Alphabetic Index FY2027

E10.21

Type 1 diabetes mellitus with diabetic nephropathy

FY2027Chapter 4: Endocrine, nutritional and metabolic diseases/E08–E13 Diabetes mellitus

BillableComplete code, valid to report
Care settingsHome Health Primary · MMTA - Endocrine

E10.21 (also written E1021) is a billable ICD-10-CM diagnosis code for type 1 diabetes mellitus with diabetic nephropathy. It is part of the FY2027 code set, effective October 1, 2026. It is one of the 87 codes in category E10 (Type 1 diabetes mellitus). The Alphabetic Index lists it under 4 entries. Its coding notes include 10 Excludes1 entries.

Guidelines tip

From the FY2027 Official Guidelines. ICD10Ref adds no rules of its own.

Diabetes codes combine the type, the body system and the complication, and as many codes as needed are assigned to describe all complications.

Guidelines I.C.4.aDiabetes: combination codesRead the official text

Excludes1

Not coded here. The listed conditions generally should not be reported together.

Inherited from E10 Type 1 diabetes mellitus
  • diabetes mellitus due to underlying condition (E08.-)
  • drug or chemical induced diabetes mellitus (E09.-)
  • gestational diabetes (O24.4-)
  • hyperglycemia NOS (R73.9)
  • neonatal diabetes mellitus (P70.2)
  • postpancreatectomy diabetes mellitus (E13.-)
  • postprocedural diabetes mellitus (E13.-)
  • secondary diabetes mellitus NEC (E13.-)
  • type 2 diabetes mellitus (E11.-)
Also from chapter/block level (1 note)
Inherited from Chapter 4 Endocrine, nutritional and metabolic diseases
  • transitory endocrine and metabolic disorders specific to newborn (P70-P74)

Care settings

How CMS programs treat this code. These are CMS claim edits and list entries, not coverage or eligibility rules.

Home Health Primary

Accepted as the primary (principal) diagnosis on a home health claim. The Home Health Grouper assigns it to the MMTA - Endocrine clinical group.

Source: CMS Home Health Grouper Software v07.2.26, effective October 1, 2026

Includes

Further defines or gives examples of the content of the category.

Inherited from E10 Type 1 diabetes mellitus
  • brittle diabetes (mellitus)
  • diabetes (mellitus) due to autoimmune process
  • diabetes (mellitus) due to immune mediated pancreatic islet beta-cell destruction
  • idiopathic diabetes (mellitus)
  • juvenile onset diabetes (mellitus)
  • ketosis-prone diabetes (mellitus)

Inclusion terms

Conditions classified to this code.

This code
  • Type 1 diabetes mellitus with intercapillary glomerulosclerosis
  • Type 1 diabetes mellitus with intracapillary glomerulonephrosis
  • Type 1 diabetes mellitus with Kimmelstiel-Wilson disease

Notes

Also from chapter/block level (1 note)
Inherited from Chapter 4 Endocrine, nutritional and metabolic diseases
  • All neoplasms, whether functionally active or not, are classified in Chapter 2. Appropriate codes in this chapter (i.e. E05.8, E07.0, E16-E31, E34.-) may be used as additional codes to indicate either functional activity by neoplasms and ectopic endocrine tissue or hyperfunction and hypofunction of endocrine glands associated with neoplasms and other conditions classified elsewhere.

Alphabetic Index terms

Terms the official Alphabetic Index lists for this code. 4 entries