Don't choose diplomas randomly. Please assess your aptitude and speak to your final year professors from medicine, surgery, orthopedics, pediatrics and obstetrics you will have an idea about you and your professional abilities to learn and grow. You have chosen two good specialties with good prospectus for career progress and professional growth. Emergency Medicine is a rapdily developing speciality wherein every Coroporate Hopsital or Major truama unit needs a qualified consultant to lead or be part of the Emergecny (Casuality) team.
Doing a fellowship in a reputed institution and further doing the F.CEM and M.CEM degrees attached to the Royal Colleges of England gives you more weightage and potential for growth. There is always a need for such qualified personnel in England too.
Diabetology fellowship is good if you have time you can do MD internal medicine followed by DM Endocrinology. This will enable you to be better equipped to practice and enter at a higher level in medical colleges or corporate hospitals.
Emergency medicine is more demanding with frequent out of hours calls and duties and ability to work under pressure. Diabetology practice can be more regulated based on your needs and desire for a work-life balance.
If you choose Emergency Medicine fellowships focussing on experience and exposure - choose St.John's Medical College Hospital, Koramangala, Bangalore or CMC Vellore or any major teaching institution with good patient inflow (trauma, snake bites, assault, poisoning). Choose a center that has an attached Emergency ICU wherein you will have access and chances to learn better.If you choose the corporate hospitals, the arrange a visit to meet the current doctors in the course, the in-charge of the department and take an honorary observership for a week (day shift and night shift), to get an idea of what the department is really like. Once you enter focus on acquiring skills of presentation ( paper and posters), publishing articles and attending conferences. If you start early, then you have a good chance of keeping yourself updated and break into the national academic science as faculty.
If you choose Diabetology fellowships, often the candidates would have completed MMBS alone or MD or DNB. Here again, CMC Vellore has got a good program, MV Diabetes center, Chennai is a reputed unit for many years.
If you are choosing from other hospitals for practical reasons, please check with the University of the state about whether the course is approved and the course approval license is current. Then approach the state medical council and check whether the council will enter the additional qualification you get in your state medical registration certificate. This is important to be legally correct and in case of future complaints from patients or medicolegal cases,unelss you meet both of the above you cannot call yourself a specialist legally.
Many doctors aspire to go abroad for a short stint and come back or settle overseas, if you have these plans, please work on them parallelly from the first year of the course because the older you are the less the chances of entering the system. Don't lose time is getting years of clinical experience and then movign abroad. If you have leadership skills focus on them and get groomed so that once you complete you can look at heading the department. Good luck.