Emphysematous cystitis (EC) is a rare disease of the urinary bladder, caused by gas-forming bacteria, which can become life-threatening without appropriate evaluation. This report describes the case of a 77-year-old male with uncontrolled diabetes mellitus type II, who presented with suprapubic pain associated with frequency, urgency, dysuria, and gross hematuria involving the passage of clots. A review of systems was negative for weight changes, history of malignancy, urolithiasis, exposure to industrial chemicals, history of gastrointestinal tract disease, radiation therapy, and trauma. The patient was febrile upon admission. Laboratory findings were significant for lactate (2.7 mg/dl), and leukocytosis (28,100/uL). Computed tomography of the abdomen and pelvis showed dense material and air within the bladder, bilateral hydronephrosis, and hydroureter. He was managed with ceftriaxone (2 gm every 24 hours for 14 days), and a urinary catheter. EC should be considered as a differential diagnosis in diabetes mellitus patients presenting with hematuria, because knowledge of this rare finding may lead to early diagnosis and appropriate management.