Diabetes mellitus is on the rise and data regarding its type, manifestations and impact on cost and length of stay are needed to assess the effectiveness of current evaluation and management. Medicare claims data can provide important information about diabetes mellitus if physicians provide complete and accurate documentation, which includes the following elements.
Specify type of diabetes
Is the patient's diabetes mellitus type 1 or type 2? A patient whose diabetes is controlled by insulin does not necessarily have type 1 disease. To promote accurate reporting and risk adjustment, avoid terminology such as non-insulin dependent diabetes mellitus (NIDDM) and insulin-dependent diabetes mellitus (IDDM). We now have an ICD-9-CM code to report long-term use of insulin (V58.67). This code is often added for type 2 diabetics using long-term insulin to support insurance payment for additional testing materials.
Secondary diabetes is now distinguishable from type 1 or type 2 diabetes. In 2008, new ICD-9-CM codes were created for diabetes caused by another disease or certain drugs. Physicians must also document the condition causing the secondary diagnosis, for example, Cushing's syndrome, cancer of the pancreas, or long-term use of steroids or other drugs.
Document diabetic manifestations
A cause-and-effect relationship between diabetes and most other conditions may not be assumed. The physician must document the relationship between the condition and diabetes unless the coding guidelines specify otherwise. A manifestation may be presumed when documented as diabetes “with,” “with mention of,” “associated with” or “in” the respective condition (e.g., diabetes with neuropathy).
- Diabetic ulcers of the lower extremities (including the heel and foot but excluding the toes) are complications/comorbidities (CCs) on an inpatient claim. The physician documentation should distinguish between diabetic ulcer and pressure or other type of ulcer and whether or not it was present on admission.
- Diabetic autonomic neuropathy is a qualifying CC generating additional reimbursement. The autonomic nervous system includes neurons of the involuntary nervous system: heart, lungs, viscera, glands and blood vessels. Signs and symptoms depend on the affected organ systems and may include changes in digestion, bowel and bladder function, sexual response, perspiration, orthostatic hypotension or hypoglycemic unawareness. The relationship between the diabetes and the autonomic neuropathy must be documented, and the neurological condition (e.g., gastroparesis, nerve palsy or mononeuropathy) must be documented by the physician or midlevel provider responsible for establishing the patient's diagnosis.
- Diabetic peripheral neuropathy classification depends on the presence of certain symptoms and/or signs that indicate involvement of a particular part of the peripheral nervous system. Examples are focal mononeuropathy or polyneuropathy.
- Diabetic nephrosis is a qualifying CC on an inpatient claim. The relationship between diabetes and the nephrosis must be documented by the physician or midlevel provider responsible for establishing the patient's diagnosis. Diabetic neuropathy is not considered a CC unless the patient also has hypertension resulting in chronic kidney disease; the corresponding stage of the latter should also be reported. Stages 4-5 are counted as CCs.
- Diabetic peripheral vascular disease is a frequent complication of diabetes. Although arteriosclerosis occurs earlier and more extensively in diabetic patients, for coding purposes coronary artery disease, cardiomyopathy and cerebrovascular disease are usually not considered complications of diabetes.
- Diabetic retinopathy is important to document even though it does not impact the MS-DRG payment. For documentation and coding accuracy, nonproliferative diabetic retinopathy should be specified as mild, moderate or severe. An additional ICD-9-CM code is used to report macular edema in a patient with diabetic retinopathy if the condition is documented by the physician.
- Osteomyelitis in a diabetic patient is always presumed to be related to the diabetes unless the physician specifically states it is due to another condition (Official Coding Guidelines 2008). Diabetic osteomyelitis is a CC when correctly coded on an inpatient claim qualifying for MS-DRG reimbursement.
- Gangrene in a diabetic patient is also presumed to be linked to the diabetes unless otherwise specified by the physician.
Document degree of control
Much has been written about glucose control and its impact on patient outcomes. From an ICD-9-CM coding perspective, uncontrolled diabetes indicates the patient's blood sugar level is not kept within acceptable levels by his or her current treatment regimen. No specific blood glucose level is considered uncontrolled. “Out of control” is equivalent to “uncontrolled,” but the terms “brittle” and “poorly controlled” are not. In addition, the terms “hypoglycemia” and “hyperglycemia” are not sufficient to classify a patient's diabetes as uncontrolled. CMS quality measures for cardiac surgery patients with controlled 6:00 a.m. blood glucose define controlled as under 200 mg/dL. Uncontrolled diabetes no longer impacts the MS-DRG assignment, but it can impact risk adjustment and help support medical necessity for admission.
Uncontrolled diabetes in a patient using an insulin pump may be due to a malfunction of the pump resulting in overdosing or underdosing of insulin. In both of these situations, an ICD-9-CM code is added to reflect a mechanical complication of the device. If the malfunction results in hypoglycemia due to an overdose of insulin, an additional ICD-9-CM code is added to indicate this. A mechanical complication is considered a CC when reported as a secondary diagnosis on a payable inpatient claim.
Diabetic ketoacidosis, diabetic nonketotic hyperosmolar coma and diabetic hypoglycemic coma are considered major complications/comorbidities (MCCs) when reported as secondary diagnoses on an inpatient claim, resulting in a substantial increase in the MS-DRG payment. Under Medicare's Value-Based Purchasing Initiative, these conditions are considered “reasonably preventable” and are not eligible for payment in 2009 if they develop during the hospital stay.