Pioglitazone prevents reactive hypoglycemia in impaired glucose tolerance

A 42-year-old woman with hypoglycemic symptoms that occurred several hours after a meal visited our hospital. The hypoglycemic symptoms appeared when she was 37 years old, and her plasma glucose level had been assessed as less than 60 mg/dL when she experienced the symptoms. One year before, she had been diagnosed with reactive hypoglycemia by 75 g-oral glucose tolerance test (OGTT), which showed a normal glucose tolerance (NGT) pattern, and had begun taking an alpha-glucosidase inhibitor and nutritional treatment. A 75 g-OGTT on admission showed hypoglycemia at 240 min after glucose loading, excessive insulin secretion and an impaired glucose tolerance (IGT) pattern. A euglycemic-hyperinsulinemic clamp study demonstrated decreased insulin sensitivity. Therefore, we suspected that she had reactive hypoglycemia associated with insulin resistance and treated her with 15 mg/day pioglitazone. Her hypoglycemic symptoms completely disappeared after treatment with pioglitazone; insulin sensitivity in a euglycemic-hyperinsulinemic clamp study improved. Another 75 g-OGTT revealed that the excessive insulin secretion and hypoglycemia at 240 min after glucose loading had disappeared, and glucose tolerance was normalized from an IGT pattern to an NGT pattern. Thus, we believe that pioglitazone is effective for reactive hypoglycemia and aggravated glycemic metabolism associated with insulin resistance.