Is it permissible to break the fast in Ramadan by using the insulin medication available twice daily, instead of using a new, expensive medication that allows for fasting?

Insulin injections do not break the fast, as they are neither food nor drink. So, the questioner sister's fast is valid. However, if fasting harms her due to diabetes, and it is a chronic illness according to a trustworthy doctor, then she may break her fast and feed a poor person for each day. She is not obligated to incur the cost of expensive medicine that she cannot afford.