You pop Nutmeg into a clean carrier and wait until she pees (I find it best to get a ham out of his/her nest or very soon after s/he has woken as they pee faster). You then dip the stick in the fresh pee.
On keto-diastix there are two colour squares, one for the ketones and one for the glucose (the ketone test is usually red/pink and the glucose usually blue). The bottle will have a chart with both of the colour squares and possible colour changes. The chart on the bottle will say which square is for glucose and which is for ketones. At this point the glucose square is the important one for Nutmeg.
The bottle will tell you how long after dipping the stick in the pee to check for colour change. At the right time, compare the glucose square to the glucose chart on the bottle and see what it says. Then you can compare the ketone square on the stick to the ketone chart. Always look one square on the stick in comparison to the chart on the bottle at a time - if you try and look at both you go cross-eyed and get confused!
There are pics here:
https://www.youtube.com/watch?v=EqPVwnhfxMA