Ketone test strips are used to measure ketones in urine, which indicates the body is burning fat for energy instead of glucose. They are used by people on low-carb or ketogenic diets to monitor their metabolic state and by individuals with diabetes, particularly those with type 1, to check for dangerously high ketone levels that could lead to diabetic ketoacidosis (DKA). To use, a person dips the strip into a urine sample, waits a specified time, and then compares the resulting color change to a chart on the bottle to determine the ketone level.