The dipstick test for diabetes shows grey for ketones on the stick. but theres no grey colour on the scale, only pinks leading to purples. ???

Probably normal: Almost certainly it's negative, or so weakly positive it doesn't matter. Even moderate to large urine ketone levels are normal in healthy people if they haven't eaten much during a few hours before testing. It doesn't mean anything for diabetes unless the glucose patch is at the highest possible level.

Expired?: It is possible that the Urine Dipsticks u are using have expired or were contaminated rendering them useless. Urine dipstick tests for Ketones is not a diagnostic test for diabetes. U can develop ketonuria from fasting, dehydration, a low carb diet, as well as uncontrolled insulin dependent diabetes. Glucose into ur urine is suggestive of diabetes, though a fasting blood glucose is the best test

Ketones: Urinary ketones are very nonspecific, which basically means they can only be interpreted within context. Most of the time they are not harmful. I am unsure how to interpret your scale without being able to see it in person. Best of luck :)