How to Succeed in Coding Diabetes Mellitus Without Really Trying

My first blog on Diabetes Mellitus (DM) covered the pathophysiology of DM Types 1, 1.5, and 2. Read Part 1 Here.

Types 1 and 2 (and even 1.5, though not “officially” recognized) are considered primary types of DM. There are other forms of DM that are due to underlying conditions or are “induced” by drugs or chemicals.

Complications of primary DM include: hyperglycemia, hypoglycemia, HHS (diabetic hyperglycemia hyperosmolar state); DKA; and hyponatremia with diabetic hyperglycemia. Diabetes can also manifest into other conditions like retinopathy, skin ulcers, and nephropathy. Today, we’ll concentrate on ICD-10-CM codes for Types 1, 1.5, and 2. Realizing the importance of fully comprehending the pathophysiology of secondary diabetes as well as all diabetic complications and manifestations, future blogs will delve into of these topics.

DM has five category codes in ICD-10-CM – category codes are E08 – E13. Note: There is no category code E12.

In examining code assignments for DM Types 1, 1.5, and 2, where might you start? Well, let us turn to the 2021 ICD-10-CM OGCR – the Official Guidelines for Coding & Reporting.

OGCR 1.C.4.a specifically addresses DM, noting the codes are combination codes that:

  • Include the type of DM and
  • The body systems affected, in addition to
  • The complications affecting specific body systems.

The guideline states that the coder should:

  • Assign as many codes within a category as are needed in order to adequately reflect all documented complications;
  • Sequence the codes based on the reason for that specific encounter; and
  • Assign a code from category E11 – Type 2 DM should the record fail to document the type of DM

CODING TYPE 1 DM – Assign a code from category E10.

  • Fourth, fifth-, and sixth-digit assignments address complications like ketoacidosis; kidney, ophthalmic, neurologic, circulatory, and “other specified” complications like diabetic arthropathy, skin, oral complications, hypo- and hyperglycemia.
  • Ophthalmic complications are further specified via coder-selected seventh digits.

CODING TYPE 2 DM – Assign a code from category E10.

  • Fourth and fifth digits address complications related to hyperosmolarity, ketoacidosis, kidney, neurologic, and circulatory systems, and hyperglycemia.
  • Depending on the circumstances (and documentation) coding arthropathy, and skin complications requires six digits.
  • Type 2 (like Type 1) ophthalmic complications require a coder-selected seventh digit.


Unlike Types 1 and 2, there is no specific category code for Type 1.5 DM. It has been my experience that the ICD-10 classification system can lag several years behind medical advances and changes to medical diagnoses and treatments.

The AHA Coding Clinic for ICD-9-CM and ICD-10-CM/PCS ©, 3Q 2018 (pages 4-5) recommends assigning code(s) from category E13, Other specified diabetes mellitus, for Type 1.5: “ Type 1.5 diabetes is a form of diabetes in which an adult has features of both type 1 and type 2 diabetes. These patients have also been described with the terms “latent autoimmune diabetes of adults” (LADA), and “slow-progressing type 1 diabetes.” The condition has also been called “double” diabetes because individuals demonstrate both the autoimmune destruction of beta cells of type 1 diabetes and the insulin resistance characteristic of type 2 diabetes. People with type 1.5 diabetes have autoantibodies to insulin-producing beta cells and gradually lose their insulin-producing capability, requiring insulin within 5-10 years of diagnosis.”

So, there you have it. Information on assigning ICD-10-CM codes tor DM Types 1, 1.5, and 2. Coders are reminded to always review the provider’s documentation, in addition to thoroughly reading all includes, excludes, and other instructional notes found under category codes E08 – E13 in the classification itself.

SUMMARY: While briefly mentioning the complications of primary diabetes mellitus (DM) and manifestations of the disease, this blog concentrates on ICD-10-CM code assignments and coding guidelines for primary diabetes mellitus (DM) – Types 1, 1.5, and 2. Complications/manifestations of DM, as well as use of insulin, oral, and other injectable medications use to treat DM will be covered in future blogs along with review of the specific ICD-10-CM codes that should be assigned. KEY WORDS: Complication – A condition that aggravates an existing disease Manifestation – A condition/disease that is caused by another disease OGCR – 2021 ICD-10-CM Official Guidelines for Coding and Reporting.

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