Clostridial gas gangrene (myonecrosis) is a rare but catastrophic condition that usually occurs in patients with underlying diseases. This paper reports a fatal case of spontaneous clostridial gas gangrene in a 60-year-old female diabetic patient. The composition of gas samples from the patient's damaged muscle was analyzed. The results showed 5.9% hydrogen, 3.4% carbon dioxide, 74.5% nitrogen and 16.1% oxygen. This gas composition supports the belief that such gas production occurs via glucose fermentation. This is the first time such an analysis has been performed in a clinical case of spontaneous clostridial gas gangrene.