Aims/Introduction: One of the reasons for the poor adherence to α-glucosidase inhibitor (αGI) treatment is the need to take medication three times a day. We hypothesized that the administration of miglitol might be effective for the next meal if the miglitol-induced inhibition of α-glucosidase activity persists until the next meal. In the present study, we evaluated whether the administration of miglitol just before or after breakfast was effective for postprandial glucose excursion after lunch without taking miglitol at lunch. We measured the plasma glucose, serum insulin and glucagon, plasma active glucagon-like peptide-1 (GLP-1), and total glucose-dependent insulinotropic polypeptide levels in non-diabetic men. Miglitol was given to each patient according to four different intake schedules (control: no drug; intake 1: drug given just before breakfast [50 mg]; intake 2: drug given 30 min after the start of breakfast [50 mg]; intake 3: drug given at the same time as intake 2, but without eating breakfast [50 mg]). Both intake 1 and intake 2 had a smaller area under the curve (AUC) for plasma glucose excursion after lunch, compared with the control. Intake 2 had a larger AUC for active GLP-1 after lunch, compared with intake 1. Intake 1 and intake 2 can improve postprandial hyperglycemia after lunch. The results of the present study raise the possibility that the administration of miglitol twice a day might be effective and might help to improve treatment adherence among diabetic patients. This trial was registered with UMIN Clinical Trial Registry (no. UMIN000002896). (J Diabetes Invest, doi: 10.1111/j.2040-1124.2011.00129.x, 2011).