgical therapy.

OBJECTIVE

The objective was to identify predictors of weight loss and reversal of comorbidity in obese patients undergoing malabsorptive bariatric surgery.

DESIGN

Morbidly obese men and women (n = 107) were studied before and 2 y after biliopancreatic diversion (BPD). Body composition, serum lipid profile, oral glucose tolerance, and blood pressure were measured. Insulin sensitivity was determined by use of a euglycemic clamp. The length of the small intestine was measured during surgery.

RESULTS

Intestinal length was 671 +/- 99 cm, and the residual absorbing intestine after BPD ranged from 54% to 24% of initial length. Patients lost an average of 36% of their initial weight, with approximately 50% of them reaching a body mass index (in kg/m(2)) < 30. Serum cholesterol decreased (from 4.58 +/- 1.11 to 3.34 +/- 0.73 mmol/L; P < 0.0001), as did serum triacylglycerols (from 1.52 +/- 0.59 to 0.88 +/- 0.35 mmol/L; P < 0.0001), whereas insulin sensitivity rose 150% (from 26 +/- 4 to 64 +/- 11 micromol . min(-1) . kg fat-free mass(-1); P < 0.0001). Diabetes (in 23% of patients before surgery) and hypertension (in 83%) were reduced (by 88% and 96%, respectively) after surgery. In a multivariate model (including sex, age, intestinal length, presence of diabetes, insulin sensitivity, and initial fat mass), age and diabetes were independent, negative predictors of weight loss, whereas initial fat mass was a strong positive predictor (r(2) = 0.51).

CONCLUSIONS

Two years after BPD in morbidly obese patients, comorbidities are largely corrected and insulin resistance is fully reversed despite persistent obesity. Initial fat mass, but not residual intestinal length, is the strongest predictor of weight loss after BPD.

Evidence-based medicine reports on obesity surgery: a critique

OBJECTIVE

To evaluate evidence in recent authoritative 'Evidence-Based Medicine' (EBM) reports on surgery for severe obesity.

METHODS

Focused review of Index Medicus citations and authors' own databases of publications on surgery for obesity, 1978-2004.

RESULTS

EBM criteria for assessment of strength of evidence requiring randomized controlled studies (RCTs) in these reports are inappropriate for evaluating invasive treatments such as surgery, which have robust physiological effects, are difficult to reverse and may have more serious side effects than the drug studies for which the criteria were promulgated. Flaws in these reports include omissions of important studies demonstrating improvements in comorbidity, factual errors in descriptions of operations and faulty analyses of outcomes of laparoscopic approaches. There are misinterpretations of cited papers, and inclusion of obsolete operations as well as a study generated during the 'learning curve' of an avowed complex procedure.

CONCLUSION

EBM analyses of surgical modalities affecting access to care require relevant evaluation criteria, true peer review and expert consultation. Authors' claims of objectivity by invoking use of evidence-based criteria applicable to drug treatment and other easily reversible forms of therapy are questionable. Decisions based on flawed EBM reports may adversely affect access to care for millions of severely obese patients.

The early effect of the Roux-en-Y gastric bypass on hormones involved in body weight regulation and glucose metabolism

OBJECTIVE

To evaluate the early effect of Roux-en-Y (RYGB) gastric bypass on hormones involved in body weight regulation and glucose metabolism. SIGNIFICANT BACKGROUND DATA: The RYGB is an effective bariatric procedure for which the mechanism of action has not been elucidated yet. Reports of hormonal changes after RYGB suggest a possible endocrine effect of the operation; however, it is unknown whether these changes are the cause or rather the effect of surgically induced weight loss. We speculated that if the mechanism of action of the RYGB involves an endocrine effect, then hormonal changes should occur early after surgery, prior to substantial body weight changes.

METHODS

Ten patients with a mean preoperative body mass index (BMI) of 46.2 kg/m (40-53 kg/m) underwent laparoscopic RYGB. Six patients had type 2 diabetes treated by oral hypoglycemic agents. Preoperatively and 3 weeks following surgery, all patients were tested for fasting glucose, insulin, glucagon, insulin-like growth factor 1 (IGF-1), leptin, gastric inhibitory polypeptide (GIP), glucagon-like peptide-1 (GLP-1), cholecystokinin (CCK), adrenocorticotropic hormone (ACTH), corticosterone, and neuropeptide Y (NPY).

RESULTS

Changes in mean BMI were rather minimal (43.2 kg/m; P = not significant), but there was a significant decrease in blood glucose (P = 0.005), insulin (P = 0.02), IGF-1 (P < 0.05), leptin (P = 0.001), and an increase in ACTH levels (P = 0.01). The other hormones were not significantly changed by surgery. All the 6 diabetic patients had normal glucose and insulin levels and did not require medications after surgery. The RYGB reduced GIP levels in diabetic patients (P < 0.01), whereas no changes in GIP levels were found in nondiabetics.

CONCLUSIONS

Roux-en-Y gastric bypass determines considerable hormonal changes before significant BMI changes take place. These results support the hypothesis of an endocrine effect as the possible mechanism of action of RYGB.

Potential of surgery for curing type 2 diabetes mellitus

OBJECTIVE

To review the effect of morbid obesity surgery on type 2 diabetes mellitus, and to analyze data that might explain the mechanisms of action of these surgeries and that could answer the question of whether surgery for morbid obesity can represent a cure for type 2 diabetes in nonobese patients as well.

SUMMARY BACKGROUND DATA

Diabetes mellitus type 2 affects more than 150 million people worldwide. Although the incidence of complications of type 2 diabetes can be reduced with tight control of hyperglycemia, current therapies do not achieve a cure. Some operations for morbid obesity not only induce significant and lasting weight loss but also lead to improvements in or resolution of comorbid disease states, especially type 2 diabetes.

METHODS

The authors reviewed data from the literature to address what is known about the effect of surgery for obesity on glucose metabolism and the endocrine changes that follow this surgery.

RESULTS

Series with long-term follow-up show that gastric bypass and biliopancreatic diversion achieve durable normal levels of plasma glucose, plasma insulin, and glycosylated hemoglobin in 80% to 100% of severely obese diabetic patients, usually within days after surgery. Available data show a significant change in the pattern of secretion of gastrointestinal hormones. Case reports have also documented remission of type 2 diabetes in nonmorbidly obese individuals undergoing biliopancreatic diversion for other indications.

CONCLUSIONS

Gastric bypass and biliopancreatic diversion seem to achieve control of diabetes as a primary and independent effect, not secondary to the treatment of overweight. Although controlled trials are needed to verify the effectiveness on nonobese individuals, gastric bypass surgery has the potential to change the current concepts of the pathophysiology of type 2 diabetes and, possibly, the management of this disease.

Potential of surgery for curing type 2 diabetes mellitus

OBJECTIVE

To review the effect of morbid obesity surgery on type 2 diabetes mellitus, and to analyze data that might explain the mechanisms of action of these surgeries and that could answer the question of whether surgery for morbid obesity can represent a cure for type 2 diabetes in nonobese patients as well.

SUMMARY BACKGROUND DATA

Diabetes mellitus type 2 affects more than 150 million people worldwide. Although the incidence of complications of type 2 diabetes can be reduced with tight control of hyperglycemia, current therapies do not achieve a cure. Some operations for morbid obesity not only induce significant and lasting weight loss but also lead to improvements in or resolution of comorbid disease states, especially type 2 diabetes.

METHODS

The authors reviewed data from the literature to address what is known about the effect of surgery for obesity on glucose metabolism and the endocrine changes that follow this surgery.

RESULTS

Series with long-term follow-up show that gastric bypass and biliopancreatic diversion achieve durable normal levels of plasma glucose, plasma insulin, and glycosylated hemoglobin in 80% to 100% of severely obese diabetic patients, usually within days after surgery. Available data show a significant change in the pattern of secretion of gastrointestinal hormones. Case reports have also documented remission of type 2 diabetes in nonmorbidly obese individuals undergoing biliopancreatic diversion for other indications.

CONCLUSIONS

Gastric bypass and biliopancreatic diversion seem to achieve control of diabetes as a primary and independent effect, not secondary to the treatment of overweight. Although controlled trials are needed to verify the effectiveness on nonobese individuals, gastric bypass surgery has the potential to change the current concepts of the pathophysiology of type 2 diabetes and, possibly, the management of this disease.

Lowering of circulating free-fatty acids levels and reduced expression of leptin in white adipose tissue in postobesity status

BACKGROUND

Our aim was to investigate the regulation of the gene expression of leptin in subcutaneous adipose tissue biopsies in morbid obesity before and after biliopancreatic diversion (BPD).

METHODS

Longitudinal study in morbidly obese subjects investigated twice: before and 6 months after BPD. Fourteen morbidly obese women, 37+/-13 years old and with a body mass index of 51.6+/-8.2 kg/m2, were studied before and 6 months after BPD (40.6+/-8.0 kg/m2). Using reverse transcriptase polymerase chain reaction analysis, the mRNA expression of leptin was investigated in adipose tissue. Plasma leptin was measured by radioimmunoassay; plasma insulin was measured by microparticle enzyme immunoassay. Free fatty acids (FFA) were measured using a colorimetric kit.

RESULTS

A significant decrease in leptin mRNA level was observed in comparison with pretreatment in BPD patients (59+/-34 vs 143+/-85 arbitrary units, P<0.01). A strict relationship between adipose tissue leptin mRNA and plasma leptin either before (R2=0.80, P<0.0001) or after BPD (R2=0.86, P<0.0001) and between plasma FFA concentration and insulin either before (R2=0.65, P<0.001) or after BPD (R2=0.92, P<0.0001) was observed. Finally, a significant correlation was found between changes in FFA and insulin (R2=0.64, P<0.001), insulin and leptin (R2=0.88, P<0.0001), and insulin and leptin mRNA (R2=0.83, P<0.0001).

CONCLUSION

These data demonstrate a high correlation between leptin mRNA expression in adipose tissue and plasma leptin in postobese subjects after BPD. The significant relationship between both leptin mRNA and plasma leptin with insulin suggests that circulating insulin might regulate leptin expression. It might be hypothesized that plasma FFA concentration can act on the insulin secretion and subsequently on the leptin secretory pathway.

Body composition and energy expenditure after weight loss following bariatric surgery

OBJECTIVES

To assess the effectiveness of biliopancreatic diversion (BPD) in the treatment of morbid obesity and to evaluate how the procedure affects body weight.

SUBJECTS

Fourteen morbidly obese subjects studied before and 30 months after BPD and fifteen healthy volunteers matched for age, sex and height (controls).

METHODS

Comparison of the following parameters were made in the study groups before surgery and 30 months after BPD and with those of the controls group: fat mass, fat-free mass, non-protein substrate oxidation, basal metabolic rate, plasma glucose, insulin and free fatty acid concentrations.

RESULTS

Obese subjects lost 60.38+/-10.71 kg of weight during 18 months following surgery and then remained stable for another 12 months, when this study was performed. Weight loss was substantially due to a loss of fat mass (FM: 60.13+/-13.01 kg before and 19.02+/-8.61 kg after BPD; p<0.001). FM were not statistically different between post-obese subjects and controls; however, post-obese patients retained significantly more fat free mass (FFM) than controls. Subsequently, basal metabolic rates of post-obese subjects were higher than those of the control group (p<0.05). Fasting non-protein respiratory quotient (npRQ) was significantly lower before BPD than 30 months after the surgery (0.798+/-0.04 vs. 0.90+/-0.048, p<0.001), suggesting that, while obese, patients oxidized more lipids than carbohydrates. Moreover, fasting and two-hour plasma glucose and insulin concentrations decreased significantly after BPD to values comparable to those of the control group.

CONCLUSION

Weight loss in obese patients after BPD is mainly due to lipid malabsorption, but increased energy expenditure associated with retaining a high FFM in physically active post-obese subjects may also play a role, enabling them to maintain long-term reduced body weights.

Plasma leptin levels after biliopancreatic diversion: dissociation with body mass index

Human obesity is associated with increased leptin levels, related to body composition and fat mass (FM). Insulin has been suggested to be a regulator of in vivo leptin secretion. To further investigate the relationships between insulin and leptin levels in human obesity, we have studied 10 obese females, aged 26-57 yr [body mass index (BMI), 42.9+/-6.3], successfully treated by biliopancreatic (BPD) diversion, in an early postoperative period (2 months after surgery, post-BPD I; BMI, 37.2+/-7.5) and a late postoperative period (16-24 months after surgery; BMI, 27.6+/-3.96). Fourteen normal female subjects (18-59 yr; BMI, 27.9+/-1.4 kg/m2) were studied as controls. In pre-BPD obese subjects, leptin levels were higher than those in controls (60.5+/-18.8 vs. 28.7+/-4.8 ng/mL; P<0.001). BMI and insulin levels were also significantly greater (P<0.0001 and P<0.03, respectively). After surgery, the three parameters considered significantly decreased (P = 0.0007 for BMI, P<0.0001 for leptin, and P = 0.038 for insulin, using Friedman's test for repeated data). Concerning the correlation between leptin and FM in our patients, control subjects and pre-BPD subjects confirmed the correlation found in the general population (r = 0.78; P<0.01). On the contrary, post-BPD patients at 2 months lay outside the general correlation between FM and leptin; in fact, patients with low leptin levels still had a high FM. Moreover, in the post-BPD patients there was no longer a significant correlation between FM and leptin. Concerning the correlation between insulin and leptin levels, a significant correlation was present in control subjects and pre-BPD patients (r = 0.46; P<0.05). Using correlation analysis for repeated measures in surgically treated obese patients, a significant correlation within the subjects was present (r = 0.91; P<0.0001). After operation, BMI and leptin levels had a different pattern of decrease; leptin decreased rapidly, without correlation with BMI, indicating that body composition is not the only factor regulating leptin levels. The consistent correlation with insulin levels suggests an important interaction between these two hormones in post-BPD obese subjects.