To correctly code an encounter with a patient who has uncontrolled type 1 diabetes complicated by ketoacidosis, you should use all five digits. The proper code would be 401.1 The fourth digit identifies the disease as benign and thus is the most specific description of your patient's condition. The point is that you must always code to the highest number of digits that best describe your patient's condition. To be certain you're using the correct number of digits, review the codes in a given category and choose the highest-level code that most specifically describes your patient's condition. Many payers, including Medicare, will deny or delay payments if you fail to do so.
Physicians are legally responsible for the codes selected and submitted to payers.
Choosing the most specific code means coding only what you know to be a fact. Patients often have ill-defined complaints, such as back pain. If you don't, you may inadvertently label the patient with an incorrect diagnosis and, as a result, the patient may have difficulty obtaining health and disability insurance or may end up paying higher insurance premiums in the future. But be aware that some body-system categories of codes include codes for nonspecific conditions. General guidelines for ICD-9 coding Code to the highest degree of specificity.