Insulin response to oral stimuli and glucose effectiveness increased in neuroglycopenia following gastric bypass

Post-Bariatric Hypoglycemia in Individuals with Obesity and Type 2 Diabetes after Laparoscopic Roux-en-Y Gastric Bypass: A Prospective Cohort Study

Post-bariatric hypoglycemia (PBH) is an increasingly recognized complication after metabolic bariatric surgery (MBS). The aim of this study is to investigate potential factors associated with PBH. A cohort of 24 patients with type 2 diabetes mellitus (T2DM) and body mass index (BMI) ≥40 kg/m2 who underwent laparoscopic Roux-en-Y gastric bypass (LRYGBP) was retrospectively investigated for PBH at 12 months. PBH was defined as postprandial glucose at 120 min below 60 mg/dL. Questionnaires based on the Edinburgh hypoglycemia scale were filled out by the participants. Glycemic parameters and gastrointestinal (GI) hormones were also investigated. Based on the questionnaires, five patients presented more than four symptoms that were highly indicative of PBH at 12 months. According to glucose values at 120 min, one patient experienced PBH at 6 months and four patients experienced it at 12 months. Postprandial insulin values at 30 min and 6 months seem to be a strong predictor for PBH (p < 0.001). GLP-1 and glucagon values were not significantly associated with PBH. PBH can affect patients with T2DM after MBS, reaching the edge of hypoglycemia. Postprandial insulin levels at 30 min and 6 months might predict the occurrence of PBH at 12 months, but this requires further validation with a larger sample size.

Canagliflozin or acarbose versus placebo to ameliorate post-bariatric hypoglycaemia - The HypoBar I randomized clinical trial protocol

INTRODUCTION

Post-bariatric hypoglycaemia (PBH) is a rare yet disabling clinical condition, mostly reported after Roux-en-Y gastric bypass (RYGB) surgery. RYGB is one of the most widely used and effective bariatric procedures. The pathophysiology of PBH remains unclear, and treatment options are limited in effectiveness and/or carry significant side effects. Acarbose slows carbohydrates digestion and absorption and is generally considered first-line pharmacological treatment for PBH but its gastrointestinal side effects limit patient compliance. Canagliflozin inhibits intestinal and renal sodium-dependent glucose absorption and reduces postprandial excursions of glucose, insulin and incretins after RYGB - effects that could be beneficial in ameliorating PBH.

AIMS

The trial aims to investigate how blood glucose levels are affected during daily living in subjects with PBH during treatment with canagliflozin or acarbose compared with placebo, and to study the meal-induced entero-endocrine mechanisms implied in the treatment responses.

METHODS

In a double-blinded, randomized, crossover clinical trial, HypoBar I will investigate the effectiveness in reducing the risk of PBH, safety, ambulatory glucose profile and entero-endocrine responses when PBH is treated with canagliflozin 300 mg twice daily during a 4-week intervention period, compared with acarbose 50 mg thrice daily or placebo.

ETHICS AND DISSEMINATION

HypoBar I is approved by the Local regulatory entities. Results will be published in peer-reviewed journals.

CONCLUSION

If effective, well-tolerated and safe, canagliflozin could be a novel treatment for people with PBH. HypoBar I might also unravel new mechanisms underlying PBH, potentially identifying new treatment targets.

TRIAL REGISTRATION

EudraCT number 2022-000157-87.

Society for Endocrinology guidelines for the diagnosis and management of post-bariatric hypoglycaemia

Post bariatric hypoglycaemia (PBH) is typically a post-prandial hypoglycaemia occurring about 2-4 hours after eating in people who have undergone bariatric surgery. PBH develops relatively late after surgery and often after discharge from post-surgical follow-up by bariatric teams, leading to variability in diagnosis and management in non-specialist centres.

AIM

to improve and standardise clinical practice in the diagnosis and management of PBH.

OBJECTIVES

(1) to undertake an up-to-date review of the current literature; (2) to formulate practical and evidence-based guidance with regards on the diagnosis and treatment of PBH; (3) to recommend future avenues for research in this condition.

METHOD

A scoping review was undertaken after an extensive literature search. A consensus on the guidance and confidence in the recommendations was reached by the steering group authors prior to review by key stakeholders.

OUTCOME

We make pragmatic recommendations for the practical diagnosis and management of PBH including criteria for diagnosis and recognition, as well as recommendations for research areas that should be explored.

Postprandial plasma GLP-1 levels are elevated in individuals with postprandial hypoglycaemia following Roux-en-Y gastric bypass - a systematic review

BACKGROUND AND AIMS

Bariatric surgery is the most effective treatment in individuals with obesity to achieve remission of type 2 diabetes. Post-bariatric surgery hypoglycaemia occurs frequently, and management remains suboptimal, because of a poor understanding of the underlying pathophysiology. The glucoregulatory hormone responses to nutrients in individuals with and without post-bariatric surgery hypoglycaemia have not been systematically examined.

MATERIALS AND METHODS

The study protocol was prospectively registered with PROSPERO. PubMed, EMBASE, Web of Science and the Cochrane databases were searched for publications between January 1990 and November 2021 using MeSH terms related to post-bariatric surgery hypoglycaemia. Studies were included if they evaluated individuals with post-bariatric surgery hypoglycaemia and included measurements of plasma glucagon-like peptide-1 (GLP-1), glucose-dependent insulinotropic polypeptide (GIP), insulin, C-peptide and/or glucagon concentrations following an ingested nutrient load. Glycated haemoglobin (HbA1c) was also evaluated. A random-effects meta-analysis was performed, and Hedges' g (standardised mean difference) and 95% confidence intervals were reported for all outcomes where sufficient studies were available. The τ2 estimate and I2 statistic were used as tests for heterogeneity and a funnel plot with the Egger regression-based test was used to evaluate for publication bias.

RESULTS

From 377 identified publications, 12 were included in the analysis. In all 12 studies, the type of bariatric surgery was Roux-en-Y gastric bypass (RYGB). Comparing individuals with and without post-bariatric surgery hypoglycaemia following an ingested nutrient load, the standardised mean difference in peak GLP-1 was 0.57 (95% CI, 0.32, 0.82), peak GIP 0.05 (-0.26, 0.36), peak insulin 0.84 (0.44, 1.23), peak C-peptide 0.69 (0.28, 1.1) and peak glucagon 0.05 (-0.26, 0.36). HbA1c was less in individuals with hypoglycaemia - 0.40 (-0.67, -0.12). There was no evidence of substantial heterogeneity in any outcome except for peak insulin: τ2 = 0.2, I2 = 54.3. No publication bias was evident.

CONCLUSION

Following RYGB, postprandial peak plasma GLP-1, insulin and C-peptide concentrations are greater in individuals with post-bariatric surgery hypoglycaemia, while HbA1c is less. These observations support the concept that antagonism of GLP-1 would prove beneficial in the management of individuals with hypoglycaemia following RYGB.PROSPERO Registration Number: CRD42021287515.

Clinical Presentation and Diagnostic Approach to Hypoglycemia in Adults Without Diabetes Mellitus

OBJECTIVE

To review the clinical presentation, causes, and diagnostic approach to spontaneous hypoglycemia in adults without diabetes mellitus.

METHODS

A literature review was performed using the PubMed and Google Scholar databases.

RESULTS

Hypoglycemia is uncommon in people who are not on glucose-lowering medications. Under normal physiologic conditions, multiple neural and hormonal counterregulatory mechanisms prevent the development of abnormally low levels of plasma glucose. If spontaneous hypoglycemia is suspected, the Whipple triad should be used to confirm hypoglycemia before pursuing further diagnostic workup. The Whipple criteria include the following: (1) low levels of plasma glucose, (2) signs or symptoms that would be expected with low levels of plasma glucose, and (3) improvement in those signs or symptoms when the level of plasma glucose increases. Spontaneous hypoglycemia can be caused by conditions that cause endogenous hyperinsulinism, including insulinoma, postbariatric hypoglycemia, and noninsulinoma pancreatogenous hypoglycemia. Spontaneous hypoglycemia can also be seen with critical illness, hepatic or renal dysfunction, hormonal deficiency, non-diabetes-related medications, and non-islet cell tumors. The initial diagnostic approach should begin by obtaining a detailed history of the nature and timing of the patient's symptoms, medications, underlying comorbid conditions, and any acute illness. A laboratory evaluation should be conducted at the time of the spontaneous symptomatic episode. Supervised tests such as a 72-hour fast or mixed-meal test may be needed to recreate the situation under which the patient is likely to experience symptoms.

CONCLUSION

We provide an overview of the physiology of counterregulatory response to hypoglycemia, its causes, and diagnostic approaches to spontaneous hypoglycemia in adults.

Glucose metabolism after bariatric surgery: implications for T2DM remission and hypoglycaemia

Although promising therapeutics are in the pipeline, bariatric surgery (also known as metabolic surgery) remains our most effective strategy for the treatment of obesity and type 2 diabetes mellitus (T2DM). Of the many available options, Roux-en-Y gastric bypass (RYGB) and vertical sleeve gastrectomy (VSG) are currently the most widely used procedures. RYGB and VSG have very different anatomical restructuring but both surgeries are effective, to varying degrees, at inducing weight loss and T2DM remission. Both weight loss-dependent and weight loss-independent alterations in multiple tissues (such as the intestine, liver, pancreas, adipose tissue and skeletal muscle) yield net improvements in insulin resistance, insulin secretion and insulin-independent glucose metabolism. In a subset of patients, post-bariatric hypoglycaemia can develop months to years after surgery, potentially reflecting the extreme effects of potent glucose reduction after surgery. This Review addresses the effects of bariatric surgery on glucose regulation and the potential mechanisms responsible for both the resolution of T2DM and the induction of hypoglycaemia.

Lower Glucose Effectiveness Is Associated with Subclinical Reactive Hypoglycemia, Snacking Habits, and Obesity

The effects of glucose effectiveness, the insulin-independent mechanism of glucose disposal, on hypoglycemia have not yet been fully investigated. Herein, in 50 males without a diagnosis of diabetes mellitus (median age 54 years, body mass index (BMI) ≥ 25), the index of glucose effectiveness (SgIo) was determined by a 75 g oral glucose tolerance test (OGTT), and continuous glucose monitoring (CGM) was performed for 6 days. The minimal glucose levels and the percentages of time below 70 mg/dL (3.9 mmol/L) (TBR70) during CGM were significantly associated with the SgIo tertile category in a biphasic manner. When TBR70 within 24 h after OGTT ≥ 0.6% was defined as subclinical reactive hypoglycemia (SRH), odds ratios of having SRH in SgIo tertile 1 (lowest) and tertile 3 (highest) compared to SgIo tertile 2 (middle) were both 11.7 (p = 0.007), while the odds ratios of the highest post-load insulin quartile were 22.9 (p = 0.001) and 1.07 (p = 0.742), respectively. The chances of having self-reported snacking habits, obesity (BMI ≥ 30), and impaired glucose tolerance were significantly higher in participants in SgIo tertile 1 compared to those in SgIo tertile 2, with odds ratios of 10.7 (p = 0.005), 11.2 (p = 0.02), and 13.8 (p = 0.002), respectively. However, there was no significant difference between SgIo tertile categories 2 and 3. In conclusion, SgIo is associated with SRH in a biphasic manner. In people with lower glucose effectiveness, the SRH-induced increase in appetite may create a vicious cycle that leads to obesity.

Unraveling, contributing factors to the severity of postprandial hypoglycemia after gastric bypass surgery

BACKGROUND

Despite the increasing prevalence of postbariatric hypoglycemia (PBH), a late metabolic complication of bariatric surgery, our understanding of its diverse manifestations remains incomplete.

OBJECTIVES

To contrast parameters of glucose-insulin homeostasis in 2 distinct phenotypes of PBH (mild versus moderate hypoglycemia) based on nadir plasma glucose.

SETTING

University Hospital (Bern, Switzerland).

METHODS

Twenty-five subjects with PBH following gastric bypass surgery (age, 41 ± 12 years; body mass index, 28.1 ± 6.1kg/m²) received 75g of glucose with frequent blood sampling for glucose, insulin, C-peptide, and glucagon-like peptide 1 (GLP)-1. Based on nadir plasma glucose (</≥50mg/dL), subjects were grouped into level 1 (L1) and level 2 (L2) PBH groups. Beta-cell function (BCF), GLP-1 exposure (λ), beta-cell sensitivity to GLP-1 (π), potentiation of insulin secretion by GLP-1 (PI), first-pass hepatic insulin extraction (HE), insulin sensitivity (SI), and rate of glucose appearance (Ra) were calculated using an oral model of GLP-1 action coupled with the oral minimal model.

RESULTS

Nadir glucose was 43.3 ± 6.0mg/dL (mean ± standard deviation) and 60.1 ± 9.1mg/dL in L2- and L1-PBH, respectively. Insulin exposure was significantly higher in L2 versus L1 (P = .004). Mathematical modeling revealed higher BCF in L2 versus L1 (34.3 versus 18.8 10^-9∗min^-1; P = .003). Despite an increased GLP-1 exposure in L2 compared to L1 PBH (50.7 versus 31.9pmol∗L^-1∗min∗10²; P = .021), no significant difference in PI was observed (P = .204). No significant differences were observed for HE, Ra, and SI.

CONCLUSIONS

Our results suggest that higher insulin exposure in PBH patients with lower postprandial nadir glucose values mainly relate to a higher responsiveness to glucose, rather than GLP-1.

Pramlintide for post-bariatric hypoglycaemia

AIMS

The aim of this study was to examine the hypothesis that pramlintide would reduce hypoglycaemia by slowing gastric emptying and reducing postprandial glucagon secretion, thus limiting postprandial glycaemic excursions and insulin secretion, and thus to determine the efficacy of pramlintide on frequency and severity of hypoglycaemia in post-bariatric hypoglycaemia (PBH).

MATERIALS AND METHODS

Participants with PBH following gastric bypass were recruited from outpatient clinics at the Joslin Diabetes Center, Boston, Massachusetts for an open-label study of pramlintide efficacy over 8 weeks. Twenty-three participants were assessed for eligibility, 20 participants had at least one pramlintide dose, and 14 completed the study. A mixed-meal tolerance test (MMTT) was performed at baseline and after 8 weeks of subcutaneous pramlintide with a sequential dose increase to a maximum of 120 micrograms (mean 69 ± 32 mcg) three times daily. The primary endpoint was change in glucose excursions during the MMTT. Secondary measures included MMTT insulin response, satiety and dumping score, percentage time with sensor glucose (SG) <3.9 mM, and number of days with minimum SG <3 mM, during masked continuous glucose monitoring.

RESULTS

There were no differences in MMTT glucose, glucagon or insulin between baseline and post treatment. We observed no significant change in satiety or dumping scores. The overall frequency of low SG values did not change, although there was substantial inter-individual variability.

CONCLUSIONS

In PBH, pramlintide does not modulate glycaemic or insulin responses, satiety, or dumping scores during an MMTT and does not impact glycaemic excursions or decrease low SG levels in the outpatient setting.

Postbariatric hypoglycemia: symptom patterns and associated risk factors in the Longitudinal Assessment of Bariatric Surgery study

BACKGROUND

Postbariatric hypoglycemia (PBH) can be a devastating complication for which current therapies are often incompletely effective. More information is needed regarding frequency, incidence, and risk factors for PBH.

OBJECTIVES

To examine hypoglycemia symptoms following Roux-en-Y gastric bypass (RYGB) and laparoscopic adjustable gastric banding (LAGB) and baseline and in-study risk factors.

SETTING

Multicenter, at 10 US hospitals in 6 geographically diverse clinical centers.

METHODS

A prospective, longitudinal cohort study of adults undergoing RYGB or LAGB as part of clinical care between 2006 and 2009 were recruited and followed until January 31, 2015, with baseline and annual postoperative research assessments. We analyzed baseline prevalence and post-operative incidence and frequency of self-reported hypoglycemia symptoms as well as potential preoperative risk factors.

RESULTS

In all groups, postoperative prevalence of hypoglycemia symptoms was 38.5%. Symptom prevalence increased postoperatively from 2.8%-36.4% after RYGB in patients without preoperative diabetes (T2D), with similar patterns in prediabetes (4.9%-29.1%). Individuals with T2D had higher baseline hypoglycemia symptoms (28.9%), increasing after RYGB (57.9%). Hypoglycemia symptoms were lower after LAGB, with 39.1% reported hypoglycemia symptoms at only 1 postoperative visit with few (4.0%) having persistent symptoms at 6 or more annual visits. Timing of symptoms was not restricted to the postprandial state. Symptoms of severe hypoglycemia were reported in 2.6-3.6% after RYGB. The dominant risk factor for postoperative symptoms was preoperative symptoms; additionally, baseline selective serotonin (SSRI) and serotonin-norepinephrine (SNRI) reuptake inhibitor use was also associated with increased risk in multivariable analysis. Weight loss and regain were not related to hypoglycemia symptom reporting.

CONCLUSION

Hypoglycemia symptoms increase over time after RYGB, particularly in patients without diabetes. In a small percentage, symptoms can be persistent or severe and require hospitalization. Preoperative hypoglycemia symptoms and SSRI/SNRI use in RYGB patients without diabetes is associated with increased risk of symptoms.

Glycemic Patterns Are Distinct in Post-Bariatric Hypoglycemia After Gastric Bypass (PBH-RYGB)

CONTEXT

Severe hypoglycemia with neuroglycopenia, termed post-bariatric hypoglycemia (PBH). typically occurs postprandially, but it is also reported after activity or mid-nocturnally.

OBJECTIVE

To quantify glycemia, glycemic variability, and magnitude/duration of low sensor glucose (SG) values in patients with PBH after Roux-en-Y gastric bypass (PBH-RYGB).

METHODS

This retrospective analysis of data from an academic medical center included individuals with PBH-RYGB (n = 40), reactive hypoglycemia without gastrointestinal surgery (Non-Surg Hypo, n = 20), prediabetes (Pre-DM, n = 14), newly diagnosed T2D (n = 5), and healthy controls (HC, n = 38). Masked continuous glucose monitoring (Dexcom G4) was used to assess patterns over 24 hours, daytime (6 am-midnight) and nighttime (midnight-6 am). Prespecified measures included mean and median SG, variability, and percent time at thresholds of sensor glucose.

RESULTS

Mean and median SG were similar for PBH-RYGB and HC (mean: 99.8 ± 18.6 vs 96.9 ± 10.2 mg/dL; median: 93.0 ± 14.8 vs 94.5 ± 7.4 mg/dL). PBH-RYGB had a higher coefficient of variation (27.3 ± 6.8 vs 17.9 ± 2.4%, P < 0.0001) and range (154.5 ± 50.4 vs 112.0 ± 26.7 mg/dL, P < 0.0001). Nadir was lowest in PBH-RYGB (42.5 ± 3.7 vs HC 49.0 ± 11.9 mg/dL, P = 0.0046), with >2-fold greater time with SG < 70 mg/dL vs HC (7.7 ± 8.4 vs 3.2 ± 4.1%, P = 0.0013); these differences were greater at night (12.6 ± 16.9 vs 1.0 ± 1.5%, P < 0.0001). Non-Surg Hypo also had 4-fold greater time with SG < 70 at night vs HC (SG < 70: 4.0 ± 5.9% vs 1.0 ± 1.5%), but glycemic variability was not increased.

CONCLUSION

Patients with PBH-RYGB experience higher glycemic variability and frequency of SG < 70 compared to HC, especially at night. These data suggest that additional pathophysiologic mechanisms beyond prandial changes contribute to PBH.

Impact of Postprandial Hypoglycemia on Weight Loss After Bariatric Surgery

INTRODUCTION

Postprandial hypoglycemia (PPHG) is a well-known complication after bariatric surgery (BS). However, it is not known whether PPHG affects weight loss after BS.

AIMS

To assess the impact of PPHG on weight loss after BS in subjects without and with type 2 diabetes mellitus (T2D).

METHODS

Data from 338 subjects who had undergone gastric bypass (RYGB) or sleeve gastrectomy (LSG) and were followed up for at least 2 years were analyzed. At each follow-up visit, the patient's anthropometric and biochemical characteristics were recorded and the Edinburgh Questionnaire was performed to evaluate the presence of PPHG symptoms.

RESULTS

Before surgery: younger age and lower BMI predicted PPHG after BS (p = 0.02 and p = 0.0008, respectively). Also, the baseline OGTT indicated that subjects who developed PPHG had an earlier glucose peak and more often had low glucose levels at 2 h compared with the no-PPHG group (p = 0.03 and p = 0.004, respectively). After surgery: Mild-to-moderate PPHG occurred equally after RYGB and LSG (38% vs 25%, p = ns when accounting for confounders), and in T2D who achieved remission and those who did not (29.5% vs 28.6%, ns). At the 2-year follow-up, occurrence of PPHG was independently associated with smaller weight loss (p = 0.0006).

CONCLUSIONS

Mild-to-moderate PPHG is a frequent complication after bariatric surgery and results in smaller weight loss after 2 years. Age, baseline BMI, and an earlier glucose peak during OGTT predict PPHG after bariatric surgery.

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.

Features of oral glucose tolerance tests in patients after Roux-en-Y gastric bypass with and without hypoglycaemia symptoms in daily life: It's all about speed

OBJECTIVE

To evaluate the glucose and insulin profiles during an oral glucose tolerance test (OGTT) after Roux-en-Y gastric bypass (RYGB) in symptomatic and asymptomatic patients.

RESEARCH DESIGN AND METHODS

This retrospective study consisted of two groups that had undergone RYGB. The symptomatic (S) group (n = 27) had an OGTT at presentation, whereas the asymptomatic (A) group (n = 99) had an OGTT 1 year after RYGB. Each group was subdivided into two groups, namely, those with glycaemia <54 mg/dL (S1/A1) and those with glycaemia >54 mg/dL (S2/A2) during OGTT. Most of the patients underwent OGTT preoperatively.

RESULTS

Preoperatively, the glucose and insulin levels, as well as the speed of increase and decrease, were similar in all groups. Postoperatively, the minimum glucose levels during the OGTT did not differ between the symptomatic and asymptomatic groups (55 ± 19 vs. 54 ± 17 mg/dL) or between the S1 and A1 subgroups (39 ± 7 vs. 43 ± 8 mg/dL). The peak glucose values were higher in the symptomatic versus the asymptomatic group (236 ± 52 vs. 189 ± 43 mg/dL; P <0.05) and in the S1 and S2 versus the A1 and A2 subgroups. The speed of glucose increase and decline was significantly higher in the symptomatic group versus the asymptomatic group, with the speed of glucose decline being the highest in the S1 subgroup.

CONCLUSION

Assessing hypoglycaemia after a gastric bypass remains challenging. Our study suggests that the main difference in glucose dynamics between symptomatic and asymptomatic patients might be the speed of glucose and insulin increase and decline during OGTT rather than the absolute values obtained.

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.

Use of flash glucose monitoring for post-bariatric hypoglycaemia diagnosis and management

Our aim was to assess the potential of flash glucose monitoring (FGM) for diagnostic workup of suspected post-bariatric hypoglycaemia (PBH). Patients (N = 13) with suspected PBH underwent a food and symptoms diary (FSD) record along with FGM over 14 days. Targeted data analysis confirmed the occurrence of low glucose events in parallel to meal-triggered symptoms. Glycaemic variability, as assessed by Mean Absolute Glucose change (MAG change), was increased, while a higher risk of glycaemic excursions towards both hyper and hypoglycaemia (ADRR_FGMGT) was observed in those with more frequent and severe hypoglycaemia. The herein described hypoglycaemia risk index (LBGI_FGMGT) with a cut-off value of 4.6 showed to have 100% sensitivity and 100% specificity for PBH. This pilot proof-of-concept study highlighted that FSD coupled with FGM followed by targeted data analysis, provides relevant insights towards PBH diagnosis and grading in a user-friendly and easy to implement study protocol. Furthermore, LBGI_FGMGT demonstrated to be an excellent index for PBH diagnosis. The unexpected improvement of glucose profile noticed along the monitoring time also unravels a possible application for PBH management.

Clinical Practice Guidelines for the Perioperative Nutrition, Metabolic, and Nonsurgical Support of Patients Undergoing Bariatric Procedures - 2019 Update: Cosponsored by American Association of Clinical Endocrinologists/American College of Endocrinology, The Obesity Society, American Society for Metabolic and Bariatric Surgery, Obesity Medicine Association, and American Society of Anesthesiologists

OBJECTIVE

The development of these updated clinical practice guidelines (CPGs) was commissioned by the American Association of Clinical Endocrinologists (AACE), The Obesity Society (TOS), American Society for Metabolic and Bariatric Surgery (ASMBS), Obesity Medicine Association (OMA), and American Society of Anesthesiologists (ASA) Boards of Directors in adherence with the AACE 2017 protocol for standardized production of CPGs, algorithms, and checklists.

METHODS

Each recommendation was evaluated and updated based on new evidence from 2013 to the present and subjective factors provided by experts.

RESULTS

New or updated topics in this CPG include: contextualization in an adiposity-based chronic disease complications-centric model, nuance-based and algorithm/checklist-assisted clinical decision-making about procedure selection, novel bariatric procedures, enhanced recovery after bariatric surgery protocols, and logistical concerns (including cost factors) in the current health care arena. There are 85 numbered recommendations that have updated supporting evidence, of which 61 are revised and 12 are new. Noting that there can be multiple recommendation statements within a single numbered recommendation, there are 31 (13%) Grade A, 42 (17%) Grade B, 72 (29%) Grade C, and 101 (41%) Grade D recommendations. There are 858 citations, of which 81 (9.4%) are evidence level (EL) 1 (highest), 562 (65.5%) are EL 2, 72 (8.4%) are EL 3, and 143 (16.7%) are EL 4 (lowest).

CONCLUSIONS

Bariatric procedures remain a safe and effective intervention for higher-risk patients with obesity. Clinical decision-making should be evidence based within the context of a chronic disease. A team approach to perioperative care is mandatory, with special attention to nutritional and metabolic issues.

Continuous glucose monitoring reveals glycemic variability and hypoglycemia after vertical sleeve gastrectomy in rats

Objective

Post–bariatric surgery hypoglycemia (PBH) is defined as the presence of neuroglycopenic symptoms accompanied by postprandial hypoglycemia in bariatric surgery patients. Recent clinical studies using continuous glucose monitoring (CGM) technology revealed that PBH is more frequently observed in vertical sleeve gastrectomy (VSG) patients than previously recognized. PBH cannot be alleviated by current medication. Therefore, a model system to investigate the mechanism and treatment is required.

Methods

We used CGM in a rat model of VSG and monitored the occurrence of glycemic variability and hypoglycemia in various meal conditions for 4 weeks after surgery. Another cohort of VSG rats with CGM was used to investigate whether the blockade of glucagon-like peptide-1 receptor (GLP-1R) signaling alleviates these symptoms. A mouse VSG model was used to investigate whether the impaired glucose counterregulatory system causes postprandial hypoglycemia.

Results

Like in humans, rats have increased glycemic variability and hypoglycemia after VSG. Postprandial hypoglycemia was specifically detected after liquid versus solid meals. Further, the blockade of GLP-1R signaling raises the glucose nadir but does not affect glycemic variability.

Conclusions

Rat bariatric surgery duplicates many features of human post–bariatric surgery hypoglycemia including postprandial hypoglycemia and glycemic variability, while blockade of GLP-1R signaling prevents hypoglycemia but not the variability.

•

VSG causes glycemic variability during ad lib feeding condition.

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Single liquid meal ingestion causes post-VSG hypoglycemia.

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Blockade of GLP-1 receptor prevents post-VSG hypoglycemia.

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.

Clinical practice guidelines for the perioperative nutrition, metabolic, and nonsurgical support of patients undergoing bariatric procedures - 2019 update: cosponsored by American Association of Clinical Endocrinologists/American College of Endocrinology, The Obesity Society, American Society for Metabolic & Bariatric Surgery, Obesity Medicine Association, and American Society of Anesthesiologists

OBJECTIVE

The development of these updated clinical practice guidelines (CPG) was commissioned by the American Association of Clinical Endocrinologists, The Obesity Society, the American Society of Metabolic and Bariatric Surgery, the Obesity Medicine Association, and the American Society of Anesthesiologists boards of directors in adherence to the American Association of Clinical Endocrinologists 2017 protocol for standardized production of CPG, algorithms, and checklists.

METHODS

Each recommendation was evaluated and updated based on new evidence from 2013 to the present and subjective factors provided by experts.

RESULTS

New or updated topics in this CPG include contextualization in an adiposity-based, chronic disease complications-centric model, nuance-based, and algorithm/checklist-assisted clinical decision-making about procedure selection, novel bariatric procedures, enhanced recovery after bariatric surgery protocols, and logistical concerns (including cost factors) in the current healthcare arena. There are 85 numbered recommendations that have updated supporting evidence, of which 61 are revised and 12 are new. Noting that there can be multiple recommendation statements within a single numbered recommendation, there are 31 (13%) Grade A, 42 (17%) Grade B, 72 (29%) Grade C, and 101 (41%) Grade D recommendations. There are 858 citations, of which 81 (9.4%) are evidence level (EL) 1 (highest), 562 (65.5%) are EL 2, 72 (8.4%) are EL 3, and 143 (16.7%) are EL 4 (lowest).

CONCLUSIONS

Bariatric procedures remain a safe and effective intervention for higher-risk patients with obesity. Clinical decision-making should be evidence-based within the context of a chronic disease. A team approach to perioperative care is mandatory with special attention to nutritional and metabolic issues.

Postprandial hypoglycaemia after Roux-en-Y gastric bypass and the effects of acarbose, sitagliptin, verapamil, liraglutide and pasireotide

AIM

To investigate the effects of acarbose, sitagliptin, verapamil, liraglutide and pasireotide on post-bariatric hypoglycaemia (PBH) after Roux-en-Y gastric bypass.

MATERIALS AND METHODS

In a randomized crossover study, 11 women who had undergone Roux-en-Y gastric bypass and had documented hypoglycaemia were each evaluated during a baseline period without treatment and during five treatment periods with the following interventions: acarbose 50 mg for 1 week, sitagliptin 100 mg for 1 week, verapamil 120 mg for 1 week, liraglutide 1.2 mg for 3 weeks and pasireotide 300 μg as a single dose. Treatment effects were evaluated by a mixed-meal tolerance test (MMTT) and, for all treatment periods except pasireotide, by 6 days of continuous glucose monitoring (CGM).

RESULTS

Treatment with acarbose and treatment with pasireotide both significantly lifted nadir glucose levels (mean ± SEM 3.9 ± 0.2 and 7.9 ± 0.4 vs 3.4 ± 0.2; P < .03) and reduced time in hypoglycaemia during the MMTTs. Acarbose reduced peak glucose levels and time in hyperglycaemia, whereas pasireotide greatly increased both variables. Acarbose and pasireotide reduced insulin and C-peptide levels, and pasireotide also diminished glucagon-like peptide-1 levels. Sitagliptin lowered nadir glucose values, while verapamil and liraglutide had no effect on hypoglycaemia. During the CGM periods, the treatments had no impact on hypoglycaemia, whereas acarbose and liraglutide reduced hyperglycaemia and glycaemic variability.

CONCLUSIONS

In an experimental setting, treatment with acarbose and pasireotide reduced PBH. Acarbose appears to have an overall glucose-stabilizing effect, whereas pasireotide leads to increased and sustained hyperglycaemia.

Mechanisms of action of a carbohydrate-reduced, high-protein diet in reducing the risk of postprandial hypoglycemia after Roux-en-Y gastric bypass surgery

BACKGROUND

Postprandial hypoglycemia is a risk after Roux-en-Y gastric bypass (RYGB).

OBJECTIVES

We speculated that a carbohydrate-reduced, high-protein (CRHP) diet might reduce the risk of hypoglycemia and therefore compared the acute effects of a conventionally recommended (CR) diet and CRHP diet [55/30 energy percent (E%) carbohydrate and 15/30 E% protein, respectively] in RYGB patients.

METHODS

Ten individuals (2 males, 8 females, mean ± SD age 47 ± 7 y; stable body mass index 31 ± 6 kg/m2; 6 ± 3 y post-RYGB) with recurrent postprandial hypoglycemia documented by plasma glucose (PG) ≤3.4 mmol/L were examined on 2 d with isoenergetic CRHP or CR diets comprising a breakfast and subsequent lunch meal.

RESULTS

Peak PG was significantly reduced on the CRHP diet after breakfast and lunch by 11% and 31% compared with the CR diet. Nadir PG increased significantly on CRHP (by 13% and 9%). Insulin secretion was reduced, and glucagon secretion increased on the CRHP diet after both meals. Glucagon-like peptide 1 and glucose-dependent insulinotropic polypeptide secretion were lower after lunch but unaltered after breakfast on CRHP; β-cell function and insulin clearance were unchanged.

CONCLUSIONS

The CRHP diet lowered glucose excursions and reduced insulin secretion and incretin hormone responses, but enhanced glucagon responses compared with the CR diet. Taken together, the results may explain the decreased glucose variability and lower risk of postprandial hypoglycemia. This study was registered at clinicaltrials.gov as NCT02665715.

Plasma FGF-19 Levels are Increased in Patients with Post-Bariatric Hypoglycemia

BACKGROUND

Hypoglycemia is an increasingly recognized complication of bariatric surgery. Mechanisms contributing to glucose lowering remain incompletely understood. We aimed to identify differentially abundant plasma proteins in patients with post-bariatric hypoglycemia (PBH) after Roux-en-Y gastric bypass (RYGB), compared to asymptomatic post-RYGB.

METHODS

Proteomic analysis of blood samples collected after overnight fast and mixed meal challenge in individuals with PBH, asymptomatic RYGB, severe obesity, or overweight recruited from outpatient hypoglycemia or bariatric clinics.

RESULTS

The top-ranking differentially abundant protein at 120 min after mixed meal was fibroblast growth factor 19 (FGF-19), an intestinally derived hormone regulated by bile acid-FXR signaling; levels were 2.4-fold higher in PBH vs. asymptomatic post-RYGB (mean + SEM, 1094 ± 141 vs. 428 ± 45, P < 0.001, FDR < 0.01). FGF-19 ELISA confirmed 3.5-fold higher concentrations in PBH versus asymptomatic (360 ± 70 vs. 103 ± 18, P = 0.025). To explore potential links between increased FGF-19 and GLP-1, residual samples from other human studies in which GLP-1 was modulated were assayed. FGF-19 levels did not change in response to infusion of GLP-1 and PYY in overweight/obese individuals. Infusion of the GLP-1 receptor antagonist exendin 9-39 in recently operated asymptomatic post-RYGB did not alter FGF-19 levels after mixed meal. By contrast, GLP-1 receptor antagonist infusion yielded a significant increase in FGF-19 levels after oral glucose in individuals with PBH. While plasma bile acids did not differ between PBH and asymptomatic post-RYGB, these data suggest unique interrelationships between GLP-1 and FGF-19 in PBH.

CONCLUSIONS

Taken together, these data support FGF-19 as a potential contributor to insulin-independent pathways driving postprandial hypoglycemia in PBH.

Roux-en-Y Gastric Bypass Is Associated With Hyperinsulinemia But Not Increased Maximal β-Cell Function

Context

Roux-en-Y gastric bypass (RYGB) is associated with postprandial hyperinsulinemia.

Objective

This study assessed whether increased blood insulin levels may be due to an increase in maximal β-cell function.

Design, Setting, and Participants

We performed a cross-sectional study at Columbia University Medical Center, New York, New York. Subjects without a history of diabetes were studied after surgery (n = 12) and were compared with nonsurgical controls (n = 10) who were mean matched for body mass index, insulin sensitivity, and hemoglobin A1c and with nonobese controls (n = 8).

Methods

Subjects underwent a mixed-meal tolerance test and on a separate day an intravenous glucose tolerance test followed by a hyperglycemic clamp (450 mg/dL; 25 mM blood glucose) and arginine stimulation. The main outcome measure was maximal insulin secretion quantified after arginine stimulation (AinsRmax).

Results

The RYGB group exhibited greater peak postprandial glucose levels and fourfold greater peak insulin levels than control groups; however, there were no significant differences in insulinogenic index or AinsRmax. Another finding was significantly greater postprandial glucagon levels in the RYGB group compared with controls.

Conclusions

Our results suggest that after RYGB, the increase in postprandial levels of insulin are not due to changes in maximal β-cell function but appear to be an appropriate response to altered nutrient flow and absorption.

PET-CT reveals increased intestinal glucose uptake after gastric surgery

BACKGROUND

Mechanisms of metabolic improvement after bariatric surgery remain incompletely understood. Intestinal glucose uptake is increased after gastric bypass in rodents, potentially contributing to reduced blood glucose and type 2 diabetes remission.

OBJECTIVE

We assessed whether intestinal glucose uptake is increased in humans after gastric surgery.

SETTING

University Hospital, United States.

METHODS

In a retrospective, case-control cohort study, positron emission tomography-computerized tomography scans performed for clinical indications were analyzed to quantify intestinal glucose uptake in patients with or without history of gastric surgery. We identified 19 cases, defined as patients over age 18 with prior gastric surgery (Roux-en-Y gastric bypass [n = 10], sleeve gastrectomy [n = 1], or Billroth I [n = 2] or II gastrectomy [n = 6]), and 43 controls without gastric surgery, matched for age, sex, and indication for positron emission tomography-computerized tomography. Individuals with gastrointestinal malignancy or metformin treatment were excluded. Images were obtained 60 minutes after ¹⁸F-fluorodeoxyglucose injection (4.2 MBq/kg), and corrected by attenuation; noncontrast low-dose computerized tomography was obtained in parallel. Fused and nonfused images were analyzed; standardized uptake values were calculated for each region by volumes of interest at the region of highest activity.

RESULTS

Both standardized uptake values maximum and mean were significantly increased by 41% to 98% in jejunum, ascending, and transverse colon in patients with prior gastric surgery (P < .05 versus controls).

CONCLUSION

Intestinal glucose uptake is increased in patients with prior gastric surgery. Prospective studies are important to dissect the contributions of weight loss, dietary factors, and systemic metabolism, and to determine the relationship with increased insulin-independent glucose uptake and reductions in glycemia.

Postprandial hypoglycaemia after Roux-en-Y gastric bypass in individuals with type 2 diabetes

AIMS/HYPOTHESIS

Postprandial hypoglycaemia (PPHG) is a complication of Roux-en-Y gastric bypass (RYGB) surgery in normoglycaemic individuals. In type 2 diabetes, RYGB improves glucose metabolism, but whether this improvement is related to the later development of PPHG is not known. We investigated the presence and mechanisms of PPHG in individuals with type 2 diabetes undergoing RYGB.

METHODS

A total of 35 obese individuals with type 2 diabetes underwent an OGTT before and 24 months after surgery. PPHG was defined as a plasma glucose level of ≤3.3 mmol/l when not taking glucose-lowering agents. Insulin sensitivity was assessed by oral glucose insulin sensitivity index and beta-cell function by mathematical modelling of the plasma glucose, insulin and C-peptide concentrations.

RESULTS

After surgery, PPHG occurred in 11 of 35 individuals who underwent RYGB. Before surgery, BMI was lower, glycaemic control less good and time of glucose peak earlier in the PPHG vs No PPHG group, and the duration of diabetes was shorter with PPHG (all p ≤ 0.05). In addition, insulin sensitivity was greater in the PPHG than No PPHG group (p = 0.03). After surgery, BMI and fasting glucose and insulin levels decreased similarly in the two groups; insulin secretion during the first hour of the OGTT increased more in the PPHG than No PPHG group (p = 0.04). Beta-cell glucose sensitivity increased more in individuals with PPHG than those without (p = 0.002). Over the same time interval, the glucagon-like peptide 1 (GLP-1) response was lower in individuals with PPHG before surgery (p = 0.05), and increased more after surgery. At 2 h after glucose ingestion in the OGTT, postsurgery plasma glucagon level was significantly lower in the PPHG than No PPHG group.

CONCLUSIONS/INTERPRETATION

In morbidly obese individuals with type 2 diabetes, spontaneous PPHG may occur after bariatric surgery independently of a remission of diabetes. Before surgery, individuals had a shorter duration and were more insulin sensitive. Two years after surgery, these individuals developed greater beta-cell glucose sensitivity, and showed greater insulin and GLP-1 release early in the OGTT.

RNA-Seq Analysis of Islets to Characterise the Dedifferentiation in Type 2 Diabetes Model Mice db/db

Type 2 diabetes (T2D) is a global health issue and dedifferentiation plays underlying causes in the pathophysiology of T2D; however, there is a lack of understanding in the mechanism. Dedifferentiation results from the loss of function of pancreatic β-cells alongside a reduction in essential transcription factors under various physiological stressors. Our study aimed to establish db/db as an animal model for dedifferentiation by using RNA sequencing to compare the gene expression profile in islets isolated from wild-type, db/+ and db/db mice, and qPCR was performed to validate those significant genes. A reduction in both insulin secretion and the expression of Ins1, Ins2, Glut2, Pdx1 and MafA was indicative of dedifferentiation in db/db islets. A comparison of the db/+ and the wild-type islets indicated a reduction in insulin secretion perhaps related to the decreased Mt1. A significant reduction in both Rn45s and Mir6236 was identified in db/+ compared to wild-type islets, which may be indicative of pre-diabetic state. A further significant reduction in RasGRF1, Igf1R and Htt was also identified in dedifferentiated db/db islets. Molecular characterisation of the db/db islets was performed via Ingenuity analysis which identified highly significant genes that may represent new molecular markers of dedifferentiation.

Hypoglycemia After Gastric Bypass Surgery: Current Concepts and Controversies

CONTEXT

Hypoglycemia, occurring after bariatric and other forms of upper gastrointestinal surgery, is increasingly encountered by clinical endocrinologists. The true frequency of this condition remains uncertain, due, in part, to differences in the diagnostic criteria and in the affected populations, as well as relative lack of patient and physician awareness and understanding of this condition. Postbariatric hypoglycemia can be severe and disabling for some patients, with neuroglycopenia (altered cognition, seizures, and loss of consciousness) leading to falls, motor vehicle accidents, and job and income loss. Moreover, repeated episodes of hypoglycemia can result in hypoglycemia unawareness, further impairing safety and requiring the assistance of others to treat hypoglycemia.

OBJECTIVE

In this review, we summarize and integrate data from studies of patients affected by hypoglycemia after Roux-en-Y gastric bypass (RYGB) surgery, obtained from PubMed searches (1990 to 2017) and reference searches of relevant retrieved articles. Whereas hypoglycemia can also be observed after sleeve gastrectomy and fundoplication, this review is focused on post-RYGB, given the greater body of published clinical studies at present.

OUTCOME MEASURES

Data addressing specific aspects of diagnosis, pathophysiology, and treatment were reviewed by the authors; when not available, the authors have provided opinions based on clinical experience with this challenging condition.

CONCLUSIONS

Hypoglycemia, occurring after gastric bypass surgery, is challenging for patients and physicians alike. This review provides a systematic approach to diagnosis and treatment based on the underlying pathophysiology.

Implementation of Low Glycemic Index Diet Together with Cornstarch in Post-Gastric Bypass Hypoglycemia: Two Case Reports

Post-bariatric hypoglycemia (PBH) is an increasingly recognized long-term complication of bariatric surgery. The nutritional treatment of PBH includes a high-fiber diet and the restriction of soluble and high-glycemic index carbohydrates; however, these measures are not always enough to prevent hypoglycemia. We evaluated the efficacy of uncooked cornstarch, a low-glycemic index carbohydrate characterized by slow intestinal degradation and absorption, in addition to a high-fiber diet, for the treatment of PBH. We report the cases of two young women suffering from severe postprandial and fasting hypoglycemia following Roux-en-Y gastric bypass (RYGB). The patients underwent Continuous Glucose Monitoring (CGM) before and 12–16 weeks after the administration of uncooked cornstarch (respectively 1.25 g/kg b.w. and 1.8 g/kg b.w.) in addition to a high-fiber diet. In both patients, CGM showed more stable glucose levels throughout monitoring, a remarkable reduction of the time spent in hypoglycemia (<55 mg/dL) both during the day (−11% for both patients) and the night (−22% and −32%), and the improvement of all glycemic variability indexes. Our report, within the limit of only two cases, suggests that the implementation of a dietary intervention through the addition of uncooked cornstarch reduces daily glycemic fluctuations and hypoglycemic episodes in patients with PBH.

Beta-cell sensitivity to glucose is impaired after gastric bypass surgery

AIMS

Patients who have undergone Roux-en-Y gastric bypass surgery (GB) have exaggerated postprandial insulin secretion, which has been attributed to increased meal glucose appearance and enhanced incretin effect. Here, we sought to determine β-cell glucose sensitivity in the absence of meal stimulation and insulinotropic gut factors.

MATERIALS AND METHODS

A total of 12 non-diabetic subjects with prior GB, and 7 matched non-surgical control subjects with normal glucose tolerance were studied. Blood glucose and insulin secretion rates were measured during a graded glucose infusion at increasing and then decreasing rates. Insulin sensitivity (S_I ) and glucose effectiveness (S_G ) were determined by the minimal model.

RESULTS

GB subjects had S_I comparable to that of control subjects. GB subjects had relative hyperglycaemia during the highest dose of glucose infusion associated with significantly reduced β-cell glucose sensitivity throughout both step-up (GB: 34 ± 6, CN: 82 ± 9 pmol min^-1 mM^-1 L, P < .0001) and step-down (GB: 31 ± 6, CN: 74 ± 9 pmol min^-1 mM^-1 L, P < .0001) phases of the glucose infusion. GB subjects also had reduced S_G (GB: 0.04 ± 0.00, CN: 0.07 ± 0.01 min^-1 , P = .004).

CONCLUSION

In the absence of enteric stimuli, β-cell sensitivity to changes in glycaemia is blunted among individuals with GB, indicating a significant shift in a fundamental property of β-cell function several years after surgery.

Roux en Y gastric bypass hypoglycemia resolves with gastric feeding or reversal: Confirming a non-pancreatic etiology

OBJECTIVE

Postprandial hypoglycemia is an infrequent but disabling complication of Roux-en-Y gastric bypass (RYGB) surgery. Controversy still exists as to whether the postprandial hyperinsulinemia observed is due to inherent changes in pancreatic β-cell mass or function or to reversible alterations caused by RYGB anatomy. We aimed to determine if gastric feeding or reversal of RYGB would normalize postprandial glucose and hormone excursions in patients with symptomatic hypoglycemia.

METHODS

We completed a prospective study of six patients with severe symptomatic RYGB hypoglycemia who underwent RYGB reversal. An additional subject without hypoglycemia who underwent RYGB reversal was also studied prospectively. Mixed meal tolerance testing (MTT) was done orally (RYGB anatomy), via gastrostomy tube in the excluded stomach in the setting of RYGB, and several months after RYGB reversal.

RESULTS

All subjects reported symptomatic improvement of hypoglycemia after reversal of RYGB. Weight gain after reversal was moderate and variable. Postprandial glucose, insulin, and GLP-1 excursions were significantly diminished with gastric feeding and after reversal. Insulin secretion changed proportional to glucose levels and insulin clearance increased after reversal. Glucagon/insulin ratios were similar throughout study. We further compared the impact of modified sleeve gastrectomy reversal surgery to those with restoration of complete stomach and found no significant differences in weight regain or in postprandial glucose or hormone levels.

CONCLUSIONS

Reversal of RYGB is an effective treatment option for severe postprandial hypoglycemia. The pathophysiology of this disorder is primarily due to RYGB anatomy resulting in altered glucose, gut, and pancreatic hormone levels and decreased insulin clearance, rather than inherent β-cell hyperplasia or hyperfunction.

Design and Clinical Evaluation of a Novel Low-Glucose Prediction Algorithm with Mini-Dose Stable Glucagon Delivery in Post-Bariatric Hypoglycemia

BACKGROUND

Postbariatric hypoglycemia (PBH) is a complication of bariatric surgery with limited therapeutic options. We developed an event-based system to predict and detect hypoglycemia based on continuous glucose monitor (CGM) data and recommend delivery of minidose liquid glucagon.

METHODS

We performed an iterative development clinical study employing a novel glucagon delivery system: a Dexcom CGM connected to a Windows tablet running a hypoglycemia prediction algorithm and an Omnipod pump filled with an investigational stable liquid glucagon formulation. Meal tolerance testing was performed in seven participants with PBH and history of neuroglycopenia. Glucagon was administered when hypoglycemia was predicted. Primary outcome measures included the safety and feasibility of this system to predict and prevent severe hypoglycemia. Secondary outcomes included hypoglycemia prediction by the prediction algorithm, minimization of time below hypoglycemia threshold using glucagon, and prevention of rebound hyperglycemia.

RESULTS

The hypoglycemia prediction algorithm alerted for impending hypoglycemia in the postmeal state, prompting delivery of glucagon (150 μg). After observations of initial incomplete efficacy to prevent hypoglycemia in the first two participants, system modifications were implemented: addition of PBH-specific detection algorithm, increased glucagon dose (300 μg), and a second glucagon dose if needed. These modifications, together with rescue carbohydrates provided to some participants, contributed to progressive improvements in glucose time above the hypoglycemia threshold (75 mg/dL).

CONCLUSIONS

Preliminary results indicate that our event-based automatic monitoring algorithm successfully predicted likely hypoglycemia. Minidose glucagon therapy was well tolerated, without prolonged or severe hypoglycemia, and without rebound hyperglycemia.

Hyperinsulinemic hypoglycemia after gastric bypass surgery: what's up and what's down?

Obesity is a global public health problem and attempts to treat this condition using life style with and without pharmacological interventions have not been successful in majority of obese individuals. To date, the most effective treatment for obesity is weight loss surgery. One of the most widely used procedures to treat obesity worldwide, Roux-en-Y gastric bypass surgery (RYGB), has shown to induce diabetes remission in addition to significant and sustainable weight loss. As the number of this procedure performed over the last two decades increased, it has become clear that a subgroup of individuals develop postprandial hypoglycemia several years after surgery. This debilitating late complication of RYGB is often associated with loss of consciousness or seizures, and in severe cases, it is only partially responsive to diet modification or other available therapeutic options. The diagnosis is often a challenge resulting in delays in receiving care in the affected individuals. Although the underlying mechanisms are under current investigations, growing evidence suggest that a combination of exaggerated meal-derived nutrient appearance to systemic circulation and altered islet and gut hormone response after eating have a role in pathogenesis of this condition. The goal of this review is to highlight new perspectives regarding this life-threatening complication of RYGB. The etiology, diagnosis, recommendation on how to distinguish from classic dumping and current available treatment based on literature review will be discussed. In addition, physiologic changes after gastric bypass predisposing to hypoglycemia syndrome will be highlighted.International Journal of Obesity advance online publication, 31 October 2017; doi:10.1038/ijo.2017.257.

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.

Molecular imaging in the investigation of hypoglycaemic syndromes and their management

There has been recent progress in molecular imaging using a variety of cellular targets for the investigation of adult non-diabetic hypoglycaemic syndromes and its integration into patient management. These targets include peptide receptors (somatostatin receptors (SSTRs) and glucagon-like peptide-1 receptor (GLP-1R)) the amine precursor uptake and decarboxylation system utilising the diphydroxyphenylaline (DOPA) analogue 6-[¹⁸F]-l-fluoro-l-3,4-dihydroxyphenylalanine (¹⁸F-FDOPA), and glycolytic metabolism with 2-[¹⁸F]fluoro-2-deoxy-d-glucose (FDG). Accurate preoperative localisation and staging is critical to enable directed surgical excision or enucleation with minimal morbidity and preservation of residual pancreatic function. Benign insulinoma has near ubiquitous dense GLP-1R expression enabling accurate localisation with radiolabelled-exendin-4 compounds (e.g. ⁶⁸Ga-NOTA-exendin-4 PET/CT), whilst the rarer and more difficult to manage metastatic insulinoma typically express SSTR and is preferably imaged with radiolabelled-SSTR analogues such as ⁶⁸Ga-DOTA-octreotate (DOTATATE) PET/CT for staging and assessment of suitability for peptide receptor radionuclide therapy (PRRT). Similar to other metastatic neuroendocrine tumours, FDG PET/CT is used in the setting of higher-grade metastatic insulinoma to provide important prognostic information that can guide treatment and determine suitability for PRRT. Interestingly, these three tracers appear to represent a spectrum of differentiation, which we conceptually describe as the 'triple-flop' phenomenon, with GLP-1R > SSTR > FDG in benign insulinoma and the opposite in higher-grade disease. This paper will review the clinical syndromes of adult hypoglycaemia (including a practical overview of the differential diagnoses to be considered), comparison of techniques for insulinoma localisation with emphasis on molecular imaging before discussing its implications for management of metastatic insulinoma.

Medical nutrition therapy for post-bariatric hypoglycemia: practical insights

Hypoglycemia is increasingly recognized as a complication of bariatric surgery. Although medications are often required, medical nutrition therapy remains the key cornerstone for successful prevention of hypoglycemia in patients with post-bariatric hypoglycemia (PBH). We provide suggested approaches to the dietary management of PBH, incorporating data from both the medical literature and extensive clinical experience in an academic referral center for PBH. The overall goal of medical nutrition therapy for PBH is to reduce postprandial surges in glucose, which often trigger surges in insulin secretion and promote subsequent hypoglycemia. Thus, strategies focus on controlled portions of low glycemic index carbohydrates, avoidance of rapidly-absorbed carbohydrates, adjustment of timing of meals and snacks, and attention to personal and cultural barriers to implementation.

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.

Insulinoma After Bariatric Surgery: Diagnostic Dilemma and Therapeutic Approaches

Hypoglycemia is increasingly recognized as a complication of bariatric surgery. Typically, hypoglycemia does not appear immediately postoperatively, but rather more than 1 year later, and usually occurs 1-3 h after meals. While rare, insulinoma has been reported after bariatric surgery. Clinical factors which should raise suspicion for insulinoma and the need for comprehensive clinical and biochemical evaluation include hypoglycemia occurring in the fasting state, predating bariatric surgery, and/or worsening immediately postoperatively, and lack of response to conservative therapy. Localization and successful resection of insulinoma can be achieved using novel endoscopic ultrasound and surgical approaches. In summary, hypoglycemia presenting shortly after gastric bypass or with a dominant fasting pattern should be fully evaluated to exclude insulinoma. Additionally, evaluation prior to gastric bypass should include screening for history of hypoglycemia symptoms.

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.

Mechanisms of Diabetes Improvement Following Bariatric/Metabolic Surgery

More than 20 years ago, Pories et al. published a seminal article, "Who Would Have Thought It? An Operation Proves to Be the Most Effective Therapy for Adult-Onset Diabetes Mellitus." This was based on their observation that bariatric surgery rapidly normalized blood glucose levels in obese people with type 2 diabetes mellitus (T2DM), and 10 years later, almost 90% remained diabetes free. Pories et al. suggested that caloric restriction played a key role and that the relative contributions of proximal intestinal nutrient exclusion, rapid distal gut nutrient delivery, and the role of gut hormones required further investigation. These findings of T2DM improvement/remission after bariatric surgery have been widely replicated, together with the observation that bariatric surgery prevents or delays incident T2DM. Over the ensuing two decades, important glucoregulatory roles of the gastrointestinal (GI) tract have been firmly established. However, the physiological and molecular mechanisms underlying the beneficial glycemic effects of bariatric surgery remain incompletely understood. In addition to the mechanisms proposed by Pories et al., changes in bile acid metabolism, GI tract nutrient sensing and glucose utilization, incretins, possible anti-incretin(s), and the intestinal microbiome are implicated. These changes, acting through peripheral and/or central pathways, lead to reduced hepatic glucose production, increased tissue glucose uptake, improved insulin sensitivity, and enhanced β-cell function. A constellation of factors, rather than a single overarching mechanism, likely mediate postoperative glycemic improvement, with the contributing factors varying according to the surgical procedure. Thus, different bariatric/metabolic procedures provide us with experimental tools to probe GI tract physiology. Embracing this approach through the application of detailed phenotyping, genomics, metabolomics, and gut microbiome studies will enhance our understanding of metabolic regulation and help identify novel therapeutic targets.

Risk of post-gastric bypass surgery hypoglycemia in nondiabetic individuals: A single center experience

OBJECTIVE

The epidemiology of post-gastric bypass surgery hypoglycemia (PGBH) is incompletely understood. This study aimed to evaluate the risk of PGBH among nondiabetic patients and associated factors.

METHODS

A cohort study of nondiabetic patients who underwent Roux-en-Y gastric bypass (RYGB) was conducted. PGBH was defined by any postoperative record of glucose < 60 mg/dL, diagnosis of hypoglycemia, or any medication use for treatment of PGBH. Kaplan-Meier analysis was used to describe PGBH occurrence, log-rank tests, and Cox regression to examine associated factors.

RESULTS

Of the 1,206 eligible patients, 86% were female with mean age of 43.7 years, mean preoperative BMI of 48.7 kg/m(2) , and a mean follow-up of 4.8 years. The cumulative incidence of hypoglycemia at 1 and 5 years post-RYGB was 2.7% and 13.3%, respectively. Incidence of PGBH was identified in 158 patients and was associated with lower preoperative BMI (P = 0.048), lower preoperative HbA1c (P = 0.012), and higher 6-month percent of excess body weight loss (%EWL) (P = 0.001). A lower preoperative HbA1c (HR = 1.73, P = 0.0034) and higher 6-month %EWL (HR = 1.96, P = 0.0074) remained independently correlated with increased risk for PGBH in multi-regression analysis.

CONCLUSIONS

The 5-year incidence of PGBH among nondiabetic individuals was 13.3% and was associated with a lower preoperative HbA1c and greater weight loss at 6 months following surgery.

Mechanisms of improved glucose handling after metabolic surgery: the big 6

For some time, it has been clear that elevated glucose is detrimental to the organism. A plethora of medicines have been introduced to reduce the fasting and postprandial glucose levels (including insulin, glucagon-like peptide receptor 1 [GLP-1] agonists, and sodium-glucose co-transporter 2 [SGLT2] inhibitors, among others). Although these medications are useful to reduce tissue exposure to glucose, no single compound and no combination have been able to totally normalize the blood sugar. Thus, it was astonishing when it was reported that surgery of the gastrointestinal tract could not only reduce obesity but also normalize the blood sugar. These discoveries have transformed diabetes research. What is it about bariatric surgery that causes the remarkable amelioration of glucose homeostasis dysregulation? The answer to this million dollar question is a billion dollar answer. However, a new perspective could shed some light and help provide a clear path for investigation. Instead of asking what does bariatric surgery do to change the pathophysiology, we can ask what pathophysiology and risk factors confer a greater success with remission and improved disease state after surgery. Work from our laboratory and others can help to offer a physiologic basis for which mechanisms may be put into play when the anatomy is altered during surgery. Here, we do not offer an explanation of the mechanism of action of bariatric surgery, but rather provide a background on the regulation of blood glucose and how it is altered during both the diseased state and, as available, the remission state.

A novel technique of Roux-en-Y gastric bypass reversal for postprandial hyperinsulinemic hypoglycaemia: A case report

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Postprandial hypoglycemia may be a serious adverse effect following Roux-en-Y gastric bypass surgery.

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Most patient can be treated with diet and pharmacological agents, but some patients need surgical reversals.

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This Roux-en-Y gastric bypass reversal alleviates severe postprandial hyperinsulinaemic hypoglycaemia.

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The technique retains some component of rapid transit of food into a shorter alimentary limb in an attempt to reduce weight regain.

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This new surgical procedure also attenuates s-GLP-1 and s-insulin responses along with improved p-glucose.

Background

We describe an evaluation of the effects of partial Roux-en-Y gastric bypass (RYGB) reversal on postprandial hyperinsulinaemic hypoglycaemia, insulin and GLP-1 levels.

Case summary

A 37 year old man was admitted with neuroglycopenia (plasma–glucose 1.6 mmol/l) 18 months after RYGB, with normal 72 h fasting test and abdominal CT. Despite dietary modifications and medical treatment, the hypoglycaemic episodes escalated in frequency. Feeding by a gastrostomy tube positioned in the gastric remnant did not prevent severe episodes of hypoglycaemia. A modified reversal of the RYGB was performed. Mixed meal tests were done perorally (PO), through the gastrostomy tube 1 (GT1), 4 weeks (GT2) after placement and 4 weeks after reversal (POr), with assessment of glucose, insulin and GLP-1 levels.

Results

Plasma–glucose increased to a maximum of 9.6, 5.4, 6.5 and 5.8 mmol/l at the PO, GT1, GT2 and POr tests respectively. The corresponding insulin levels were 2939, 731, 725 and 463 pmol/l. A decrease of plasma–glucose followed: 2.2, 3.0, 3.9 and 2.9 mmol/l respectively and insulin levels were suppressed at 150 min: 45, 22, 21 and 14 pmol/l, respectively. GLP-1 levels increased in the PO test (60 min: 122 pmol/l, 21 fold of basal), but was attenuated in the two latter tests (12–23 pmol/l at 60 min).

Conclusions

Reduction of plasma–glucose, insulin and GLP-1 excursions and symptoms were seen after gastric tube placement and partial RYGB reversal. This attenuation of GLP-1 response to feeding could reflect an adaptation to nutrients.

Hyperinsulinemic Hypoglycemia after Bariatric Surgery: Diagnosis and Management Experience from a Spanish Multicenter Registry

BACKGROUND

Severe postprandial hypoglycemia after bariatric surgery is a rare but invalidating complication. Our aim was to describe the different tests performed for its diagnosis and their outcomes as well as the response to the prescribed pharmacological and surgical treatments.

METHODS

Multicenter, retrospective systematic review of cases with recurrent severe postprandial hypoglycemia.

RESULTS

Over 11 years of follow-up, 22 patients were identified. The test most used to provoke hypoglycemia was the oral glucose load test followed by the mixed meal test which was the least standardized test. With pharmacological treatment, 3 patients were symptom-free (with octreotide) and in 12 patients hypoglycemic episodes were attenuated. Seven patients had persistent hypoglycemic episodes and underwent surgery. Partial pancreatectomy was performed in 3 patients who had positive selective arterial calcium stimulation, and nesidioblastosis was confirmed in 2 patients. Reconversion to normal anatomy was performed in 3 patients, and 1 patient underwent a resection of the 'candy cane' roux limb, with resolution of hypoglycemia in all cases.

CONCLUSIONS

There is high heterogeneity in the evaluation and treatment options for postoperative hypoglycemia. In patients that do not respond to pharmacological treatment, reconstruction of gastrojejunal continuity may be the safest and most successful procedure.