Constipation is common in elderly patients with diabetes mellitus (DM); its prevalence is estimated as up to 60% among patients with diabetic neuropathy. Acarbose, an alpha-glucosidase inhibitor, has a beneficial role in controlling DM, although one of its side effects is diarrhea. This study evaluates the efficacy of acarbose in improving constipation using transit time (TT) studies in elderly long-term care (LTC) patients.