Hyperinsulinemic hypoglycemia with nesidioblastosis: histologic features and growth factor expression

Spontaneous Hypoglycemia in a Non-diabetic Patient: A Diagnostic and Therapeutic Conundrum

Hypoglycaemia is a medical emergency requiring an immediate intervention to prevent neuroglycopenic symptoms such as confusion, seizures, and coma. While evaluating for the cause of hypoglycemia, after excluding common causes like insulin use or sepsis, other causes involving endogenous hypoglycemia need to be evaluated. A cause to be considered is nesidioblastosis. This rare entity is also known as non-insulinoma pancreatogenous hypoglycemia syndrome. There have been instances where this disorder has been mistaken as insulinoma due to the characteristics shared by the two. Here, we present a case of a non-diabetic male experiencing symptoms of giddiness and palpitations for the past two years who had been extensively evaluated to rule out insulinoma and was diagnosed with nesidioblastosis.

Diagnosis of pancreatic focal nesidioblastosis assisted by dual‑nuclide tracer positron emission tomography/computed tomography: A case report

Nesidioblastosis is a rare cause of hyperinsulinemic hypoglycemia in adults and its clinical features are similar to those of insulinoma with recurrent hypoglycemic attacks. The present study reports the case of a 48-year-old man who visited the Affiliated Hospital of Zunyi Medical University (Zunyi, China) with a 5-year history of recurrent hypoglycemic symptoms such as dizziness and palpitations. Abdominal magnetic resonance imaging (MRI) showed a mass of ~1.2x1.0 cm in the head of the pancreas, which was suspected to be an insulinoma. For confirmation, the patient underwent both fluorine-18-fluorodeoxyglucose (18F-FDG) and gallium-68-labeled 1,4,7,10-tetraazacyclododecane-1,4,7,10-teraacetic acid-d-Phel-Tyr3-Thr8-OC (68Ga-DOTATATE) positron emission tomography/computed tomography (PET/CT), which showed a moderately increased uptake of 18F-FDG but no uptake of 68Ga-DOTATATE in the corresponding lesion. The patient subsequently underwent surgery to remove the lesion, which was pathologically confirmed as a pancreatic nesidioblastosis. This case showed that nesidioblastosis should be considered a differential diagnosis for insulinoma and that dual nuclear tracer PET/CT imaging is helpful for differentiating between the two. If conventional imaging techniques such as ultrasound, CT and MRI cannot identify the cause of hypoglycemia in future cases, dual-nuclide tracer PET/CT imaging should be considered.

Non-insulinoma pancreatogenous hypoglycemia syndrome (NIPHS)/Nesidioblastosis as the underlying cause of recurrent hypoglycemia in a diabetic adult

Non-insulinoma pancreatogenous hypoglycemia syndrome (NIPHS), without previous bariatric surgery, is a rare form of hypoglycemia in adult patients and is associated with nesidioblastosis. Adult-onset nesidioblastosis in diabetic patients is rare and histologically identical to "non-insulinoma pancreatogenous hypoglycemia syndrome (NIPHS)". Nesidioblastosis is rare in adults and clinically and biochemically mimics Insulinoma. In the literature, there have only been four cases of adult nesidioblastosis that followed diabetes mellitus. We report a case of nesidioblastosis in a 36-year-old diabetic female presenting with dizziness, sweating, and palpitations for three years. Selective non-invasive techniques failed to detect a tumor. Based on the pursuit of an insulinoma, a distal pancreatectomy specimen was received at our laboratory, and a diagnosis of nesidioblastosis was made. She is currently on follow-up with a favorable outcome. The definitive diagnosis of nesidioblastosis is made on a histological basis. The preferred form of treatment is pancreatic surgical resection. Nesidioblastosis should be taken into consideration in cases where diabetes transforms into hyperinsulinemic hypoglycemia.

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.

BYPASS-OMA: Hypoglycemic Hyperinsulinemic Nesidioblastosis after Gastric Bypass Surgery-A Case Report and Review of the Literature

This rare case vignette describes hypoglycemic, hyperinsulinemic nesidioblastosis in a female patient with prior Roux-en-Y gastric bypass. The patient presented with severe symptomatic hypoglycemia resistant to IV dextrose and diazoxide, requiring surgical resection. Traditional imaging found nonspecific findings, and biochemical analysis was inconsistent with insulinoma. A gallium-68 dotatate PET scan was utilized to successfully localize the tumor in the distal pancreas. She underwent laparoscopic resection of the distal pancreatic lesion with resolution of her symptoms and return to euglycemia. The histological evaluation confirmed the diagnosis of nesidioblastosis. Nesidioblastosis is a rare complication of bariatric surgery that may be more clinically relevant with rising prevalence of obesity. Diagnosis with conventional imaging modalities may be challenging; however, the dotatate PET scan may have high utility in detecting lesions. It is essential for clinicians to consider nesidioblastosis in the differential diagnosis of hyperinsulinemic hypoglycemic conditions and recognize there may be a link with increasing rates of bariatric surgery.

Use of Selective Arterial Calcium Stimulation Testing in Identification of Insulinoma in a Patient After Bariatric Surgery

OBJECTIVE

Insulinomas are rare in the post-bariatric surgery setting. The differential diagnosis for hypoglycemia is broad, requiring laboratory testing to verify endogenous hyperinsulinemic hypoglycemia. Selective arterial calcium stimulation testing (SACST) can help localize abnormal insulin production. We describe a patient with histologically confirmed insulinoma after bariatric surgery diagnosed with the aid of SACST.

METHODS

We present a 67 year old woman with a history of Roux-en-Y bypass surgery who presented with endogenous hyperinsulinemic hypoglycemia. Initially, no pancreatic lesion was identified radiologically. We pursued SACST to localize the source of insulin production.

RESULTS

The SACST successfully localized the source of hyperfunctioning islet cells to the pancreatic tail with absolute insulin values in a range consistent with insulinoma. Additional radiologic studies showed a small tumor in the pancreatic tail. Pathology showed a well-differentiated neuroendocrine tumor, compatible with insulinoma.

CONCLUSION

This case study illustrates the usefulness of SACST for the diagnosis and localization of insulinoma.

Surgical Treatment for Postprandial Hypoglycemia After Roux-en-Y Gastric Bypass: a Literature Review

Roux-en-Y gastric bypass (RYGB) is an effective treatment for severe obesity and obesity-related comorbidities. Postprandial hypoglycemia may occur as a long-term complication after RYGB. This study reviews the literature on surgical treatment for intractable post-RYGB hypoglycemia to provide updated information. A search was performed in Embase and PubMed, and 25 papers were identified. Thirteen papers on reversal were included. Resolution of postprandial hypoglycemic symptoms occurred in 42/48 (88%) patients after reversal. Twelve papers on pancreatectomy were included. Resolution occurred in 27/50 (54%) patients after pancreatectomy. The optimal surgical treatment for intractable post-RYGB hypoglycemia has not been defined, but reversal of RYGB seems to be more effective than other treatments. Further research on etiology and long-term evaluation of surgical outcomes may refine treatment options.

Tumor-insular Complex in Neoadjuvant Treated Pancreatic Ductal Adenocarcinoma Is Associated With Higher Residual Tumor

The tumor microenvironment in pancreatic ductal adenocarcinoma (PDAC) plays a vital role in treatment response, and therefore, patient survival. We and others have observed an intimate association of neoplastic ductal cells with non-neoplastic islet cells, recapitulating the ductoinsular complex. We define this phenomenon as tumor-insular complex (TIC). Herein, we describe the clinicopathologic characteristics of TIC in neoadjuvant treated PDAC cases for the first time. We retrospectively reviewed the pathology of 105 cases of neoadjuvant treated PDAC resected at our institution. TIC was noted in 35 cases (33.3%), the mean tumor bed size was 2.7±1.0 cm, mean percentage of residual tumor 40±28% and mean Residual Tumor Index (RTI) (an index previously established as a prognostic parameter by our group) was 1.1±1.0. TIC was significantly associated with perineural invasion (P=0.001), higher tumor bed size (P=0.007), percentage of residual tumor (P=0.009), RTI (P=0.001), ypT stage (P=0.045), and poor treatment response, grouped by a previously established criteria (P=0.010). Using our prior binary reported prognostic cutoff for RTI of ≤0.35 and >0.35, TIC was associated with a RTI >0.35 (P=0.002). Moreover, patients who did not receive neoadjuvant radiation were associated with a higher frequency of TIC (P=0.003). In this cohort, RTI but not TIC was also shown to be a significant independent prognosticator for recurrence-free survival and overall survival on multivariate analysis. In conclusion, TIC is significantly associated with a more aggressive neoplasm which shows a poor treatment response. Further studies will be needed to better understand the tumor biology of TICs.

Nationwide survey of endogenous hyperinsulinemic hypoglycemia in Japan (2017-2018): Congenital hyperinsulinism, insulinoma, non-insulinoma pancreatogenous hypoglycemia syndrome and insulin autoimmune syndrome (Hirata's disease)

AIMS/INTRODUCTION

We aimed to investigate the nationwide incidence, treatment details and outcomes of patients with endogenous hyperinsulinemic hypoglycemia (EHH), including those with transient/persistent congenital hyperinsulinism (CHI), insulinoma, non-insulinoma pancreatogenous hypoglycemia syndrome and insulin autoimmune syndrome (Hirata's disease) in Japan.

MATERIALS AND METHODS

A nationwide, questionnaire-based survey was carried out to determine the number of patients with EHH who were treated for hypoglycemia or hypoglycemia-related complications in 2017-2018. The questionnaires were sent to all hospitals in Japan with >300 beds, and with pediatric and/or adult clinics likely managing EHH patients. The secondary questionnaires were sent to obtain the patients' date of birth, sex, age at onset, treatment details and post-treatment outcomes.

RESULTS

A total of 447 patients with CHI (197 transient CHI, 225 persistent CHI and 25, unknown histology), 205 with insulinoma (118 benign, 18 malignant and 69 unknown subtype), 111 with non-insulinoma pancreatogenous hypoglycemia syndrome (33 post-gastric surgery HH, 57 postprandial HH, 10 nesidioblastosis and 11 unknown subtype) and 22 with insulin autoimmune syndrome were identified. Novel findings included: (i) marked improvement in the prognosis of persistent CHI over the past 10 years; (ii) male dominance in the incidence of transient CHI; (iii) non-insulinoma pancreatogenous hypoglycemia syndrome emerging as the second most common form of EHH in adults; (iv) frequent association of diabetes mellitus with insulin autoimmune syndrome; and (v) frequent post-treatment residual hypoglycemia and impaired quality of life.

CONCLUSIONS

The first nationwide, all age group survey of EHH showed the current status of each type of EHH disorder and the unmet needs of the patients.

Nesidioblastosis and Insulinoma: A Rare Coexistence and a Therapeutic Challenge

Background: Nesidioblastosis and insulinoma are disorders of the endocrine pancreas causing endogenous hyperinsulinemic hypoglycemia. Their coexistence is very unusual and treatment represents a still unresolved dilemma. Case Description: The patient was a 43-year-old Caucasian woman, with a 2-year history of repeated severe hypoglycemic events. The diagnostic work-up was strongly suggestive of insulinoma and the patient was submitted to surgical treatment carried out laparoscopically under robotic assistance. However, surgical exploration and intraoperative ultrasonography failed to detect a pancreatic tumor. Resection was therefore carried out based on the results of selective intra-arterial calcium stimulation test, following a step-up approach, eventually leading to a pancreatoduodenectomy at the splenic artery. The histopathology examination and the immunohistochemical staining were consistent with adult-onset nesidioblastosis. After surgery, the patient continued to experience hypoglycemia with futile response to medical treatments (octreotide, calcium antagonists, diazoxide, and prednisone). Following multidisciplinary evaluation and critical review of a repeat abdominal computed tomography scan, a small nodular lesion was identified in the tail of the pancreas. The nodule was enucleated laparoscopically and the pathological examination revealed an insulinoma. In spite of the insulinoma resection, glycemic values were only partially restored, with residual nocturnal hypoglycemia. Administration of uncooked cornstarch (1.25 g/kg body weight) at bedtime was associated with significant improvement of interstitial glucose levels (p < 0.0001) and reduction of nocturnal hypoglycemia episodes (p = 0.0002). Conclusions: This report describes a rare coexistence of adult-onset nesidioblastosis and insulinoma, suggesting the existence of a wide and continuous spectrum of proliferative β-cell changes. Moreover, we propose that uncooked cornstarch may offer an additional approach to alleviate the hypoglycemic episodes when surgery is impracticable/unaccepted.

The Effects of Bariatric Surgery on Islet Function, Insulin Secretion, and Glucose Control

Although bariatric surgery was developed primarily to treat morbid obesity, evidence from the earliest clinical observations to the most recent clinical trials consistently demonstrates that these procedures have substantial effects on glucose metabolism. A large base of research indicates that bariatric surgeries such as Roux-en-Y gastric bypass (RYGB), vertical sleeve gastrectomy (VSG), and biliopancreatic diversion (BPD) improve diabetes in most patients, with effects frequently evident prior to substantial weight reduction. There is now unequivocal evidence from randomized controlled trials that the efficacy of surgery is superior to intensive life-style/medical management. Despite advances in the clinical understanding and application of bariatric surgery, there remains only limited knowledge of the mechanisms by which these procedures confer such large changes to metabolic physiology. The improvement of insulin sensitivity that occurs with weight loss (e.g., the result of diet, illness, physical training) also accompanies bariatric surgery. However, there is evidence to support specific effects of surgery on insulin clearance, hepatic glucose production, and islet function. Understanding the mechanisms by which surgery affects these parameters of glucose regulation has the potential to identify new targets for therapeutic discovery. Studies to distinguish among bariatric surgeries on key parameters of glucose metabolism are limited but would be of considerable value to assist clinicians in selecting specific procedures and investigators in delineating the resulting physiology. This review is based on literature related to factors governing glucose metabolism and insulin secretion after the commonly used RYGB and VSG, and the less frequently used BPD and adjustable gastric banding.

Concurrent Adult-Onset Diffuse β-Cell Nesidioblastosis and Pancreatic Neuroendocrine Tumor: A Case Report and Review of the Literature

Nesidioblastosis is an uncommon cause of organic persistent hyperinsulinemic hypoglycemia in adults. We report a case of adult-onset diffuse β-cell nesidioblastosis in a 49-year-old woman who was status-post Roux-en-Y gastric bypass and distal pancreatectomy for a well-differentiated pancreatic neuroendocrine tumor. While the neuroendocrine tumor was suspected to be an insulinoma, persistent hypoglycemia postoperatively suggested either incomplete resection or a second pancreatic neoplasm. Completion pancreatectomy revealed islet β-cell hyperplasia and nuclear pleomorphism consistent with β-cell nesidioblastosis. The patient's blood glucose levels normalized after completion pancreatectomy. While β-cell nesidioblastosis and insulinomas can coexist in the same patient, pathologists should be aware of β-cell nesidioblastosis as a potential cause for hyperinsulinemic hypoglycemia and should exclude it in patients who have not shown definitive clinical response after surgical excision of a pancreatic neuroendocrine tumor.

Benign Tumors and Tumorlike Lesions of the Pancreas

The pancreas is a complex organ that may give rise to large number of neoplasms and non-neoplastic lesions. This article focuses on benign neoplasms, such as serous neoplasms, and tumorlike (pseudotumoral) lesions that may be mistaken for neoplasm not only by clinicians and radiologists, but also by pathologists. The family of pancreatic pseudotumors, by a loosely defined conception of that term, includes a variety of lesions including heterotopia, hamartoma, and lipomatous pseudohypertrophy. Autoimmune pancreatitis and paraduodenal ("groove") pancreatitis may also lead to pseudotumor formation. Knowledge of these entities will help in making an accurate diagnosis.

Heterogeneity of proliferative markers in pancreatic β-cells of patients with severe hypoglycemia following Roux-en-Y gastric bypass

AIMS

Severe postprandial hypoglycemia with neuroglycopenia is an increasingly recognized, debilitating complication of Roux-en-Y gastric bypass (RYGB) surgery. Increased secretion of insulin and incretin hormones is implicated in its pathogenesis. Histopathologic examination of pancreas has demonstrated increased islet size and/or nuclear diameter in post-RYGB patients who underwent pancreatectomy for severe refractory hypoglycemia with neuroglycopenia (RYGB + NG). We aimed to determine whether β-cell proliferation or apoptosis is altered in RYGB + NG.

METHODS

We performed an observational study to analyze markers of proliferation, apoptosis, cell cycle, and transcription factor expression in pancreatic tissue from affected RYGB + NG patients (n = 12), normoglycemic patients undergoing pancreatic surgery for benign lesions (controls, n = 6), and individuals with hypoglycemia due to insulinoma (n = 52).

RESULTS

Proliferative cell nuclear antigen (PCNA) expression was increased in insulin-positive cells in RYGB + NG patients (4.5-fold increase, p < 0.001 vs. controls) and correlated with β-cell mass. Ki-67 immunoreactivity was low in both RYGB + NG and controls, but did not differ between groups. Phospho-histone H3 levels did not differ between RYGB + NG and controls. PCNA and Ki-67 were both significantly lower in both controls and RYGB + NG than insulinomas. Markers of apoptosis and cell cycle (M30, p27, and p21) did not differ between groups. PDX1 and menin exhibited similar expression patterns, while FOXO1 appeared to be more cytosolic in RYGB + NG.

CONCLUSIONS

Markers of proliferation are heterogeneous in patients with severe post-RYGB hypoglycemia. Increased β-cell proliferation in some individuals may contribute to increased β-cell mass observed in severely affected patients.

Dumping syndrome after esophageal, gastric or bariatric surgery: pathophysiology, diagnosis, and management

BACKGROUND

Dumping syndrome, a common complication of esophageal, gastric or bariatric surgery, includes early and late dumping symptoms. Early dumping occurs within 1 h after eating, when rapid emptying of food into the small intestine triggers rapid fluid shifts into the intestinal lumen and release of gastrointestinal hormones, resulting in gastrointestinal and vasomotor symptoms. Late dumping occurs 1-3 h after carbohydrate ingestion, caused by an incretin-driven hyperinsulinemic response resulting in hypoglycemia. Clinical recommendations are needed for the diagnosis and management of dumping syndrome.

METHODS

A systematic literature review was performed through February 2016. Evidence-based medicine was used to develop diagnostic and management strategies for dumping syndrome.

RESULTS

Dumping syndrome should be suspected based on concurrent presentation of multiple suggestive symptoms after upper abdominal surgery. Suspected dumping syndrome can be confirmed using symptom-based questionnaires, glycemia measurements and oral glucose tolerance tests. First-line management of dumping syndrome involves dietary modification, as well as acarbose treatment for persistent hypoglycemia. If these approaches are unsuccessful, somatostatin analogues should be considered in patients with dumping syndrome and impaired quality of life. Surgical re-intervention or continuous enteral feeding may be necessary for treatment-refractory dumping syndrome, but outcomes are variable.

CONCLUSIONS

Implementation of these diagnostic and treatment recommendations may improve dumping syndrome management.

The treatment of hyperinsulinemic hypoglycaemia in adults: an update

BACKGROUND

Treatment of hyperinsulinemic hypoglycaemia (HH) is challenging due to the rarity of this condition and the difficulty of differential diagnosis. The aim of this article is to give an overview of the recent literature on the management of adult HH.

METHODS

A search for reviews, original articles, original case reports between 1995 and 2016 in PubMed using the following keywords: hyperinsulinemic hypoglycaemia, insulinoma, nesidioblastosis, gastric bypass, autoimmune hypoglycaemia, hyperinsulinism, treatment was performed.

RESULTS

One hundred and forty articles were selected and analysed focusing on the most recent treatments of HH.

CONCLUSIONS

New approaches to treatment of HH are available including mini-invasive surgical techniques and alternative local-regional ablative therapy for benign insulinoma and everolimus for malignant insulinoma. A correct differential diagnosis is of paramount importance to avoid unnecessary surgical operations and to implement the appropriate treatment mainly in the uncommon forms of HH, such as nesidioblastosis and autoimmune hypoglycaemia.

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.

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.

Spontaneous hypoglycemia: diagnostic evaluation and management

Spontaneous hypoglycemia is a puzzling clinical problem and an important reason for referral to endocrinologists. Several clinical conditions such as insulinomas, non-insulinoma pancreatogenous hypoglycemia syndrome, insulin autoimmune syndrome, postprandial hypoglycemia (reactive hypoglycemia), non-islet cell tumor hypoglycemia, primary adrenal insufficiency, hypopituitarism, and critical illness can be associated with spontaneous hypoglycemia. Rarely, in patients with mental health issues, factious hypoglycemia from extrinsic insulin use or ingestion of oral hypoglycemic agents can obfuscate the clinical picture for clinicians trying to identify an organic cause. In those presenting with Whipple's triad (symptoms ± signs of hypoglycemia, low plasma glucose, and resolution symptoms ± signs after hypoglycemia correction), a 72-h supervised fast test with measurement of plasma insulin, c-peptide, pro-insulin, and beta-hydroxybutyrate levels, coupled with plasma/urine sulphonylurea screen, forms the first step in diagnostic evaluation. A mixed meal test is preferable for those with predominantly postprandial symptoms. Additional non-invasive and/or invasive diagnostic evaluation is necessary if an organic hypoglycemic disorder is suspected. With the aid of a few brief clinical case scenarios, we discuss the diagnostic evaluation and management of spontaneous hypoglycemia through this comprehensive article.

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.

Selective Arterial Calcium Stimulation With Hepatic Venous Sampling Differentiates Insulinoma From Nesidioblastosis

CONTEXT

In adult patients with endogenous hyperinsulinemic hypoglycemia and negative or inconclusive noninvasive imaging, insulinoma and non-insulinoma pancreatogenous hypoglycemic syndrome (NIPHS) resulting from diffuse nesidioblastosis must be considered in the differential diagnosis. It is not known whether the biochemical results of selective arterial calcium stimulation (SACST) with hepatic venous sampling can differentiate insulinoma from diffuse nesidioblastosis.

OBJECTIVE

To determine the specificity of SACST with hepatic venous sampling in differentiating insulinoma from diffuse nesidioblastosis.

DESIGN

Retrospective review (January 1996 to March 2014).

SETTING

Tertiary referral center.

PATIENTS OR OTHER PARTICIPANTS

A total of 116 patients with biochemical evidence of endogenous hyperinsulinemic hypoglycemia and negative or inconclusive noninvasive imaging who were subsequently shown at surgery to have insulinoma (n = 42) or nesidioblastosis (n = 74) after undergoing SACST with hepatic venous sampling.

INTERVENTION(S)

SACST with hepatic venous sampling before pancreatic exploration.

MAIN OUTCOME MEASURE(S)

Receiver operating characteristic curves were generated from the biochemical results of SACST to determine the specificity of the maximum hepatic venous insulin concentration (mHVI) and the relative-fold increase in hepatic venous insulin concentration (rHVI) over baseline after calcium injection from the dominant artery in differentiating insulinoma from nesidioblastosis.

RESULTS

The mHVI (21.5-fold; P < .001) and rHVI (3.9-fold; P < .001) were significantly higher in the insulinoma group compared to the nesidioblastosis group. The areas under the receiver operating characteristic curve for mHVI and rHVI were excellent (0.94; P < .0001) and good (0.83; P < .0001), respectively, for differentiating insulinoma from nesidioblastosis. mHVI cutoffs of > 91.5 and > 263.5 μIU/mL were 95 and 100% specific for insulinoma, respectively. A 19-fold increase in rHVI over baseline was 99% specific for insulinoma.

CONCLUSIONS

These data suggest that the mHVI and rHVI at SACST may be useful in differentiating insulinoma from nesidioblastosis with high specificity in patients with hyperinsulinemic hypoglycemia and negative or inconclusive noninvasive imaging.

[Nesidioblastosis in the adult: a case report]

BACKGROUND

Nesidioblastosis is a rare cause of endocrine disease which represents between 0.5% - 5% of cases. This has been associated with other conditions, such as in patients previously treated with insulin or sulfonylurea, in anti-tumour activity in pancreatic tissue of patients with insulinoma, and in patients with other tumours of the Langerhans islet cells. In adults it is presented as a diffuse dysfunction of β cells of unknown cause.

CLINICAL CASE

The case concerns 46 year-old female, with a history of Sheehan syndrome of fifteen years of onset, and with repeated events characterized with hypoglycaemia in the last three years. Body scan was performed with octreotide, revealing an insulinoma in the pancreatic region. A distal pancreatectomy was performed on the patient. The study reported a pancreatic fragment 8.5 × 3 × 1.5 cm with abnormal proliferation of pancreatic islets in groups of varying size, some of them in relation to the ductal epithelium. Histopathology study was showed positive for chromogranin, confirmed by positive synaptophysin, insulin and glucagon, revealing islet hyperplasia with diffuse nesidioblastosis with negative malignancy. The patient is currently under metabolic control and with no remission of hypoglycaemic events.

CONCLUSIONS

Nesidioblastosis is a disease of difficult diagnosis should be considered in all cases of failure to locate an insulinoma, as this may be presented in up to 4% of persistent hyperinsulinaemic hypoglycaemia.

A rare complication of gastric bypass (weight loss) surgery: nesidioblastosis

Here, we present the case of a 31-year-old woman patient who underwent distal pancreatectomy with the history of gastric bypass surgery for obesity. The final histopathological diagnosis of the lesion was nesidioblastosis. Nesidioblastosis is the most common cause of organic persistent hyperinsulinemic hypoglycemia in newborns; however, it is rare in adults. In adults, it is difficult to diagnose nesidioblastosis with only clinical findings. The definitive diagnosis of the disease depends on the histopathological examination of pancreatic tissue and the exclusion of insulinoma.

[Nesidioblastosis (diagnosis, surgical treatment)]

INTRODUCTION

Nesidioblastosis (NB) is rare disease with organic hyperinsulinism syndrome and caused by diffuse hyperplasia and/or hypertrophy of pancreatic islands of Langerhans.

MATERIAL AND METHODS

The results of surgical treatment of 3 patients with NB are presented. In all patients the diagnosis was suspected at the preoperative stage and confirmed by histological examination later. Herewith in 2 patients NB was combined with insulinoma. All patients underwent corpora-caudal pancreatectomy.

RESULTS

In postoperative period one patient hadn't episodes of hypoglycemia for the entire follow-up period (5 months), in another patient hypoglycemic states occurred at 1.5 months after surgery. The third patient required pancreatic head extirpation at 11 days after surgery due to persistent severe course of organic hyperinsulinism. In immediate postoperative period in the same patient hyperinsular hypoglycemia was observed that pointed on extrapancreatic source of insulin secretion. However contrast-enhanced CT did not reveal any formations.

CONCLUSION

Thus, corpora-caudal pancreatectomy is preferable as surgical treatment. Results of surgical management can provide a complete regression of the symptoms, but do not guarantee absence of recurrence and even any changes in frequency and severity of hypoglycemic states.

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.

Insulin-like growth factor 1 predicts post-load hypoglycemia following bariatric surgery: a prospective cohort study

Postprandial hypoglycemia is a complication following gastric bypass surgery, which frequently remains undetected. Severe hypoglycemic episodes, however, put patients at risk, e.g., for syncope. A major cause of hypoglycemia following gastric bypass is hyperinsulinemic nesidioblastosis. Since pancreatic islets in nesidioblastosis overexpress insulin-like growth factor 1 (IGF-1) receptor α and administration of recombinant IGF-1 provokes hypoglycemia, our main objective was to investigate the occurrence of post-load hypoglycemia one year after bariatric surgery and its relation to pre- and post-operative IGF-1 serum concentrations. We evaluated metabolic parameters including 2 h 75 g oral glucose tolerance test (OGTT) and measured IGF-1 serum concentration in thirty-six non-diabetic patients (29 f/7 m), aged 41.3±2.0 y with a median (IQR) BMI of 30.9 kg/m2 (27.5-34.3 kg/m2), who underwent elective bariatric surgery (predominantly gastric bypass, 83%) at our hospital. Post-load hypoglycemia as defined by a 2 h glucose concentration <60 mg/dl was detected in 50% of patients. Serum insulin and C-peptide concentration during the OGTT and HOMA-IR (homeostatic model assessment-insulin resistance) were similar in hypoglycemic and euglycemic patients. Strikingly, pre- and post-operative serum IGF-1 concentrations were significantly higher in hypoglycemic patients (p = 0.012 and p = 0.007 respectively). IGF-1 serum concentration before surgery negatively correlated with 2 h glucose concentration during the OGTT (rho = -0.58, p = 0.0003). Finally, IGF-1 serum concentrations before and after surgery significantly predicted post-load hypoglycemia with odds ratios of 1.28 (95%CI:1.03-1.55, p = 0.029) and 1.18 (95%CI:1.03-1.33, p = 0.015), respectively, for each 10 ng/ml increment. IGF-1 serum concentration could be a valuable biomarker to identify patients at risk for hypoglycemia following bariatric surgery independently of a diagnostic OGTT. Thus, IGF-1 testing could help to prevent a significant complication of gastric bypass surgery.

Postprandial hyperinsulinemic hypoglycemia after gastric bypass surgical treatment

An association between post-Roux-en-Y gastric bypass (RYGB) hypoglycemia and nesidioblastosis was reported in 2005 and may cause serious neuroglycopenic symptoms. Most patients with postprandial hypoglycemia after RYGB respond to nutritional and medical treatment. A subset of patients, however, may not respond adequately and surgery may be considered. This review describes the current experience with surgical intervention for severe post-RYGB hypoglycemia. PubMed and MEDLINE searches were made for reports describing clinical outcome after such surgery. Fourteen papers including 75 patients were identified. Different surgical interventions were applied including gastric tube placement, reversal of the bypass with and without concomitant sleeve resection, gastric pouch restriction, and pancreatic resection and reresection. Pancreatic resection was performed in 51 (68%) patients, 17 (23%) had RYGB reversal and eleven (15%) had gastric pouch restriction alone. Eight (11%) patients received 2 or more consecutive procedures for hypoglycemia and combined interventions were made in several patients. Resolution of the symptoms occurred in 34/51 (67%) patients after pancreatic resection, 13/17 (76%) after reversal, and 9/11 (82%) after pouch restriction. Mean follow up, however, was short for most series and the methods applied for evaluation of hypoglycemia varied. Weight regain, diabetes and recurrent symptoms were late complications. The optimal therapy for hypoglycemia after RYGB is not defined. Long-term evaluations and knowledge about the physiology of post-RYGB hypoglycemia, may enable therapy with improved control of the glucose excursions.

Tumors, IGF-2, and hypoglycemia: insights from the clinic, the laboratory, and the historical archive

Tumors of mesenchymal and epithelial origin produce IGF-2, which activates pathways in the tumors. In a minority of patients, the tumors (hepatomas, fibromas, and fibrosarcomas are the most common among many) release into the circulation enough IGF-2-related peptides to mimic the fasting hypoglycemia characteristic of patients with insulin-producing islet-cell tumors. Rarely, markedly elevated IGF-2 levels produce somatic changes suggestive of acromegaly. Typically, the elevated IGF-2 levels are associated with suppressed plasma levels of insulin, IGF-1, and GH. Complicating the pathophysiology are the IGF binding proteins (IGFBPs) that can bind IGF-2 and IGF-1, modifying hormone metabolism and action. IGFBP concentrations are often altered in the presence of these tumors. At the cellular level, the 3 hormone-related ligands, IGF-2, IGF-1, and insulin, all bind to 4 (or more) types of IGF-1 receptor (IGF-1R) and insulin receptor (IR). Each receptor has its own characteristic affinity for each ligand, a tyrosine kinase, and overlapping profiles of action in the target cells. The IGF-2R, in addition to binding mannose-6-phosphate-containing proteins, provides an IGF-2 degradation pathway. Recent evidence suggests IGF-2R involvement also in signal transduction. Surgery, the treatment of choice, can produce a cure. For patients not cured by surgery, multiple therapies exist, for the tumor and for hypoglycemia. Potential future therapeutic approaches are sketched. From 1910 to 1930, hypoglycemia, insulin, insulinomas, and non-islet-cell tumors were recognized. The latter third of the century witnessed the emergence of the immunoassay for insulin; the IGFs, their binding proteins, and assays to measure them; and receptors for the insulin-related peptides as well as the intracellular pathways beyond the receptor. In closing, we replace non-islet-cell tumor hypoglycemia, an outdated and misleading label, with IGF-2-oma, self-explanatory and consistent with names of other hormone-secreting tumors.

The ductal origin of structural and functional heterogeneity between pancreatic islets

Islets form in the pancreas after the first endocrine cells have arisen as either single cells or small cell clusters in the epithelial cords. These cords constitute the developing pancreas in one of its earliest recognizable stages. Islet formation begins at the time the cords transform into a branching ductal system, continues while the ductal system expands, and finally stops before the exocrine tissue of ducts and acini reaches its final expansion. Thus, islets continuously arise from founder cells located in the branching and ramifying ducts. Islets arising from proximal duct cells locate between the exocrine lobules, develop strong autonomic and sensory innervations, and pass their blood to efferent veins (insulo-venous efferent system). Islets arising from cells of more distal ducts locate within the exocrine lobules, respond to nerve impulses ending at neighbouring blood vessels, and pass their blood to the surrounding acini (insulo-acinar portal system). Consequently, the section of the ductal system from which an islet arises determines to a large extent its future neighbouring tissue, architecture, properties, and functions. We note that islets interlobular in position are frequently found in rodents (rats and mice), whereas intralobularly-located, peripheral duct islets prevail in humans and cattle. Also, we expound on bovine foetal Laguesse islets as a prominent foetal type of type 1 interlobular neuro-insular complexes, similar to neuro-insular associations frequently found in rodents. Finally, we consider the probable physiological and pathophysiological implications of the different islet positions within and between species.

Nesidioblastosis. A case of hyperplasia of the islets of Langerhans in the adult

INTRODUCTION

Nesidioblastosis is a rare disease caused by hyperplasia of pancreatic islets, developing a state of hypoglycemia due to an increase in the insulin production. It is the leading cause of hyperinsulinic hypoglycemia in childhood, whereas in adults it only represents the 0.5-5% of cases. The pathogenesis is still unknown. We have studied several genetic mutations associated with dependent potassium channel of ATP present in the beta cells of the pancreas, as well as in patients underwent bariatric surgery because of the metabolic changes involved.

REPORT

Woman (38 years old) attends consultation of General Surgery derived from Endocrinology before symptoms of persistent hypoglycemia. Factitious hypoglycemia and syndromes of neuroendocrine origin were ruled out. Imaging tests failed to identify space-occupying lesions. The medical treatment failed, persisting hypoglycemia symptoms. Before the given analytical and radiological findings obtained, and the persistence of symptoms affecting the quality of life of the patient, we opted for surgical treatment performing a pancreatectomy of the 80% of the gland. The final pathologic diagnosis was nesidioblastosis.

DISCUSSION

Nesidioblastosis is a rare pathology, but it must be present in the differential diagnosis of hypoglycemia symptoms with endogenous hyperinsulinism in adults, once the intake of sulfonylureas and possible pancreatic neoformations have been ruled out.

Dual origin, development, and fate of bovine pancreatic islets

Endocrine cells are evident at an early stage in bovine pancreatic development when the pancreas still consists of primitive epithelial cords. At this stage, the endocrine cells are interspersed between the precursor cells destined to form the ductulo-acinar trees of later exocrine lobules. We here demonstrate that, in bovine fetuses of crown rump length ≥ 11 cm, the endocrine cells become increasingly segregated from the developing exocrine pancreas by assembly into two units that differ in histogenesis, architecture, and fate. Small numbers of 'perilobular giant islets' are distinguishable from larger numbers of 'intralobular small islets'. The two types of islets arise in parallel from the ends of the ductal tree. Aside from differences in number, location, and size, the giant and small islets differ in cellular composition (predominantly insulin-synthesising cells vs. mixtures of endocrine cells), morphology (epithelial trabeculae with gyriform and rosette-like appearance vs. compact circular arrangements of endocrine cells), and in their relationships to intrapancreatic ganglia and nerves. A further difference becomes apparent during the antenatal period; while the 'interlobular small islets' persist in the pancreata of calves and adult cattle, the perilobular giant islets are subject to regression, characterised by involution of the parenchyma, extensive haemorrhage, leukocyte infiltration (myeloid and T-cells) and progressive fibrotic replacement. In conclusion, epithelial precursor cells of the ductolo-acinar tree may give rise to populations of pancreatic islets with different histomorphology, cellular composition and fates. This should be taken into account when using these cells for the generation of pancreatic islets for transplantation therapy.

Glucagon-like peptide-1 receptor imaging with [Lys40(Ahx-HYNIC- 99mTc/EDDA)NH2]-exendin-4 for the detection of insulinoma

PURPOSE

The objective of this article is to present a new method for the diagnosis of insulinoma with the use of [Lys(40)(Ahx-HYNIC-(99m)Tc/EDDA)NH2]-exendin-4.

METHODS

Studies were performed in 11 patients with negative results of all available non-isotopic diagnostic methods (8 with symptoms of insulinoma, 2 with malignant insulinoma and 1 with nesidioblastosis). In all patients glucagon-like peptide-1 (GLP-1) receptor imaging (whole-body and single photon emission computed tomography/CT examinations) after the injection of 740 MBq of the tracer was performed.

RESULTS

Both sensitivity and specificity of GLP-1 receptor imaging were assessed to be 100 % in patients with benign insulinoma. In all eight cases with suspicion of insulinoma a focal uptake in the pancreas was found. In six patients surgical excision of the tumour was performed (type G1 tumours were confirmed histopathologically). In one patient surgical treatment is planned. One patient was disqualified from surgery. In one case with malignant insulinoma pathological accumulation of the tracer was found only in the region of local recurrence. The GLP-1 study was negative in the other malignant insulinoma patient. In one case with suspicion of nesidioblastosis, a focal accumulation of the tracer was observed and histopathology revealed coexistence of insulinoma and nesidioblastosis.

CONCLUSION

[Lys(40)(Ahx-HYNIC-(99m)Tc/EDDA)NH2]-exendin-4 seems to be a promising diagnostic tool in the localization of small insulinoma tumours, but requires verification in a larger series of patients.

Nesidioblastosis in a simmental calf

A 2-day-old Simmental calf with arthrogryposis and astasia was subjected to necropsy examination. The calf was normoglycaemic and normoinsulinaemic. Microscopically, pancreatic tissue was hyperplastic with an irregular lobular arrangement of pancreatic islets. Newly-formed islet cells budded from intralobular or intercalated ducts (so-called ductulo-insular complexes) and there were prominent blood vessels with telangiectatic features surrounded by rows of cuboidal-columnar islet cells. The newly-formed islets expressed insulin antigen immunohistochemically. The lesion was diagnosed as nesidioblastosis, an uncommon abnormality previously associated with the double muscling trait in cattle.

Effects of duodenal-jejunal exclusion on beta cell function and hormonal regulation in Goto-Kakizaki rats

BACKGROUND

The aim of our work was to investigate the hormones that control glycemic status and in vitro β-cell function in diabetes mellitus after a duodenal-jejunal exclusion in Goto-Kakizaki rats (Taconic, Denmark).

METHODS

Twenty-three rats (age, 12-14 wk) were randomized as follows: group 1 (n = 14), no intervention (control); or group 2 (n = 9), duodenal-jejunal exclusion.

RESULTS

In group 2, levels of glucagon and leptin were lower than in group 1 at 1 week and at 8 weeks. Glucagon-like peptide 1 levels had a significant increase at 8 weeks from basal value in group 2 and this value was higher than in group 1. The insulin secretion at 60 minutes in group 2 was higher than in group 1 (group 1, 12.9 ± 12.0 μg/L vs group 2, 41.9 ± 36.3 μg/L; P < .05). Messenger RNA (mRNA) expression of insulin at 2 months was higher in the rat pancreas of the experimental group than in the control group (group 1, .99 ± .48 mRNA amount vs group 2, 1.66 ± .33 mRNA amount; P < .05).

CONCLUSIONS

Gastrojejunal bypass in this model improves glucose ratios, with a significant increase of glucagon-like peptide 1 and decrease of homeostasis model assessment, glucagon, and leptin levels after surgery. This type of surgery improves mRNA insulin expression in pancreatic islets and insulin secretion as well.

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.

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.

Update: metabolic and cardiovascular consequences of bariatric surgery

Obesity is a disease state with polygenic inheritance, the phenotypic penetrance of which has been greatly expanded by the attributes of modern civilization. More than two-thirds of obese persons have comorbidities, many of which are characteristic of cardiometabolic risk syndrome (CMRS) in addition to other life-quality-reducing complaints. The CMRS is associated with increased cardiovascular events and mortality. Individuals with a body mass index greater than 35 infrequently achieve or maintain weight loss adequate to resolve these metabolic and anatomic issues by lifestyle or pharmacologic strategies. Data suggest that some of these patients may be better served by bariatric surgery.

Hyperinsulinemic hypoglycemia after Roux-en-Y gastric bypass: unraveling the role of gut hormonal and pancreatic endocrine dysfunction

BACKGROUND

Profound hypoglycemia occurs rarely as a late complication after Roux-en-Y gastric bypass (RYGB). We investigated the role of glucagon-like-peptide-1 (GLP-1) in four subjects who developed recurrent neuro-glycopenia 2 to 3 y after RYGB.

METHODS

A standardized test meal (STM) was administered to all four subjects. A 2 h hyperglycemic clamp with GLP-1 infusion during the second hour was performed in one subject, before, during a 4 wk trial of octreotide (Oc), and after 85% distal pancreatectomy. After cessation of both glucose and GLP-1 infusion at the end of the 2 h clamp, blood glucose levels were monitored for 30 min. Responses were compared with a control group (five subjects 12 mo status post-RYGB without hypoglycemic symptoms).

RESULTS

During STM, both GLP-1 and insulin levels were elevated 3- to 4-fold in all subjects, and plasma glucose-dependent insulinotropic peptide (GIP) levels were elevated 2-fold. Insulin responses to hyperglycemia ± GLP-1 infusion in one subject were comparable to controls, but after cessation of glucose infusion, glucose levels fell to 40 mg/dL. During Oc, the GLP-1 and insulin responses to STM were reduced (>50%). During the clamp, insulin response to hyperglycemia alone was reduced, but remained unchanged during GLP-1. Glucagon levels during hyperglycemia alone were suppressed and further suppressed after the addition of GLP-1. With the substantial drop in glucose during the 30 min follow-up, glucagon levels failed to rise. Due to persistent symptoms, one subject underwent 85% distal pancreatectomy; postoperatively, the subject remained asymptomatic (blood glucose: 119-220 mg/dL), but a repeat STM showed persistence of elevated levels of GLP-1. Histologically enlarged islets, and β-cell clusters scattered throughout the acinar parenchyma were seen, as well as β-cells present within pancreatic duct epithelium. An increase in pancreatic and duodenal homeobox-1 protein (PDX-1) expression was observed in the subject compared with control pancreatic tissue.

CONCLUSIONS

A persistent exaggerated hypersecretion of GLP-1, which has been shown to be insulinotropic, insulinomimetic, and glucagonostatic, is the likely cause of post-RYGB hypoglycemia. The hypertrophy and ectopic location of β-cells is likely due to overexpression of the islet cell transcription factor, PDX-1, caused by prolonged hypersecretion of GLP-1.

Roux-en-Y gastric bypass promotes expression of PDX-1 and regeneration of β-cells in Goto-Kakizaki rats

AIM: To study the effects of Roux-en-Y gastric bypass (RYGB) on the expression of pancreatic duodenal homeobox-1 (PDX-1) and pancreatic β-cell regeneration/ neogenesis, and their possible mechanisms in diabetics.

METHODS: Three groups of randomly selected non-obese diabetic Goto-Kakizaki (GK) rats were subjected to RYGB, sham-RYGB and sham-operation (sham-op) surgery, respectively. The rats were euthanized at post-operative 1, 2, 4 and 12 wk. Their pancreases were resected and analyzed using reverse transcription polymerase chain reaction to detect the mRNA of PDX-1. Anti-PDX-1 immunohistochemical (IHC) staining and Western blotting were used to detect the protein of PDX-1. Double IHC staining of anti-Brdu and -insulin was performed to detect regenerated β-cells. The index of double Brdu and insulin positive cells was calculated.

RESULTS: In comparison with sham-RYGB and sham-op groups, a significant increase in the expressions of PDX-1 mRNA in RYGB group was observed at all experimental time points (1 wk: 0.378 ± 0.013 vs 0.120 ± 0.010, 0.100 ± 0.010, F = 727.717, P < 0.001; 2 wk: 0.318 ± 0.013 vs 0.110 ± 0.010, 0.143 ± 0.015, F = 301.509, P < 0.001; 4 wk: 0.172 ± 0.011 vs 0.107 ± 0.012, 0.090 ± 0.010, F = 64.297, P < 0.001; 12 wk: 0.140 ± 0.007 vs 0.120 ± 0.010, 0.097 ± 0.015, F = 16.392, P < 0.001); PDX-1 protein in RYGB group was also increased significantly (1 wk: 0.61 ± 0.01 vs 0.21 ± 0.01, 0.15 ± 0.01, F = 3031.127, P < 0.001; 2 wk: 0.55 ± 0.00 vs 0.15 ± 0.01, 0.17 ± 0.01, F = 3426.455, P < 0.001; 4 wk: 0.39 ± 0.01 vs 0.18 ± 0.01, 0.22 ± 0.01, F = 882.909, P < 0.001; 12 wk: 0.41 ± 0.01 vs 0.20 ± 0.01, 0.18 ± 0.01, F = 515.833, P < 0.001). PDX-1 mRNA and PDX-1 protein production showed no statistical significance between the two sham groups. Many PDX-1 positive cells could be found in the pancreatic islets of the rats in RYGB group at all time points. In addition, the percentage of Brdu-insulin double staining positive cells was higher in RYGB group than in the other two groups (1 wk: 0.22 ± 0.13 vs 0.03 ± 0.06, 0.03 ± 0.06, P < 0.05; 2 wk: 0.28 ± 0.08 vs 0.00 ± 0.00, 0.03 ± 0.06, P < 0.05; 4 wk: 0.24 ± 0.11 vs 0.07 ± 0.06, 0.00 ± 0.00, P < 0.001; 12 wk: 0.20 ± 0.07 vs 0.03 ± 0.06, 0.00 ± 0.00, P < 0.05).

CONCLUSION: RYGB can increase the expression of pancreatic PDX-1 and induce the regeneration of β-cells in GK rats. The associated regeneration of islet cells may be a possible mechanism that how RYGB could improve type 2 diabetes mellitus.