adenosine triphosphate (ATP)-sensitive K+ channels, which causes hyperpolarization of the β-cell membrane, with a reduced rate of opening of voltage-dependent Ca2+ channels and the eventual elimination of Ca2+ influx (11, 12). Adverse reactions in the form of fluid retention and edema have also been reported, highlighting the need for strict caution in patients with a decreased cardiac or renal function (13). For this reason, we exercised caution when increasing the current patient’s dose of treatment. Consequently, CGM showed that the serious hypoglycemic attacks resolved with the oral administration of diazoxide at a dose of 250 mg/ day. Gill et al. (13) reported that symptoms improved and/or resolved in 59% of 40 insulinoma patients who received diazoxide over a period of approximately seven years. In Japan,