['Blood glucose concentration has been shown to be an important factor in gastric motility. However, the effect of hyperglycemia on gastric myoelectrical activity has not yet been studied in patients with diabetes.', 'Surface electrogastrography was performed in eight patients with type I diabetes mellitus under normoglycemic and hyperglycemic conditions (glucose clamp technique) and in eight normoglycemic control subjects.', 'In the early postprandial state, the frequency of the normal pacemaker rhythm tended to be higher during hyperglycemia than during normoglycemia (3.10 +/- 0.27 vs. 2.92 +/- 0.19 cycle/min; P = 0.061). The frequency decrease that occurs immediately after a meal was found less frequently during hyperglycemia (in 25% vs. 75% of the patients; P = 0.046). Higher harmonics of the 3-cycle/min component, indicating an electrogastrographic waveform change, were found less often during hyperglycemia (in 13% vs. 63% of the patients; P = 0.039). Dysrhythmias (in particular, tachygastrias) were more prevalent during hyperglycemia (40.6% vs. 6.5% of the time; P = 0.028). No differences were found between normoglycemic patients and control subjects.'] Does hyperglycemia induce abnormalities of gastric myoelectrical activity in patients with type I diabetes mellitus?