Defining clinically important hypoglycemia in patients with postbariatric hypoglycemia

Does GLP-1 cause post-bariatric hypoglycemia: 'Computer says no'

BACKGROUND AND OBJECTIVE

Patients who underwent Roux-en-Y Gastric Bypass surgery for treatment of obesity or diabetes can suffer from post-bariatric hypoglycemia (PBH). It has been assumed that PBH is caused by increased levels of the hormone GLP-1. In this research, we elucidate the role of GLP-1 in PBH with a physiology-based mathematical model.

METHODS

The Eindhoven Diabetes Simulator (EDES) model, simulating postprandial glucose homeostasis, was adapted to include the effect of GLP-1 on insulin secretion. Parameter sensitivity analysis was used to identify parameters that could cause PBH. Virtual patient models were created by defining sets of models parameters based on 63 participants from the HypoBaria study cohort, before and one year after bariatric surgery.

RESULTS

Simulations with the virtual patient models showed that glycemic excursions can be correctly simulated for the study population, despite heterogeneity in the glucose, insulin and GLP-1 data. Sensitivity analysis showed that GLP-1 stimulated insulin secretion alone was not able to cause PBH. Instead, analyses showed the increased transit speed of the ingested food resulted in quick and increased glucose absorption in the gut after surgery, which in turn induced postprandial glycemic dips. Furthermore, according to the model post-bariatric increased rate of glucose absorption in combination with different levels of insulin sensitivity can result in PBH.

CONCLUSIONS

Our model findings implicate that if initial rapid improvement in insulin sensitivity after gastric bypass surgery is followed by a more gradual decrease in insulin sensitivity, this may result in the emergence of PBH after prolonged time (months to years after surgery).

Postbariatric hypoglycemia, abdominal pain and gastrointestinal symptoms after Roux-en-Y gastric bypass explored by continuous glucose monitoring

BACKGROUND

Abdominal pain and postbariatric hypoglycemia (PBH) are common after bariatric surgery.

OBJECTIVES

This study aimed to explore the potential relationship between abdominal pain, gastrointestinal symptoms, and PBH more than a decade after Roux-en-Y gastric bypass (RYGB) and whether continuous glucose monitoring (CGM) with dietary intervention has an educational role in reducing symptoms.

SUBJECTS

At two public hospitals in Norway (one University Hospital) 22 of 46 invited patients who reported abdominal pain more than weekly took part. Recruited from a prospective follow-up study of 546 patients 14.5 years after RYGB.

METHODS

They used a CGM for two 14-day periods, with a dietary intervention between periods. The Gastrointestinal Symptom Rating Scale (GSRS) and the Dumping Severity Score (DSS) questionnaires were completed at the start and end of the study.

RESULTS

The 22 women had preoperative age 39.6 ± 7.7 years and body mass index (BMI) 42.0 ± 4.0 kg/m2, present age 54.6 ± 7.7 years and BMI 29.8 ± 4.8 kg/m2. The total GSRS score and DSS of early dumping decreased after the diet intervention. The number of events with Level 1 (<3.9 mmol/L) or Level 2 (<3.0 mmol/L) hypoglycemia did not change in the second period. Half of the patients had fewer, three had unchanged, and eight had more frequent events with Level 1 hypoglycemia after the intervention. Ten patients had Level 2 hypoglycemia.

CONCLUSION

Though inconclusive findings, a personalized dietary intervention reduces GSRS. This intervention was accompanied by lower mean absolute glucose in patients with recurrent abdominal pain after bariatric surgery. However, further studies are needed to explore the benefits of CGM in this setting.

Relationship Between Symptom Perception and Postprandial Glycemic Profiles in Patients With Postbariatric Hypoglycemia After Roux-en-Y Gastric Bypass Surgery

OBJECTIVE

Post-bariatric surgery hypoglycemia (PBH) is a metabolic complication of Roux-en-Y gastric bypass (RYGB). Since symptoms are a key component of the Whipple's triad to diagnose nondiabetic hypoglycemia, we evaluated the relationship between self-reported symptoms and postprandial sensor glucose profiles.

RESEARCH DESIGN AND METHODS

Thirty patients with PBH after RYGB (age: 50.1 [41.6-60.6] years, 86.7% female, BMI: 26.5 [23.5-31.2] kg/m2; median [interquartile range]) wore a blinded Dexcom G6 sensor while recording autonomic, neuroglycopenic, and gastrointestinal symptoms over 50 days. Symptoms (overall and each type) were categorized into those occurring in postprandial periods (PPPs) without hypoglycemia, or in the preceding dynamic or hypoglycemic phase of PPPs with hypoglycemia (nadir sensor glucose <3.9 mmol/L). We further explored the relationship between symptoms and the maximum negative rate of sensor glucose change and nadir sensor glucose levels.

RESULTS

In 5,851 PPPs, 775 symptoms were reported, of which 30.6 (0.0-59.9)% were perceived in PPPs without hypoglycemia, 16.7 (0.0-30.1)% in the preceding dynamic phase and 45.0 (13.7-84.7)% in the hypoglycemic phase of PPPs with hypoglycemia. Per symptom type, 53.6 (23.8-100.0)% of the autonomic, 30.0 (5.6-80.0)% of the neuroglycopenic, and 10.4 (0.0-50.0)% of the gastrointestinal symptoms occurred in the hypoglycemic phase of PPPs with hypoglycemia. Both faster glucose dynamics and lower nadir sensor glucose levels were related with symptom perception.

CONCLUSIONS

The relationship between symptom perception and PBH is complex, challenging clinical judgement and decision-making in this population.

Use of Continuous Glucose Monitoring in Patients Following Bariatric Surgery: A Scoping Review

The objective of this scoping review was to summarize the emerging literature on the use of continuous glucose monitoring (CGM) in post-bariatric surgery patients, with a focus on its features (e.g., device, mode, and accuracy), as well as purposes and outcomes of utilization. Three databases (PubMed, EMBASE, and Web of Science) were searched to obtain relevant studies. Results suggested that most studies used CGM for 3-7 days under blinded mode. Accuracy data were available in only one study, which reported a mean absolute relative difference of 21.7% for Freestyle Libre. The primary applications of CGM were for elucidating glucose patterns and assessing glycemic treatment outcomes. No study has tested the effect of CGM as an intervention strategy to enhance glucose control.

Persistent post-bariatric-surgery hypoglycemia: A long-term follow-up reassessment

BACKGROUND AND AIM

Post-bariatric-surgery hypoglycemia (PBH) is a serious complication of bariatric surgery (BS). In our previous study about three quarters of the patients developed PBH. However long-term follow-up data is lacking to determine whether this condition improves with time. The aim of the current study was to re-assess post-BS patients who participated in our previous study and determine whether there are changes in the frequency and/or severity of hypoglycemic events.

METHODS AND RESULTS

Twenty-four post-BS, post Roux-en-Y gastric-bypass (RYGB = 10), post omega-loop gastric-bypass (OLGB = 9) and post sleeve-gastrectomy (SG = 5) individuals were reevaluated in a follow-up study 34.4 ± 4 months after their previous assessment and 67 ± 17 months since surgery. The evaluation included: a dietitian assessment, a questionnaire, meal-tolerance test (MTT) and a one-week masked continuous glucose monitoring (CGM). Hypoglycemia and severe hypoglycemia were defined by glucose levels ≤54 mg/dl and ≤40 mg/dl, respectively. Thirteen patients reported questionnaire meal-related complaints, mainly non-specific. During MTT, hypoglycemia occurred in 75% of the patients, and severe hypoglycemia in a third, but none was associated with specific complaints. During CGM, 66% of patients developed hypoglycemia and 37% had severe hypoglycemia. We did not observe significant improvements in hypoglycemic events compared to the previous assessment. Despite the high frequency of hypoglycemia, it did not necessitate hospitalizations or lead to death.

CONCLUSIONS

PBH did not resolve within long-term follow-up. Intriguingly, most patient were unaware of these events which can lead to underestimation by the medical staff. Further studies are needed to determine possible long term sequela of repeated hypoglycemia.

Counter-regulatory responses to postprandial hypoglycaemia in patients with post-bariatric hypoglycaemia vs surgical and non-surgical control individuals

AIMS/HYPOTHESIS

Post-bariatric hypoglycaemia is an increasingly recognised complication of bariatric surgery, manifesting particularly after Roux-en-Y gastric bypass. While hyperinsulinaemia is an established pathophysiological feature, the role of counter-regulation remains unclear. We aimed to assess counter-regulatory hormones and glucose fluxes during insulin-induced postprandial hypoglycaemia in patients with post-bariatric hypoglycaemia after Roux-en-Y gastric bypass vs surgical and non-surgical control individuals.

METHODS

In this case-control study, 32 adults belonging to four groups with comparable age, sex and BMI (patients with post-bariatric hypoglycaemia, Roux-en-Y gastric bypass, sleeve gastrectomy and non-surgical control individuals) underwent a postprandial hypoglycaemic clamp in our clinical research unit to reach the glycaemic target of 2.5 mmol/l 150-170 min after ingesting 15 g of glucose. Glucose fluxes were assessed during the postprandial and hypoglycaemic period using a dual-tracer approach. The primary outcome was the incremental AUC of glucagon during hypoglycaemia. Catecholamines, cortisol, growth hormone, pancreatic polypeptide and endogenous glucose production were also analysed during hypoglycaemia.

RESULTS

The rate of glucose appearance after oral administration, as well as the rates of total glucose appearance and glucose disappearance, were higher in both Roux-en-Y gastric bypass groups vs the non-surgical control group in the early postprandial period (all p<0.05). During hypoglycaemia, glucagon exposure was significantly lower in all surgical groups vs the non-surgical control group (all p<0.01). Pancreatic polypeptide levels were significantly lower in patients with post-bariatric hypoglycaemia vs the non-surgical control group (median [IQR]: 24.7 [10.9, 38.7] pmol/l vs 238.7 [186.3, 288.9] pmol/l) (p=0.005). Other hormonal responses to hypoglycaemia and endogenous glucose production did not significantly differ between the groups.

CONCLUSIONS/INTERPRETATION

The glucagon response to insulin-induced postprandial hypoglycaemia is lower in post-bariatric surgery individuals compared with non-surgical control individuals, irrespective of the surgical modality. No significant differences were found between patients with post-bariatric hypoglycaemia and surgical control individuals, suggesting that impaired counter-regulation is not a root cause of post-bariatric hypoglycaemia.

TRIAL REGISTRATION

ClinicalTrials.gov NCT04334161.

Study protocol for a randomised, double-blind, placebo-controlled crossover trial assessing the impact of the SGLT2 inhibitor empagliflozin on postprandial hypoglycaemia after gastric bypass

INTRODUCTION

Postprandial hypoglycaemia after gastric bypass surgery (also known as postbariatric hypoglycaemia or PBH) is an increasingly encountered clinical problem. PBH is characterised by meal-induced rapid spikes and consequent falls in glycaemia, resulting in both hypoglycaemia burden and high glycaemic variability. Despite its frequency, there is currently no approved pharmacotherapy. The purpose of this investigation is to evaluate efficacy and safety of empagliflozin 25 mg, a sodium-glucose cotransporter 2-inhibitor, to reduce glucose excursions and hypoglycaemia burden in patients with PBH after gastric bypass surgery.

METHODS AND ANALYSIS

In a prospective, single-centre, randomised, double-blind, placebo-controlled, crossover trial, we plan to enrol 22 adults (≥18 years) with PBH after Roux-en-Y gastric bypass surgery (plasma or sensor glucose <3.0 mmol/L). Eligible patients will be randomised to receive empagliflozin 25 mg and placebo once daily, each for 20 days, in random order. Study periods will be separated by a 2-6 weeks wash-out period. The primary efficacy outcome will be the amplitude of plasma glucose excursion (peak to nadir) during a mixed meal tolerance test. Results will be presented as paired-differences±SD plus 95% CIs with p values and hypothesis testing for primary and secondary outcomes according to intention-to-treat. Secondary outcomes include continuous glucose monitoring-based outcomes, further metabolic measures and safety.

ETHICS AND DISSEMINATION

The DEEP-EMPA trial (original protocol title: Randomized, double-blind, placebo-controlled crossover trialassessing the impact of the SGLT2 inhibitor empagliflozin onpostprandial hypoglycaemia after gastric bypass) was approved by the Bern Ethics Committee (ID 2021-01187) and Swissmedic (Ref. Number: 102663190) in October and November 2021, respectively. First results are expected in the first quarter of 2023 and will be disseminated via peer-reviewed publications and presented at national and international conferences. The acronym DEEP was derived from an overarching project title (DEciphering the Enigma of Postprandial Hyperinsulinaemic Hypoglycaemia after Bariatric Surgery), the term EMPA stands for the drug empagliflozin.

TRIAL REGISTRATION NUMBER

NCT05057819.

Digital Solutions to Diagnose and Manage Postbariatric Hypoglycemia

Postbariatric hypoglycemia (PBH) is an increasingly recognized late metabolic complication of bariatric surgery, characterized by low blood glucose levels 1-3 h after a meal, particularly if the meal contains rapid-acting carbohydrates. PBH can often be effectively managed through appropriate nutritional measures, which remain the cornerstone treatment today. However, their implementation in daily life continues to challenge both patients and health care providers. Emerging digital technologies may allow for more informed and improved decision-making through better access to relevant data to manage glucose levels in PBH. Examples include applications for automated food analysis from meal images, digital receipts of purchased food items or integrated platforms allowing the connection of continuously measured glucose with food and other health-related data. The resulting multi-dimensional data can be processed with artificial intelligence systems to develop prediction algorithms and decision support systems with the aim of improving glucose control, safety, and quality of life of PBH patients. Digital innovations, however, face trade-offs between user burden vs. amount and quality of data. Further challenges to their development are regulatory non-compliance regarding data ownership of the platforms acquiring the required data, as well as user privacy concerns and compliance with regulatory requirements. Through navigating these trade-offs, digital solutions could significantly contribute to improving the management of PBH.