How do we get my mother-in-law to eat good, nutritional food?

Oh boy do I have questions. My mother-in-law has been diagnosed with diabetes and when I first met her, she would get sugarfree ice cream and a small piece of cake for her and I. Than she found out she is diabetic and that went out the window and she eats everything - sweet cookies, cupcakes, candy. Now she is in the hospital and all she wants to eat is sweet stuff. We have tried to get her to eat regular food and she says she is not hungry and we are running out of ideas.