ICD-10 Codes for Diabetes Mellitus (E08–E13)

The five diabetes categories

ICD-10-CM organizes diabetes mellitus by type and underlying cause, not by a single code. Start by choosing the right category, then add the characters that describe the complication.

Gestational diabetes is coded separately from chapter O — O24.4- (gestational diabetes mellitus in pregnancy), not from E08–E13.

Type 2 diabetes (E11) — the codes you'll use most

The base code is E11.9 (type 2 diabetes mellitus without complications), but it's only correct when no complication is documented. In ongoing care, many established patients have at least one, and ICD-10 expects the combination code that captures it:

Need a code that isn't here? Search the full E11 family in the lookup tool. Type 1 mirrors this structure under E10 (for example E10.9, E10.65, E10.22).

How to choose the right diabetes code

Work through four questions in order:

1. What type or cause is it?

That sets the category — E10 for type 1, E11 for type 2, E08/E09/E13 for the secondary forms. When the type isn't stated, ICD-10 defaults to type 2 (E11).

2. Is there a complication?

If a complication is documented, use the combination code that names it (kidney, eye, nerve, circulatory, skin) rather than the “without complications” code. These are single combination codes — you don't code the diabetes and the complication separately at the category level.

3. Does it need a second, paired code?

Some combination codes still require an additional code for full specificity. The common ones: with CKD (E11.22), also code the stage from N18.-; with a foot ulcer (E11.621), also code the ulcer site and severity from L97.-. Code as many complications as the record documents. Watch the kidney pair specifically: E11.22 (paired with the N18 stage) is for documented chronic kidney disease, while E11.21 is diabetic nephropathy — they're distinct, chosen by what's documented, not interchangeable.

4. What's the treatment status?

For a type 2 patient on long-term medication, add a status code: Z79.4 (long-term use of insulin) or Z79.84 (long-term use of oral hypoglycemic drugs). If the patient is on both insulin and an oral agent, assign both Z79.4 and Z79.84 (per the FY2026 ICD-10-CM guidelines). Do not add Z79.4 for type 1, where insulin use is inherent.

Common diabetes coding mistakes

• Defaulting to E11.9. The biggest one. Many established diabetic patients have a documented complication; E11.9 understates the condition, drives unspecified-diagnosis denials, and undercounts risk adjustment (HCC) capture.
• Coding “uncontrolled” diabetes. There is no uncontrolled code. Translate it to the documented state — with hyperglycemia (E11.65) or with hypoglycemia.
• Forgetting the paired code. Using E11.22 without the N18.- stage, or E11.621 without the L97.- ulcer code, leaves the claim under-specified.
• Missing the insulin/drug status. Omitting Z79.4 or Z79.84 on a type 2 patient on long-term therapy is a frequent omission that affects severity capture.
• Underestimating how broad “with” is. The presumed-link list is wider than many coders expect — it even includes osteomyelitis (diabetes with osteomyelitis is presumed related → E11.69, plus an added code for the osteomyelitis itself). The assumption stops only when the provider documents the two conditions as unrelated, or a guideline requires explicit linkage.

A worked example

The other diabetes types

Beyond type 1 and type 2, three categories cover the rest, and each mirrors the same complication structure. E08 is diabetes due to an underlying condition (for example a pancreatic disorder); E09 is drug- or chemical-induced diabetes (for example steroid-induced); and E13 is other specified diabetes (for example postpancreatectomy or a monogenic form). Gestational diabetes is separate again — coded from O24.4- by control method, not from E08–E13. When the type isn't documented at all, ICD-10 defaults to type 2 (E11).

What the note needs to document

To code diabetes to the highest specificity, the clinical note should make these explicit:

• The type or cause (type 1, type 2, drug-induced, secondary)
• Each complication by organ system, and its detail (e.g. CKD stage, retinopathy type and macular-edema status, neuropathy type)
• The current glycemic state when relevant (hyperglycemia / hypoglycemia)
• Long-term insulin or oral-agent use

Frequently asked questions