Explore the Basics of Diabetes Mellitus

Explore the Basics of Diabetes Mellitus

With so many complications that involve many specialties, correct coding is essential on many levels.

Diabetes mellitus (DM) is a systemic condition prevalent throughout the United States and the seventh leading cause of death nationwide, according to the Centers for Disease Control and Prevention (CDC). There are three main types of diabetes coders will encounter: type 1, type 2, and gestational. We’ll cover the bases for what you need to know about type 1 and type 2 and highlight the guidelines for coding.

ICD-10-CM

DM can occur due to an underlying condition, poisoning, adverse effect, or other specified cause. DM that results from another condition is secondary diabetes. Expanded ICD-10-CM categories for secondary DM identify the causal mechanism. If the type of DM is not documented, chapter-specific guidelines designate type 2 as the default.

All DM codes are combination codes that include the type, affected body system, and manifestation (i.e., complication). For example, E10.620 Type 1 diabetes mellitus with diabetic dermatitis tells us the patient has type 1 diabetes with a complication of diabetic dermatitis. No additional code is necessary. Some categories of DM have instructional notes to further specify complications, such as the stage of kidney disease or the site of a skin ulcer.

The age of the patient does not determine which type of DM they have. Type 1 is often diagnosed in children, adolescents, and young adults, but it can also occur later in life.

The category codes for type 1 and type 2 are easy to remember: DM is an endocrine condition (E for endocrine), type 1 is category E10 Type 1 diabetes mellitus (1 + 0 = 1, or type 1), and type 2 is category E11 Type 2 diabetes mellitus (1 + 1 = 2, or type 2).

Report the mechanism causing secondary DM, rather than the type of DM (i.e., type 1 or 2). The three ICD-10-CM categories for secondary diabetes are:

E08          Diabetes mellitus due to underlying condition

E09          Drug or chemical induced diabetes mellitus

E13          Other specified diabetes mellitus

Diabetes Is Complicated

DM leads to complications such as kidney failure, lower-limb amputation, and adult-onset blindness. Due to the many complications, coders working in a wide variety of specialties will find themselves coding diabetes. Correct coding aids coordination of care.

All categories of DM contain combination codes for diabetes and the complication (or lack thereof). Complications assigned specific codes include:

  • Hyperosmolarity
  • Ketoacidosis
  • Kidney complications
  • Ophthalmic complications
  • Neurological complications
  • Circulatory complications
  • Other specified complications

The characters that represent the complications are repeated from one category to the next when comparing codes for the same complication across the categories. For example:

E08.3511             Diabetes mellitus due to underlying condition with proliferative diabetic retinopathy with macular edema, right eye

E11.3511             Type 2 diabetes mellitus with proliferative diabetic retinopathy with macular edema, right eye

The last four characters in both codes represent the same complication. This example reminds us of another pattern found in ICD-10-CM: In most codes that contain laterality, 1 represents right and 2 indicates left. There are also some occurrences of 3 for bilateral.

Type 2 DM is the most common, with type 1 affecting approximately 5 percent of the U.S. population, according to the American Diabetes Association. Let’s examine an example of each.

Type 1: E10

Category guidelines contain an Includes note to clarify terms we may see coded as type 1 DM:

  • Brittle diabetes (mellitus)
  • Diabetes (mellitus) due to autoimmune process
  • Diabetes (mellitus) due to immune medicated pancreatic islet beta-cell destruction
  • Idiopathic diabetes (mellitus)
  • Juvenile onset diabetes (mellitus)
  • Ketosis-prone diabetes (mellitus)

As with all DM categories, an Excludes 1 note excludes all other DM, including gestational, neonatal, and postprocedural.

Even with the availability of many combination codes, there are some subcategories that have a “Use additional code” instruction.

Example:

E10.621 Type 1 diabetes mellitus with foot ulcer

L97.412  Non-pressure chronic ulcer of right heel and midfoot with fat layer exposed

This example brings up the coding conundrum of associated conditions: Providers should indicate diabetic-related conditions as such; however, real documentation is often ambiguous. The convention guidelines are clear that conditions listed “with,” “should be coded as related even in the absence of provider documentation explicitly linking them.” The guideline also says the documentation must state the condition(s) are unrelated, if that’s the case. Coding Clinic, Second Quarter 2018, clarifies that a causal relationship is not assumed when the diabetic complication is not elsewhere classified (NEC).

Type 2: E11

Category guidelines contain an Includes note to clarify terms we may see that are coded as type 2 diabetes mellitus: diabetes (mellitus) due to insulin secretory defect, diabetes not otherwise specified (NOS), and insulin resistant diabetes (mellitus). Again, we see a large Excludes 1 note for all other diabetes mellitus.

This category also instructs us to use an additional code to identify control:

Insulin (Z79.4 Long term (current) use of insulin)

Oral antidiabetic drugs (Z79.84 Long term (current) use of oral hypoglycemic drugs)

Oral hypoglycemic drugs (Z79.84)

You will also see this instruction with categories E08, E09, and E13. The ICD-10-CM Official Guidelines for Coding and Reporting, chapter four specific guidelines, clarifies the use of Z79 Long term (current) drug therapy. If the patient is treated with both insulin and oral hypoglycemic drugs only, code the long-term use of insulin with code Z79.4. This code is not for use when the insulin is used to temporarily control blood sugar levels during an encounter.

Example:

E11.621 Type 2 diabetes mellitus with foot ulcer

L97.412 Non-pressure chronic ulcer of right heel and midfoot with fat layer exposed

Listed below are the three secondary DM categories with guidelines and examples. All three categories instruct us to use an additional code (Z79.4) for insulin use. Chapter-specific guidelines state not to assign this code, however, if the insulin is given to temporarily bring blood sugar under control during an encounter.

DM Due to Underlying Condition: E08

Category guidelines give sequencing instructions: Code first the underlying condition. There is an Excludes 1 note for all other DM, including gestational, neonatal, and postprocedural.

Example:

P35.0      Congenital rubella syndrome

E08.00    Diabetes mellitus due to underlying condition with hyperosmolarity without nonketotic hyperglycemic-hyperosmolar coma (NKHHC)

E09          Drug or chemical induced diabetes mellitus

Code E09 also has an Excludes 1 note for all other DM. Category guidelines give sequencing instructions. Sequencing depends on encounter circumstances:

Poisoning – improper use of a medication (e.g., overdose, wrong substance given or taken in error, wrong route of administration)

Adverse effect – from drug, correctly prescribed and properly administered

Category guidelines:

Code first poisoning due to drug or toxin, if applicable (T36-T65 with fifth or sixth character of 1-4 or 6)

Use additional code for adverse effect, if applicable, to identify the drug (T36-T50 with fifth or sixth character 5)

Examples:

T37.5x1A            Poisoning by antiviral drugs, accidental (unintentional), initial encounter

E09.51    Drug or chemical induced diabetes mellitus with diabetic peripheral angiopathy without gangrene

or

E09.51    Drug or chemical induced diabetes mellitus with diabetic peripheral angiopathy without gangrene

T38.0x5A            Adverse effect of glucocorticoids and synthetic analogues, initial encounter

E13          Other specified diabetes mellitus

Use category E13 for DM due to genetic defects of beta-cell function or insulin action, postpancreatectomy DM, postprocedural DM, or secondary DM NEC.

Example:

E13.43    Other specified diabetes mellitus with diabetic autonomic (poly) neuropathy

Take Some Advice

Combination coding is tricky. Watch for code character detail; the number of characters in DM coding varies from four to seven. Always refer to the official guidelines when in doubt. Don’t be afraid to have a discussion with your provider(s) about their documentation habits. To help with combination coding, see Guideline Tips. These can be written near the category or cut off and included in your ICD-10-CM code book on the appropriate page.

Guideline Tips
E08 DM due toE09 Drug or chemicalE13 Other specified
1)
Underlying condition
1) Poisoning1) E091) E13
2) E082) E092) Adverse effect2)
Insulin use (Z79.4)
3)
Insulin use (Z79.4)
3)
Insulin use (Z79.4)
3)
Insulin use (Z79.4)

Do You Code Gestational Diabetes?

If you are interested in sharing your coding expertise on gestational diabetes in Healthcare Business Monthly magazine, please contact our editorial staff: Stacy Chaplain, Michelle Dick ([email protected]), or Renee Dustman ([email protected]). You can also submit articles for publication via our website.


Resources

CDC: www.cdc.gov/

American Diabetes Association, Statistics About Diabetes Overall Numbers, Diabetes and Prediabetes: www.diabetes.org/diabetes-basics/statistics/

ICD-10-CM Official Guidelines for Coding and Reporting FY 2019:
www.cdc.gov/nchs/icd/data/10cmguidelines-FY2019-final.pdf

code-books-shipping

ICD-10-CM/PCS Coding Clinic, Second Quarter ICD-10. June 6, 2018. Effective with discharges: 6-7.

Norma Panther

Norma A. Panther, CPC, CPC-I, CEMC, CHONC, CIRCC, CPMA, CCS-P, CHC, has more than 25 years of experience in coding, auditing, education, and consulting. She is active in her local AAPC chapter and is currently serving on the 2018-2021 AAPC NAB. Panther works in Corporate Compliance at H. Lee Moffitt Cancer Center. She is a member of the Lakeland, Fla., local chapter.

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