October 24, 2011
Coding for Diabetes Mellitus
In type 1 diabetes mellitus (DM), beta cells are destroyed by an autoimmune process that usually leads to a complete loss of insulin production. The majority of patients who develop type 1 DM will do so prior to age 25, with an increased prevalence due to heredity or in patients with other autoimmune diseases. Type 1 DM patients are dependent on insulin.
In type 2 DM, the pancreas continues to produce insulin but doesn’t produce enough and doesn’t utilize it properly (insulin resistance).
Secondary diabetes is diabetes or glucose intolerance that develops from disorders or conditions other than type 1 or type 2 diabetes or gestational diabetes. Secondary diabetes may bring out primary diabetes in people who are predisposed to developing primary diabetes. Common causes of secondary diabetes include but are not limited to pancreatitis, pancreatectomy; malnutrition, endocrinopathies, and drugs, chemical agents, and toxins.
DM is assigned to ICD-9-CM category 250. Secondary diabetes is classified to category 249. When the physician documents DM, additional documentation is necessary to completely classify the condition: type 1 vs. type 2, uncontrolled vs. controlled, and manifestations associated with the condition, if any.
The fourth-digit subcategory identifies any condition or manifestation associated with diabetes. The fifth-digit subclassification refers to type 1 or type 2 DM and whether it is controlled or uncontrolled.
DM defaults to type 2 if not specifically documented, as this is the most common type. The fact that the patient receives insulin during the hospital stay has no effect on diabetes classification (AHA Coding Clinic for ICD-9-CM, 2005, first quarter, page 44).
Uncontrolled diabetes is a nonspecific term indicating a patient’s glucose levels are not within acceptable levels in relation to the current treatment regime. There can be a variety of reasons for this, including noncompliance, insulin resistance, dietary indiscretion, and current illness. Uncontrolled diabetes should not be reported unless the physician’s documentation supports the diagnosis and should not be reported based on blood glucose levels. Uncontrolled diabetes should be coded only when the physician documents uncontrolled diabetes or out-of-control diabetes (AHA Coding Clinic for ICD-9-CM, 1993, fourth quarter, page 19). However, documentation of “poorly controlled” requires additional clarification from the physician to determine whether this is uncontrolled or controlled diabetes (AHA Coding Clinic for ICD-9-CM, 2002, second quarter, page 13).
Hemoglobin A1c (HbA1c) levels measure overall blood glucose concentrations during the previous two to three months. When there is excess circulating glucose in the bloodstream, the glucose attaches itself to hemoglobin (glycosylation). This is measured in three subsets of hemoglobin (A1a, A1b, and A1c) as the percentage of red blood cells that are glycosylized. Since a red blood cell has a half-life of approximately 120 days, it is possible to measure average glucose concentrations (hence diabetic control) over a two- to three-month period.
If the patient is admitted with a diabetic condition or has a condition due to diabetes, the diabetic code from category 250 must be sequenced as the principal diagnosis followed by the manifestations as secondary diagnoses. Conditions are coded in this manner even though the ICD-9-CM alphabetic index may not indicate dual coding (AHA Coding Clinic for ICD-9-CM, 1991, third quarter, page 8). In other words, the physician must state a cause-and-effect relationship between the manifestation and the diabetes before it can be coded as a diabetic condition. Two exceptions to this rule are gangrene and osteomyelitis. If a diabetic patient is admitted with gangrene or osteomyelitis with no other documented causes of those conditions, then it is automatically reported as a diabetic condition without a cause-and-effect relationship established by the physician (AHA Coding Clinic for ICD-9-CM, 2004, first quarter, pages 14-15).
If a patient is admitted with uncontrolled diabetes and there are no other diabetic manifestations documented, then assign code 250.02 or 250.03. However, if the patient has a documented diabetic manifestation (eg, diabetic neuropathy) with the uncontrolled diabetes, assign the diabetic code related to the manifestation (eg, 250.62 or 250.63). This is the case even though the manifestation was not the reason for the admission.
A patient may have diabetic complications in more than one body system. Report as many diabetic manifestations as are needed to fully describe the patient’s condition. Sequence the diabetic condition that necessitated the admission as the principal diagnosis. If treatment was directed toward all conditions equally, any diabetic condition may be sequenced as the principal diagnosis (AHA Coding Clinic for ICD-9-CM, 2005, first quarter, page 45).
Coding and sequencing for DM 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 Consulting Services. 3M Consulting Services is a business of 3M Health Information Systems, a supplier of coding and classification systems to more than 5,000 healthcare providers. The company and its representatives do not assume any responsibility for reimbursement decisions or claims denials made by providers or payers as the result of the misuse of this coding information. More information about 3M Health Information Systems is available at www.3mhis.com or by calling 800-367-2447.
ICD-10-CM Coding for Diabetes Mellitus
• Diabetes mellitus due to underlying condition (E08);
• Drug- or chemical-induced diabetes mellitus (E09);
• Type 1 diabetes mellitus (E10);
• Type 2 diabetes mellitus (E11); and
• Other specified diabetes mellitus (E13).
If DM is due to an underlying condition, drug induced, or chemical induced, then that condition is sequenced first.
In ICD-10-CM, DM is indicated in combination with the type of diabetes, the body system affected, and the complications affecting the body system rather than requiring two or more codes as in ICD-9-CM. For example, type 2 DM with mild nonproliferative diabetic retinopathy with macular edema is completely classified with one ICD-10-CM code (E11.321).
ICD-10-CM does not classify DM by control status. However, inadequately controlled, out-of-control, or poorly controlled diabetes are coded to diabetes, by type, with hyperglycemia.
— Audrey Howard