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ICD-10-CM 2027 diagnosis code

F51.01Primary insomnia

✓ Billable / specific

F51.01 is a valid, billable ICD-10-CM code for primary insomnia. It can be reported on claims for dates of service from October 1, 2026 – September 30, 2027.

Code unchanged since ICD-10-CM took effect on October 1, 2015. Source: official FY2027 ICD-10-CM release from CDC/NCHS and CMS. Page updated September 29, 2026. About our data

About F51.01

F51.01 is the ICD-10-CM diagnosis code for primary insomnia. It belongs to category F51 (sleep disorders not due to a substance or known physiological condition), block F50-F59 (behavioral syndromes associated with physiological disturbances and physical factors) and chapter 5 (mental, Behavioral and Neurodevelopmental disorders). It is billable, so it can be reported on its own for dates of service from October 1, 2026 through September 30, 2027.

Within F51.0 (insomnia not due to a substance or known physiological condition), F51.01 is specifically for primary insomnia. Related codes cover adjustment insomnia (F51.02), Paradoxical insomnia (F51.03), Psychophysiologic insomnia (F51.04), insomnia due to other mental disorder (F51.05) and other insomnia not due to a substance or known physiological condition (F51.09).

It is not a CC or MCC, so as a secondary diagnosis it doesn't change the MS-DRG severity level.

In MS-DRG v44.0, it is part of the grouping logic for DRG 887 (Other Mental Disorder Diagnoses, relative weight 1.1139), in MDC 19 (Mental Diseases and Disorders), as a principal or secondary diagnosis. The DRG a claim lands in depends on the principal diagnosis, procedures and any CC/MCC secondary diagnoses.

It has been part of ICD-10-CM since the code set took effect on October 1, 2015 and hasn't changed since.

Before ICD-10, this condition was coded in ICD-9-CM as 307.42 (persistent disorder of initiating or maintaining sleep).

Coding notes

Applicable toConditions and synonyms classified to this code
  • Idiopathic insomnia

Notes that apply from higher levels

Instructions written at a parent level also apply to F51.01.

› From F51.0 Insomnia not due to a substance or known physiological condition
Excludes2
› From F51 Sleep disorders not due to a substance or known physiological condition
Excludes2
  • organic sleep disorders (G47.-)

Broader instructions also apply from Chapter 5: Mental, Behavioral and Neurodevelopmental disorders.

Alphabetic index entries

4 entries

Terms in the official ICD-10-CM index that lead to F51.01.

Codes whose notes reference F51.01

MS-DRG v44.0 grouping

All DRGs →

Inpatient MS-DRGs this diagnosis can group to, as the principal or a secondary diagnosis, depending on the rest of the claim.

MDC 19 · Mental Diseases and Disorders

ICD-9-CM equivalent

Converter →
  • 307.42Persistent disorder of initiating or maintaining sleepapproximate

From the CMS 2018 General Equivalence Mappings (GEMs), the final GEMs release.

Code history

  1. 2016
  2. 2017
  3. 2018
  4. 2019
  5. 2020
  6. 2021
  7. 2022
  8. 2023
  9. 2024
  10. 2025
  11. 2026
  12. 2027
  • FY2016 (effective 10/1/2015): Added (first year of ICD-10-CM)
  • No changes since FY2016.

Common questions about F51.01

Is F51.01 billable?

Yes. F51.01 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).

Can F51.01 be used as a principal diagnosis?

Yes. The Medicare Code Editor doesn't restrict F51.01 as a principal diagnosis.

Is F51.01 a CC or MCC?

No. F51.01 is neither a CC nor an MCC under MS-DRG v44.0.

What DRG does F51.01 group to?

F51.01 is used in the MS-DRG v44.0 logic for MS-DRG 887 (Other Mental Disorder Diagnoses). Which one applies depends on whether it is the principal diagnosis and on the rest of the claim.

What is the ICD-9 code for F51.01?

The CMS General Equivalence Mappings map F51.01 to ICD-9-CM 307.42.