A method for treating a breathing person suffering from diabetes utilizes a valve system that is interfaced to the person's airway and is configured to decrease or prevent respiratory gas flow to the person's lungs during at least a portion of an inhalation event. The person is permitted to inhale and exhale through the valve system. During inhalation, the valve system functions to produce a vacuum within the thorax to increase blood flow back to the right heart of the person, thereby increasing cardiac output and blood circulation in order to treat the person suffering from diabetes.