Hyperinsulinemic Hypoglycemia Developing Late after Gastric Bypass

The Impact of Cholecystectomy in Patients with Post-Bariatric Surgery Hypoglycemia

BACKGROUND

Metabolic surgery is the foremost treatment for obesity and its associated medical conditions. Nonetheless, post-bariatric hypoglycemia (PBH) emerges as a prevalent complication. PBH pathophysiology implicates heightened insulin and glucagon-like peptide 1 (GLP-1) levels, with bile acids (BA) contributing to GLP-1 release. A plausible association exists between cholecystectomy and PBH, which is attributed to alterations in BA metabolism and ensuing hormonal responses. The objective of this retrospective cohort study was to evaluate the impact of cholecystectomy on PBH pharmacological treatment, diagnostic timelines and metabolic parameters.

MATERIALS AND METHODS

Patients diagnosed with PBH after bariatric surgery were evaluated based on their history of cholecystectomy. Demographic, anthropometric and clinical data were collected. Mixed meal tolerance tests (MMTT) results were compiled to assess metabolic responses.

RESULTS

Of the 131 patients with PBH included in the study, 29 had prior cholecystectomy. The time to PBH diagnosis was similar across groups. Patients with prior cholecystectomy required higher doses of acarbose (p = 0.046), compared to those without prior cholecystectomy. Additionally, MMTT revealed higher insulin (t = 60 min: p = 0.010 and t = 90 min: p = 0.034) and c-peptide levels (t = 60 min: p = 0.008) and greater glycemic variability in patients with prior cholecystectomy (p = 0.049), highlighting the impact of cholecystectomy on glucose metabolism.

CONCLUSION

Our study offers novel insights into PBH pharmacotherapy, indicating that PBH patients with a history of cholecystectomy require elevated doses of acarbose for symptom control than PBH patients without such surgical history. Furthermore, our findings underscore the pivotal role of hyperinsulinism in PBH aetiology, emphasizing the significance of the BA-GLP-1-insulin axis.

Diagnosis and management of post-bariatric surgery hypoglycemia

INTRODUCTION

While bariatric surgery remains the most effective treatment for obesity that allows substantial weight loss with improvement and possibly remission of obesity-associated comorbidities, some postoperative complications may occur. Managing physicians need to be familiar with the common problems to ensure timely and effective management. Of these complications, postoperative hypoglycemia is an increasingly recognized complication of bariatric surgery that remains underreported and underdiagnosed.

AREA COVERED

This article highlights the importance of identifying hypoglycemia in patients with a history of bariatric surgery, reviews pathophysiology and addresses available nutritional, pharmacological and surgical management options. Systemic evaluation including careful history taking, confirmation of hypoglycemia and biochemical assessment is essential to establish accurate diagnosis. Understanding the weight-dependent and weight-independent mechanisms of improved postoperative glycemic control can provide better insight into the causes of the exaggerated responses that lead to postoperative hypoglycemia.

EXPERT OPINION

Management of post-operative hypoglycemia can be challenging and requires a multidisciplinary approach. While dietary modification is the mainstay of treatment for most patients, some patients may benefit from pharmacotherapy (e.g. GLP-1 receptor antagonist); Surgery (e.g. reversal of gastric bypass) is reserved for unresponsive severe cases. Additional research is needed to understand the underlying pathophysiology with a primary aim in optimizing diagnostics and treatment options.

Dumping syndrome after bariatric surgery: prevalence, pathophysiology and role in weight reduction - a systematic review

Background

Dumping syndrome is a frequent and wellknown adverse event after bariatric surgery and covers a dynamic spectrum of early and late dumping. Accelerated gastric emptying is generally considered to be the cause of gastrointestinal and vasomotor complaints. However, there is much uncertainty regarding the exact pathophysiology of dumping. It has been speculated that the syndrome is a desired consequence of bariatric surgery and contributes to more efficient weight loss, but supporting data are scarce.

Methods

A systematic search was conducted in PubMed in July-August 2021. The prevalence of dumping after the most frequently performed bariatric procedures was analyzed, as well as underlying pathophysiology and its role in weight reduction.

Results

Roux-en-Y gastric bypass (RYGB) is associated with the highest postoperative prevalence of dumping. The fast transit induces neurohumoral changes which contribute to an imbalance between postprandial glucose and insulin levels, resulting in hypoglycemia which is the hallmark of late dumping. Early dumping can, when received in a positive way, become a tool to maintain a strict dietary pattern, but no significant relationship to the degree of weight loss has been shown. However, late dumping is detrimental and promotes overall higher caloric intake.

Conclusion

Dumping syndrome is common after bariatric surgery, especially after RYGB. The pathophysiology is complex and ambiguous. Currently available data do not support dumping as a necessary condition to induce weight loss after bariatric surgery.

Diffuse, Adult-Onset Nesidioblastosis/Non-Insulinoma Pancreatogenous Hypoglycemia Syndrome (NIPHS): Review of the Literature of a Rare Cause of Hyperinsulinemic Hypoglycemia

Differential diagnosis of hypoglycemia in the non-diabetic adult patient is complex and comprises various diseases, including endogenous hyperinsulinism caused by functional β-cell disorders. The latter is also designated as nesidioblastosis or non-insulinoma pancreatogenous hypoglycemia syndrome (NIPHS). Clinically, this rare disease presents with unspecific adrenergic and neuroglycopenic symptoms and is, therefore, often overlooked. A combination of careful clinical assessment, oral glucose tolerance testing, 72 h fasting, sectional and functional imaging, and invasive insulin measurements can lead to the correct diagnosis. Due to a lack of a pathophysiological understanding of the condition, conservative treatment options are limited and mostly ineffective. Therefore, nearly all patients currently undergo surgical resection of parts or the entire pancreas. Consequently, apart from faster diagnosis, more elaborate and less invasive treatment options are needed to relieve the patients from the dangerous and devastating symptoms. Based on a case of a 23-year-old man presenting with this disease in our department, we performed an extensive review of the medical literature dealing with this condition and herein presented a comprehensive discussion of this interesting disease, including all aspects from epidemiology to therapy.

Recommendations for the diagnosis and treatment of hypoglycaemia after bariatric surgery

Postprandial hyperinsulinaemic hypoglycaemia is a common complication of bariatric surgery. Although in general its evolution is mild and self-limited, it can lead to neuroglycopaenia and compromise the patient's safety and quality of life. The aim of this document is to offer some recommendations to facilitate the clinical care of these complex patients, reviewing the aetiopathogenesis, its diagnosis and treatment that, sequentially, will include dietary and pharmacological measures and surgery in refractory cases. In the absence of high-quality studies, the diagnostic and therapeutic approach proposed is based on the consensus of experts of the Grupo de Obesidad de la Sociedad Española de Endocrinología y Nutrición [Obesity Group of the Spanish Society of Endocrinology and Nutrition], GOSEEN. Those undergoing bariatric surgery should be informed of the possibility of developing this complication.

Evaluation and Management of Patients Referred for Post-Bariatric Surgery Hypoglycemia at a Tertiary Care Center

PURPOSE

Following bariatric surgery, patients can develop non-specific symptoms self-described as hypoglycemia. However, confirming hypoglycemia can be technically challenging, and therefore, these individuals are frequently treated empirically. This study aimed to describe what diagnostic evaluation and therapeutic interventions patients referred for post-bariatric surgery hypoglycemia undergo.

METHODS

Retrospective observational cohort study of patients with a history of bariatric surgery was evaluated for post-bariatric surgery hypoglycemia in a tertiary referral center from 2008 to 2017. We collected demographic and bariatric surgery information, clinical presentation of symptoms referred to as hypoglycemia, laboratory and imaging studies performed to evaluate these symptoms, and symptom management and outcomes.

RESULTS

A total of 60/2450 (2.4%) patients who underwent bariatric surgery were evaluated in the Department of Endocrinology for hypoglycemia-related symptoms. The majority were middle-aged women without type 2 diabetes who had undergone Roux-en-Y gastric bypass. Thirty-nine patients (65%) completed a biochemical assessment for hypoglycemia episodes. Six (10%) had confirmed hypoglycemia by Whipple's triad, and four (6.7%) met the criteria for post-bariatric surgery hypoglycemia based on clinical and biochemical criteria. All patients were recommended dietary modification as the initial line of treatment, and this intervention resulted in most patients reporting at least some improvement in their symptoms. Eight patients (13%) were prescribed pharmacotherapy, and two patients required additional interventions for symptom control.

CONCLUSIONS

In our experience, evaluation for hypoglycemia-related symptoms after bariatric surgery was rare. Hypoglycemia was confirmed in the minority of patients. Even without establishing a diagnosis of hypoglycemia, dietary changes were a helpful strategy for symptom management for most patients.

Postprandial Normoglycemic Hypokalemia-an Overlooked Complication to Gastric Bypass Surgery?

Obesity is one of the major health problems of the world, and one of the most common surgical treatments is the Roux-en-Y gastric bypass surgery. This can however lead to problems with postprandial hypoglycemia, but sometimes, the meal test does not render any signs of hypoglycemia. Here, 3 cases are presented with postprandial normoglycemic hypokalemia.

Non-pharmacological Treatment Options in the Management of Diabetes Mellitus

The global prevalence of diabetes, especially type 2 diabetes mellitus, has reached epidemic proportions in the last few decades of the 20th century because of the obesity pandemic resulting from adverse lifestyles. Diabetes as a consequence of obesity (diabesity), continues to increase exponentially in the 21st century. Although there are a multitude of drugs for the effective management of diabesity with modest benefits, most patients will require insulin for control of diabetes at some stage that would worsen obesity, and thereby diabesity. Therefore, effective non-pharmacological therapy needs to be expedited in all patients with diabesity. These measures include medical nutrition interventions, change of lifestyles and bariatric surgery. Non-pharmacological interventions are also useful for the effective management of even type 1 diabetes mellitus when used along with insulin therapy especially in those with obesity. This review summarises the current evidence base for the non-pharmacological interventions in the management of diabetes.

Is testing for postprandial hyperinsulinemic hypoglycemia after gastric bypass necessary?

INTRODUCTION

Postprandial hyperinsulinemic hypoglycemia (pHH) is an increasingly reported complication after Roux-en-Y gastric bypass (RYGB). As pHH can cause life-threatening emergencies if occurring without warning symptoms, challenge testing may detect patients at risk. The study objective was to determine the frequency of occurrence of pHH with or without symptoms of hypoglycemia after RYGB.

METHODS

We undertook an observational cohort study of consecutive, unselected patients approximately one year after uncomplicated RYGB. To simulate normal habits, all patients received a standardized carbohydrate-rich solid mixed meal. Plasma glucose and insulin were measured at 30, 60, 90, 120, and 150 min thereafter. Symptoms were classified as autonomous or neuroglycopenic. Patients with hypoglycemia (plasma glucose <3.0 mmol/L [55 mg/dL]), were tested a second time with a protein-rich solid mixed meal.

RESULTS

113 patients were included. Total weight loss at the first follow-up check (14 ± 0.4 months) was 33.97 ± 9.3%. After the carbohydrate-rich meal, glucose dropped to <3.0 mmol/L in 13.2% (n = 15) of patients vs no drop to <3.0 mmol/L after a protein-rich meal. The pHH occurred in 11.5% (n = 13) of patients. Asymptomatic patients (5.3%, n = 6) carried an increased risk (p = 0.008) for pHH. One patient needed emergency treatment after sudden loss of consciousness after the carbohydrate-rich meal.

CONCLUSIONS

The occurrence of pHH was quite high in our study population with 11.5% thereof 5.3% asymptomatic. We therefore suggest that detection of these patients warrants a screening of patients after RYGB. At-risk patients should than be adequately advised to avoid carbohydrate-rich meals in order to optimize risk management.

One-Anastomosis Jejunal Interposition with Gastric Remnant Resection (Branco-Zorron Switch) for Severe Recurrent Hyperinsulinemic Hypoglycemia after Gastric Bypass for Morbid Obesity

BACKGROUND

The anatomical and physiological changes after Roux-en-Y gastric bypass for morbid obesity can lead to severe hyperinsulinemic hypoglycemia with neuroglycopenia in a small percentage of patients. The exact physiologic mechanism is not completely understood. Surgical reversal to the original anatomy and distal or total pancreatectomy are current therapeutic options to reverse the hypoglycemic effect, with substantial associated morbidity. Our group reports a pilot clinical series of a novel surgical technique using one-anastomosis jejunal interposition with gastric remnant resection (Branco-Zorron Switch).

METHODS

Patients with severe symptomatic hyperinsulinemic hypoglycemia refractory to conservative therapy were treated using the technique. The procedure started with resection of the remnant stomach close to pylorus. The alimentary limb was sectioned at 20 cm from the gastrojejunal anastomosis, and the rest of the alimentary limb was resected until the Y-Roux anastomosis. A hand-sutured anastomosis was then performed with the proximal alimentary limb and the remnant antrum.

RESULTS

Four patients were successfully submitted to the procedure with reversal of the symptomatology and normalization of insulin levels, postprandial glucose levels, and oral glucose tolerance test, with a mean follow-up of 24.3 months. Mean operative time was 188 min, and patients recovered without postoperative complications.

CONCLUSION

Patients suffering from severe hyperinsulinemic hypoglycemia after gastric bypass may be efficiently treated by this innovative procedure, avoiding extreme surgical therapy such as pancreatectomy or restoring the gastric anatomy, while still maintaining sustained weight loss. Studies with larger series and longer follow-up are still needed to define the role of this therapy in managing this entity.

Effect of meal size and texture on gastric pouch emptying and glucagon-like peptide 1 after gastric bypass surgery

BACKGROUND

Roux-en-Y gastric bypass (RYGB) accelerates gastric pouch emptying, enhances postprandial glucagon-like peptide 1 (GLP-1) and insulin, and lowers glucose concentrations. To prevent discomfort and reactive hypoglycemia, it is recommended that post-RYGB patients eat small, frequent meals and avoid caloric drinks. However, the effect of meal size and texture on GLP-1 and metabolic response has not been studied.

OBJECTIVES

To demonstrate that frequent minimeals and solid meals (S) elicit less GLP-1 and insulin release and less reactive hypoglycemia and are better tolerated compared with a single isocaloric liquid meal (L).

SETTING

A university hospital.

METHODS

In this prospective study, 32 RYGB candidates were enrolled and randomized to L or S groups before gastric bypass. Each subject received an L or S 600-kcal single meal (SM) administered at hour 0 or three 200-kcal minimeals administered at hours 0, 2, and 4 on 2 separate days. Twenty-one patients were retested 1 year after RYGB. Blood and visual analogue scale measurements were collected up to 6 hours postprandially. Outcome measures included gastric pouch emptying, glucose, insulin, and GLP-1; hunger, fullness, and stomach discomfort were measured by visual analogue scale.

RESULTS

Twenty-one were patients retested after RYGB (L: n = 12; S: n = 9). Meal texture had a significant effect on peak GLP-1 (L-SM: 106.1 ± 67.2 versus S-SM: 45.3 ± 25.2 pM, P = .004), peak insulin, and postprandial glucose. Hypoglycemia was more frequent after the L-SM meal compared with the S-SM. Gastric pouch emptying was 2.4 times faster after RYGB but was not affected by texture.

CONCLUSIONS

Meal texture and size have significant impact on tolerance and metabolic response after RYGB.

Incidence and Predictive Factors of Postprandial Hyperinsulinemic Hypoglycemia After Roux-en-Y Gastric Bypass: A Five year Longitudinal Study

BACKGROUND

Postprandial hyperinsulinemic hypoglycemia (PHH) is often reported after Roux-en-Y gastric bypass (RYGB). In the absence of a prospective study, the clinical and biological determinants of PHH remain unclear.

OBJECTIVE

To determine the incidence and predictive factors of PHH after RYGB.

METHODS

Participants were 957 RYGB patients enrolled in an ongoing longitudinal cohort study. We analyzed the results of an oral glucose tolerance test (OGTT) routinely performed before surgery and 1 and/or 5 years after. PHH was defined as blood glucose < 50 mg/dL AND plasma insulin > 3 mU/L at 120 minutes post glucose challenge. Validated indices of insulin sensitivity (Matsuda index), beta-cell function (Insulinogenic index), and beta-cell mass (fasting C-peptide: glucose ratio) were calculated, from glucose, insulin, and c-peptide values measured during OGTT.

RESULTS

OGTT results were available in all patients at baseline, in 85.6% at 12 months and 52.8% at 60 months. The incidence of PHH was 0.5% at baseline, 9.1% * and 7.9%* at 12 months and 60 months following RYGB (*: P < 0.001). In multivariate logistic regression analysis, PHH after RYGB was independently associated with lower age (P = 0.005), greater weight loss (P = 0.031), as well as higher beta-cell function (P = 0.002) and insulin sensitivity (P < 0.001), but not with beta-cell mass (P = 0.381). A preoperative elevated beta-cell function was an independent predictor of PHH after RYGB (receiver operating characteristics curve area under the curve 0.68, P = 0.04).

CONCLUSIONS:

The incidence of PHH significantly increased after RYGB but remained stable between 1 and 5 years. The estimation of beta-cell function with an OGTT before surgery can identify patients at risk for developing PHH after RYGB.

The Impact of Bariatric Surgery on Type 2 Diabetes Mellitus and the Management of Hypoglycemic Events

Recent studies discussed the benefit of bariatric surgery on obese patients diagnosed with type 2 diabetes mellitus (T2DM). Several factors play an essential role in predicting the impact of bariatric surgery on T2DM, such as ABCD score (age, BMI, C-peptide, and duration of the disease), HbA1c, and fasting blood glucose, incretins [glucagon-like peptide-1 (GLP-1) and gastric inhibitory peptide (GIP)]. DiaRem score known to include factors such as age, HbA1c, medication, and insulin usage used to predict the remission of T2DM, but it has some limitations. An extensive literature search was conducted on PubMed and Google Scholar using keywords such as gastric bypass, T2DM, bariatric surgery, GLP-1, GIP, and post bariatric hypoglycemia. Restrictive-malabsorptive procedures are most effective in treating T2DM patients based on changes induced in appetite through regulation of gastrointestinal hormones, with decreased hunger and increased satiation. We provide a review of bariatric surgery influence on T2DM and management of post-intervention hypoglycemic events. Post-bariatric surgery hypoglycemia is a serious complication especially when patients develop life-threatening neuroglycopenia with loss of consciousness and seizure. The avoidance of this adverse event may be achieved by strict dietary modification including a restriction on carbohydrates as well as foods with high glycemic index. Further research will provide more information on post-bariatric surgery hyperinsulinemic hypoglycemia pathophysiology and management.

Evaluation of carbohydrate restriction as primary treatment for post-gastric bypass hypoglycemia

BACKGROUND

Up to 15% of patients who have undergone Roux-en-Y gastric bypass (RYGB) surgery may eventually develop symptoms of hypoglycemia.

OBJECTIVES

To evaluate the daily life efficacy of a carbohydrate (carb)-restricted dietary advice (CRD) of 6 meals per day with a 30 g carb maximum per meal in patients with documented post-RYGB hypoglycemia.

SETTING

Teaching hospital, the Netherlands.

METHODS

Frequency and severity of hypoglycemic events before and after CRD were assessed retrospectively in 41 patients with documented post-RYGB hypoglycemia, based on medical records and telephone questionnaires. Hypoglycemia was defined as a blood glucose level<3.0 mmol/L. Results are expressed as mean values±standard error or median and range.

RESULTS

CRD decreased the number of hypoglycemic events per month from 17.1 (1.5-180) to 2.5 (0-180), i.e., a decline of 85% (P<.001). The lowest blood glucose measured during a hypoglycemic event increased from 2.1±.4 to 2.6±.2 mmol/L (P = .004). The number of patients who had required outside help in the treatment of hypoglycemia, decreased from 23 to 6 (P<.001). In 14 patients (34.1%) the diet-induced reduction of hypoglycemia was insufficient and required the start of insulin suppressive therapy.

CONCLUSION

A CRD, consisting of 6 meals per day with up to 30 g carbs each, is an effective treatment of post-RYGB hypoglycemia in the majority of patients. Additional medication is needed in about a third of patients.

Evaluation, Medical Therapy, and Course of Adult Persistent Hyperinsulinemic Hypoglycemia After Roux-en-Y Gastric Bypass Surgery: A Case Series

OBJECTIVE

To describe the evaluation and treatment of hyperinsulinemic hypoglycemia in adults who had undergone gastric bypass surgery. A small number of patients who undergo Roux-en-Y bypass surgery develop postprandial hypoglycemia in the absence of dumping. In some cases, such patients have been treated with pancreatectomy.

METHODS

We report the demographics, diagnostic results, response to medical therapy, and subsequent course of 6 referral patients with post-Roux-en-Y gastric bypass hypoglycemia.

RESULTS

Characteristic clinical and metabolic parameters consistent with hyperinsulinemic hypoglycemia were identified. Parameters were similar for both spontaneous and glucose-challenge-induced hypoglycemia. In the context of exclusively postprandial symptoms, simultaneous glucose ≤55 mg/dL, insulin ≥17 μU/mL, C peptide ≥3.0 ng/mL, and insulin to glucose ratio >0.3 were associated with Roux-en-Y gastric bypass hyperinsulinemic hypoglycemia. Five of 6 patients improved on therapy consisting of dietary modification plus either calcium channel blockade, acarbose, or both. Two patients have remained on therapy for 12 to 15 months. The nonresponder was atypical and had had hypoglycemic events for several decades. Three treated patients were subsequently observed to have undergone partial or complete remission from hypoglycemic episodes after 2 to 37 months of therapy. None of the 6 have undergone pancreatectomy, and none have evidence of insulinoma. Invasive diagnostic procedures were of limited utility.

CONCLUSION

In a subset of patients with post-Roux-en-Y gastric bypass hyperinsulinemic hypoglycemia, medical management can be efficacious and an alternative to partial pancreatectomy. In some cases, the disorder remits spontaneously.

Post-gastric bypass hypoglycaemia: a review

Bariatric surgery is a highly effective treatment for severe obesity, resulting in substantial weight loss and normalizing obesity-related comorbidities. However, long-term consequences can occur, such as postbariatric surgery hypoglycaemia. This is a challenging medical problem, and the number of patients presenting with it has been increasing. Roux-en-Y gastric bypass (RYGB) is the most popular bariatric procedure, and it is the surgery most commonly associated with the development of postbariatric surgery hypoglycaemia. To date, the pathogenesis of this condition has not been completely established. However, various factors - particularly increased postprandial glucagon-like peptide (GLP)-1 secretion - have been considered as crucial mediator. The mechanisms responsible for diabetic remission after bariatric surgery may be responsible for the development of hypoglycaemia, which typically occurs 1-3 h after a meal and is concurrent with inappropriate hyperinsulinaemia. Carbohydrate-rich foods usually provoke hypoglycaemic symptoms, which can typically be alleviated by strict dietary modifications, including carbohydrate restriction and avoidance of high glycaemic index foods and simple sugars. Few patients require further medical intervention, such as medications, but some patients have required a pancreatectomy. Because this option is not always successful, it is no longer routinely recommended. Clinical trials are needed to further determine the pathophysiology of this condition as well as the best diagnostic and treatment approaches for these patients.

Hypoglycaemia after gastric bypass: mechanisms and treatment

Hypoglycaemia after gastric bypass can be severe, but is uncommon, and is sometimes only revealed through monitoring glucose concentrations. The published literature is limited by the heterogeneity of the criteria used for diagnosis, arguing in favour of the Whipple triad with a glycaemia threshold of 55 mg/dl as the diagnostic reference. Women who lost most of their excess weight after gastric bypass, long after the surgery was performed, and who did not have diabetes before surgery are at the greatest risk. In this context, hypoglycaemia results from hyperinsulinism, which is either generated by pancreas anomalies (nesidioblastosis) and/or caused by an overstimulation of β cells by incretins, mainly glucagon-like peptide-1 (GLP-1). Glucose absorption is both accelerated and increased because of the direct communication between the gastric pouch and the jejunum. This is a post-surgical exaggeration of a natural adaptation that is seen in patients who have not undergone surgery in whom glucose is infused directly into the jejunum. There is not always a correspondence between symptoms and biological traits; however, hyperinsulinism is constant if hypoglycaemia is severe and there are neuroglucopenic symptoms. The treatment relies firstly on changes in eating habits, splitting food intake into five to six daily meals, slowing gastric emptying, reducing the glycaemic load and glycaemic index of foods, using fructose and avoiding stress at meals. Pharmacological treatment with acarbose is efficient, but other drugs still need to be validated in a greater number of subjects (insulin, glucagon, calcium channel blockers, somatostatin analogues and GLP-1 analogues). Lastly, if the surgical option has to be used, the benefits (efficient symptom relief) and the risks (weight regain, diabetes) should be weighed carefully.

Post-prandial hypoglycemia results from a non-glucose-dependent inappropriate insulin secretion in Roux-en-Y gastric bypassed patients

BACKGROUND

After Roux-en-Y gastric bypass (RYGB), hypoglycemia can occur and be associated with adverse events such as intense malaise and impaired quality of life.

OBJECTIVE

To compare insulin secretion, sensitivity, and clearance between two groups of patients, with or without hypoglycemia, after an oral glucose tolerance test (OGTT 75-g), and also to compare real-life glucose profiles within these two groups.

SETTING

Bariatric surgery referral center.

METHODS

This study involves a prospective cohort of 46 consecutive patients who complained of malaise compatible with hypoglycemia after RYGB, in whom an OGTT 75-g was performed. A plasma glucose value of lower than 2.8 mmol/L (50 mg/dl) between 90 and 120 min after the load was considered to be a significant hypoglycemia. The main outcome measures were insulin sensitivity, beta-cell function, and glycemic profiles during the test. Glucose parameters were also evaluated by continuous glucose monitoring (CGM) in a real-life setting in 43 patients.

RESULTS

Twenty-five patients had plasma glucose that was lower than 2.8 mmol/L between 90 and 120 from the load (HYPO group). Twenty-one had plasma glucose that was higher than 2.8 mmol/L (NONHYPO group). The HYPO patients were younger, had lost more weight after RYGB, were less frequently diabetic before surgery, and displayed higher early insulin secretion rates compared with the NONHYPO patients after the 75-g OGTT, and they had lower late insulin secretion rates. The HYPO patients had lower interstitial glucose values in real life, which suggests that a continuum exists between observations with an oral glucose load and real-life interstitial glucose concentrations.

CONCLUSIONS

This study suggests that HYPO patients after RYGB display an early increased insulin secretion rate when tested with an OGTT. CGM shows that HYPO patients spend more time below 3.3 mmol/L when compared with NONHYPO patients. This phenotype of patients should be monitored carefully after RYGB.

Adverse effects during the oral glucose tolerance test in post-bariatric surgery patients

OBJECTIVE

The oral glucose tolerance test (OGTT) is used in the screening of gestational diabetes, in diagnosis of type 2 diabetes in conjunction with fasting blood glucose and glycated hemoglobin. The aim of this study was to examine the incidence and risk factors of adverse effects of OGTT in patients who underwent bariatric surgery, in addition to proposing standardization for ordering the OGTT in these patients.

SUBJECTS AND METHODS

This study assessed the incidence of adverse effects in 128 post-bariatric surgery patients who underwent the OGTT. Descriptive and logistic regression analysis were performed, the dependent variables were defined as the presence of signs (tremor, profuse sweating, tachycardia), symptoms (nausea, diarrhea, dizziness, weakness), and hypoglycemia (blood glucose ≤ 50 mg/dL).

RESULTS

One hundred and seventeen participants (91.4%) were female; 38 (29.7%) participants were pregnant. High incidence (64.8%) of adverse effects was observed: nausea (38.4%), dizziness (30.5%), weakness (25.8%), diarrhea (23.4%), hypoglycemia (14.8%), tachycardia (14.1%), tremor (13.3%), profuse sweating (12.5%) and one case of severe hypoglycemia (24 mg/dL). The presence of signs was associated with hypoglycemia (OR = 8.1, CI 95% 2.6-25.1). The arterial hypertension persisted as a risk factor for the incidence of signs (OR = 3.6, CI 95% 1.2-11.3). Fasting glucose below 75 mg/dL increased the risk of hypoglycemia during the test (OR = 9.5, CI 95% 2.6-35.1).

CONCLUSION

In this study, high incidence of adverse effects during the OGTT was observed in post-bariatric surgery patients. If these results are confirmed by further studies, the indication and regulation of the OGTT procedure must be reviewed for these patients.

Effects of gastric bypass on FoxO1 expression in the liver and pancreas of diabetic rats

AIM

To explore the mechanism by which gastric bypass surgery (GBS) ameliorates type 2 diabetes mellitus (T2DM) by investigating whether FoxO1 (a transcription factor that plays a crucial role in the regulation of glycolipid metabolism) expression is altered in the liver and pancreatic islet cells in a rat model of GBS-treated T2DM.

METHODS

Sprague-Dawley rats were randomly divided into four groups (n = 10 rats each): diabetic rats treated by GBS (DM + GBS), diabetic rats subjected to sham operation (DM + sham), normal control rats (control), and diabetic rats without surgery (DM). Fasting levels of blood glucose (BG), insulin, and glucagon-like peptide-1 (GLP-1) were measured in all groups before and 4, 8, 16, and 24 weeks after operation. Rats were killed 24 weeks after surgery. Liver and pancreas expressions of FoxO1 were investigated by immunohistochemistry and Western blotting analyses.

RESULTS

In the DM + GBS group, fasting BG before and 24 weeks after surgery decreased from 20.2 ± 2.1 to 7.7 ± 1.1 mmol/L, respectively; fasting insulin showed no change (2.9 ± 0.1 and 3.0 ± 0.1 mU/L, respectively); and fasting GLP-1 increased from 8.7 ± 0.9 to 23.5 ± 0.2 pmol/L, respectively. Fasting BG levels after surgery in the DM + GBS group were significantly lower than those in the DM + sham and DM groups. FoxO1 expression levels in the liver and pancreatic islets of the DM + GBS group were reduced compared to those in the DM + sham and DM groups. FoxO1 in the pancreatic β-cells was expressed mainly in the cytoplasm.

CONCLUSIONS

Gastric bypass may improve type 2 diabetes mellitus by changing FoxO1 expression in the liver and pancreatic islet cells.

Recognition and management of hyperinsulinemic hypoglycemia after bariatric surgery

Hyperinsulinemic hypoglycemia with neuroglycopenia is an increasingly recognized complication of Roux-en-Y gastric bypass (RYGB) due to the changes in gut hormonal milieu. Physicians should be aware of this complication to ensure timely and effective treatment of post-RYGB patients, who present to them with hypoglycemic symptoms. Possible causes of hypoglycemia in these patients include late dumping syndrome, nesidioblastosis and rarely insulinoma. Systematic evaluation including history, biochemical analysis, and diagnostic testing might help in distinguishing among these diagnoses. Continuous glucose monitoring is also a valuable tool, revealing the episodes in the natural environment and can also be used to monitor treatment success. Treatment should begin with strict low carbohydrate diet, followed by medication therapy. Therapy with diazoxide, acarbose, calcium channel blockers and octreotide have been proven to be beneficial, but the response apparently is highly variable. When other treatment options fail, surgical options can be considered.

Impact of Carbohydrate Content and Glycemic Load on Postprandial Glucose After Roux-en-Y Gastric Bypass

BACKGROUND

Abnormal glucose profiles have been described after Roux-en-Y gastric bypass (RYGB) with intense postprandial hyperglycemic peaks in some but not all the patients. The underlying mechanisms of these anomalies are not totally understood.

OBJECTIVE

The aim of this study is to determine whether or not the composition of the meal impacts the existence and maximum interstitial glucose (IG) concentration, measured under real-life conditions.

DESIGN

Retrospective cohort.

SETTING

Referral bariatric surgery left.

METHODS

Continuous glucose monitoring (CGM) and meal composition were recorded for at least 3 days on an outpatient basis in 56 patients after RYGB. The presence of postprandial peaks defined by IG above 140 mg/dl, the maximum postprandial IG, the carbohydrate content, and the glycemic load of the meals were analyzed.

RESULTS

Thirty-two patients had a hyperglycemic peak (PEAK), and 24 did not (NO PEAK). The average max IG was 159.6 ± 33.0 mg/dl in PEAK individuals and 111.8 ± 13.0 mg/dl in NO PEAK. Age was significantly higher in PEAK, but no other parameter was different between the two groups, including meal composition. In the PEAK patients, in multivariate analyses, carbohydrate content in model one and glucose load in model two explained respectively 50 and 26 % of maximum IG variance. For each gram of ingested carbohydrates, interstitial glucose increased by 1.68 mg/dl.

CONCLUSIONS

Following a gastric bypass, under real-life conditions, irrespective of the carbohydrate content of the meal, some patients develop postprandial hyperglycemic peaks, whereas others do not. In patients with postprandial hyperglycemic peaks, the maximum IG depends on the carbohydrate content of the meal.

Effect of carbohydrate restriction in patients with hyperinsulinemic hypoglycemia after Roux-en-Y gastric bypass

BACKGROUND

Hyperinsulinemic hypoglycemia is a rare complication of Roux-en-Y gastric bypass (RYGB) surgery. Meals with a high carbohydrate (carb) content and high glycemic index (GI) may provoke these hypoglycemic attacks. The aim of this study is to assess the effects of reducing meal carb content and GI on glycemic responses in patients with post-RYGB hypoglycemia.

METHODS

Fourteen patients with post-RYGB hypoglycemia underwent two meal tests: a mixed meal test (MMT) with a carb content of 30 g and a meal test with the low GI supplement, Glucerna SR 1.5® (Glucerna meal test (GMT)). Plasma glucose and serum insulin levels were measured for a period of 6 h.

RESULTS

Peak glucose levels were reached at T 30 during GMT and at T 60 during MMT, and they were 1.5 ± 0.3 mmol/L lower during GMT than during MMT (7.5 ± 0.4 vs 9.0 ± 0.4 mmol/L, P < 0.005). GMT induced the most rapid rise in plasma insulin: at T 30 plasma, insulin was 30.7 ± 8.5 mU/L higher during GMT than during MMT (P < 0.005). None of the carb-restricted meals induced post-prandial hypoglycemia.

CONCLUSION

A 30-g carb-restricted meal may help to prevent post-prandial hypoglycemia in patients with post-RYGB hypoglycemia. The use of a liquid, low GI, supplement offers no additional advantage.

Post-Gastric Bypass Hyperinsulinemic Hypoglycemia: Fructose is a Carbohydrate Which Can Be Safely Consumed

CONTEXT

Postprandial hypoglycemia after gastric bypass surgery is a serious problem. Available treatments are often ineffective.

OBJECTIVE

The objective was to test the hypotheses that injection of rapid-acting insulin before a high-carbohydrate meal or replacement of other carbohydrates with fructose in the meal would prevent hypoglycemia.

DESIGN

This was a randomized, crossover trial comparing a high-carbohydrate meal with premeal saline injection (control), a high-carbohydrate meal with premeal insulin injection, and a high-fructose meal with total carbohydrate content similar to the control meal.

SETTING

The setting was an academic medical center.

PATIENTS

Ten patients with post-gastric bypass hyperinsulinemic hypoglycemia participated.

INTERVENTIONS

Interventions included lispro insulin injected before test meals and replacement of other carbohydrates with fructose in test meals.

MAIN OUTCOME MEASURE

The main outcome measure was plasma glucose < 60 mg/dL after test meals.

RESULTS

After the control meal, mean peak glucose and insulin were 173 ± 47 mg/dL and 134 ± 55 mU/L, respectively; mean glucose nadir was 44 ± 15 mg/dL; and eight of 10 subjects demonstrated glucose < 60 mg/dL. Five subjects demonstrated a glucose nadir < 40 mg/dL. There were no significant differences in the corresponding values after premeal insulin treatment, except that the mean glucose nadir of 34 ± 10 mg/dL was lower (P < .05). After the fructose meal, mean peak postprandial glucose and insulin were 117 ± 20 mg/dL and 45 ± 31 mU/L, respectively (both P < .001 for comparison with control), mean glucose nadir was 67 ± 10 mg/dL (P < .001), and two of 10 subjects demonstrated glucose < 60 mg/dL (P < .05).

CONCLUSIONS

People with post-gastric bypass hypoglycemia can consume a meal sweetened with fructose with little risk of hypoglycemia. Treatment with rapid-acting insulin before a carbohydrate-containing meal did not prevent hypoglycemia.

Endocrine and metabolic complications after bariatric surgery

Bariatric surgery is the most effective therapeutic option for obese patients; however, it carries substantial risks, including procedure-related complications, malabsorption, and hormonal disturbance. Recent years have seen an increase in the bariatric surgeries performed utilizing either an independent or a combination of restrictive and malabsorptive procedures. We review some complications of bariatric procedures more specifically, hypoglycemia and osteoporosis, the recommended preoperative assessment and then regular follow up, and the therapeutic options. Surgeon, internist, and the patient must be aware of the multiple risks of this kind of surgery and the needed assessment and follow up.

Increased risk of OGTT-induced hypoglycemia after gastric bypass in severely obese patients with normal glucose tolerance

BACKGROUND

Hypoglycemic episodes are described after bariatric surgery.

OBJECTIVE

To report the prevalence of hypoglycemia after a 75 g oral glucose load (OGTT) after Roux-en-Y gastric bypass (RYGB) and adjustable gastric banding (LAGB), and to identify predicting factors.

SETTING

Bariatric surgery referral center.

METHODS

Prospective cohort of 351 consecutive patients before and 12 months after bariatric surgery, on whom an OGTT was performed. The main outcome measure was postchallenge hypoglycemia (PCHy), defined as a 120 minute plasma glucose value<2.8 mmol/L (50.4 mg/dL).

RESULTS

Only patients with an RYGB presented with PCHy. It occurred in 23 patients or a prevalence of 10.4% after an RYGB. The OR was 25.5 (95% CI 3.4-191; P<.001) compared with before surgery. Patients with PCHy after surgery had a lower glycated hemoglobin (HbA1c), and a lower 2-hour postchallenge value before surgery. Before surgery, patients with normal glucose tolerance had an increased risk of PCHy after surgery (OR 8.6, 95% CI 2.0-37.6; P< .001).

CONCLUSIONS

The prevalence of OGTT-induced hypoglycemia is increased 25.5 times, 12 months after an RYGB. This is not observed after a gastric banding.

Hypoglycemia after Roux-En-Y gastric bypass: detection rates of continuous glucose monitoring (CGM) versus mixed meal test

BACKGROUND

Neuroglucopenic hypoglycemia might be an underestimated threat for roux-en-Y gastric bypass (RYGB) patients leading to fatigue, syncope, seizures or even accidental deaths. Different measurements can assess hypoglycemia such as a finger-stick glucometer, an Oral Glucose Tolerance Test, a Mixed Meal-Test (MMT) or, as introduced recently, continuous glucose monitoring (CGM).

SETTING

University Hospital, Austria.

METHODS

To assess the incidence of hypoglycemic episodes under real life conditions, 5-day CGM was performed in a series of 40 patients at a mean of 86 months after RYGB. The detection rates were compared to a mixed meal-test.

RESULTS

CGM detected hypoglycemic episodes of <55 mg/dL or <3.05 mmol/L in 75% of the patients, while MMT indicated hypoglycemia in 29% of the patients. CGM also detected nocturnal hypoglycemic episodes in 15 (38%) of the patients. A mean of 3±1 hypoglycemic episodes per patient with a mean duration of 71±25 minutes were observed by CGM.

CONCLUSIONS

Assessed under real life conditions by CGM, post-RYGB hypoglycemia was found more frequently than expected. CGM revealed hypoglycemic episodes in 75% of the patients while MMT had a lower detection rate. Thus, CGM may have a role for screening but also for the evaluation of dietary modifications, drug therapy or surgical intervention for hypoglycemia after RYGB.

More symptoms but similar blood glucose curve after oral carbohydrate provocation in patients with a history of hypoglycemia-like symptoms compared to asymptomatic patients after Roux-en-Y gastric bypass

BACKGROUND

Laparoscopic Roux-en-Y gastric bypass (LRYGB) is an effective treatment for obesity through altering several physiologic mechanisms. Some patients experience symptoms suggestive of hypglycemia after LRYGB, but whether these symptoms always are associated with low blood glucose are unclear. The objective of this study was to investigate the correlation between symptoms suggestive of hypglycemia, plasma glucose levels and gut hormones involved in glycemic control.

METHODS

Eight LRYGB patients with hypglycemia-like symptoms (SY) and 8 patients with no hypglycemia-like symptoms (ASY) ingested a liquid carbohydrate meal. Insulin, plasma-glucose, glucagon-like peptide 1 (GLP-1) and glucagon were measured intermittently 180 minutes postprandially. In addition, pulse rate, blood pressure and symptoms were assessed.

RESULTS

Plasma glucose at 120 min was lower in the ASY mean (95% CI) 2.4 (1.6,3.3) mmol/L (43.2 mg/dL) compared to the SY group 3.0 (3.1,4.6) mmol/L (54.6 mg/dL), (P = .050). The ASY group had larger reduction in plasma glucose than the SY group from pre- to 120 min postmeal -2.2 (-2.8,-1.7) mmol/L (-39.6 mg/dL) versus -1.1 (-1.7,-0.4) mmol/L (-19.8 mg/dL), (P = .011). The concentrations of insulin, GLP-1 and glucagon did not differ significantly between groups. Blood pressure was similar between groups, but the AUC for pulse rate was higher in the SY than ASY group 13009 (11148,14870) versus 11569 (10837,12300) beats/180 minutes, (P = .038). The SY group reported more symptoms than the ASY group, AUC for Sigstad scale 60 to 180 minutes was 970 (-274,1667) for SY versus 170 for ASY (-39,379), (P = .028).

CONCLUSION

Patients with a history of symptoms suggestive of hypglycemia after LRYGB neither demonstrated lower plasma glucose nor greater insulin response compared to asymptomatic patients in response to a liquid carbohydrate meal, but perceived more symptoms.

Using miglitol at 30 min before meal is effective in hyperinsulinemic hypoglycemia after a total gastrectomy

A 45-year-old woman who had undergone total gastrectomy for gastric cancer presented with a history of postprandial hypoglycemic episodes with loss of consciousness after meals. Laboratory findings revealed marked hyperinsulinemia and hypoglycemia after a meal. We first treated the patient with octreotide; however, she was unable to continue the treatment because of adverse effects of the drug, such as nausea and headache. Diazoxide was used next for preventing hyperinsulinemia; however, this was not effective for suppressing the postprandial insulin secretion. Since hypoglycemia following gastrectomy is thought to be caused by rapid delivery of nutrients into the duodenum, we performed a meal tolerance test while varying the timing of administration of miglitol in relation to the meal. Miglitol was administered 30 min before, just before, or both 30 min and just before a meal. In the case of administration just before a meal, insulin secretion was suppressed, although hypoglycemia was not prevented. Administration of the drug 30 min before a meal prevented postprandial hypoglycemia by slowing the increase of the blood glucose and serum insulin levels following the meal to a greater degree than administration just before a meal. Miglitol administration both 30 min and just before a meal caused an even smoother increase in blood glucose and serum insulin levels following the meal. In this report, we propose a new therapeutic approach for reactive hypoglycemia after gastrectomy, namely, administration of miglitol 30 min before meals.

Bariatric emergencies: current evidence and strategies of management

BACKGROUND

The demand for bariatric surgery is increasing and the postoperative complications are seen more frequently. The aim of this paper is to review the current outcomes of bariatric surgery emergencies and to formulate a pathway of safe management.

METHODS

The PubMed and Google search for English literatures relevant to emergencies of bariatric surgery was made, 6358 articles were found and 90 papers were selected based on relevance, power of the study, recent papers and laparoscopic workload. The pooled data was collected from these articles that were addressing the complications and emergency treatment of bariatric patients. 830,998 patients were included in this review.

RESULTS

Bariatric emergencies were increasingly seen in the Accident and Emergency departments, the serious outcomes were reported following complex operations like gastric bypass but also after gastric band and the causes were technical errors, suboptimal evaluation, failure of effective communication with bariatric teams who performed the initial operation, patients factors, and delay in the presentation. The mortality ranged from 0.14%-2.2% and increased for revisional surgery to 6.5% (p = 0.002). Inspite of this, mortality following bariatric surgery is still less than that of control group of obese patients (p = value 0.01).

CONCLUSIONS

Most mortality and catastrophic outcomes following bariatric surgery are preventable. The awareness of bariatric emergencies and its effective management are the gold standards for best outcomes. An algorithm is suggested and needs further evaluation.

Outcomes of community-dwelling adults without diabetes mellitus who require ambulance services for hypoglycemia

OBJECTIVE

We evaluate the prevalence, etiology, and outcomes of hypoglycemia requiring emergency medical services (EMS) in patients without diabetes mellitus (non-DM).

METHODS

We reviewed medical records of all ambulance calls for non-DM with blood glucose <70 mg/dl in Olmsted County, Minnesota, between January 1, 2003, and December 31, 2009.

RESULTS

A total of 131 patients (age 51 ± 19 years; 54 % females) made 142 EMS calls, while 10 patients made repeated calls. Causes of hypoglycemia were critical illness (42; 32%), alcohol and polysubstance use (36; 27.5 %), insulinoma/bariatric surgery (10; 8%), restricted oral intake (7; 5%), and multiple factors (3; 27.5 %). Patients with alcohol and polysubstance abuse were younger (p = .002). A total of 54 patients had additional hypoglycemia predisposing comorbidities/factors [adrenal insufficiency (2), end-stage renal disease (11) and chronic liver disease (7), beta blockers use (34), and pentamidine use (1)]. Repeated calls and emergency room transportation were similar, but hospitalization varied across the etiologies, with the lowest proportion in the multiple-factor-related hypoglycemia group (p = .01). Duration of follow-up was 1.28 (interquartile range 0.13-2.70) years. A total of 38 patients died, and age-adjusted mortality varied across different etiologies (p < .001), with highest among critically ill. Cancer caused the highest number of deaths (7/38; 18%), while 1 death was due to hypoglycemia.

CONCLUSIONS

There were multiple etiologies for hypoglycemic episodes in community-dwelling non-DM that required EMS. Critical illness, multifactorial causes, and alcohol/polysubstance abuse were common causes. Hospitalization and mortality were higher with critical illnesses.

Usefulness of acarbose and dietary modifications to limit glycemic variability following Roux-en-Y gastric bypass as assessed by continuous glucose monitoring

BACKGROUND

About 70% of the patients operated on for a gastric bypass (Roux-en-Y gastric bypass [RYGB]) suffer from dumping syndrome. In these patients, previous studies have demonstrated a high glycemic variability with hypoglycemia and with altered continuous glucose monitoring (CGM) profiles. The aim of this study was to evaluate the effect of treatment with dietary counseling plus acarbose administration on the symptoms and on the characteristics of the CGM profile.

SUBJECTS AND METHODS

Eight consecutive patients with dumping syndrome were given dietary counseling for 6 weeks and also treated with acarbose (50-100 mg three times a day). Their symptoms and the features of the CGM were compared before and after treatment.

RESULTS

The symptoms disappeared in seven patients. There was a significant increase in the time to the interstitial glucose (IG) peak and a reduction in the rate of the IG increase after a meal and in the rate of the IG decrease following the peak. The time below 60 mg/dL was significantly decreased, and the minimal IG value was significantly increased. The maximum and mean IG levels and the time above 140 mg/dL were decreased, but not significantly. Six patients spent more than 1% of the time with IG values below 60 mg/dL before treatment, but after treatment this was reduced to one patient. Before treatment only one patient had an IG level neither below 60 or above 140 mg/dL, and after treatment four patients were in this category.

CONCLUSIONS

Dietary counseling and acarbose treatment eliminated the symptoms and improved the CGM profile of patients suffering from dumping syndrome after RYGB.

Comparative effectiveness of bariatric surgery and nonsurgical therapy in adults with type 2 diabetes mellitus and body mass index <35 kg/m2

BACKGROUND

Outcomes of bariatric surgery in patients with a body mass index (BMI) <35 kg/m(2) have been an active area of investigation. We examined the comparative effectiveness of Roux-en-Y gastric bypass (RYGB) to routine medical management (nonsurgical controls; NSCs) in achieving appropriate targets defined by the American Diabetes Association for type 2 diabetes mellitus (T2DM) in patients with class I obesity (BMI 30.0-34.9 kg/m(2)) T2DM at 1 year.

METHODS

We identified patients undergoing RYGB (N = 17) with both class I obesity and T2DM and compared them to similar NSC (N = 17) treated in the Primary Care Center. Data were collected at baseline and 1 year for systolic blood pressure (SBP), as well as blood levels for low-density lipoprotein (LDL) cholesterol and hemoglobin A1c (HbA1c).

RESULTS

After RYGB, BMI decreased from 34.6 ± 0.8 kg/m(2) to 25.8 ± 2.5 kg/m(2) (P < .001) and HbA1c decreased from 8.2 ± 2.0% to 6.1 ± 2.7% (P < .001). The NSC cohort had no significant change in either BMI or HbA1c. SBP and LDL did not significantly change in either group. The RYGB group had a decrease in medication use compared to the NSC group (P < .001). The RYGB group ceased the use of antihypertensive and antihyperlipidemia medications by 1 year despite abnormal values.

CONCLUSION

RYGB can be performed in patients with both a BMI <35 kg/m(2) and T2DM with better weight loss, glycemic control, and fewer antihyperglycemic medications than NSC. Inappropriate cessation of medications may partially explain the persistent increase in both SBP and LDL after RYGB.

Surgical treatment of type 2 diabetes: the surgeon perspective

Type 2 diabetes mellitus (T2DM) is a major health priority globally, having achieved pandemic status in the twenty-first century. Several gastrointestinal procedures that were primarily designed to treat morbid obesity result in dramatic remission of diabetes. Studies in experimental rodent models and humans have shown that the glycemic benefits of surgery are at least in part weight-independent and extend to non-morbidly obese subjects with T2DM. Bariatric procedures differ in their ability to ameliorate type 2 diabetes, with intestinal bypass procedures being more effective than purely restrictive procedures. Several studies have demonstrated that the benefits of bariatric surgery extend beyond amelioration of hyperglycemia and include improvement in other cardiovascular risk factors such as dyslipidemia and hypertension. The safety and cost-effectiveness of bariatric surgery are also well established by several studies. In this paper, the authors present the surgeon perspective on the management of type 2 diabetes focusing on the efficacy, safety and cost-effectiveness of metabolic surgery. The available evidence warrants the inclusion of metabolic surgery in the treatment algorithm of type 2 diabetes.

Advances in the etiology and management of hyperinsulinemic hypoglycemia after Roux-en-Y gastric bypass

INTRODUCTION

Hyperinsulinemic hypoglycemia with severe neuroglycopenia has been identified as a late complication of Roux-en-Y gastric bypass (RYGB) in a small number of patients.

DISCUSSION

The rapid resolution of type 2 diabetes mellitus after RYGB is probably related to increased secretion of the incretin hormones glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1), and patients with post-RYGB hypoglycemia demonstrate prolonged elevations of GIP and GLP-1 compared to non-hypoglycemic post-RYGB patients. Nesidioblastosis has been identified in some patients with post-RYGB hypoglycemia and is likely due to the trophic effects of GIP and GLP-1 on pancreatic islets.

CONCLUSIONS

Treatment of hypoglycemia after RYGB should begin with strict dietary (low carbohydrate) alteration and may require a trial of diazoxide, octreotide, or calcium-channel antagonists, among other drugs. Surgical therapy should include consideration of a restrictive form of bariatric procedure, with or without reconstitution of gastrointestinal continuity. Partial or total pancreatic resection should be avoided.

Metabolic surgery for type 2 diabetes

Conventional bariatric operations, including Roux-en-Y gastric bypass (RYGB), laparoscopic adjustable gastric banding, and biliopancreatic diversion (BPD) appear to be a safe and effective treatment for many severely obese patients with type 2 diabetes mellitus (T2DM). These operations improve glucose homeostasis through a variety of mechanisms, however, not only due to reduced food intake and body weight. Research to elucidate the weight-independent antidiabetic mechanisms of gastrointestinal (GI) surgery and to clarify the molecular mechanisms responsible for the benefits of GI surgery on glucose homeostasis is a compelling research objective. We review the existing knowledge regarding the clinical outcomes and of the mechanisms of GI surgery to treat T2DM.

Body mass index and outcomes from pancreatic resection: a review and meta-analysis

INTRODUCTION

There are 1.6 billion adults worldwide who are overweight, with body mass indices (BMI) between 25 and 30, while more than 400 million are obese (BMI >30). Obesity predicts the incidence of and poor outcomes from pancreatic cancer. Obesity has also been linked to surgical complications in pancreatectomy, including increased length of hospital stay, surgical infections, blood loss, and decreased survival. However, BMI's impact on many complications following pancreatectomy remains controversial.

METHODS

We performed a MEDLINE search of all combinations of "BMI" with "pancreatectomy," "pancreatoduodenectomy," or "pancreaticoduodenectomy." From included studies, we created pooled and weighted estimates for quantitative and qualitative outcomes. We used the PRISMA criteria to ensure this project's validity.

RESULTS

Our primary cohort included 2,736 patients with BMI <30, 1,682 with BMI >25, and 546 with BMI between 25 and 30. Most outcomes showed no definitive differences across BMIs. Pancreatic fistula (PF) rates ranged from 4.7% to 31.0%, and four studies found multivariate association between BMI and PF (range odds ratio 1.6-4.2). Pooled analyses of PF by BMI showed significant association (p < 0.05).

CONCLUSION

BMI increases the operative complexity of pancreatectomy. However, with aggressive peri- and post-operative care, increases in BMI-associated morbidity and mortality may be mitigated.

High glycemic variability assessed by continuous glucose monitoring after surgical treatment of obesity by gastric bypass

BACKGROUND

Obesity surgery elicits complex changes in glucose metabolism that are difficult to observe with discontinuous glucose measurements. We aimed to evaluate glucose variability after gastric bypass by continuous glucose monitoring (CGM) in a real-life setting.

METHODS

CGM was performed for 4.2 ± 1.3 days in three groups of 10 subjects each: patients who had undergone gastric bypass and who were referred for postprandial symptoms compatible with mild hypoglycemia, nonoperated diabetes controls, and healthy controls.

RESULTS

The maximum interstitial glucose (IG), SD of IG values, and mean amplitude of glucose excursions (MAGE) were significantly higher in operated patients and in diabetes controls than in healthy controls. The time to the postprandial peak IG was significantly shorter in operated patients (42.8 ± 6.0 min) than in diabetes controls (82.2 ± 11.1 min, P = 0.0002), as were the rates of glucose increase to the peak (2.4 ± 1.6 vs. 1.2 ± 0.3 mg/mL/min; P = 0.041). True hypoglycemia (glucose <60 mg/dL) was rare: the symptoms were probably more related to the speed of IG decrease than to the glucose level achieved. Half of the operated patients, mostly those with a diabetes background before surgery, had postprandial glucose concentrations above 200 mg/dL (maximum IG, 306 ± 59 mg/dL), in contrast to the normal glucose concentrations in the fasting state and 2 h postmeal.

CONCLUSIONS

Glucose variability is exaggerated after gastric bypass, combining unusually high and early hyperglycemic peaks and rapid IG decreases. This might account for postprandial symptoms mimicking hypoglycemia but often seen without true hypoglycemia. Early postprandial hyperglycemia might be underestimated if glucose measurements are done 2 h postmeal.

Diabetes resolution and hyperinsulinaemia after metabolic Roux-en-Y gastric bypass

The global prevalence of type 2 diabetes mellitus and impaired glucose metabolism continues to rise in conjunction with the pandemic of obesity. The metabolic Roux-en-Y gastric bypass operation offers the successful resolution of diabetes in addition to sustained weight loss and excellent long-term outcomes in morbidly obese individuals. The procedure consists of the physiological BRAVE effects: (i) Bile flow alteration; (ii) Reduction of gastric size; (iii) Anatomical gut rearrangement and altered flow of nutrients; (iv) Vagal manipulation and (v) Enteric gut hormone modulation. This operation provides anti-diabetic effects through decreasing insulin resistance and increasing the efficiency of insulin secretion. These metabolic outcomes are achieved through weight-independent and weight-dependent mechanisms. These include the foregut, midgut and hindgut mechanisms, decreased inflammation, fat, adipokine and bile metabolism, metabolic modulation, shifts in gut microbial composition and intestinal gluconeogenesis. In a small minority of patients, gastric bypass results in hyperinsulinaemic hypoglycaemia that may lead to nesidioblastosis (pancreatic beta-cell hypertrophy with islet hyperplasia). Elucidating the precise metabolic mechanisms of diabetes resolution and hyperinsulinaemia after surgery can lead to improved operations and disease-specific procedures including 'diabetes surgery'. It can also improve our understanding of diabetes pathogenesis that may provide novel strategies for the management of metabolic syndrome and impaired glucose metabolism.

Hypoglycemia complicating bariatric surgery: incidence and mechanisms

PURPOSE OF REVIEW

To discuss the clinical scope and frequency of hypoglycemia following bariatric surgery, and possible mechanisms mediating this potentially life-threatening complication.

RECENT FINDINGS

Consequent to the rise in severe obesity, bariatric surgery is being performed with ever increasing frequency. Although data continue to accumulate supporting the myriad metabolic and other health benefits of bariatric surgery, there are also concerns regarding the mounting reports of severe hypoglycemia. The problem is particularly significant following gastric bypass, with the first concerns raised in 2005 following a case series reported from the Mayo Clinic. A Swedish nationwide cohort study recently estimated the frequency of this complication suggesting it was less than 1%. Hypotheses regarding the mechanism(s) by which hypoglycemia arise following gastric bypass range from beta cell expansion to altered beta cell function as well as nonbeta cell factors.

SUMMARY

Regardless of the incidence, the severity of hypoglycemia for select patients following gastric bypass necessitates that we strive to gain a better understanding of the underlying mechanisms. With such knowledge, those patients at greater risk for this complication might be identified preoperatively, and decisions regarding their surgical management optimized to reduce this risk.

Abnormal glucose tolerance testing following gastric bypass demonstrates reactive hypoglycemia

BACKGROUND

Symptoms of reactive hypoglycemia have been reported by patients after Roux-en-Y gastric bypass (RYGB) surgery who experience maladaptive eating behavior and weight regain. A 4-h glucose tolerance test (GTT) was used to assess the incidence and extent of hypoglycemia.

METHODS

Thirty-six patients who were at least 6 months postoperative from RYGB were administered a 4-h GTT with measurement of insulin levels. Mean age was 49.4±11.4 years, mean preoperative body mass index (BMI) was 48.8±6.6 kg/m2, percent excess BMI lost (%EBL) was 62.6 ± 21.6%, mean weight change from nadir weight was 8.2±8.6 kg, and mean follow-up time was 40.5±26.7 months. Twelve patients had diabetes preoperatively.

RESULTS

Thirty-two of 36 patients (89%) had abnormal GTT. Six patients (17%) were identified as diabetic based on GTT. All six of these patients were diabetic preoperatively. Twenty-six patients (72%) had evidence of reactive hypoglycemia at 2 h post glucose load. Within this cohort of 26 patients, 14 had maximum to minimum glucose ratio (MMGR)>3:1, 5 with a ratio>4:1. Eleven patients had weight regain greater than 10% of initial weight loss (range 4.9-25.6 kg). Ten of these 11 patients (91%) with weight recidivism showed reactive hypoglycemia.

CONCLUSIONS

Abnormal GTT is a common finding post RYGB. Persistence of diabetes was noted in 50% of patients with diabetes preoperatively. Amongst the nondiabetic patients, reactive hypoglycemia was found to be more common and pronounced than expected. Absence of abnormally high insulin levels does not support nesidioblastosis as an etiology of this hypoglycemia. More than 50% of patients with reactive hypoglycemia had significantly exaggerated MMGR. We believe this may be due to the nonphysiologic transit of food to the small intestine due to lack of a pyloric valve after RYGB. This reactive hypoglycemia may contribute to maladaptive eating behaviors leading to weight regain long term. Our data suggest that GTT is an important part of post-RYGB follow-up and should be incorporated into the routine postoperative screening protocol. Further studies on the impact of pylorus preservation are necessary.

Glucose-stimulated insulin secretion in gastric bypass patients with hypoglycemic syndrome: no evidence for inappropriate pancreatic beta-cell function

BACKGROUND

Roux-en-Y gastric bypass surgery (RYGB) has been associated with a hypoglycemic syndrome characterized by postprandial hypoglycemia and hyperinsulinemia. The syndrome is believed to occur due to insulin hypersecretion from either pancreatic beta-cell hyperplasia or hyperfunction.

METHODS

Eight RYGB patients with hypoglycemic syndrome had insulin secretion rates determined during a 240-min graded intravenous glucose infusion. They were compared to 34 nondiabetic, nonsurgical individuals who were divided based on their insulin sensitivity status as measured by the insulin suppression test: insulin-sensitive (n = 8), insulin intermediate (n = 7), and insulin-resistant (n = 19).

RESULTS

RYGB patients had insulin concentrations and HOMA-IR similar to the insulin-sensitive reference group. In addition, integrated insulin secretion rates were comparable to the insulin-sensitive group and significantly lower than the insulin intermediate (p <or= 0.046) and insulin-resistant groups (p <or= 0.001). Pancreatic beta-cell sensitivity to glucose (slope relating glucose and ISR) was lowest in the RYGB group (p <or= 0.04).

CONCLUSIONS

Patients with hypoglycemic syndrome post-RYGB do not have generalized hypersecretion of insulin and appear to have appropriate insulin secretion rate in response to intravenous glucose.

Glucagon treatment for post-gastric bypass hypoglycemia

Hyperinsulinemic hypoglycemia is a recently described complication of Roux-en-Y gastric bypass (RYGB). We hypothesized that glucagon administration would help maintain normal postprandial plasma glucose concentrations by stimulating hepatic glucose output, and if so, represent a new therapeutic option for postbypass hypoglycemia. In this study, we compared the insulin and glycemic response to a mixed meal with and without concomitant glucagon infusion in a patient with severe recurrent hypoglycemia after RYGB. Although effective in transiently raising postprandial plasma glucose values, glucagon infusion was also associated with higher insulin concentrations, and failed to prevent symptomatic hypoglycemia. This case demonstrates that glucagon may have limited clinical utility in the treatment of post-RYGB hyperinsulinemic hypoglycemia.

Metabolic surgery to treat type 2 diabetes: clinical outcomes and mechanisms of action

Several gastrointestinal (GI) operations that were designed to promote weight loss can powerfully ameliorate type 2 diabetes mellitus (T2DM). Although T2DM is traditionally viewed as a chronic, relentless disease in which delay of end-organ complications is the major treatment goal, GI surgery offers a novel endpoint: complete disease remission. Ample data confirm the excellent safety and efficacy of conventional bariatric operations-especially Roux-en-Y gastric bypass and laparoscopic adjustable gastric banding-to treat T2DM in severely obese patients. Use of experimental procedures as well as conventional bariatric operations is increasingly being explored in less obese diabetic patients, with generally favorable results, although further assessment of risk:benefit profiles is needed. Mounting evidence indicates that certain operations involving intestinal diversions improve glucose homeostasis through varied mechanisms beyond reduced food intake and body weight, for example by modulating gut hormones. Research to elucidate such mechanisms should facilitate the design of novel pharmacotherapeutics and dedicated antidiabetes GI manipulations. Here we review evidence regarding the use and study of GI surgery to treat T2DM, focusing on available published reports as well as results from the Diabetes Surgery Summit (DSS) in Rome and the World Congress on Interventional Therapies for T2DM in New York City.