What is the ruling on a wife directing words to her husband – who is incapacitated due to illness – that might hurt him, for his own benefit, and does her reward for patience thereby become lost?

If the husband's failure to adhere to the doctor's instructions causes him harm, then it is not permissible for him to violate them, as Allah Almighty says: "And do not kill yourselves." Advising him to do so is a confirmed requirement, because preserving life is a necessity, and the wife should advise him with politeness and affection. However, if it is proven that there is no harm in discontinuing some medications, despite potential hardship, then he has a choice. Since diabetes can destroy its sufferer if treatment is neglected, the husband must take measures for safety, and the wife must assist him in that.