E10.21 ICD-10-CM Code: Type 1 diabetes mellitus with diabetic nephropathy
HCC Buddy Code Card
Digital ICD-10 code-book layout with official code detail, always-visible risk models, Code Trumping, and Buddy coding guidance.
FY 2026 Apr update / Endocrine, nutritional and metabolic diseases (E00-E89) / Diabetes mellitus (E08-E13)
E10.21
Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidanceType 1 diabetes mellitus with diabetic nephropathy
Type 1 diabetes with kidney damage characterized by protein loss in urine, indicating early to moderate kidney disease from diabetes.
Buddy Insight
Type 1 diabetes mellitus with diabetic nephropathy represents early to moderate kidney damage from Type 1 diabetes, characterized by persistent albuminuria that progresses through stages from microalbuminuria to overt proteinuria.
CMS-HCC V28
MappedHCC 37
RAF 0.245
CMS-HCC V24
MappedHCC 18
RAF 0.302
ACA/HHS
00
RAF 0
ESRD/PACE
MappedHCC 18
RAF 0.0
RXHCC
MappedHCC 30
RAF 0.0
Code Trumping
Basket needed
Code Book Path
Inclusion Terms
Official- Type 1 diabetes mellitus with intercapillary glomerulosclerosis
- Type 1 diabetes mellitus with intracapillary glomerulonephrosis
- Type 1 diabetes mellitus with Kimmelstiel-Wilson disease
Excludes 2
OfficialICD-10-CM does not list Excludes 2 notes for E10.21 in this effective period.
Related Child Codes
Includes
OfficialICD-10-CM does not list Includes notes for E10.21 in this effective period.
Excludes 1
OfficialICD-10-CM does not list Excludes 1 notes for E10.21 in this effective period.
Code First
OfficialICD-10-CM does not list Code First sequencing instructions for E10.21 in this effective period.
Use Additional
OfficialICD-10-CM does not list Use Additional Code instructions for E10.21 in this effective period.
Code Also
OfficialICD-10-CM does not list Code Also instructions for E10.21 in this effective period.
Buddy Documentation Tip
MEAT Support
Audit Caution
Common Mistakes
Last updated: FY2026 ICD-10-CM Apr update, Apr 1, 2026 through Sep 30, 2026. CMS-HCC V28 is 100% phased in for payment year 2026.
Is E10.21 an HCC code?
Yes. E10.21 maps to Diabetes with Chronic Complications under the CMS-HCC V28 risk adjustment model (and Diabetes with Chronic Complications under V24).
HCC Category Mapping
RAF weights shown are the community, non-dual, aged base weights from the CMS risk adjustment model file. Actual per-patient RAF contribution depends on member segment, interactions, and the model year used by the payer. V28 is the CMS-HCC model phased in over payment years 2024–2026; V24 remains in use during the transition and for historical data.
MEAT Criteria for E10.21
For E10.21to count as a valid HCC diagnosis in a given encounter, the provider's documentation must show MEAT: Monitor, Evaluate, Assess, or Treat. A diagnosis from a prior year does not carry forward automatically, it has to be re-documented and supported each calendar year.
- MMonitor: signs, symptoms, disease progression, or lab trending documented in the note
- EEvaluate: test results, medication response, or physical findings reviewed by the provider
- AAssess: explicit mention in the assessment or plan with acknowledgment of status
- TTreat: medication, referral, procedure, therapy, or counseling tied to the diagnosis
Only one of M/E/A/T is required to support the code, but the documentation must be specific enough to show that the provider actually addressed E10.21 during that encounter, not just copy-forwarded from a problem list.
What This Code Means
E10.21 is the ICD-10-CM diagnosis code for type 1 diabetes mellitus with diabetic nephropathy. Type 1 diabetes with kidney damage characterized by protein loss in urine, indicating early to moderate kidney disease from diabetes. E10.21 sits in the ICD-10-CM chapter for endocrine, nutritional and metabolic diseases (e00-e89), within the section covering diabetes mellitus (e08-e13).
Under the CMS-HCC V28 risk adjustment model, E10.21 maps to Diabetes with Chronic Complications (HCC 37) with a community, non-dual, aged base RAF weight of 0.245. Under the older V24 model, E10.21 mapped to the same category but with a base RAF weight of 0.302, V28 recalibrated weights across the entire model. V28 is the CMS-HCC risk adjustment model that reached 100% phase-in for payment year 2026, replacing V24 which was used during the PY2024–PY2025 transition.
Verify documentation specifies diabetic nephropathy rather than other kidney conditions. Because E10.21 maps to a payment HCC, the provider's documentation must satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) for the encounter to count toward the patient's Medicare Advantage risk adjustment score. When documentation is ambiguous, coders should issue a provider query rather than assume the highest-specificity variant.
HCC Buddy maintains structured V28 and V24 mapping, RAF weights, and MEAT documentation criteria for E10.21 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Verify documentation specifies diabetic nephropathy rather than other kidney conditions
- •This code indicates kidney involvement but may need additional codes if chronic kidney disease stage is documented
Clinical Significance
Type 1 diabetes mellitus with diabetic nephropathy represents early to moderate kidney damage from Type 1 diabetes, characterized by persistent albuminuria that progresses through stages from microalbuminuria to overt proteinuria. Diabetic nephropathy is the leading cause of end-stage renal disease in the United States. In Type 1 diabetes, nephropathy typically develops 10-15 years after diagnosis and is a strong predictor of cardiovascular mortality, making early detection through annual screening and aggressive management with ACE inhibitors or ARBs critical.
Documentation Requirements
- ✓The provider must document diabetic nephropathy with supporting evidence such as urine albumin-to-creatinine ratio, 24-hour urine protein, or documented microalbuminuria.
- ✓The diagnosis must be linked to Type 1 diabetes.
- ✓If chronic kidney disease staging is also present, E10.22 may be more appropriate.
- ✓Current medications including nephroprotective agents should be documented.