E10 vs R73.9
E10 and R73.9 can never be reported together. ICD-10-CM declares them mutually exclusive with an Excludes1 note, meaning the two conditions cannot occur in the same patient — so exactly one of them is correct for any given encounter.
The official note, declared on E10
hyperglycemia NOS (R73.9)
E10
Type 1 diabetes mellitus
Not billable
- Chapter 4
- Endocrine, nutritional and metabolic diseases
- Section
- E08-E13
Use when the record says
- 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)
R73.9
Hyperglycemia, unspecified
BillableUnspecified
- Chapter 18
- Symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified
- Section
- R70-R79
Indexed under
- Hyperglycemia, hyperglycemic (transient)
- Elevated, elevation › blood sugar
- Findings, abnormal, inconclusive, without diagnosis › blood sugar › high
- Sugar › blood › high
These two codes sit in different chapters of the Tabular List, which is usually the clearest signal that they describe different underlying processes rather than different degrees of the same one.
Excludes1 is not always absolute: where two conditions covered by the note are genuinely unrelated, CMS guidance permits reporting both. Document the reasoning rather than assuming it. More on Excludes1 vs Excludes2 · FY2027