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September 26, 2005

Coding for Diabetes Mellitus
For The Record
Vol. 17 No. 20 P. 45

Diabetes mellitus is assigned to AHA Coding Clinic for ICD-9-CM category 250. Fourth and fifth digits are needed to complete the code: The fourth digit identifies any condition or manifestation associated with diabetes, and the fifth digit refers to type 1 or type 2 diabetes and whether the diabetes is controlled or uncontrolled.

Type of Diabetes
Documentation of type 1 or type 2 diabetes is the important information needed to assign the appropriate fifth digit. The fact that the patient receives insulin during the hospital stay has no effect on code assignment. Only documentation of the type of diabetes (1 or 2) affects code assignment. If a patient with type 2 diabetes routinely uses insulin, code V58.67, Long-term (current) use of insulin, should be assigned as a secondary diagnosis (AHA Coding Clinic for ICD-9-CM, 2005, first quarter, page 44).

The fifth-digit subclassification for category 250 was modified effective with discharges on or after October 1, 2004. Specifically, the fifth digit “1” now states “type I [juvenile type], not stated as uncontrolled.” “Insulin dependent type” and “IDDM type” were deleted from the title. Since IDDM (insulin-dependent diabetes mellitus) is deleted from the title, it no longer affects code assignment. If the physician documents only IDDM, the coder should assign code 250.00. Fifth digit “0” now states “type II or unspecified type, not stated as uncontrolled.”

AHA Coding Clinic for ICD-9-CM advises the coder to query the physician for clarification if the documentation is not clear regarding the type of diabetes or if there is conflicting documentation (AHA Coding Clinic for ICD-9-CM, 1997, fourth quarter, page 33, and 1997, second quarter, page 14). If there is any conflicting information, then the code assignment is based on the type of diabetes documented. Without further clarification diabetes type, the default is type 2. (AHA Coding Clinic for ICD-9-CM, 2005, first quarter, page 44.)

Controlled vs. Uncontrolled
Documentation regarding controlled or uncontrolled diabetes is also needed to assign the appropriate fifth digit for diabetes. Type 1 uncontrolled diabetes is assigned to code 250.x3. Type 2 uncontrolled diabetes is classified to code 250.x2. Uncontrolled diabetes should not be coded unless the physician’s documentation supports the diagnosis. “Fifth digits indicating uncontrolled diabetes should not be assigned based on blood glucose levels; these codes should only be used when the physician documents uncontrolled diabetes” (AHA Coding Clinic for ICD-9-CM, 1993, fourth quarter, page 19). As a guideline, patients with diabetes with a fasting blood sugar level greater than 250 usually warrant querying the physician for clarification of uncontrolled status.

If the physician documents “poorly controlled” diabetes, query the physician as to whether he or she is stating that the patient’s diabetes is uncontrolled. It cannot be assumed that “poorly controlled” diabetes means “uncontrolled” without additional documentation from the physician (AHA Coding Clinic for ICD-9-CM, 2002, second quarter, page 13).

Diabetes Manifestations
If the patient is admitted with a diabetic condition or with a condition due to diabetes, the diabetic code (250.xx) must be sequenced as the principal diagnosis followed by the code for the specific condition. Conditions are coded in this manner even though the ICD-9-CM alphabetic index may not indicate dual coding (AHA Coding for ICD-9-CM, 1991, third quarter, page 8).

There must be a cause-and-effect relationship between the diabetes and the condition before it can be coded as a diabetic condition. The fact that the patient has diabetes and another condition does not necessitate coding it as a diabetic condition. For example, if a diabetic patient is admitted with a foot ulcer, the foot ulcer cannot be coded as a diabetic complication unless the physician documents that it is due to diabetes or that it is a diabetic foot ulcer. Without further clarification from the physician, code 707.15 would be sequenced as the principal diagnosis followed by code 250.0x.

AHA Coding Clinic for ICD-9-CM assumes a relationship between diabetes and gangrene and diabetes and osteomyelitis. In other words, if diabetes and gangrene or diabetes and osteomyelitis are documented in the medical record with no other stated cause, it is assumed to be a diabetic complication (eg, 250.7x or 250.8x). However, if the osteomyelitis or gangrene has a documented stated cause other than diabetes, then it will not be coded as a diabetic complication (AHA Coding Clinic for ICD-9-CM, 2004, first quarter, pages 14-15).

Effective October 1, the following new codes were created for diabetic retinopathy:

• 362.03, Nonproliferative diabetic retinopathy NOS (not otherwise specified)

• 362.04, Mild nonproliferative diabetic retinopathy

• 362.05, Moderate nonproliferative diabetic retinopathy

• 362.06, Severe nonproliferative diabetic retinopathy

• 362.07, Diabetic macular edema

Note: Code 362.07 must be used with a code for diabetic retinopathy (362.01-362.06)

A patient may have diabetic complications in more than one system. Assign as many codes from category 250 as are needed to fully describe the patient’s condition (AHA Coding Clinic for ICD-9-CM, 2005, first quarter, page 45). Sequence as the principal diagnosis the diabetic condition that necessitated the admission. If treatment was directed toward all conditions equally, any associated code from category 250 may be sequenced as the principal diagnosis.

Coding and sequencing for diabetes mellitus are dependent on the physician documentation in the medical record and application of the Official Coding Guidelines for inpatient care. Also, use specific AHA Coding Clinic for ICD-9-CM and American Medical Association CPT Assistant references to ensure complete and accurate coding.

— This information was prepared by Audrey Howard, RHIA, of 3M Health Information Systems (800-367-2447), a supplier of coding and classification systems to nearly 5,000 healthcare providers. The company and its representatives do not assume any responsibility for reimbursement decisions or claims denials made by providers or payors as the result of the misuse of this coding information.

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