Hello dear,
Given the history that your sister is diabetic & suffering from severe infection, the management of blood sugar level is of prime importance.
Other than that, a low calorie low fat diet should be followed such as:
1. Avoid eating white breads, rice and pasta. They have high calories and increases the blood sugar level.
2. Consume low fat versions of milk and cheese and avoid oily foods.
3. Have a diet rich in low calorie protein foods such as egg whites, fish, etc.
4. It is better to avoid soft drinks and fruit juices which are rich in calories.
Instead, drink large amount of water (about 8 to 10 glasses) throughout the day.
5.
Dietary fiber such as whole grains, vegetables, fruits, and nuts can also be included in the diet.
Wishing her a good health.
Take care.