The strip is inserted in a small glucose meter, which provides a numeric reading of her blood-sugar level. Each strip costs about $1. That’s at least $12 a day, or more than $4,300 a year.

You are also prohibited from selling test strips that have expired, been used, or are in open boxes. With so many players entering this fast-growing market, not every party may be on the up and up.

Test strips are a multi-billion-dollar industry. A 2012 study found that among insulin-dependent patients who monitor their blood sugar, strips accounted for nearly one-quarter of pharmacy costs.

The strips are inserted into a mixture of water and the drug to be tested, and they return a positive result when xylazine is present. However, they cannot test for quantity or potency of the drug.