If your father has had good control of his diabetes during those 20 years, then his heart is very likely to be in good shape. How old is he? Heart problems are one of the most likely causes of death for all people, diabetic, or not. I have been a diabetic for 64 years and I am 70 years old. I use very tight control and my diabetes has not caused me any problems. My heart is in great shape, Does your father have a healthy diet, does he exercise every day, is he overweight, does he have a lot of high blood sugar? These factors determine whether he has the potential for heart problems.