Answer: Checked the meter before using it
Step-by-step explanation:
The text says that Tim only realized that he had to check the equipment after noticing that all the patients for the day had high blood sugar levels. This was a bit reckless of him because he should have checked the equipment before he started using it for the day.
This is a very important concept in medicine because a malfunctioning equipment could be the difference between life and death and so it is important that such things are noticed ahead of time.