The first study, done in England, looked at 10,232 people aged 45 to 79, including several hundred with diabetes. They were studied for six years and were given a test that, with one reading, reveals a person's average blood sugar for the past two to three months.
Q : What does "with one reading" mean in the sentence? I think "by cheking just one result figure of someone's test"
What do you think?
All the best,