D-3-Hydroxybutyrate is a type of keton, ketons are produced during fat breakdown, when glucose is not available as energy source or enough insulin not there to regulate glucose. Beta Hydroxybutyrate a ketone body that is predominantly present in those who suffering from DKA, severe diabetic ketoacidosis for those with type1 diabetes, as well as type 2 diabetes and people following keto diet. Use serum as specimen