Symptomatic Hypoglycemia After Gastric Bypass: Incidence and Predictive Factors in a Cohort of 1,138 Consecutive Patients

Adverse Health Outcomes Associated with Hypoglycemia Following Bariatric Surgery

Introduction: Hypoglycemia is prevalent among patients postbariatric surgery, but its clinical implications remain unclear. The purpose of this study was to examine the longitudinal associations of hypoglycemia (i.e., occurrence in the past 3 months, frequency in the past 7 days, number of severe episodes in the past 3 months, and symptoms) with depressive symptoms, quality of life (QoL), work productivity, and weight loss over an 84-month follow-up period after bariatric surgery. Methods: This secondary analysis used data from the Longitudinal Assessment of Bariatric Surgery-2 study. Hypoglycemia, depressive symptoms, QoL, and work productivity were self-reported. Weight was primarily based on objective measures. Linear mixed modeling with time-lagged techniques was used for analysis, adjusting for potential covariates such as age and gender. Results: Across the 84-month follow-up, 20%-30% of participants (N = 552) reported experiencing hypoglycemia in the past 3 months. Hypoglycemia occurrence was positively associated with depressive symptoms [β = 2.4; 95% confidence interval (CI): 1.7, 3.0] and negatively associated with physical (β = -4.2; 95% CI: -5.1, -3.3) and mental QoL (β = -3.4; 95% CI: -4.4, -2.4). These associations became stronger with increased frequency of hypoglycemia, a higher number of severe episodes, and the presence of symptoms. Additionally, hypoglycemia occurrence was associated with several domains of work productivity, including presenteeism (β = 5.8; 95% CI: 3.4, 8.2), work productivity loss (β = 5.6; 95% CI: 2.6, 8.6), and activity impairment (β = 8.8; 95% CI: 6.0, 11.6), with the strength of these associations increasing with greater hypoglycemic frequency. Conclusions: This study highlights the critical role of hypoglycemia in patients' physical and psychosocial well-being postbariatric surgery. Future studies employing more rigorous measures of hypoglycemia and expanded outcomes (e.g. cognitive function) are needed to fully understand its clinical relevance.

Incidence and risk factors of post-metabolic and bariatric surgery hypoglycemia: a systematic review

OBJECTIVE

This study aimed to systematically review the existing literature to summarize the incidence and risk factors of post-metabolic and bariatric surgery hypoglycemia (MBSH).

METHODS

We searched PubMed, Medline, Embase, and the Cochrane Library databases for the studies published from inception to August 2023. Randomized controlled trials and analytical studies that investigated the incidence or risk factors of MBSH after different surgery techniques (including Roux-en-Y gastric bypass, sleeve gastrectomy, gastric banding, duodenal switch, omega-loop gastric bypass, and vertical banded gastroplasty) were involved. The incidence and risk factors of MBSH were extracted and described separately based on different diagnostic criteria and then summarized the risk factors and their statistical findings collectively.

RESULTS

Twenty-nine studies were reviewed with follow-up ranging from 1 to 22 years. The incidence of MBSH ranged significantly across different diagnostic methods: 2.6-66.4% (self-report), 6.6-61.8% (oral glucose tolerance test), 29.4-78.6% (mixed-meal tolerance test), and 50-75% (continuous glucose monitoring). Patients with a mean age of 49.8 years and 89.0% of them were women with a better glycemic control who undergo RYGB and achieve 86.5% of estimated weight loss from surgery should be particularly vigilant about the possibility of developing MBSH. Distinct biomarkers such as IGF-1 (OR 1.06), fasting glicentin (AUC 0.81), HbA1c (AUC 0.76), and absolute weight reduction (AUC 0.72), greater fluctuations in glucose (OR 1.98) are valuable in promptly detecting MBSH. Specifically, patients with prior cholecystectomy or antidepressant therapy should be particularly cautious.

CONCLUSION

The review highlights higher MBSH risk in younger women with significant weight loss after RYGB, and those with prior cholecystectomy or antidepressant use. Systematic summarization of MBSH criteria allowed us to identify the predictors for MBSH, which can aid in early diagnosis and treatment, reducing the need for prolonged monitoring.

Predictors and weight impact of postbariatric hypoglycemia after Roux-en-Y gastric bypass surgery: a prospective observational cohort study

BACKGROUND

Postbariatric hypoglycemia (PBH) is a challenging condition affecting quality of life of patients after bariatric surgery. However, its incidence and predictive factors remain debated.

OBJECTIVES

To determine the incidence of PBH, identify predictors of PBH and assess its association with weight trajectory after bariatric surgery.

SETTING

University Hospital.

METHODS

Prospective observational cohort study including 222 nondiabetic patients who underwent Roux-en-Y gastric bypass between 2014 and 2021, had an oral glucose tolerance test (OGTT) and/or A1C (glycated hemoglobin) measurement prior to surgery and were followed for at least 12 months. Diagnosis of PBH was made when symptoms of hypoglycemia were accompanied by a postprandial plasma glucose level < 3.9 mmol/l or a glycemia < 3.9 mmol/l during continuous glucose monitoring, with resolution of symptomatology after carbohydrate consumption. Univariable and multivariable logistic regression analyses were performed to identify factors associated with PBH.

RESULTS

Out of 222 patients, 71 (32%) were diagnosed with PBH. The highest incidence rate was observed at 2 years postbariatric surgery with a cumulative incidence of 26.5%. Predictive factors for higher risk of PBH were younger age at surgery (OR = .97; 95% CI: .94-.99; P = .049) and early dumping syndrome (OR = 3.05; 95% CI: 1.62-6.04; P = .0008). In multivariable logistic regression, higher glycemia at 2 hours during preoperative OGTT was associated with lower risk of PBH (OR = .8; 95% CI: .63-.98; P = .04). PBH was not associated with weight trajectory after surgery in our cohort.

CONCLUSIONS

Younger age at time of surgery and lower blood glucose at 120 minute during preoperative OGTT are risk factors for PBH. Early dumping syndrome is significantly associated with PBH and could be used as a red flag to help identify patients at risk of PBH.

An Imbalance of Pathophysiologic Factors in Late Postprandial Hypoglycemia Post Bariatric Surgery: A Narrative Review

With a rise in obesity and more patients opting for bariatric surgery, it becomes crucial to understand associated complications like postprandial hypoglycemia (PPH). After bariatric surgery, significant changes are seen in insulin sensitivity, beta cell function, glucagon-like peptide 1 (GLP-1) levels, the gut microbiome, and bile acid metabolism. And in a small subset of patients, exaggerated imbalances in these functional and metabolic processes lead to insulin-glucose mismatch and hypoglycemia. The main treatment for PPH involves dietary modifications. For those that do not respond, medications or surgical interventions are considered to reverse some of the imbalances. We present a few case reports of patients that safely tolerated GLP-1 agonists. However, larger randomized control trials are needed to further characterize PPH and understand its treatment.

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.

Roux-en-Y Gastric Bypass Increases Glycemic Excursions During Pregnancy and Postpartum: A Prospective Cohort Study

OBJECTIVE

Roux-en-Y gastric bypass (RYGB) and pregnancy markedly alter glucose metabolism, but evidence on glucose metabolism in pregnancy after RYGB is limited. Thus, the aims of the Bariatric Surgery and Consequences for Mother and Baby in Pregnancy study were to investigate interstitial glucose (IG) profiles during pregnancy, risk factors associated with hypoglycemia, and the association between fetal growth and hypoglycemia in pregnant women previously treated with RYGB, compared with control participants.

RESEARCH DESIGN AND METHODS

Twenty-three pregnant women with RYGB and 23 BMI- and parity-matched pregnant women (control group) were prospectively studied with continuous glucose monitoring in their first, second, and third trimesters, and 4 weeks postpartum. Time in range (TIR) was defined as time with an IG level of 3.5-7.8 mmol/L.

RESULTS

Women with RYGB were 4 years (interquartile range [IQR] 0-7) older than control participants. Pregnancies occurred 30 months (IQR 15-98) after RYGB, which induced a reduction in BMI from 45 kg/m2 (IQR 42-54) presurgery to 32 kg/m2 (IQR 27-39) prepregnancy. Women with RYGB spent decreased TIR (87.3-89.5% vs. 93.3-96.1%; P < 0.01) owing to an approximately twofold increased time above range and increased time below range (TBR) throughout pregnancy and postpartum compared with control participants. Women with increased TBR had a longer surgery-to-conception interval, lower nadir weight, and greater weight loss after RYGB. Finally, women giving birth to small-for-gestational age neonates experienced slightly increased TBR.

CONCLUSIONS

Women with RYGB were more exposed to hypoglycemia and hyperglycemia during pregnancy compared with control participants. Further research should investigate whether hypoglycemia during pregnancy in women with RYGB is associated with decreased fetal growth.

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.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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