Thanks for writing your query.
As you had mentioned that your weight is 50 kg & height is 5ft 4, so based on that your BMI comes to 18.9 that means you are normal weight.
If the BMI is less than 18.5 than only it is considered as underweight
. So presently you need not worry .
Have a healthy diabetic diet, follow your daily exercise routine. Take your diabetes
& heart medicines on time.
Your aim should be to keep your sugar levels in control.Have routine health checkup once in year.
Wish you good health.