Intestinal pneumatosis is a rare entity of unclear etiopathogenesis characterized by the presence of gaseous cystic or linear collections within the intestinal wall. Intestinal pneumatosis may be primary and idiopathic in origin or, more frequently, it accompanies various clinical conditions. Rarely, the development of intestinal pneumatosis is attributed to the pharmacotherapy with different drugs. This is a case report of cystic pneumatosis limited to the large intestine with predominant clinical presentation of chronic watery diarrhea in a 64-year-old man suffering from diabetes mellitus treated with metformin and acarbose. The patient had been referred to the outpatient gastroenterology clinic for further investigation of numerous polyp-like lesions found on colonoscopy. There was no history of cigarette smoking, drug abuse or extraintestinal complaints. The patient was in a good general condition and his laboratory tests were normal. No relevant abnormalities were found on chest X-ray, esophagogastroduodenoscopy or abdominal ultrasound, but computed tomography showed intramural gas-filled bubbles in the cecum and splenic flexure without signs of perforation or any other significant pathology in the abdominal cavity. The final diagnosis of pneumatosis cystoides coli (PCC), possibly related to treatment with acarbose, was established. On a follow-up visit after discontinuation of acarbose the patient reported no complaints and remained asymptomatic for the next 12 months. To conclude, drug-related PCC should be considered in a differential diagnosis of gastrointestinal symptoms and/or polyp-like lesions disclosed on colonoscopy in diabetic patients treated with acarbose.