My mom was just recently considered diabetic but is confused on why she's losing weight. How do I explain this process to her?

My mom has been overweight for a while and has had on going hypertension. Her doctors have always told her that she is a borderline diabetic but she just can’t seem to change her eating or exercise habits. Recently she has been losing weight (without trying) and now her doctor has said she’s developed diabetes. She thinks that because she’s lost weight her chances should have gone down but I’m trying to explain why losing weight unexplainably is actually a sign of diabetes. She’s very health iliterate and although I’m going to school for health science I really don’t know much about diabetes yet. How can I explain this to her in a very basic way and help her understand what she needs to do now to help herself?