In ICD-10-CM coding Diabetes Mellitus has one of the longest lists of alphabetical index entries as well as its tabular list broken into five different categories with code sets ranging from (E08.-)-(E13.-). Diabetes Mellitus is a true example of the use of the “with” convention (an assumed relationship between conditions) within the ICD-10-CM guidelines, as it has many casual relationships with other conditions, representing an assumed relationship to other condition when listed together in the medical record and in absence of the providers documentation that the conditions are unrelated they are linked to one another and reported through the use of combination codes. Diabetes Mellitus can also represent “etiology” (the cause of the other condition) where the provider will document the condition as a single diagnostic statement such as “Diabetic Neuropathy”. When abstracting Diabetic conditions and assigning codes a solid knowledge and understanding of the ICD-10-CM guidelines is essential for accurate coding.
In this article I will discuss the following:
- A description of Diabetes Mellitus and its types
- Common medications, insulins, and non-insulin injectables
- Review of ICD-10-CM Official Guidelines I.C.4 for Diabetes Mellitus
- Category Code Blocks E08-E13 Tabular List Notes
- Explanation of the “with” convention and “etiology”
- Combination codes representing Diabetes linked to other conditions through “etiology” and the “with” convention
- Real life coding scenarios to provide visual to coding Diabetes in action
What is Diabetes Mellitus?
Diabetes mellitus refers to a group of diseases that affect how the body uses blood sugar, known as glucose. Glucose is the body’s main source of energy, fueling the brain, tissues, and muscles. The hormone insulin, produced by the pancreas, is essential for regulating this process. After eating, carbohydrates break down into glucose, raising blood sugar levels. In response, the pancreas releases insulin, which allows glucose to enter the body’s cells to provide energy. Any extra glucose is stored in the liver as glycogen. Between meals, when insulin levels are low, the liver releases glycogen back into the bloodstream as glucose to keep blood sugar within a healthy range. When the body cannot produce enough insulin or cannot use it properly, diabetes develops, disrupting the body’s ability to turn food into energy.
Type 1 Diabetes
Type 1 diabetes, once called juvenile or insulin-dependent diabetes, is a chronic condition in which the pancreas produces little or no insulin. Genetics and certain viruses may contribute to its development. It often begins in childhood or adolescence but can appear in adults as well. There is no cure, and treatment focuses on blood sugar management with insulin, diet, and lifestyle changes to prevent complications.
- Caused by an autoimmune reaction where the body attacks itself by mistake
- This reaction stops your body from producing insulin
- Approximately 5–10% of people who have diabetes have type 1
- Symptoms of type 1 diabetes often develop quickly
- It’s usually diagnosed in children, teens, and young adults
- If you have type 1 diabetes, you’ll need to take insulin every day to survive
- Currently, no one knows how to prevent type 1 diabetes
Type 2 Diabetes
Type 2 diabetes occurs when the body does not use insulin effectively, causing sugar to build up in the blood. Once called adult-onset diabetes, it is more common in older adults but increasingly affects children due to rising obesity rates. In this condition, the pancreas may not make enough insulin, and the body’s cells respond poorly to it. Over time, high blood sugar can damage the eyes, kidneys, nerves, and heart. While there is no cure, type 2 diabetes can often be managed with weight loss, healthy eating, and exercise. If these measures are not enough, medications or insulin therapy may be needed
- Too much sugar circulates in the blood
- About 90–95% of people with diabetes have type 2
- You may not notice any symptoms, so it’s important to get your blood sugar tested if you’re at risk
- It develops over many years and is usually diagnosed in adults
- If you have type 2 diabetes, you might need to take insulin or medication
- Type 2 diabetes can be prevented or delayed with healthy lifestyle changes
There are two main categories of injectable medications for diabetes management: insulins and non-insulin injectables. Below is a list of common examples from each group.
| Category | Medications |
| 💎 Insulin Injectables | Humulin, Humalog, Lantus, Levemir, Novolog, Toujeo, Tresiba |
| 💎 Non-Insulin Injectables | Byetta, Bydureon, Ozempic, Trulicity, Victoza |
Oral Medications
💎 Meglitinides
- Repaglinide
- Nateglinide
💎 Sulfonylureas
- Glipizide (Glucotrol XL)
- Glimepiride (Amaryl)
- Glyburide (DiaBeta, Glynase)
💎 Dipeptidyl-peptidase 4 (DPP-4) Inhibitors
- Saxagliptin (Onglyza)
- Sitagliptin (Januvia)
- Linagliptin (Tradjenta)
- Alogliptin (Nesina)
💎 Biguanides
- Metformin (Fortamet, Glumetza, others)
💎 Thiazolidinediones (TZDs)
- Rosiglitazone (Avandia)
- Pioglitazone (Actos)
Gestational Diabetes
Gestational diabetes is a type of diabetes first diagnosed during pregnancy, also called gestation. Like other forms of diabetes, it affects how the body’s cells use glucose, leading to high blood sugar that can impact both the pregnancy and the baby’s health.
The positive news is that gestational diabetes can often be managed. Eating healthy foods, exercising, and taking medication if needed can help control blood sugar. Good management keeps both mother and baby healthy and may reduce complications during delivery.
For most people, blood sugar returns to normal soon after childbirth. However, having gestational diabetes increases the risk of developing type 2 diabetes later in life, which means regular monitoring of blood sugar is important after pregnancy.
Diabetes and Foot Amputation
Complications of diabetes can include nerve damage and poor circulation, both of which raise the risk of developing skin sores (ulcers) on the feet. These ulcers can worsen quickly if not treated.
The positive news is that managing blood sugar and practicing good foot care can significantly reduce the risk of developing ulcers.
If a foot ulcer does occur, it’s critical to seek care right away. Many amputations of the lower leg and foot begin with an untreated ulcer. A wound that fails to heal can lead to serious tissue and bone damage, sometimes requiring the removal of a toe, foot, or part of the leg.
Risk Factors for Amputation
People with diabetes may have a higher risk for amputation if they have:
💎 High blood sugar levels
💎 Smoking history
💎 Peripheral neuropathy (nerve damage in the feet)
💎 Calluses or corns
💎 Foot deformities
💎 Peripheral artery disease (poor circulation in the legs/arms)
💎 A history of foot ulcers
💎 Previous amputation
💎 Vision problems
💎 Kidney disease
💎 High blood pressure above 140/80 mm Hg
I.C.4: Endocrine, Nutritional, and Metabolic Diseases (E00–E89)
a. Diabetes Mellitus
Diabetes mellitus codes are combination codes. They include the type of diabetes mellitus, the body system affected, and any complications involving that system.
Use as many codes from a category as are needed to describe all complications of the disease. Sequence the codes according to the reason for the specific encounter. Assign as many codes from categories E08–E13 as necessary to identify all conditions related to the patient’s diabetes.
1) Type of Diabetes
Age is not the only factor in determining the type of diabetes. While most type 1 diabetics develop the condition before puberty, it can also occur later in life. For this reason, type 1 diabetes is also called juvenile diabetes.
(a) Presymptomatic Type 1 Diabetes Mellitus
- Assign codes E10.A- (Type 1 diabetes mellitus, presymptomatic) for early-stage type 1 diabetes before the onset of symptoms.
(b) Type 2 Diabetes Mellitus in Remission
- Assign code E11.A (Type 2 diabetes mellitus without complications, in remission) when the provider documents that the condition is in remission.
- If documentation is unclear about remission status, query the provider.
- Note: The term “resolved” does not mean remission.
2) Type of Diabetes Mellitus Not Documented
If the medical record does not specify the type of diabetes, assign E11.- (Type 2 diabetes mellitus).
3) Diabetes Mellitus and the Use of Insulin, Oral Hypoglycemics, and Injectable Non-Insulin Drugs
If the record does not indicate the type of diabetes but does indicate insulin use, assign E11.- (Type 2 diabetes mellitus).
Also assign additional codes from category Z79 to identify long-term (current) use of medications:
- Z79.4 → Long-term insulin use
- Z79.84 → Long-term oral hypoglycemic drug use
- Z79.85 → Long-term injectable non-insulin drug use
If the patient is treated with combinations:
- Oral drugs + insulin → Z79.4 and Z79.84
- Insulin + injectable non-insulin → Z79.4 and Z79.85
- Oral drugs + injectable non-insulin → Z79.84 and Z79.85
⚠️ Do not assign Z79.4 if insulin is used temporarily during an encounter to lower blood sugar.
4) Diabetes Mellitus in Pregnancy and Gestational Diabetes
- See Section I.C.15.g: Diabetes mellitus in pregnancy.
- See Section I.C.15: Gestational (pregnancy-induced) diabetes.
5) Complications Due to Insulin Pump Malfunction
(a) Underdose of Insulin Due to Pump Failure
- Assign a code from T85.6 (mechanical complication of other specified internal and external prosthetic devices, implants, and grafts) to identify the pump malfunction. This should be the principal or first-listed code.
- Follow with T38.3X6- (underdosing of insulin and oral hypoglycemic [antidiabetic] drugs).
- Also assign codes for the diabetes type and any related complications caused by the underdosing.
(b) Overdose of Insulin Due to Pump Failure
- Assign a code from T85.6– Mechanical complication of other specified internal and external prosthetic devices, implants, and grafts, followed by T38.3X1- (poisoning by insulin and oral hypoglycemic [antidiabetic] drugs, accidental/unintentional).
6) Secondary Diabetes Mellitus
Codes from the following categories identify complications or manifestations of secondary diabetes:
- E08 → Diabetes mellitus due to underlying condition
- E09 → Drug- or chemical-induced diabetes mellitus
- E13 → Other specified diabetes mellitus
Secondary diabetes is always caused by another condition or event, such as:
- Cystic fibrosis
- Pancreatic cancer
- Pancreatectomy
- Adverse drug effect
- Poisoning
(a) Secondary Diabetes and the Use of Medications
For patients with secondary diabetes who regularly use medications, assign additional codes from Z79:
- Oral drugs + insulin → Z79.4 and Z79.84
- Insulin + injectable non-insulin → Z79.4 and Z79.85
- Oral drugs + injectable non-insulin → Z79.84 and Z79.85
⚠️ Do not assign Z79.4 if insulin is used temporarily to control blood sugar.
(b) Assigning and Sequencing Secondary Diabetes Codes and Causes
Sequence secondary diabetes codes according to the Tabular List instructions for categories E08, E09, and E13.
Examples:
- Secondary Diabetes Due to Pancreatectomy
- Assign E89.1 (postprocedural hypoinsulinemia).
- Assign a code from E13 as the principal/first-listed diagnosis.
- Assign a code from Z90.41- (acquired absence of pancreas) as an additional code.
- Secondary Diabetes Due to Drugs
- May result from adverse effects of correctly given drugs, poisoning, or sequela of poisoning.
- See Section I.C.19.e for adverse effects/poisoning guidelines.
- See Section I.C.20 for external cause code reporting.
E08 Diabetes Mellitus due to an underlying condition
See Official Guidelines, “Assigning and sequencing secondary diabetes codes and its causes” I.C.4.a.6.b, “Diabetes mellitus in pregnancy” I.C.15.g
| Code 1st (Underlying Condition) | Use Additional Code to identify control using: | Excludes1 |
| Congenital rubella (P35.0) | Injectable non-insulin antidiabetic drugs (Z79.85) | Drug or chemical induced diabetes mellitus (E09.-) |
| Cushing’s syndrome (E24.-) | Insulin (Z79.4) | Gestational diabetes (O24.4-) |
| Cystic fibrosis (E84.-) | Oral antidiabetic drugs (Z79.84) | Neonatal diabetes mellitus (P70.2) |
| Malignant neoplasm (C00–C96) | Oral hypoglycemic drugs (Z79.84) | Post-pancreatectomy diabetes mellitus (E13.-) |
| Malnutrition (E40–E46) | Postprocedural diabetes mellitus (E13.-) | |
| Pancreatitis and other diseases of the pancreas (K85–K86.-) | Secondary diabetes mellitus NEC (E13.-) | |
| Type 1 diabetes mellitus (E10.-) | ||
| Type 2 diabetes mellitus (E11.-) |
E09 Drug or Chemical Induced Diabetes Mellitus
See Official Guidelines “Secondary diabetes mellitus” I.C.4.a.6, “Diabetes mellitus in pregnancy” I.C.15.g
| Code First | Use Additional Code to identify control such as: | Excludes1 |
| Poisoning due to drug or toxin, if applicable (T36–T65 with 5th or 6th character 1–4) | Adverse effect, if applicable, to identify drug (T36-T50 with fifth or sixth character 5) | Diabetes mellitus due to underlying condition (E08.-) |
| Injectable non-insulin antidiabetic drugs (Z79.85) | Gestational diabetes (O24.4-) | |
| Insulin (Z79.4) | Neonatal diabetes mellitus (P70.2) | |
| Oral antidiabetic drugs (Z79.84) | Postpancreatectomy diabetes mellitus (E13.-) | |
| Oral hypoglycemic drugs (Z79.85) | Postprocedural diabetes mellitus (E13.-) | |
| Secondary diabetes mellitus NEC (E13.-) | ||
| Type 1 diabetes mellitus (E10.-) | ||
| Type 2 diabetes mellitus (E11.-) |
E10 Type 1 Diabetes Mellitus
See Official Guidelines, “Diabetes Mellitus in pregnancy” I.C.15.g, “Presymptomatic Type 1 Diabetes Mellitus” I.C.4.a.1
| Includes | Excludes 1 |
| Brittle Diabetes (mellitus) | Diabetes mellitus due to underlying condition (E08.-) |
| Diabetes (Mellitus) due to immune medicated pancreatic islet beta-cell destruction | Gestational diabetes (O24.4-) |
| Idiopathic diabetes (mellitus) | Neonatal diabetes mellitus (P70.2) |
| Juvenile onset diabetes (mellitus) | Postpancreatectomy diabetes mellitus (E13.-) |
| Ketosis-prone diabetes (mellitus) | Postprocedural diabetes mellitus (E13.-) |
| Secondary diabetes mellitus NEC (E13.-) | |
| Drug and chemical induced diabetes mellitus (E09.-) | |
| Type 2 diabetes mellitus (E11.-) | |
| Hypoglycemia NOS R73.9 |
E11 Type 2 Diabetes Mellitus
See Official Guidelines, “Diabetes mellitus”, I.C.4.a, “Diabetes mellitus in pregnancy” I.C.15.g
TIP: Default to code E11.- In the providers absence of documentation of the type of Diabetes
| Includes | Use Additional Code to identify control such as: | Excludes1 |
| Diabetes (mellitus) due to insulin secretory defect | Injectable non-insulin antidiabetic drugs (Z79.85) | Diabetes mellitus due to underlying condition (E08.-) |
| Diabetes NOS | Insulin (Z79.4) | Gestational diabetes (O24.4-) |
| Insulin resistant diabetes (mellitus) | Oral antidiabetic drugs (Z79.84) | Neonatal diabetes mellitus (P70.2) |
| Oral hypoglycemic drugs (Z79.85) | Postpancreatectomy diabetes mellitus (E13.-) | |
| Postprocedural diabetes mellitus (E13.-) | ||
| Secondary diabetes mellitus NEC (E13.-) | ||
| Type 1 diabetes mellitus (E10.-) | ||
| Drug or chemical induced diabetes mellitus (E09.-) |
E13 Other Specified Diabetes Mellitus
See Official Guidelines: “Secondary diabetes mellitus” I.C.4.a.6, “Diabetes mellitus in pregnancy” I.C.15.g
| Includes | Use Additional Code to identify control such as: | Excludes1 |
| Diabetes mellitus due to genetic defects of beta-cell function | Injectable non-insulin antidiabetic drugs (Z79.85) | Diabetes (mellitus) due to autoimmune process (E10.-) |
| Diabetes mellitus due to genetic defects in insulin action | Insulin (Z79.4) | Diabetes (mellitus) due to immune medicated pancreatic islet beta-cell destruction (E10.-) |
| Postpancreatectomy diabetes mellitus | Oral antidiabetic drugs (Z79.84) | Diabetes mellitus due to underlying condition (E08.-) |
| Postprocedural diabetes mellitus | Oral hypoglycemic drugs (Z79.85) | Drug or chemical induced diabetes mellitus (E09.-) |
| Secondary diabetes mellitus | Gestational diabetes (O24.-) | |
| Secondary diabetes mellitus | Neonatal diabetes mellitus (P70.2) | |
| Type 1 diabetes mellitus (E10.-) |
Official Guidelines I.13 Etiology/ Manifestation
- Certain conditions involve an underlying cause (etiology) that leads to manifestations across multiple body systems. In these cases, ICD-10-CM coding conventions require the underlying condition to be sequenced first, when applicable, followed by the manifestation. To guide coders, the etiology code is marked with a “use additional code” note, while the manifestation code includes a “code first” note. These instructional notes establish the correct sequencing order: etiology first, then manifestation.
Official Guidelines I.15 “With”
- In ICD-10-CM, the terms “with” or “in” are interpreted to mean “associated with” or “due to.” When these words appear in a code title, the Alphabetic Index (under a main term or subterm), or in a Tabular List instructional note, the classification presumes a causal relationship between the conditions they link. These conditions should be coded as related, even without explicit provider documentation, unless the record clearly states they are unrelated or another guideline requires documented linkage (for example, the sepsis guideline for acute organ dysfunction). If conditions are not linked by these terms in the classification, or if guidelines specifically require explicit documentation, then the provider must clearly document the relationship before coding them as related.
- In the Alphabetic Index, the word “with” is sequenced immediately after the main term or subterm rather than in strict alphabetical order.
There are several conditions in ICD-10-CM that are assumed to have a causal relationship with diabetes. These codes reflect common diabetic complications affecting multiple body systems. While not an exhaustive list, the table below highlights some of the most frequently used Type 2 diabetes combination codes for coding practice.
Commonly Used Type 2 Diabetes Combination Codes
| ICD-10-CM Code | Description |
| E11.22 | Type 2 diabetes mellitus with diabetic chronic kidney disease 👉 Use additional code to identify stage of CKD (N18.1–N18.6) |
| E11.21 | Type 2 diabetes mellitus with diabetic nephropathy (includes intercapillary glomerulosclerosis, intracapillary glomerulonephrosis, Kimmelstiel-Wilson disease) |
| E11.51 | Type 2 diabetes mellitus with diabetic peripheral angiopathy without gangrene |
| E11.52 | Type 2 diabetes mellitus with diabetic peripheral angiopathy with gangrene (includes diabetic gangrene) |
| E11.36 | Type 2 diabetes mellitus with diabetic cataract |
| E11.40 | Type 2 diabetes mellitus with diabetic neuropathy, unspecified |
| E11.42 | Type 2 diabetes mellitus with diabetic polyneuropathy (includes diabetic neuralgia) |
| E11.43 | Type 2 diabetes mellitus with diabetic autonomic (poly)neuropathy (includes diabetic gastroparesis) |
| E11.44 | Type 2 diabetes mellitus with diabetic amyotrophy |
| E11.49 | Type 2 diabetes mellitus with other diabetic neurological complication |
| E11.3299 | Type 2 diabetes mellitus with mild nonproliferative diabetic retinopathy without macular edema, unspecified eye |
| E11.59 | Type 2 diabetes mellitus with other circulatory complications |
| E11.61 | Type 2 diabetes mellitus with diabetic arthropathy |
| E11.610 | Type 2 diabetes mellitus with diabetic neuropathic arthropathy (includes Charcot’s joints) |
| E11.618 | Type 2 diabetes mellitus with other diabetic arthropathy |
| E11.620 | Type 2 diabetes mellitus with diabetic dermatitis |
| E11.621 | Type 2 diabetes mellitus with foot ulcer 👉Use additional code to identify site of ulcer (L97.4-, L97.5-) |
| E11.622 | Type 2 diabetes mellitus with other foot ulcer 👉Use additional code to identify site of ulcer (L97.1-L97.9, L98.41-L98.49) |
| E11.628 | Type 2 diabetes mellitus with other skin complications |
| E11.630 | Type 2 diabetes mellitus with periodontal disease |
| E11.641 | Type 2 diabetes mellitus with hypoglycemia with coma |
| E11.649 | Type 2 diabetes mellitus with hypoglycemia without coma 👉 Use additional code for hypoglycemia level, if applicable (E16.A-) |
Coding Scenarios
🔹 Scenarios Where Provider States Diabetic (Etiology Explicit)
Scenario 1
Provider Documentation:
“Patient has diabetic polyneuropathy.”
Code Assignment:
- E11.42 – Type 2 diabetes mellitus with diabetic polyneuropathy
Index Path:
Diabetes, diabetic, type 2, with polyneuropathy → E11.42
Scenario 2
Provider Documentation:
“Patient has diabetic chronic kidney disease stage 3b.”
Code Assignment:
- E11.22 – Type 2 diabetes mellitus with diabetic chronic kidney disease
- N18.32 – Chronic kidney disease, stage 3b
Index Path:
Diabetes, diabetic, type 2, with chronic kidney disease → E11.22
CKD, stage 3b → N18.32
🔹 Scenarios Where Conditions Are Documented Separately but Linked by With Convention
Scenario 3
Provider Documentation:
“Patient has type 2 diabetes mellitus. Exam today shows cataracts.”
Code Assignment:
- E11.36 – Type 2 diabetes mellitus with diabetic cataract
Index Path:
Diabetes, diabetic, type 2, with cataract → E11.36
Scenario 4
Provider Documentation:
“Patient has type 2 diabetes mellitus and presents with a foot ulcer on the right heel with necrosis of bone.”
Code Assignment:
- E11.621 – Type 2 diabetes mellitus with foot ulcer
- L97.414 – Non-pressure chronic ulcer of right heel and midfoot with necrosis of bone
Index Path:
Diabetes, diabetic, type 2, with ulcer, foot → E11.621
Ulcer, foot, heel, right, with necrosis of bone → L97.414
Closing Thoughts
Diabetes Mellitus truly lives up to its “dating profile” of looking for a casual relationship. Within the ICD-10-CM, it connects itself to countless other conditions through both explicit provider documentation (etiology) and the “with” convention, which assumes a relationship even when the provider does not directly link the conditions. From polyneuropathy to chronic kidney disease, cataracts to foot ulcers, diabetes demonstrates just how complex and far-reaching its coding pathways can be. For coders, this means we must not only recognize the underlying disease but also understand the conventions, sequencing rules, and combination codes that bring the full picture into focus. Accuracy depends on carefully navigating the Alphabetic Index, following “code first” and “use additional code” instructions, and knowing when an assumed relationship applies. Ultimately, coding diabetes isn’t just about picking a code it’s about understanding the story behind the condition, its complications, and the relationships it forms. By mastering these guidelines, coders can ensure documentation integrity, support proper reimbursement, and most importantly, reflect the patient’s clinical reality with precision.
Works Cited
• ICD-10-CM Official Guidelines for Coding and Reporting FY 2026. Updated Oct. 1, 2025 – Sept. 30, 2026.
• “Diabetes Treatment: Using Insulin to Manage Blood Sugar.” Mayo Clinic, www.mayoclinic.org.
• “Type 2 Diabetes – Symptoms and Causes.” Mayo Clinic, www.mayoclinic.org.
• “Type 1 Diabetes – Symptoms and Causes.” Mayo Clinic, www.mayoclinic.org.
• “Gestational Diabetes – Symptoms & Causes.” Mayo Clinic, www.mayoclinic.org.
• “Diabetes Treatment: Medications for Type 2 Diabetes.” Mayo Clinic, www.mayoclinic.org.
• ICD-10-CM Coding Expert 2025. AAPC.
• Codify. AAPC, http://www.aapc.com/codify.