Type 2 Diabetes Uncontrolled ICD-10: Codes, Guidelines & Examples

Type 2 Diabetes Uncontrolled ICD-10 coding often appears straightforward, but the correct diagnosis code depends on what the provider actually documents. In ICD-10-CM, there is no diagnosis code whose official description is simply “uncontrolled type 2 diabetes.” Documentation may instead support type 2 diabetes with hyperglycemia, E11.65, hypoglycemia, ketoacidosis, hyperosmolarity, or one or more diabetic complications.

The distinction matters for billing. Selecting E11.9 when hyperglycemia or a diabetic complication is documented may result in undercoding. Assigning E11.65 from an abnormal glucose or A1C result without provider documentation can create a compliance problem. Missing combination codes, additional complication codes, long-term medication status codes, or payer-specific medical necessity requirements can also contribute to denials and delayed reimbursement. The FY 2026 guidelines emphasize complete documentation and require coders to use the ICD-10-CM conventions, Alphabetic Index, Tabular List, and applicable reporting guidelines.

This guide explains the correct ICD-10-CM approach to uncontrolled type 2 diabetes, the difference between E11.65 and E11.9, related diabetes complication codes, commonly associated CPT and HCPCS codes, sequencing rules, documentation requirements, billing examples, inpatient versus outpatient rules, and clean-claim practices.

What Is the ICD-10 Code for Uncontrolled Type 2 Diabetes?

The code most commonly associated with poorly controlled or out-of-control type 2 diabetes with hyperglycemia is E11.65, Type 2 diabetes mellitus with hyperglycemia. The ICD-10-CM Index directs terms such as “inadequately controlled,” “out of control,” and “poorly controlled” diabetes to diabetes by type with hyperglycemia.

However, coders should not treat the word “uncontrolled” as permission to automatically assign E11.65 in every case. If the documentation makes clear that the lack of control refers to hyperglycemia, E11.65 is generally supported. If “uncontrolled” could refer to hypoglycemia, major glucose fluctuations, or another acute diabetic condition, the record should be clarified rather than interpreted clinically by the coder.

E11.9, Type 2 diabetes mellitus without complications, is different. It is appropriate when type 2 diabetes is documented and no reportable diabetic complication or hyperglycemic condition is documented. It should not be substituted for E11.65 when the provider has documented hyperglycemia. CMS’s FY 2026 code set lists both E11.65 and E11.9 as separate diagnoses.

These diagnoses are separately recognized in the FY 2026 code set.

Which ICD-10-CM Version Applies in 2026?

For dates of service from April 1 through September 30, 2026, the applicable official guidance is the FY 2026 ICD-10-CM update effective April 1, 2026. The official document states this effective period directly.

FY 2026 originally began October 1, 2025. An April 1, 2026 update was subsequently issued. Coding teams therefore need to validate codes against the version effective for the actual date of service rather than simply relying on the calendar year.

The FY 2027 ICD-10-CM files have already been published, but they apply beginning October 1, 2026, rather than to August or September 2026 encounters.

This date distinction is especially important when EHR pick lists, encoder software or internal code sheets have been updated before the new code set becomes effective.

Type 2 Diabetes ICD-10-CM Master Reference Table

Type 2 diabetes codes are combination codes. They can identify the diabetes type together with the affected body system and diabetic complication. More than one E11.- code may be reported when needed to capture multiple documented diabetic complications.

CMS’s FY 2026 definitions manual confirms these E11.- categories, including E11.65, E11.9 and E11.A.

This table is not every possible E11.- code. Ophthalmic complications alone contain numerous codes based on retinopathy type, severity, macular edema and laterality. Greater specificity should be used whenever the documentation supports it.

Important Additional Diagnosis Codes Used With Type 2 Diabetes

Several Z codes can help describe ongoing treatment. FY 2026 guidance specifically instructs coders to identify long-term use of insulin, oral hypoglycemic drugs and injectable non-insulin antidiabetic drugs when applicable.

For a type 2 diabetic patient who routinely takes both insulin and an oral hypoglycemic medication, Z79.4 and Z79.84 may both be reported. If insulin and a non-insulin injectable antidiabetic drug are both used long term, Z79.4 and Z79.85 may both apply.

Do not assign Z79.4 merely because insulin was administered temporarily during an encounter to bring a type 2 patient’s glucose under control. The FY 2026 guideline specifically excludes temporary insulin use from this long-term-use coding instruction.

Common CPT and HCPCS Codes Related to Uncontrolled Type 2 Diabetes Billing

An ICD-10 diagnosis code tells the payer why the patient was evaluated or treated. CPT and HCPCS codes report what service, test or procedure was performed. There is therefore no single CPT code for uncontrolled type 2 diabetes.

The appropriate procedure code depends on the actual service, documentation, provider type, setting, payer and coverage requirements.

CMS recognizes office/outpatient codes 99202–99205 and 99211–99215, and its CY 2026 Physician Fee Schedule policies took effect January 1, 2026. CMS coverage materials also identify 83036, 82947, 82948, 82962, 82043 and 82570 in diabetes-related laboratory and monitoring contexts.

For diabetes self-management training, Medicare uses G0108 for individual sessions and G0109 for group sessions. Medical nutrition therapy may involve 97802–97804 and, in qualifying Medicare situations, G0270 or G0271. Coverage requirements extend beyond simply having an E11.- diagnosis code.

A correct diabetes diagnosis code does not automatically guarantee reimbursement for any of these procedures. Medical necessity, frequency limits, provider eligibility, ordering requirements, modifiers, bundling edits and payer-specific coverage rules still apply. CMS, for example, publishes limited-coverage guidance for several laboratory codes used in diabetic monitoring.

1. Start With the Provider’s Diagnosis

Begin with the provider’s documented assessment, not the laboratory report.

If the assessment states:

“Type 2 diabetes mellitus with hyperglycemia”

the supported diagnosis is E11.65.

If the only information available is an elevated glucose or A1C value, the coder should not independently diagnose hyperglycemia as a diabetic complication.

The FY 2026 guidelines stress that accurate code assignment depends on complete documentation and that the provider is the practitioner legally accountable for establishing the diagnosis.

2. Confirm the Diabetes Type

Determine whether the patient has type 1, type 2, drug-induced, secondary or another specified form of diabetes.

If the diabetes type is not documented, ICD-10-CM guidance states that the default is E11.-, Type 2 diabetes mellitus. Treatment with insulin alone does not automatically convert the patient to type 1 diabetes.

3. Determine What “Uncontrolled” Means

Review the provider’s wording.

“Poorly controlled with persistent hyperglycemia” supports E11.65.

“Uncontrolled with recurrent hypoglycemic episodes” points toward a hypoglycemia code rather than E11.65.

If the note simply says “uncontrolled diabetes” and the intended clinical condition is unclear, a compliant provider query can prevent an unsupported assumption.

4. Identify Every Documented Diabetic Complication

A patient may have hyperglycemia and diabetic neuropathy at the same time.

For example:

1. E11.65 – type 2 diabetes with hyperglycemia
2. E11.42 – type 2 diabetes with diabetic polyneuropathy

The official guidelines permit as many codes within the appropriate diabetes category as needed to identify the patient’s associated conditions.

5. Review “Use Additional Code” Instructions

Some combination diagnoses require another code to fully describe the condition.

For diabetic CKD, E11.22 identifies the relationship between diabetes and CKD, while an additional N18.- code identifies the CKD stage.

Diabetic foot ulcers similarly require E11.621 plus an additional ulcer code identifying the site and severity where documented. ICD-10-CM’s tabular structure contains these additional-code instructions.

6. Capture Long-Term Diabetes Medication Use

For type 2 diabetes treated routinely with insulin, oral hypoglycemic drugs or injectable non-insulin medications, review whether Z79.4, Z79.84 and/or Z79.85 should be added.

These codes describe treatment status; they do not replace the E11.- diagnosis code.

7. Sequence According to the Reason for the Encounter

There is no rule saying E11.65 must always be first-listed.

The diabetes codes should be sequenced according to the condition chiefly responsible for the encounter and any specific tabular instructions. The FY 2026 diabetes guideline expressly states that diabetic combination codes should be sequenced based on the reason for the particular encounter.

8. Match the Diagnosis to the Billed Service

Before claim submission, confirm that the diagnosis supports the service billed.

An A1C test, CGM interpretation, office E/M service, diabetes education session and medical nutrition therapy service each have different documentation and coverage requirements. CMS advises providers to use codes at the highest supported specificity and to follow coverage requirements applicable to the service.

Good diabetes documentation supports accurate coding, appropriate reimbursement and audit defensibility. A note should make it possible to distinguish uncomplicated diabetes from hyperglycemia, hypoglycemia and specific complications without requiring the coder to interpret clinical values.

Documentation Requirements for E11.65 and Related Codes

Good diabetes documentation supports accurate coding, appropriate reimbursement and audit defensibility. A note should make it possible to distinguish uncomplicated diabetes from hyperglycemia, hypoglycemia and specific complications without requiring the coder to interpret clinical values.

Weak Documentation

“DM uncontrolled. A1C high.”

The statement identifies diabetes but leaves several questions. The diabetes type may be unclear, and “uncontrolled” does not clearly state whether the issue is hyperglycemia, hypoglycemia or another problem.

Better Documentation

“Type 2 diabetes mellitus, poorly controlled with persistent hyperglycemia. Continue metformin and increase basal insulin.”

This clearly supports the diabetes type and hyperglycemia diagnosis and also provides treatment context.

Possible coding:

1. E11.65
2. Z79.4, if insulin use is long term
3. Z79.84, if the oral hypoglycemic drug is used long term

The FY 2026 guidelines allow both Z79.4 and Z79.84 when both forms of therapy are used chronically.

Strong Documentation

“Type 2 diabetes mellitus with persistent hyperglycemia and diabetic CKD stage 3b. Patient uses long-term basal insulin and oral antidiabetic medication.”

Possible coding may include:

1. E11.65
2. E11.22
3. Applicable N18.- code for stage 3b CKD
4. Z79.4
5. Z79.84

Final coding must follow the exact documentation and current Tabular List instructions.

High-Risk Type 2 Diabetes Coding Scenarios

E11.65 vs E11.9

E11.65 describes type 2 diabetes with hyperglycemia. E11.9 describes type 2 diabetes without complications. These codes are not interchangeable.

Example

Provider documents: “Type 2 diabetes, poorly controlled with hyperglycemia.”

Possible coding:

1. E11.65

Using E11.9 would fail to capture the documented hyperglycemia.

Hyperglycemia and Other Diabetic Complications

Hyperglycemia does not prevent coding another documented diabetic complication.

Example

“Type 2 diabetes with hyperglycemia and diabetic polyneuropathy.”

Possible coding:

1. E11.65
2. E11.42

ICD-10-CM allows multiple diabetes combination codes when they are necessary to describe all associated conditions.

Type 2 Diabetes With CKD

Diabetic CKD normally requires the diabetes combination code plus a code identifying the CKD stage.

Example

“Type 2 diabetes with CKD stage 4 and hyperglycemia.”

Possible coding:

1. E11.22
2. Applicable N18.- stage 4 code
3. E11.65

The additional N18.- code supplies CKD stage specificity.

Type 2 Diabetes With Foot Ulcer

For a documented diabetic foot ulcer, E11.621 identifies the diabetic complication, while an additional ulcer code identifies the ulcer’s location and severity.

Example

“Type 2 diabetes with diabetic right heel ulcer extending to fat layer.”

Possible coding approach:

1. E11.621
2. Appropriate L97.- code based on documented site, laterality and severity
3. E11.65, if hyperglycemia is also documented

Do not choose the L97.- code without sufficient ulcer documentation.

DKA and Hyperosmolar States

Type 2 diabetes can be coded with ketoacidosis or hyperosmolarity when those conditions are diagnosed.

Relevant codes include:

• E11.10 – ketoacidosis without coma
• E11.11 – ketoacidosis with coma
• E11.00 – hyperosmolarity without coma
• E11.01 – hyperosmolarity with coma

These conditions should not be reduced to E11.65 merely because hyperglycemia is also clinically present. The specific acute diabetic diagnosis should drive code selection.

Insulin Pump Malfunction

Insulin pump malfunction follows special coding rules. For an underdose caused by pump failure, FY 2026 guidance directs coding first to the applicable T85.6- mechanical complication, followed by the underdosing code from T38.3X6-, plus the diabetes code and complications caused by the underdose as appropriate.

An overdose due to pump malfunction follows a different sequence, including the pump complication and applicable poisoning code. This is a good example of why diabetes-related encounters should not automatically be reduced to E11.65.

Diabetes During Pregnancy

Pre-existing type 2 diabetes complicating pregnancy is primarily classified in O24.1-, rather than simply reporting E11.65 as the first-listed obstetric diagnosis. Pregnancy-specific coding and sequencing rules must be reviewed whenever diabetes affects pregnancy, childbirth or the puerperium. The FY 2026 guidelines contain a separate diabetes-in-pregnancy section.

Secondary or Drug-Induced Diabetes

Not every adult patient with hyperglycemia has E11.- diabetes.

Categories E08, E09 and E13 address diabetes due to an underlying condition, drug- or chemical-induced diabetes and other specified diabetes. FY 2026 guidance specifically distinguishes these forms from E11.- type 2 diabetes and provides separate sequencing instructions.

Type 2 Diabetes Uncontrolled ICD-10 Coding Examples

These approaches reflect the combination-code, documentation and uncertain-diagnosis principles in the FY 2026 Official Guidelines.

Can E11.65 Be Coded From a High A1C or Glucose Result Alone?

No. A coder should not establish type 2 diabetes with hyperglycemia solely because an A1C or blood glucose result is elevated. Clinical evidence can support the provider’s diagnosis, but diagnosis coding still depends on documentation and applicable coding conventions.

The FY 2026 guidelines state that accurate coding requires complete medical-record documentation and define the provider as the qualified practitioner legally accountable for establishing the patient’s diagnosis.

For inpatient records, abnormal laboratory, imaging, pathology or other diagnostic findings generally are not reported unless the provider indicates their clinical significance. If an abnormal result appears clinically significant and treatment or further investigation is occurring, querying the provider may be appropriate.

A compliant query might therefore ask the provider to clarify whether persistent elevated glucose represents hyperglycemia associated with the patient’s documented type 2 diabetes. It should not direct the provider toward E11.65.

Outpatient vs. Inpatient Type 2 Diabetes Coding

Outpatient Encounters

In outpatient and professional office coding, do not code diagnoses documented as probable, suspected, questionable, rule-out, compatible with, consistent with, working diagnosis or similar uncertain language.

Instead, code the highest degree of certainty available for that encounter, such as confirmed conditions, symptoms, signs, abnormal findings or the documented reason for the visit.

For example:

“Possible type 2 diabetes with hyperglycemia; testing ordered.”

The outpatient coder should not automatically assign E11.65 unless the diagnosis has been established according to the documentation and coding rules.

Inpatient Admissions

For qualifying inpatient admissions to short-term acute, long-term care and psychiatric hospitals, uncertain diagnoses documented at discharge as probable, suspected, likely, questionable, possible, still to be ruled out or similar wording may be coded as though the condition existed.

This is a major difference between inpatient and outpatient diagnosis coding and a frequent source of errors when one set of rules is applied to both settings.

Common Type 2 Diabetes Coding and Billing Mistakes

Using E11.9 When Hyperglycemia Is Documented

Problem: The provider documents type 2 diabetes with hyperglycemia, but the claim reports E11.9.

Correct approach: Report the more specific supported code, E11.65. CMS recognizes E11.65 and E11.9 as distinct diagnoses.

Assigning E11.65 From A1C Alone

Problem: The A1C is elevated, so the coder adds E11.65 without provider documentation.

Correct approach: Code from the documented diagnosis. Query when clarification is clinically and coding-relevant rather than creating a diagnosis from a test result.

Missing Additional Diabetic Complications

Problem: Only E11.65 is submitted even though diabetic neuropathy or CKD is documented.

Correct approach: Capture all applicable diabetic combination codes. ICD-10-CM permits multiple codes from the diabetes category when needed to describe all associated conditions.

Forgetting the CKD Stage

Problem: E11.22 is reported without the additional N18.- code despite documented CKD stage.

Correct approach: Follow the Tabular List instruction and add the appropriate CKD stage code.

Missing Long-Term Medication Codes

Problem: The patient routinely uses insulin and oral antidiabetic medication, but treatment-status codes are omitted.

Correct approach: Consider Z79.4 and Z79.84 when documentation supports long-term use.

Assigning Z79.4 for Temporary Insulin

Problem: Insulin is administered only during an acute encounter and Z79.4 is added.

Correct approach: Do not use Z79.4 solely for temporary insulin used to control glucose during the encounter.

Using E11.- for Secondary Diabetes

Problem: Diabetes caused by medication, pancreatic disease or another underlying condition is automatically coded as type 2 diabetes.

Correct approach: Review categories E08, E09 and E13 and their sequencing instructions.

Assuming a Diagnosis Code Guarantees Payment

Problem: The claim contains E11.65, so staff assume a laboratory test, CGM service or diabetes education service will automatically be covered.

Correct approach: Verify medical necessity, frequency, provider eligibility and payer policy for the specific billed service. CMS coverage guidance demonstrates that diabetes-related laboratory services can be subject to limited-coverage requirements.

Best Practices for Clean Type 2 Diabetes Claims

Build Diagnosis-Specific Documentation Prompts

EHR templates can prompt the clinician to specify:

• diabetes type;
• hyperglycemia or hypoglycemia;
• diabetic kidney disease;
• neuropathy;
• retinopathy;
• peripheral angiopathy;
• foot or other skin ulcers;
• DKA or hyperosmolarity;
• medication use; and
• reason for treatment changes.

The goal is not to force a diagnosis. It is to capture the clinical specificity already known by the treating provider.

Create Targeted Coding Edits

Useful edits may flag combinations such as:

• “poorly controlled” with E11.9;
• E11.22 without an N18.- stage when CKD stage is documented;
• E11.621 without a supported ulcer-site code;
• long-term insulin documented without review of Z79.4; or
• abnormal A1C used to generate E11.65 without a provider diagnosis.

These edits should prompt human review rather than automatically changing the provider’s diagnosis.

Review Payer Policies Before High-Risk Services

A diagnosis may establish the clinical reason for a service without satisfying every coverage requirement.

For diabetes-related care, pay particular attention to policies governing:

• A1C testing;
• repeated glucose testing;
• CGM services and supplies;
• DSMT;
• medical nutrition therapy;
• DME;
• frequency limits; and
• laboratory panels.

CMS maintains specific coverage and billing rules for diabetes self-management training, glucose testing and medical nutrition therapy.

Audit E11.9 Usage

A high rate of E11.9 is not automatically incorrect. However, it can be useful to review whether providers are documenting diabetic complications or hyperglycemia elsewhere in the same chart while the claim continues to use only the uncomplicated diabetes code.

The purpose of the audit is documentation and coding accuracy, not increasing code severity.

Query Instead of Assuming

When documentation is clinically meaningful but ambiguous, a compliant query is safer than coder inference.

Examples include:

• “uncontrolled diabetes” without clarification;
• CKD documented without clarity about the diabetic relationship when required;
• conflicting diabetes types;
• unclear acute diabetic conditions; or
• documentation suggesting secondary diabetes without a stated cause.

Queries should be non-leading and based on information already present in the record.

Pre-Submission Verification Checklist

Frequently Asked Questions

What is the ICD-10 code for uncontrolled type 2 diabetes?

E11.65 is commonly used when uncontrolled or poorly controlled type 2 diabetes is documented as hyperglycemia. The official diagnosis is “Type 2 diabetes mellitus with hyperglycemia.” Do not automatically assign it when the meaning of “uncontrolled” is unclear.

What is the difference between E11.65 and E11.9?

E11.65 identifies type 2 diabetes with hyperglycemia, while E11.9 identifies type 2 diabetes without complications. If the provider documents hyperglycemia, E11.65 provides greater supported specificity.

Is “uncontrolled diabetes” an official ICD-10 diagnosis description?

No. There is no E11.- code whose official description is simply “uncontrolled type 2 diabetes.” Coding must identify what the lack of control represents, such as hyperglycemia or hypoglycemia.

Can E11.65 and E11.42 be coded together?

Yes, when both hyperglycemia and diabetic polyneuropathy are documented. ICD-10-CM allows multiple diabetes combination codes when necessary to describe all of a patient’s diabetic complications.

Can E11.65 be coded from a high A1C?

Not solely from the laboratory value. The provider should establish the diagnosis. If the record contains clinically significant abnormal results but the diagnosis is unclear, a compliant query may be appropriate.

Should Z79.4 be reported with E11.65?

It may be appropriate when the patient with type 2 diabetes routinely uses insulin long term. Z79.4 should not be assigned merely because insulin was given temporarily during an encounter.

Can Z79.4 and Z79.84 be billed together?

Yes, when a type 2 diabetic patient routinely uses both insulin and an oral hypoglycemic drug. FY 2026 guidance specifically instructs reporting both long-term-use codes in that situation.

What code is used for type 2 diabetes with CKD?

E11.22 identifies type 2 diabetes with diabetic chronic kidney disease. An additional N18.- code is generally needed to report the CKD stage.

What code is used for a diabetic foot ulcer?

E11.621 identifies type 2 diabetes with foot ulcer. An additional L97.- code is generally required to describe the ulcer’s site and severity based on the documentation.

Does E11.65 guarantee payment for an A1C test?

No. Correct diagnosis coding is only one part of reimbursement. Coverage can also depend on medical necessity, frequency, payer policy, the test performed and other billing requirements. CMS maintains coverage rules for diabetes-related laboratory testing.

How are uncertain diabetes diagnoses handled in outpatient care?

Do not report a probable, suspected or rule-out diagnosis as established in the outpatient setting. Code to the highest degree of certainty available for that encounter.

Are inpatient uncertain-diagnosis rules different?

Yes. In qualifying inpatient settings, diagnoses documented at discharge as probable, suspected, likely, possible or similar terms may be coded as though established. This rule does not apply to ordinary outpatient encounters.

Conclusion

Correct Type 2 Diabetes Uncontrolled ICD-10 coding starts with clear provider documentation. When poor control specifically means hyperglycemia, E11.65 is generally the relevant type 2 diabetes code. E11.9 should be reserved for documentation supporting type 2 diabetes without complications rather than being used as a default when a more specific diabetic condition is already documented.

Billing teams should also look beyond E11.65. Diabetic CKD, neuropathy, foot ulcers, hypoglycemia, ketoacidosis, hyperosmolarity and other complications may require different or additional codes. Long-term therapy codes such as Z79.4, Z79.84 and Z79.85 should be reviewed when applicable, and procedure claims must pair accurate ICD-10 coding with correctly selected CPT/HCPCS codes and payer-specific medical necessity requirements.

For 2026 claims, always validate the code against the ICD-10-CM version effective on the date of service, follow the Tabular List and Official Guidelines, and query the provider rather than making clinical assumptions. That approach supports cleaner claims, more defensible coding and a lower risk of avoidable denials or audit findings.