It's widely known that Diabetics have an increased risk of heart disease.
Less publicised is that in diabetics the chest pain usually associated with angina/heart attack may be experienced as breathlessness. (The medical term is an "angina equivalent".) Whereas significant chest pain would have you ringing the doctor or an ambulance, unfortunately breathlessness may be dismissed as being a bit unfit.
So if you start gettting unusually breathless on exercise or after a large meal, although it might be something else, its worth mentioning this to your doctor so he can arrange cardiac screening alongside the other investigations.
This knowledge comes from working in a regional cardiac unit, where several diabetic patients referred with "heart failure" (meaning their heart pumping less efficiently) actually had nearly-blocked arteries with breathlessness as the only symptom. The consultants referred to breathlessness as a known angina equivalent in diabetes, it was well known to the consultants but apparently not to GPs.
Sue