Hypoglycemia After Gastric Bypass Successfully Treated With Calcium Channel Blockers: Two Case Reports

Persistent Insulin Autoimmune Syndrome in a Caucasian Male in the Absence of Triggers

Insulin autoimmune syndrome (IAS) or Hirata disease is a rare condition presenting as recurrent hypoglycemia, and associated with elevated insulin levels in the presence of insulin autoantibodies (IAAs) in patients who were never exposed to exogenous insulin and with no evidence of pancreatic abnormalities. IAS is much more frequent in East Asians, especially the Japanese population, compared to the lower incidence in Caucasians. However, it can be associated with other autoimmune diseases or drug use like methimazole and alpha-lipoic acid (ALA). We report a case of a 47-year-old Caucasian male presenting with a 12-month history of worsening episodes of fasting and post-prandial hypoglycemia associated with symptoms of dizziness, tremors, palpitations, and unconsciousness associated with hypoglycemia. Symptoms resolved with the administration of carbohydrate-containing foods, establishing Whipple's triad. At an outside facility, he had initial labs that showed elevated insulin levels (141 µU/ml) with normal glucose, C-peptide, and proinsulin levels, but there was no availability of an IAA lab assay. Given his symptoms, severity, and frequency of hypoglycemia, he was admitted to the hospital for a 72-hour fast, which showed the lowest glucose level of 64 mg/dl with inappropriately high insulin of 22.2 µU/ml, low C-peptide of 0.57 ng/ml, and undetectable proinsulin of <1.6 pmol/L, but with IAA being >50 U/ml (0.0-0.4 U/ml). He was treated with intensive dietary counseling with a low-carbohydrate diet and prednisone 20 mg twice daily initially. Additionally, he could not tolerate octreotide, diazoxide, and acarbose due to side effects. He is currently on prednisone 10 mg daily and nifedipine with no further hypoglycemic episodes, but still has a high IAA of >50 U/ml and serum insulin levels of 70-112 µU/ml. Our case highlights the importance of recognizing hypoglycemia and checking for IAA levels as first-line diagnostic tests, in the absence of which there could be a delay in diagnosis and leading to unnecessary lab and imaging testing. Our case is unique since it happened in a Caucasian without any prior exposure to a triggering factor and has not undergone self-remission yet, which happens in most of IAS cases.

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.

Medical Nutrition Therapy and Other Approaches to Management of Post-bariatric Hypoglycemia: A Team-Based Approach

PURPOSE OF REVIEW

This manuscript provides a review of post-bariatric hypoglycemia (PBH) with a special focus on the role of the registered dietitian-nutritionist (RDN) and medical nutrition therapy (MNT) recommendations as foundational for management.

RECENT FINDINGS

As the number of bariatric surgeries rises yearly, with 256,000 performed in 2019, PBH is an increasingly encountered late complication. Following Roux-en-Y (RYGB) or vertical sleeve gastrectomy (VSG), about 1/3 of patients report symptoms suggestive of at least mild postprandial hypoglycemia, with severe and/or medically confirmed hypoglycemia in 1-10%. Anatomical alterations, changes in GLP1 and other intestinally derived hormones, excessive insulin response, reduced insulin clearance, impaired counterregulatory hormone response to hypoglycemia, and other factors contribute to PBH. MNT is the cornerstone of multidisciplinary treatment, with utilization of personal continuous glucose monitoring to improve safety when possible. While many individuals require pharmacotherapy, there are no currently approved medications for PBH. Increasing awareness and identification of individuals at risk for or with PBH is critical given the potential impact on safety, nutrition, and quality of life. A team-based approach involving the individual, the RDN, and other clinicians is essential in providing ongoing assessment and individualization of MNT in the long-term management of PBH.

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.

Severe post-gastric bypass hypoglycemia in pregnancy

Post-bariatric surgery hypoglycemia (PBH) is a serious and relatively prevalent complication of bariatric surgery and is often underdiagnosed due to unawareness. PBH can have a profound effect on health and quality of life. Data regarding the natural history and management of PBH during pregnancy are lacking. Here we describe a case of a 34-year-old woman who presented with intractable PBH during the second trimester of her third pregnancy, three years after a Roux-en-Y gastric bypass (RYGB). Treatment with nifedipine showed partial response and eventually intravenous (IV) glucose was needed until birth.

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.

Potential contribution of the gut microbiota to hypoglycemia after gastric bypass surgery

Obesity has become a global health problem. Lifestyle modification and medical treatment only appear to yield short-term weight loss. Roux-en-Y gastric bypass (RYGB) is the most popular bariatric procedure, and it sustains weight reduction and results in the remission of obesity-associated comorbidities for obese individuals. However, patients who undergo this surgery may develop hypoglycemia. To date, the diagnosis is challenging and the prevalence of post-RYGB hypoglycemia (PRH) is unclear. RYGB alters the anatomy of the upper gastrointestinal tract and has a combined effect of caloric intake restriction and nutrient malabsorption. Nevertheless, the physiologic changes after RYGB are complex. Although hyperinsulinemia, incretin effects, dysfunction of β-cells and α-cells, and some other factors have been widely investigated and are reported to be possible mediators of PRH, the pathogenesis is still not completely understood. In light of the important role of the gut microbiome in metabolism, we hypothesized that the gut microbiome might also be a critical link between RYGB and hypoglycemia. In this review, we mainly highlight the current possible factors predisposing individuals to PRH, particularly related to the gut microbiota, which may yield significant insights into the intestinal regulation of glucose metabolic homeostasis and provide novel clues to improve the treatment of type 2 diabetes mellitus.

Hypoglycemia After Upper Gastrointestinal Surgery: Clinical Approach to Assessment, Diagnosis, and Treatment

CONTEXT

Post-bariatric hypoglycemia (PBH) is an increasingly encountered complication of upper gastrointestinal surgery; the prevalence of this condition is anticipated to rise given yearly increases in bariatric surgical procedures. While PBH is incompletely understood, there is a growing body of research describing the associated factors, mechanisms, and treatment approaches for this condition.

EVIDENCE ACQUISITION

Data are integrated and summarized from studies of individuals affected by PBH and hypoglycemia following upper gastrointestinal surgery obtained from PubMed searches (1990-2020).

EVIDENCE SYNTHESIS

Information addressing etiology, incidence/prevalence, clinical characteristics, assessment, and treatment were reviewed and synthesized for the practicing physician. Literature reports were supplemented by clinical experience as indicated, when published data were not available.

CONCLUSION

PBH can be life-altering and severe for a subset of individuals. Given the chronic nature of this condition, and sequelae of both acute and recurrent episodes, increasing provider awareness of both the condition and associated risk factors is critical for assessment, prompt diagnosis, treatment, and preoperative identification of individuals at risk.