ICD-10 training: Coding for diabetes

In order to understand diabetes coding in ICD-10, it’s worth making a comparison of the structural differences between ICD-9-CM and ICD-10-CM. 

Diabetes mellitus (DM) codes in ICD-10-CM are combination codes that include the type of DM, the body system affected, and the complication affecting that body system as part of the code description. Subcategory levels first specify the type of complication by system, such as diabetes with kidney complications, ophthalmic complications, neurological complications, and circulatory complications. The subclassification level then describes the particular manifestation. 

For example:

E11.3: Type 2 diabetes mellitus with ophthalmic complications.
E11.32: Type 2 diabetes mellitus with mild nonproliferative diabetic retinopathy.
E11.321: Type 2 diabetes mellitus with mild nonproliferative diabetic retinopathy with macular edema.
E11.329: Type 2 diabetes mellitus with mild nonproliferative diabetic retinopathy without macular edema.

A subcategory for diabetes mellitus with other specified complications is also provided that includes codes for DM with diabetic neuropathic arthropathy, diabetic dermatitis, foot ulcer, other skin ulcer, periodontal disease, hypoglycemia, and hyperglycemia.

As many codes as are needed to describe all of the associated complications that the patient has should be assigned from a particular category. Because of this code structure, there is no instructional note found under diabetes mellitus codes in ICD-10-CM requiring an additional code to identify the manifestation since it is already part of the code description.

There are specific diabetes codes that do require additional codes in order to identify the manifestation further, such as diabetes with foot ulcer to identify the site of the ulcer, or diabetes with chronic kidney disease to identify the stage of chronic kidney disease. For example, the code E10.621 ( Type 1 diabetes mellitus with foot ulcer) requires the use of an additional code to identify the site of the ulcer (L97.4-, L97.5-)
 

ICD-10-CM codes do not require an additional fifth digit to identify the type of diabetes mellitus and whether it is controlled or uncontrolled. Cases that are noted as ‘inadequately controlled,’ ‘poorly controlled,’ or ‘out of control’ are coded to the diabetes, by type, with hyperglycemia:

E11.65: Type 2 diabetes mellitus with hyperglycemia.

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Secondary diabetes mellitus
Secondary diabetes mellitus is coded as either diabetes due to an underlying condition (category E08), drug or chemical induced diabetes (category E09), or other types of secondary diabetes mellitus NEC (category E13) which includes diabetes due to genetic defects of beta-cell function or insulin action, and postsurgical or postpancreatectomy cases of diabetes.

Sequencing of secondary diabetes codes in relation to the cause of the DM is assigned according to tabular instructions. Category E08 instructions state to code first the underlying condition, such as Cushing’s syndrome, cystic fibrosis, malnutrition, or a malignant neoplasm. Category E09 instructions state to code first poisoning due to drug or toxin (T36-T65) and use the appropriate fifth or sixth character ‘1-4’ or ‘6’ for poisoning. If the secondary diabetes is due to an adverse effect of a drug or chemical, then instructions direct the coder to use an additional code for the adverse effect (T36-T50) with fifth or sixth character ‘5’.

Cases of diabetes occurring with hyperosmolarity, with ketoacidosis, and with hypoglycemia must all be coded as with or without coma:

E10.10: Type 1 diabetes mellitus with ketoacidosis without coma
E10.11: Type 1 diabetes mellitus with ketoacidosis with coma
E08.00 : Diabetes mellitus due to underlying condition with hyperosmolarity without nonketotic hyperglycemic-hyperosmolar coma (NKHHC).
E08.00: Diabetes mellitus due to underlying condition with hyperosmolarity with coma.
E13.641: Other specified diabetes mellitus with hypoglycemia with coma.
E13.649: Other specified diabetes mellitus with hypoglycemia without coma.

In ICD-10-CM, only Type 1 diabetes is listed with the possible manifestation of ketoacidosis with or without coma. Type 2 and all secondary types are listed with the possible manifestation of hyperosmolarity with or without coma.

Diabetes mellitus in pregnancy, childbirth, or the puerperium
Diabetes mellitus in pregnancy, childbirth, or the puerperium is not simply coded as to episode of care in ICD-10-CM.

Codes must first be selected as either pre-existing DM type 1, pre-existing DM type 2, unspecified pre-existing DM, gestational DM, other pre-existing DM, and unspecified DM.

The second axis of coding specifies whether in pregnancy, in childbirth, or in the puerperium, and all but the gestational diabetes mellitus codes also must specify the trimester of pregnancy.

Valid code examples include:

O24.011: Pre-existing diabetes mellitus, type 1, in pregnancy, first trimester.
O24.12: Pre-existing diabetes mellitus,
type 2, in childbirth.
O24.33: Unspecified pre-existing diabetes mellitus in the puerperium.
O24.812: Other pre-existing diabetes mellitus in pregnancy, second trimester.

Cases of gestational diabetes are reported as in pregnancy, in childbirth, or in the puerperium and each of these subcategories is further specified as to diet controlled, insulin controlled, or unspecified control:

O24.41: Gestational diabetes mellitus in pregnancy.
O24.410: Gestational diabetes mellitus in pregnancy, diet controlled.
O24.414: Gestational diabetes mellitus in pregnancy, insulin controlled.
O24.419: Gestational diabetes mellitus in pregnancy, unspecified control.

Prepare for code changes
Occasional changes have been made to the coding of diabetes mellitus in ICD-10-CM between draft versions, so even those
already familiar with diabetes codes in ICD-10-CM will want to review the coding of diabetes in ICD-10-CM to maintain an accurate knowledge base.