Question

How to determine if a sugar is reducing or nonreducing?

Answer 1

A. Diabetes. Once you have a way of quickly and easily measuring the concentration of sugar, then you can determine how much insulin is needed to counteract it.

Next question. What would be an easy, visual way to detect the presence of glucose? Especially something that doesn’t require you to be an expert chemist?

Ideally, you’d like a chemical reaction that results in a color change.

Think about pregnancy tests: you just pee on a stick and know within a few minutes whether you’re pregnant.  You don’t need to know any chemistry. It’s brainless.

A test for blood sugar suitable for diabetics should have a similar ease of use.

This brings us (via aldehydes) to the topic of reducing sugars, since they are the basis of a historically important color-based test for blood glucose.