Welcome to HCM,
You are diabetic and irregular pulse and your EKG revealed old myocardial infarct
which is possible in diabetic what is called silent myocardial infarct.
This abnormality in should be investigated for cause like significant ischemia and coronary lesion.
You're Echo study was normal that is there is no regional wall motion abnormality.
and difficulty in sleep possibly due to anxiety.
It is right approach to get a stress test (Nuclear) if there are evidences of reversible myocardial ischemia
than a coronary angiography
with PTCA and stent may be required.In case it is negative medical management is to be continued,
Please take care of your diabetes and just relax once your extent of disease is investigated it can be treated.
If you have significant palpitation
and any other symptom that needs immediate attention you can visit ER.