A patient who developed symptomatic reactive hypoglycemia 14 years after total gastrectomy and was successfully treated with miglitol

We report the case of an 85-year-old man who had undergone total gastrectomy 14 years prior to admission at our hospital. He lost consciousness and was urgently hospitalized. His blood samples showed severe hypoglycemia (plasma glucose level 8 mg/dl) with hyperinsulinemia (immunoreactive insulin level 174.4 μU/ml) on admission. Laboratory data and imaging studies showed there was no insulinoma. He took garenoxacin mesilate hydrate for flu several days before admission. Such severe hypoglycemia did not recur after cessation of garenoxacin, and it was reported that hypoglycemia was induced by garenoxacin, which promoted insulin secretion, which indicated that garenoxacin had the possibility of inducing severe hypoglycemia. After admission, reactive hypoglycemia by dumping syndrome was diagnosed by mixed-meal tolerance test. The patient began developing symptoms after medication with irbesartan (angiotensin receptor blocker) for essential hypertension 1 month before admission. This preceded irbesartan, which is known to increase insulin sensitivity and may cause symptomatic dumping syndrome. Laboratory data also showed the presence of insulin autoimmune syndrome with a high titer of anti-insulin autoantibody. Although the antibody showed a low affinity and a high bound capacity, blood glucose profile during admission only showed the pattern of reactive hypoglycemia. Therefore, insulin autoimmune syndrome was unlikely the cause of hypoglycemic events in this case. The meal tolerance test showed better efficacy of miglitol to inhibit postmeal hyperglycemia and subsequent hyperinsulinemia than did acarbose and voglibose. We speculate that the angiotensin receptor blocker caused symptomatic dumping syndrome, and only miglitol among α-glucosidase inhibitors suppressed the symptom.