A nurse is reviewing guidelines to prevent diabetic ketoacidosis (DKA) during periods of illness with a client who has type 1 diabetes mellitus. Which of the following instructions should the nurse include in the teaching?

Choice A reason: Testing blood glucose every 8 hours is insufficient during illness, which can cause rapid glucose spikes in type 1 diabetes. Guidelines recommend testing every 2–4 hours to prevent DKA, making this choice incorrect for effective management. Choice B reason: Limiting fluid intake to 360 mL every 8 hours risks dehydration, a DKA trigger, during illness. Adequate hydration is essential to dilute glucose and prevent acidosis, making this instruction incorrect and harmful for DKA prevention. Choice C reason: Checking urine for ketones during illness detects early ketosis, a precursor to DKA in type 1 diabetes. Positive ketones prompt insulin adjustments, preventing acidosis progression, making this a critical instruction and the correct choice. Choice D reason: Withholding insulin during illness is dangerous, as stress hormones increase glucose, risking DKA. Insulin must be continued or adjusted based on glucose and ketone levels, making this instruction incorrect and harmful.