Not sure if this will be of any help to you, but I would try to relate Cor Pulmonale and DM based on the theory that DM damages the blood vessels/arteries over time (think about Macrovascular damage). I am not 100% sure about this, but I am thinking damage from the arteries,athlerscleorosis, metabolic syndome and HTN could cause this. Not sure if the client is overweight, but obesity causes DM, many of which have poor diets, high cholesterol, etc. That increases the risk of plaque build up (athlerscleoris), narrows the arteries, which increase blood pressure, increased blood pressure causes the heart to have to work harder sometimes leading to cardiomyopathy which eventually ends up in heart failure. I have never heard of Cor Pulmonale, but after reading that its a condition of the heart, then this is my best guess. I apologize if it makes no sense!