Increased risk of OGTT-induced hypoglycemia after gastric bypass in severely obese patients with normal glucose tolerance

Combined laparoscopic Roux-en-Y gastric bypass reversal and gastric banding to treat severe hyperinsulinemic hypoglycemia: A case report and surgical video

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Non insulinoma pancreatogenous hypoglycemia syndrome is a recently described complication of Roux-en-Y gastric bypass

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Currently, there is no Gold Standard treatment.

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In this case, we successfully performed a combined laparoscopic reversal of gastric bypass and gastric banding

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.

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

OBJECTIVE

After Roux-en-Y gastric bypass (RYGB), postprandial hyperinsulinemic hypoglycemia (PPHH) is particularly critical because of the risk of trauma. The aim of this study was to assess the incidence and identify risk factors for symptomatic PPHH.

METHODS

Patients with RYGB were classified into moderate PPHH (MH) or severe hypoglycemia (SH), which is defined as patients with neuroglycopenic symptoms. Logistic multivariate linear regressions were performed to identify predictive factors for symptomatic PPHH and more specifically for SH with neuroglycopenic symptoms. Patients with diabetes and those with a follow-up shorter than 2 years were excluded.

RESULTS

Among the 1,138 patients, 44.2% had at least one episode of hypoglycemia with a mean delay of 25.5 (21.3) months, 32.6% had MH, and 11.6% had SH. The annual incidence rate of SH was 2.5% the first year, 3.7% the second year, and 1.5% the third year. Independent predictive factors for higher risk of SH were: younger age (odds ratio [OR] = 1.01; 95% CI: 1.05-16.69; P = 0.0007), lower BMI after RYGB (OR = 1.61; 95% CI: 1.17-2.22; P = 0.0035), and maximal weight loss (OR = 1.04; 95% CI = 1.39-1.23; P = 0.0106), whereas higher preoperative BMI was protective (OR = 0.78; 95% CI: 0.64-0.95; P = 0.0112).

CONCLUSIONS

This observational cohort study showed that the incidence of severe PPHH with neuroglycopenic symptoms after RYGB was higher than expected.

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.

Continuous Glucose Monitoring in Bariatric Patients Undergoing Laparoscopic Sleeve Gastrectomy and Laparoscopic Roux-En-Y Gastric Bypass

BACKGROUND

Few investigations have been conducted that compared blood glucose in patients with diabetes mellitus (DM2) and morbid obesity who had undergone laparoscopic sleeve gastrectomy (LSG) or gastric bypass (LRYGB). We aimed to compare the effects of these procedures using continuous glucose monitoring (CGM).

METHODS

We prospectively studied patients that had qualified for LSG or LRYGB. The inclusion criteria were DM2 of ≤ 5 years, for which patients were taking oral anti-diabetic drugs, or no glucose metabolism disorder; and morbid obesity. CGM was performed between admission and the 10th postoperative day.

RESULTS

We studied 16 patients with DM2 and 16 without. Eighteen patients underwent LSG and 14 underwent LRYGB. The median hemoglobin A1c was 5.5% (5.4-5.9%) in DM2 patients, which did not differ from control (p = 0.460). Preoperative mean daily glucose concentration was similar between DM2 and control patients (p = 0.622). For patients with DM2, LRYGB was associated with more frequent low glucose status, and these episodes lasted longer than in DM2 patients that underwent LSG (p = 0.035 and 0.049, respectively). DM2 patients that underwent LRYGB demonstrated lower glucose concentrations from third postoperative day than those that underwent LSG. Patients without DM2 did not demonstrate differences in daily mean glucose concentrations, or in incidence nor duration of hypoglycemia throughout the observation period.

CONCLUSION

A significantly larger reduction in interstitial glucose concentration is present from third day in patients with DM2 who undergo LRYGB vs. LSG, accompanied by a lower incidence and shorter duration of low glucose episodes.

Prevalence of hypoglycaemia in a random population after Roux-en-Y gastric bypass after a meal test

OBJECTIVE

Roux-en-Y gastric bypass (RYGB) is an effective way to induce sustainable weight loss and can be complicated by postprandial hyperinsulinaemic hypoglycaemia (PHH). To study the prevalence and the mechanisms behind the occurrence of hypoglycaemia after a mixed meal tolerance test (MMTT) in patients with primary RYGB.

DESIGN

This is a cross-sectional study of patients 4 years after primary RYGB.

METHODS

From a total population of 550 patients, a random sample of 44 patients completed the total test procedures. A standardized mixed meal was used as stimulus. Venous blood samples were collected at baseline, every 10 min during the first half hour and every 30 min until 210 min after the start. Symptoms were assessed by questionnaires. Hypoglycaemia is defined as a blood glucose level below 3.3 mmol/L.

RESULTS

The prevalence of postprandial hypoglycaemia was 48% and was asymptomatic in all patients. Development of hypoglycaemia was more frequent in patients with lower weight at surgery (P = 0.045), with higher weight loss after surgery (P = 0.011), and with higher insulin sensitivity calculated by the homeostasis model assessment indexes (HOMA2-IR, P = 0.014) and enhanced beta cell function (insulinogenic index at 20 min, P = 0.001).

CONCLUSION

In a randomly selected population 4 years after primary RYGB surgery, 48% of patients developed a hypoglycaemic event during an MMTT without symptoms, suggesting the presence of hypoglycaemia unawareness in these patients. The findings in this study suggest that the pathophysiology of PHH is multifactorial.

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.

Frequency of Hypoglycaemia after Different Bariatric Surgical Procedures

OBJECTIVES

The frequency of postprandial hypoglycaemia after different operative procedures of bariatric surgery (BS) is unknown, although this complication is potentially dangerous. Predictors and severity of hypoglycaemia after Roux-en-Y gastric bypass (RYGB), sleeve gastrectomy, and gastric banding were investigated in a large prospective study.

METHODS

This study was performed at an excellence centre for BS at a tertiary care institution. Data of 333 patients (mean BMI: 44.9 ± 9.6 kg/m2; mean age: 40 ± 10 years; 80.7% women) were analysed in a prospective study with a 2-year observation period after BS. All patients underwent a 2-hour oral glucose tolerance test (OGTT) with measurements of blood glucose (BG) and insulin. For the purpose of this study, hypoglycaemia was defined as a post-challenge BG <2.8 mmol/L during the OGTT.

RESULTS

72 (25.6%) of 281 patients showed post-challenge hypoglycaemia after surgery. Hypoglycaemia was different after various procedures: 32.6% of patients after RYGB, 22.6% after sleeve gastrectomy, but only 2.3% after gastric banding had hypoglycaemia. In the whole group, patients with hypoglycaemia had lost more weight (p = 0.013), had a slightly greater decrease in BMI (p = 0.037), a greater change in 2-hour post-challenge BG (p = 0.001), and a smaller change in 1-hour post-challenge insulin (p = 0.004) compared to patients without hypoglycaemia.

CONCLUSION

This prospective study shows a higher prevalence of severe hypoglycaemia (25.6%) after BS than anticipated from retrospective registers. A systematic evaluation of glucose and insulin levels by OGTT 2 years post-surgery may help to identify patients at increased risk for symptomatic and asymptomatic hypoglycaemia.

Incidence and Predictors of Hypoglycemia 1 Year After Laparoscopic Sleeve Gastrectomy

INTRODUCTION

Hypoglycemia is a known adverse event following gastric bypass. The incidence of hypoglycemia after laparoscopic sleeve gastrectomy (LSG) is still under investigation. The aim of our study was to verify the presence of oral glucose tolerance test (OGTT)-related hypoglycemia after LSG and to identify any baseline predictors of its occurrence.

METHODS

We analyzed 197 consecutive non-diabetic morbid obese patients that underwent LSG. All patients were studied before and 12 months after LSG. Evaluation included anthropometric parameters, 3-h OGTT for blood glucose (BG), insulin and c-peptide, lipid profile, interleukin-6 (IL-6), tumor necrosis factor alpha (TNF-α), highly sensitive C-reactive protein (hsCRP), and leptin. Hypoglycemia was defined as BG ≤ 2.7 mmol/l.

RESULTS

After surgery, 180 patients completed the OGTT. Eleven patients did not complete the test for gastric intolerance, and in six patients, the test was stopped earlier for the onset of severe symptomatic hypoglycemia. Of the patients, 61/186 (32.8%) had at least one OGTT-related hypoglycemia. The highest frequency of hypoglycemic events occurred 150' after glucose load (20.2%). At baseline, patients with hypoglycemic events after surgery (Hypo) were younger (40 ± 11 vs 46 ± 10 years; p < 0.001), less obese (BMI 46 ± 5.7 vs 48.4 ± 7.9 kg/m²; p < 0.05), and had a worse lipid profile as compared to patients without hypoglycemic events (N-Hypo). Moreover, after LSG, Hypo patients compared with N-Hypo presented a higher weight loss (%EBMIL 80 ± 20 vs 62 ± 21%; p < 0.001). Low age, low fasting glucose, and high triglyceride levels before LSG were independent predictors of hypoglycemia development after surgery (r ² = 0.131).

CONCLUSION

These findings confirm the high incidence of post-prandial hypoglycemia 1 year after LSG. Hypoglycemia is more frequent in younger patients with lower fasting glucose and higher triglyceride levels before 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.

Hypoglycemia during oral glucose tolerance test among post-bariatric surgery pregnant patients: incidence and perinatal significance

BACKGROUND

While hypoglycemia during an oral glucose tolerance test (OGTT) has been shown to occur in a considerable portion of nonpregnant post-bariatric surgery (BS) patients, its incidence among pregnant post-BS patients evaluated for gestational diabetes has only been sparsely studied.

OBJECTIVES

We investigated OGTT results and pregnancy outcomes in pregnant women who underwent 3 types of bariatric procedures before pregnancy.

SETTING

A university hospital.

METHODS

From medical records, data were collected on glucose measurements during a 100-g, 3-hour OGTT, as well as maternal and fetal outcomes.

RESULTS

Of 119 post-BS pregnant patients included in the study, 55 underwent laparoscopic sleeve gastrectomy, 34 laparoscopic adjustable gastric banding, and 30 laparoscopic Roux-en-Y gastric bypass surgery. Hypoglycemia (<55 mg/dL) was encountered in 59 (49.6%) patients during the OGTT. Among them, the nadir plasma glucose levels occurred 2 hours after glucose ingestion in 25 (42.4%) and after 3 hours in 34 (57.6%), with a median value of 47 (44-52) mg/dL. The risk of hypoglycemia was higher among women with prior laparoscopic Roux-en-Y gastric bypass surgery (83.3%) than among those with prior laparoscopic sleeve gastrectomy (54.5%; P = .009) or laparoscopic adjustable gastric banding (11.8%; P<.0001). Time from surgery to conception was significantly shorter among women with evidence of hypoglycemia during OGTT (median 711 versus 1246 days, P = .002). Compared with patients without evidence of hypoglycemia, patients who experienced hypoglycemia had lower rates of gestational diabetes (P = .03) but higher proportions of low birth weight (P = .01) and small for gestational age infants (P = .03).

CONCLUSIONS

Because hypoglycemia is common during OGTT among post-BS parturients, other diagnostic methods should be considered in this setting. The association found between hypoglycemia and poor fetal growth warrants investigation as to whether interventions to prevent hypoglycemia will improve fetal outcome.

Incidence and Predictive Factors of Postprandial Hyperinsulinemic Hypoglycemia After Roux-en-Y Gastric Bypass: A Five year Longitudinal Study

BACKGROUND

Postprandial hyperinsulinemic hypoglycemia (PHH) is often reported after Roux-en-Y gastric bypass (RYGB). In the absence of a prospective study, the clinical and biological determinants of PHH remain unclear.

OBJECTIVE

To determine the incidence and predictive factors of PHH after RYGB.

METHODS

Participants were 957 RYGB patients enrolled in an ongoing longitudinal cohort study. We analyzed the results of an oral glucose tolerance test (OGTT) routinely performed before surgery and 1 and/or 5 years after. PHH was defined as blood glucose < 50 mg/dL AND plasma insulin > 3 mU/L at 120 minutes post glucose challenge. Validated indices of insulin sensitivity (Matsuda index), beta-cell function (Insulinogenic index), and beta-cell mass (fasting C-peptide: glucose ratio) were calculated, from glucose, insulin, and c-peptide values measured during OGTT.

RESULTS

OGTT results were available in all patients at baseline, in 85.6% at 12 months and 52.8% at 60 months. The incidence of PHH was 0.5% at baseline, 9.1% * and 7.9%* at 12 months and 60 months following RYGB (*: P < 0.001). In multivariate logistic regression analysis, PHH after RYGB was independently associated with lower age (P = 0.005), greater weight loss (P = 0.031), as well as higher beta-cell function (P = 0.002) and insulin sensitivity (P < 0.001), but not with beta-cell mass (P = 0.381). A preoperative elevated beta-cell function was an independent predictor of PHH after RYGB (receiver operating characteristics curve area under the curve 0.68, P = 0.04).

CONCLUSIONS:

The incidence of PHH significantly increased after RYGB but remained stable between 1 and 5 years. The estimation of beta-cell function with an OGTT before surgery can identify patients at risk for developing PHH after RYGB.

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.

Evaluation of carbohydrate restriction as primary treatment for post-gastric bypass hypoglycemia

BACKGROUND

Up to 15% of patients who have undergone Roux-en-Y gastric bypass (RYGB) surgery may eventually develop symptoms of hypoglycemia.

OBJECTIVES

To evaluate the daily life efficacy of a carbohydrate (carb)-restricted dietary advice (CRD) of 6 meals per day with a 30 g carb maximum per meal in patients with documented post-RYGB hypoglycemia.

SETTING

Teaching hospital, the Netherlands.

METHODS

Frequency and severity of hypoglycemic events before and after CRD were assessed retrospectively in 41 patients with documented post-RYGB hypoglycemia, based on medical records and telephone questionnaires. Hypoglycemia was defined as a blood glucose level<3.0 mmol/L. Results are expressed as mean values±standard error or median and range.

RESULTS

CRD decreased the number of hypoglycemic events per month from 17.1 (1.5-180) to 2.5 (0-180), i.e., a decline of 85% (P<.001). The lowest blood glucose measured during a hypoglycemic event increased from 2.1±.4 to 2.6±.2 mmol/L (P = .004). The number of patients who had required outside help in the treatment of hypoglycemia, decreased from 23 to 6 (P<.001). In 14 patients (34.1%) the diet-induced reduction of hypoglycemia was insufficient and required the start of insulin suppressive therapy.

CONCLUSION

A CRD, consisting of 6 meals per day with up to 30 g carbs each, is an effective treatment of post-RYGB hypoglycemia in the majority of patients. Additional medication is needed in about a third of patients.

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.

Prevalence, severity, and predictors of symptoms of dumping and hypoglycemia after Roux-en-Y gastric bypass

BACKGROUND

Roux-en-Y gastric bypass (RYGB) results in pronounced weight loss in morbidly obese patients but may also cause adverse effects like early dumping and hypoglycemia. Prevalence data on these complications and their potential predictors are sparse.

OBJECTIVE

To assess the prevalence and possible predictors of early dumping and hypoglycemia in a population-based cohort of RYGB patients.

SETTING

University Hospital, Denmark.

DESIGN

A questionnaire survey was performed in the Central Denmark Region including RYGB-operated patients (years 2006-2011, n = 2238) and a nonoperated comparison cohort (n = 89). The Dumping Rating Scale and the Edinburgh Hypoglycemia Scoring System, together with demographic and clinical characteristics, were used, and possible predictors were examined by logistic regression.

RESULTS

The response rate was 64% (1429/2238). In total, 9.4% (134/1429) and 6.6% (95/1429) experienced moderate or severe symptoms of early dumping and hypoglycemia, respectively, which were significantly higher than in the comparison cohort. Because 3.4% (95% CI: 2.5-4.4) of the RYGB group experienced both early dumping and hypoglycemia, the total prevalence of 1 or both conditions was 12.6 (95% CI 10.9-14.4). Possible predictors for both conditions were body mass index (BMI)<25 kg/m² (odds ratio [OR] 1.70 (95% CI: 0.98-2.95) and OR 1.60 (95% CI: .83-3.06), respectively) compared with patients with BMI 25-30 kg/m². Younger age seemed to increase the risk of both conditions (<35 yr: OR 1.75 (95% CI: 1.11-2.75) and OR .59 (95% CI: .93-2.72), respectively) compared with patients>45 years.

CONCLUSION

Symptoms of early dumping and hypoglycemia were rather common with a prevalence of 1 or both conditions of 12.6% after RYGB. Predictors included younger age and a lower BMI.

Hypoglycaemia after gastric bypass: mechanisms and treatment

Hypoglycaemia after gastric bypass can be severe, but is uncommon, and is sometimes only revealed through monitoring glucose concentrations. The published literature is limited by the heterogeneity of the criteria used for diagnosis, arguing in favour of the Whipple triad with a glycaemia threshold of 55 mg/dl as the diagnostic reference. Women who lost most of their excess weight after gastric bypass, long after the surgery was performed, and who did not have diabetes before surgery are at the greatest risk. In this context, hypoglycaemia results from hyperinsulinism, which is either generated by pancreas anomalies (nesidioblastosis) and/or caused by an overstimulation of β cells by incretins, mainly glucagon-like peptide-1 (GLP-1). Glucose absorption is both accelerated and increased because of the direct communication between the gastric pouch and the jejunum. This is a post-surgical exaggeration of a natural adaptation that is seen in patients who have not undergone surgery in whom glucose is infused directly into the jejunum. There is not always a correspondence between symptoms and biological traits; however, hyperinsulinism is constant if hypoglycaemia is severe and there are neuroglucopenic symptoms. The treatment relies firstly on changes in eating habits, splitting food intake into five to six daily meals, slowing gastric emptying, reducing the glycaemic load and glycaemic index of foods, using fructose and avoiding stress at meals. Pharmacological treatment with acarbose is efficient, but other drugs still need to be validated in a greater number of subjects (insulin, glucagon, calcium channel blockers, somatostatin analogues and GLP-1 analogues). Lastly, if the surgical option has to be used, the benefits (efficient symptom relief) and the risks (weight regain, diabetes) should be weighed carefully.

Post-prandial hypoglycemia results from a non-glucose-dependent inappropriate insulin secretion in Roux-en-Y gastric bypassed patients

BACKGROUND

After Roux-en-Y gastric bypass (RYGB), hypoglycemia can occur and be associated with adverse events such as intense malaise and impaired quality of life.

OBJECTIVE

To compare insulin secretion, sensitivity, and clearance between two groups of patients, with or without hypoglycemia, after an oral glucose tolerance test (OGTT 75-g), and also to compare real-life glucose profiles within these two groups.

SETTING

Bariatric surgery referral center.

METHODS

This study involves a prospective cohort of 46 consecutive patients who complained of malaise compatible with hypoglycemia after RYGB, in whom an OGTT 75-g was performed. A plasma glucose value of lower than 2.8 mmol/L (50 mg/dl) between 90 and 120 min after the load was considered to be a significant hypoglycemia. The main outcome measures were insulin sensitivity, beta-cell function, and glycemic profiles during the test. Glucose parameters were also evaluated by continuous glucose monitoring (CGM) in a real-life setting in 43 patients.

RESULTS

Twenty-five patients had plasma glucose that was lower than 2.8 mmol/L between 90 and 120 from the load (HYPO group). Twenty-one had plasma glucose that was higher than 2.8 mmol/L (NONHYPO group). The HYPO patients were younger, had lost more weight after RYGB, were less frequently diabetic before surgery, and displayed higher early insulin secretion rates compared with the NONHYPO patients after the 75-g OGTT, and they had lower late insulin secretion rates. The HYPO patients had lower interstitial glucose values in real life, which suggests that a continuum exists between observations with an oral glucose load and real-life interstitial glucose concentrations.

CONCLUSIONS

This study suggests that HYPO patients after RYGB display an early increased insulin secretion rate when tested with an OGTT. CGM shows that HYPO patients spend more time below 3.3 mmol/L when compared with NONHYPO patients. This phenotype of patients should be monitored carefully after RYGB.

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.

Impact of Carbohydrate Content and Glycemic Load on Postprandial Glucose After Roux-en-Y Gastric Bypass

BACKGROUND

Abnormal glucose profiles have been described after Roux-en-Y gastric bypass (RYGB) with intense postprandial hyperglycemic peaks in some but not all the patients. The underlying mechanisms of these anomalies are not totally understood.

OBJECTIVE

The aim of this study is to determine whether or not the composition of the meal impacts the existence and maximum interstitial glucose (IG) concentration, measured under real-life conditions.

DESIGN

Retrospective cohort.

SETTING

Referral bariatric surgery left.

METHODS

Continuous glucose monitoring (CGM) and meal composition were recorded for at least 3 days on an outpatient basis in 56 patients after RYGB. The presence of postprandial peaks defined by IG above 140 mg/dl, the maximum postprandial IG, the carbohydrate content, and the glycemic load of the meals were analyzed.

RESULTS

Thirty-two patients had a hyperglycemic peak (PEAK), and 24 did not (NO PEAK). The average max IG was 159.6 ± 33.0 mg/dl in PEAK individuals and 111.8 ± 13.0 mg/dl in NO PEAK. Age was significantly higher in PEAK, but no other parameter was different between the two groups, including meal composition. In the PEAK patients, in multivariate analyses, carbohydrate content in model one and glucose load in model two explained respectively 50 and 26 % of maximum IG variance. For each gram of ingested carbohydrates, interstitial glucose increased by 1.68 mg/dl.

CONCLUSIONS

Following a gastric bypass, under real-life conditions, irrespective of the carbohydrate content of the meal, some patients develop postprandial hyperglycemic peaks, whereas others do not. In patients with postprandial hyperglycemic peaks, the maximum IG depends on the carbohydrate content of the meal.