NASHVILLE, TENN. – Postprandial hyperinsulinemic hypoglycemia after gastric bypass surgery can be managed or even corrected by medical management with calcium channel blockers or acarbose.
First described in 2005, it is a rare complication distinct from dumping syndrome, which is common after bypass. For unknown reasons, the pancreas starts to oversecrete insulin in response to even small meals a few months to a few decades after gastric bypass surgery. Until now, treatment has often meant partial or even total pancreatectomy (N. Engl. J. Med. 2005;353:249-54).
Dr. John Mordes
“The message from me is very simple: There’s a medical alternative to surgery. Before you take these people to surgery, try medical management,” said Dr. John Mordes, an endocrinologist and professor of medicine at the University of Massachusetts Medical School in Worcester.
The study involved five patients, who were seen there after suddenly developing severe, sometimes daily, postprandial hypoglycemic attacks from 1 to 26 years after Roux-en-Y bypass; several had passed out after meals. On 75-g fasting-glucose challenges, their insulin levels were at or above 17 microU/mL, despite glucose concentrations at or below 54 mg/dL. None of the patients had evidence of insulinomas, and none was on exogenous insulin or diabetes drugs. Their hemoglobin A1c levels were below 6% (Endocr. Pract. 2015;21:237-46).
The first patient refused surgery, “so we researched the literature” and found that nifedipine helped infants with congenital nesidioblastosis in a study from India. The drug worked at a dose of 30 mg extended release once daily; 30 mg t.i.d. worked in the second patient. Calcium channel blockers blunt insulin secretion, which probably explains why nifedipine helped, Dr. Mordes said at the annual meeting of the American Association of Clinical Endocrinologists.
Both patients stopped taking the pills on their own after about 3 years; their symptoms hadn’t returned after a year or more of follow-up.
The third and fourth patients couldn’t tolerate nifedipine, so Dr. Mordes tried acarbose to slow absorption of glucose from the gut; it also worked. One patient has had only two mild attacks on 50 mg t.i.d for 15 months; the fourth was symptom free while on 25 mg t.i.d for 2 months. That patient stopped the drug at that point, and remained symptom free for 9 more months, but since then has had about one attack a month. The fifth patient has been symptom free for about 6 months on a combination of nifedipine 20 mg t.i.d. and acarbose 50 mg t.i.d, and has no intention of stopping either.
The subjects gained from a few to almost 50 pounds while on the drugs, which might also have contributed to their recovery. Overall, they “are fine now. None of them have needed surgery,” and they’re happy to have avoided it, Dr. Mordes said.
All that’s needed to diagnose the problem is a history of exclusively postprandial symptoms of hypoglycemia with no vasomotor or bowel symptoms suggestive of dumping, plus confirmatory blood work. Invasive tests aren’t necessary, he said.
A sixth patient didn’t respond to nifedipine, acarbose, or the insulinoma drug diazoxide, but she was atypical in that she had a decades-long history of nocturnal hypoglycemic events following a gastric bypass in Mexico at age 13 years for pyloric stenosis. “Something is very different about her,” Dr. Mordes said.
He said he had no relevant financial disclosures, and no outside funding for his work.