Roux-en-Y Gastric Bypass Increases Glycemic Variability and Time in Hypoglycemia in Patients With Obesity and Prediabetes or Type 2 Diabetes: A Prospective Cohort Study

Increased glycemic variability in pregnant women with Roux-en-Y gastric bypass compared with sleeve gastrectomy

INTRODUCTION

Bariatric surgery is associated with adverse pregnancy outcomes such as reduced birth weight and premature birth. One possible mechanism for this is increased glycemic variability (GV) which occurs after bariatric surgery. The objective of this study was to compare the effect of Roux-en-Y gastric bypass (RYGB) versus vertical sleeve gastrectomy (SG) on GV during pregnancy and to investigate the relationships of GV, type of bariatric surgery and maternal and neonatal outcomes.

RESEARCH DESIGN AND METHODS

Fourteen pregnant women after RYGB and 14 after SG were investigated with continuous glucose monitoring in their second or third trimester in this observational study carried out as part of routine clinical care.

RESULTS

Pregnant women with RYGB had similar mean interstitial glucose values but significantly increased indices of GV and a lower %time in range 3.9-7.8 mmol/L (70-140 mg/dL), compared with SG.

CONCLUSIONS

Pregnant women who have undergone RYGB have greater GV during pregnancy compared with those who have undergone SG. Further research is needed to establish the relationship between GV and pregnancy outcomes to determine the preferred bariatric operation in women of reproductive age, and whether interventions to reduce GV might improve outcomes.

Randomized, double-blind, placebo-controlled crossover trial of once daily empagliflozin 25 mg for the treatment of postprandial hypoglycaemia after Roux-en-Y gastric bypass

Aims To investigate the effect of empagliflozin on glucose dynamics in individuals suffering from postbariatric hypoglycaemia (PBH) after Roux-en-Y gastric bypass (RYGB). Methods Twenty-two adults with PBH after RYGB were randomized to empagliflozin 25 mg or placebo once daily over 20 days in a randomized, double-blind, placebo-controlled, crossover trial. The primary efficacy outcome was the amplitude of plasma glucose excursion (peak to nadir) during a mixed meal tolerance test (MMTT). Outcomes of the outpatient period were assessed using continuous glucose monitoring (CGM) and an event-tracking app. Results The amplitude of glucose excursion during the MMTT was 8.1±2.4 mmol/L with empagliflozin vs 8.1±2.6 mmol/L with placebo (mean±SD, p=0.807). CGM-based mean amplitude of glucose excursion (MAGE) during the 20 day-period was lower with empagliflozin than placebo (4.8±1.3 vs 5.2±1.6. p=0.028). Empagliflozin reduced the time spent with CGM values >10.0 mmol/L (3.8±3.5 % vs. 4.7±3.8 %, p =0.009), but not the time spent with CGM values <3.0 mmol/L (1.7±1.6 % vs. 1.5±1.5 %, p=0.457). No significant difference was observed in the quantity and quality of recorded symptoms. Eleven adverse events occurred with empagliflozin (three drug-related) and six with placebo. Conclusions Empagliflozin 25 mg reduces glucose excursions but not hypoglycaemia in individuals with PBH.

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.

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.

Roux-en-Y gastric bypass versus best medical treatment for type 2 diabetes mellitus in adults with body mass index between 27 and 32 kg/m2: A 5-year randomized controlled trial

AIMS

To evaluate the effects of Roux-en-Y gastric bypass (RYGB) versus best medical treatment in Asians with type 2 diabetes mellitus (T2DM) and class I obesity.

METHODS

In this 5-year single-centre, open-label randomized controlled trial, participants were randomized to RYGB or medical treatment including newer classes of diabetes medications (ClinicalTrials.gov:NCT02041234). The primary endpoint was diabetes remission defined as HbA1c ≤ 6% (≤42 mmol/mol) and discontinuation of glucose-lowering medication at 12 months post-intervention and beyond. Glycaemia and weight changes were assessed. Continuous glucose monitoring was performed.

RESULTS

Of 28 subjects randomized, 26 were analyzed in the final cohort (14 medical, 12 RYGB; age:44 ± 10 years, 34.6% males, BMI:29.4 ± 1.6 kg/m²). At 12 months, 50% of RYGB subjects achieved diabetes remission; 83% stopped all glucose-lowering medications. By year 5, 42% were in remission. None attained diabetes remission in the medical group. Percentage declines in fasting plasma glucose, HbA1c and BMI were significantly greater in the RYGB arm (all P < 0.05). Early improvements in glycaemic variability and time in range were similar in both treatment arms. Hypoglycaemia and surgical complications were observed in some RYGB subjects.

CONCLUSIONS

Over 5 years, RYGB outperforms best medical treatment in glycemia and weight improvements for Asians with T2DM and class I obesity.

Utility of Continuous Glucose Monitoring vs Meal Study in Detecting Hypoglycemia After Gastric Bypass

CONTEXT

Gastric bypass (GB) increases postprandial glucose excursion, which in turn can predispose to the late complication of hypoglycemia. Diagnosis remains challenging and requires documentation of symptoms associated with low glucose and relief of symptom when glucose is normalized (Whipple triad).

OBJECTIVE

To compare the yield of mixed meal test (MMT) and continuous glucose monitoring system (CGMS) in detecting hypoglycemia after GB.

SETTING

The study was conducted at General Clinical Research Unit, Cincinnati Children's Hospital (Cincinnati, OH, USA).

METHODS

Glucose profiles were evaluated in 15 patients with documented recurrent clinical hypoglycemia after GB, 8 matched asymptomatic GB subjects, and 9 healthy weight-matched nonoperated controls using MMT in a control setting and CGMS under free-living conditions.

RESULTS

Patients with prior GB had larger glucose variability during both MMT and CGMS when compared with nonsurgical controls regardless of their hypoglycemic status. Sensitivity (71 vs 47%) and specificity (100 vs 88%) of MMT in detecting hypoglycemia was superior to CGMS.

CONCLUSIONS

Our findings indicate that a fixed carbohydrate ingestion during MMT is a more reliable test to diagnose GB-related hypoglycemia compared with CGMS during free-living state.

Post-Bariatric Hypoglycemia Is Associated with Endothelial Dysfunction and Increased Oxidative Stress

Post-bariatric hypoglycemia (PBH) is a potentially serious complication that may occur after bariatric surgery. Recurrent hypoglycemia may exert detrimental effects on vascular function. The aim of the present study was to evaluate endothelial function and oxygen reactive compounds in patients who experience PBH compared with controls. We performed a cross-sectional study on subjects with PBH (HYPO) and those without (NO-HYPO), detected by seven-day continuous glucose monitoring (CGM) performed at least twelve months after bariatric surgery. We enrolled 28 post-bariatric subjects (17.9% males, mean age 40.6 ± 10.7 years), with 18 in the HYPO group and 10 in the NO-HYPO group. In the two groups, we measured brachial artery flow-mediated dilation (FMD), oxidized low-density lipoproteins (oxLDL) and reactive oxygen metabolites (D-ROMs). The HYPO group had significantly lower FMD values than the NO-HYPO group (3.8% ± 3.0 vs. 10.5% ± 2.0, p < 0.001). A significant correlation was found between FMD and the time spent in hypoglycemia (rho = −0.648, p < 0.001), the number of hypoglycemic events (rho = −0.664, p < 0.001) and the mean glucose nadir (rho = 0.532, p = 0.004). The HYPO group showed significantly higher levels of D-ROMs (416.2 ± 88.7 UCARR vs. 305.5 ± 56.3 UCARR, p < 0.001) and oxLDLs (770.5 ± 49.7 µEq/L vs. 725.1 ± 51.6 µEq/L, p = 0.035) compared to the NO-HYPO group. In the multiple linear regression analysis, hypoglycemia independently predicted FMD values (β = −0.781, p < 0.001), D-ROMs (β = 0.548, p = 0.023) and oxLDL levels (β = 0.409, p = 0.031). PBH is associated with impaired endothelial function accompanied by increased oxidative stress.