Conference Coverage

True postbariatric hyperinsulinemic hypoglycemia is rare



– True post–bariatric surgery hyperinsulinemic hypoglycemia is rare among bariatric surgery patients, based on a decade’s worth of experience from the Mayo Clinic, Rochester, Minn.

Dr. Cortes, an endocrinology fellow at the Mayo Clinic, Rochester, Minn Kari Oakes/MDedge News

Dr. Tiffany Cortes

Of 2,386 patients who had bariatric surgery at Mayo, 60 (2.6%) had a postsurgical diagnosis code associated with hypoglycemia in their medical record. However, just five of them (0.25%) had documentation meeting the criteria for Whipple’s Triad, which consists of low blood glucose levels, symptoms associated with the low glucose levels, and symptom resolution when glucose levels are corrected, Tiffany Cortes, MD, reported in an oral presentation at Obesity Week, which is presented by the Obesity Society and the American Society for Metabolic and Bariatric Surgery .

“Postbariatric hypoglycemia is an infrequent occurrence among patients who present with suspicious symptoms,” said Dr. Cortes, an endocrinology fellow at the clinic.

Post–bariatric surgery hypoglycemia is characterized by neuroglycopenia with a documented plasma glucose of less than 54 mg/dL with symptom resolution after a rise in glucose levels; neuroglycopenia that occurs 1-3 hours after a meal; and symptom onset more than 6 months after bariatric surgery, said Dr. Cortes.

Previous work had found that the overall prevalence of post–bariatric surgery hyperinsulinemic hypoglycemia ranged from 17%-34%, with severe symptoms seen in fewer than 1% of surgery recipients.

Bariatric surgery, especially Roux-en-Y gastric bypass (RYGB), may result in wide postprandial blood glucose excursions, with a spike occurring about 30 minutes after eating. For symptomatic individuals, this postprandial glucose peak will prompt an insulin surge followed by a rapid and steep decline in serum glucose.

Looking at Mayo Clinic medical records from mid-2008 to the end of 2017, Dr. Cortes and her colleagues wanted to determine the prevalence of hyperinsulinemic hypoglycemia in the bariatric surgery population.

Additionally, the researchers wanted to see how patients who presented with symptoms suspicious for the syndrome were evaluated and to understand the efficacy of treatments.

Patients who had a diagnosis of type 1 diabetes mellitus and those who were on insulin or sulfonylureas were excluded from the retrospective chart review.

Of the 60 patients evaluated in the endocrinology clinic for symptoms suspicious for hyperinsulinemic hypoglycemia, 51 (85%) were female, and 14 had a diagnosis of diabetes before surgery. Mean patient age at surgery was 43 years.

These symptomatic patients had a mean presurgical body mass index (BMI) of 42.8 kg/m2 (range, 38.6-49.3 kg/m2). Their mean time to maximal weight loss was 1.3 years after surgery, with symptoms beginning at 1.4 years after surgery. Patients lost a mean 37.4% of their body mass to reach a mean nadir BMI of 26.2.

Overall, about two-thirds of the surgeries performed were RYGB. Of patients with hypoglycemic symptoms, 73.3% had an RYGB. Revision of gastric bypass was the next most common surgery, at 21.8% overall; these patients constituted 15% of the hypoglycemic symptom group.

Of the patients with symptoms, 80% noted symptoms only after eating, with half of patients describing symptoms coming on 1-3 hours after eating. A little over a third of the patients didn’t describe the exact timing of symptoms.

Just 20 patients had a complete hypoglycemia work up bundle documented in their medical record, said Dr. Cortes. This consisted of measures of serum glucose, insulin, and C-peptide levels. Of the 20 patients, 5 met Whipple’s Triad criteria, and 4 of these patients received a diagnosis of hyperinsulinemic hypoglycemia.

Two patients had a 72-hour fast, and neither of them met diagnostic criteria. Seventeen patients had a mixed meal tolerance test, with one individual meeting diagnostic criteria for and receiving a diagnosis of hypoinsulinemic hyperglycemia.

Of the five patients meeting diagnostic criteria (0.20% of surgical population), all had received RYGB, and two had previous weight loss procedures, said Dr. Cortes. For four of the patients, the surgical indication was weight loss; the other patient had an indication of gastroesophageal reflux disease (GERD).

“Dietary interventions are the most effective treatment” for post–bariatric surgery hyperinsulinemic hypoglycemia in the Mayo Clinic experience, said Dr. Cortes.

Turning to the investigators’ examination of treatment recommendations for the 60 patients who reported hypoglycemic symptoms, most (95%) received an initial recommendation to manage symptoms by diet changes.

Most patients (77%) had at least one follow-up visit, with over half of these patients (61%) reporting improvement in symptoms, and seven patients (16%) reporting resolution. Twelve patients (27%) either remained the same or had not had a recurrence of symptoms.

Medication was prescribed for 12 patients; of them, 8 received the alpha glucosidase inhibitor acarbose and 7 responded, according to the record review. No one reported worsening of symptoms on acarbose.

Other individual patients were prescribed octreotide alone, or octreotide, pasireotide, or diazoxide in combination with acarbose, with variable results.

Dr. Cortes reported no conflicts of interest and no external sources of funding.

SOURCE: Cortes T et al. Obesity Week 2018, Abstract T-OR-2015.

Next Article: