Guidelines for Proper Coding of Diabetes

Diabetes mellitus is one of the most common diseases seen in Medicare beneficiaries. It can also be one of the most challenging conditions to code properly under the Centers for Medicare & Medicaid Services (CMS) Hierarchical Condition Codes (HCC) model, due to its complexity and resultant complications and manifestations.

The CMS-HCC model requires the use of ICD-9-CM diagnosis codes to provide beneficiary health status information and support the medical necessity for treatment rendered. The CMS-HCC model uses the specificity of these codes to identify the severity of the disease or condition; therefore, it is important that all illnesses be coded to the highest level of specificity.

It is also critical that each of the ICD-9-CM diagnosis codes be reflected in the medical record documentation. Proper coding and supporting documentation are necessary to facilitate proper payment.

To help physician offices address these challenges, the CMS and the National Center for Health Statistics (NCHS) have provided the following guidelines for coding and documenting diabetes and its complications using the HCC model.

Diabetes mellitus codes
Category 250 identifies diabetes mellitus and its complications or manifestations. The three-digit category code is followed by a decimal point, followed by two additional digits. All codes in this category require five digits to document the highest level of specificity.

The fourth digit in a diabetes mellitus code designates any complications or manifestations in the patient's condition due to diabetes. Examples include ketoacidosis (250.1X), hyperosmolarity (250.2X), renal manifestations (250.4X), ophthalmologic manifestations (250.5X), neurological manifestations (250.6X) and circulatory manifestations (250.7X). If there is no complication, then 250.0X should be used.

Although there are codes for nearly every possible complication, some complications do not fall into an available category. In these cases, the code for "diabetes with other specified manifestations" (250.8X) should be used. However, this code can only be used if the manifestation/complication is specified in the documentation. If the documentation does not state a specific manifestation/complication, then the code for "diabetes with unspecified complication" (250.9X) should be used.

The fifth digit in the diabetes mellitus diagnosis code indicates if the patient has Type I or Type II diabetes and whether the patient's condition is controlled or uncontrolled. The chart below shows the appropriate fifth digit to use depending on the situation:

Insulin use should not be considered when determining the type and should not affect the fifth digit of the 250-category code. Use the additional code (V58.67) for patients with Type II diabetes who require long-term (current) insulin use.

Remember, codes must be chosen based solely on documentation. If the condition is not documented, then do not code for it.

Code sequence
In addition to specifying complications and/or manifestations in the fourth digit of the 250-category code, each complication and/or manifestation must also be reported using the specific code from the appropriate category. However, the code in category 250 should always be listed first on the encounter form.

For example, a patient with diabetic nephropathy would be coded as follows:

1. 250.4X  - diabetes mellitus with renal manifestations
2. 583.81  - diabetic nephropathy
   

Here are a few additional examples to illustrate the diabetic coding process.

1. Documentation states:
   Patient has uncontrolled diabetes mellitus, complicated with chronic renal failure.
   250.42  - diabetes mellitus with renal manifestations, Type II or unspecified type, uncontrolled
   585.9  - chronic renal failure
   Always search for diseases in the alphabetic index and confirm them with the tabular list.
   
2. Documentation states:
   Patient has controlled diabetes mellitus and takes insulin.
   250.00  - diabetes mellitus type II or unspecified type, not stated as
   uncontrolled
   V58.67  - long-term (current) insulin usage
   
3. Documentation states:
   Impression: Diabetes mellitus diet controlled with complications.
   250.90  - diabetes mellitus with unspecified complications, type II or unspecified type, not stated as uncontrolled
   
4. Documentation states:
   Impression: Insulin dependent diabetes mellitus complicated with diabetic neuropathy.
   250.60  - diabetes mellitus with neurological manifestations, Type II or unspecified type, not stated as uncontrolled
   357.2  - diabetic neuropathy
   V58.67 - long-term (current) insulin usage

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