2027 ICD-10-CM Diagnosis Code G99.0Autonomic neuropathy in diseases classified elsewhere
ICD-10-CM Codes›G00–G99›G89-G99›G99
- Billable — Valid for Submission
- CC — Complication or Comorbidity
- Chronic Condition
G99.0 is a billable ICD-10-CM diagnosis code for autonomic neuropathy in diseases classified elsewhere. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 73 through 74. As a secondary diagnosis, it counts as a complication or comorbidity (CC) and moves an inpatient stay to a higher severity level within its MS-DRG family. It does not count, however, when the principal diagnosis is one of 25 closely related codes. The code is a manifestation code that cannot be reported as the principal diagnosis. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Other nervous system disorders (often hereditary or degenerative).
G99.0 does not risk-adjust for Medicare Advantage under the CMS-HCC V28 model. It still risk-adjusts in the ESRD (V21) category 75 for payment year 2027.
Code Identity
Code Classification
Code EditsBilling
Medicare Code Editor checks that affect claim validity for G99.0.
Medicare Risk Adjustment (HCC)Billing
G99.0 does not risk-adjust for Medicare Advantage under the CMS-HCC V28 model, but it maps to payment categories in the other CMS models shown below.
Source: CMS Payment Year 2027 risk adjustment mappings and model software. Weights are relative factors, not dollar amounts; a beneficiary's total RAF also includes demographics and interactions. Browse all CMS-HCC categories.
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Autoimmune disorder of autonomic nerve
- Autoimmune disorder of autonomic nervous system
- Autoimmune ganglionopathy
- Autonomic neuropathy due to Allgrove syndrome
- Autonomic neuropathy due to endocrine disease
- Autonomic neuropathy due to Fabry disease
- Autonomic neuropathy due to medication induced hypoglycemia
- Autonomic neuropathy due to metabolic disease
- Autonomic neuropathy due to multiple endocrine neoplasia type 2b
- Autonomic neuropathy due to Refsum Disease
- Autonomic neuropathy due to Tangier disease
- Neuropathy associated with hypoglycemia
- Nutritional autonomic neuropathy
Instructional NotesGuidance
Instructions from the official ICD-10-CM Tabular List that apply to G99.0: its own notes plus those printed at Chapter 6. A note printed at a category, block or chapter applies to every code under it.
Excludes1
Not coded here: the excluded code is never reported together with this one, unless the two conditions are unrelated.
Excludes2
Not included here: the excluded condition is not part of this code, but a patient may have both, so both codes may be reported.
- certain conditions originating in the perinatal period (P04-P96)
- certain infectious and parasitic diseases (A00-B99)
- complications of pregnancy, childbirth and the puerperium (O00-O9A)
- congenital malformations, deformations, and chromosomal abnormalities (Q00-Q99)
- endocrine, nutritional and metabolic diseases (E00-E88)
- injury, poisoning and certain other consequences of external causes (S00-T88)
- neoplasms (C00-D49)
- symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R94)
Code First
The underlying condition named in the note is sequenced before this code.
Source: CMS ICD-10-CM Tabular List. How to read instructional notes.
Referenced in Other NotesGuidance
Instructional notes printed at other codes that name G99.0, its category, or a range that includes it.
Use Additional Code 2
These codes say to use an additional code from the note, and G99.0 is one of the codes named.
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Patient EducationClinical
Autonomic Nervous System Disorders
Your autonomic nervous system is the part of your nervous system that controls involuntary actions, such as the beating of your heart and the widening or narrowing of your blood vessels. When something goes wrong in this system, it can cause serious problems, including:
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert G99.0 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About G99.0Overview
What is the ICD-10 code for autonomic neuropathy in diseases classified elsewhere?
The ICD-10-CM code for autonomic neuropathy in diseases classified elsewhere is G99.0 (sometimes written as G990). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
Is G99.0 a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report autonomic neuropathy in diseases classified elsewhere on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
What MS-DRG does G99.0 group to?
On inpatient claims, autonomic neuropathy in diseases classified elsewhere maps to MS-DRG 74, 73, with relative weights from 1.0172 to 1.5773 depending on complications. Higher weights mean higher Medicare reimbursement.
Is G99.0 a CC or MCC?
CMS lists G99.0 as a CC (complication or comorbidity) for FY 2027. Reported as a secondary diagnosis, it moves the inpatient stay to a higher-weighted DRG within its severity family. It does not count when the principal diagnosis is one of the 25 closely related codes in its exclusion list.
Can G99.0 be a principal diagnosis?
No. This is a manifestation code: autonomic neuropathy in diseases classified elsewhere describes the manifestation of an underlying disease rather than the disease itself, so the underlying condition is sequenced first.
Does G99.0 risk-adjust for Medicare Advantage payment?
Not for Medicare Advantage: G99.0 maps to no category in the CMS-HCC V28 model. It still risk-adjusts in the ESRD (V21) category 75 (Polyneuropathy).
