2026 ICD-10-CM Diagnosis Code E66.89Other obesity not elsewhere classified

ICD-10-CM Codes›E00–E89›E65-E68›E66

ICD-10-CM E66.89
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

E66.89 is a billable ICD-10-CM diagnosis code for other obesity not elsewhere classified. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 640 through 641. The code is flagged as a questionable admission, since it rarely justifies inpatient admission on its own. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Obesity.

Code Identity

ICD-10-CM Code
E66.89
Billable Status
Yes — Valid for Submission
Code Describes
Other obesity not elsewhere classified
Short Description
Other obesity not elsewhere classified
Same as the full description in the CMS dataset.
Parent Code
E66.8
Other obesity

Code Classification

ChapterE00–E89Endocrine, nutritional and metabolic diseases
SectionE65-E68Overweight, obesity and other hyperalimentation
CategoryE66Overweight and obesity
This CodeE66.89Other obesity not elsewhere classified

Code EditsBilling

Medicare Code Editor checks that affect claim validity for E66.89.

Questionable admission codes
Some diagnoses are not usually sufficient justification for admission to an acute care hospital. For example, if a patient is given code R030 for elevated blood pressure reading, without diagnosis of hypertension, then the patient would have a questionable admission, since elevated blood pressure reading is not normally sufficient justification for admission to a hospital. The following list contains diagnosis codes identified as questionable admission when used.

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Adult-onset obesity
  • Android obesity
  • Aniridia, ptosis, intellectual disability, familial obesity syndrome
  • Buffalo obesity
  • Central obesity
  • Childhood obesity
  • Clark Baraitser syndrome
  • Common polygenetic childhood obesity
  • Congenital aniridia
  • Congenital hypoplasia of external genitalia
  • Congenital hypoplasia of male external genitalia
  • Congenital hypoplasia of penis
  • Constitutional obesity
  • Early-onset obesity, hyperphagia, severe developmental delay syndrome
  • Endogenous obesity
  • Excessive eating
  • Familial obesity
  • Finding of quantity of eating
  • Genetic childhood obesity disorder
  • Genetic non-syndromic childhood obesity
  • Genetic obesity disorder
  • Genetic syndromic childhood obesity
  • Gynecoid obesity
  • Hydrocephalus with obesity and hypogonadism syndrome
  • Hyperinsulinar obesity
  • Hyperplastic obesity
  • Hyperplastic-hypertrophic obesity
  • Hypertrophic obesity
  • Hypogonadal obesity
  • Hypoplasia of distal phalanx of hand
  • Hypothalamic disorder of appetite
  • Hypothalamic obesity
  • MEHMO syndrome
  • Morbid obesity
  • MORM syndrome
  • Obesity by adipocyte growth pattern
  • Obesity by contributing factors
  • Obesity caused by energy imbalance
  • Obesity due to CEP19 deficiency
  • Obesity due to melanocortin 4 receptor deficiency
  • Obesity due to prohormone convertase I deficiency
  • Obesity due to SIM1 deficiency
  • Obesity of endocrine origin
  • Obesity, colitis, hypothyroidism, cardiac hypertrophy, developmental delay syndrome
  • Peripheral obesity
  • Pulmonary hypertension associated with chronic underventilation
  • Pulmonary hypertension due to lung disease and/or hypoxia
  • Pulmonary hypertension with extreme obesity
  • Rapid-onset childhood obesity, hypothalamic dysfunction, hypoventilation, autonomic dysregulation syndrome
  • Severe early-onset obesity insulin resistance syndrome due to SH2B1 deficiency
  • Severe obesity
  • Short stature, brachydactyly, obesity, global developmental delay syndrome
  • Syndromic X-linked intellectual disability type 7

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

External Cause of Injuries IndexGuidance

References for this code in the External Cause of Injuries Index.

    • Obesity
      • constitutional
    • Obesity
      • endocrine
    • Obesity
      • endogenous
    • Obesity
      • familial
    • Obesity
      • glandular
    • Obesity
      • specified type NEC

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR END009
Obesity
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • Morbid Obesity

    an excess of body weight, normally defined as an individual with a body mass index greater than 35 or a body weight greater than one hundred percent of ideal body weight.

Patient EducationClinical

Obesity

Obesity is a disease that means having too much body fat. It is different from being overweight, which means weighing too much. Both terms mean that your weight is greater than what's considered healthy for your height.

The full article covers:

  • What is obesity?
  • What raises your risk of obesity?
  • How is obesity diagnosed?
  • What health problems can obesity cause?
  • What are the treatments for obesity?

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Code History & ChangesHistory

Replacement E66.89 replaces the following previously assigned code(s):

  • E66.8 - Other obesity
FY 2025AddedAdded to the ICD-10-CM code setEffective October 1, 2024.
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About E66.89Overview

Is E66.89 (Other obesity) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report other obesity not elsewhere classified on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does E66.89 group to?

When other obesity not elsewhere classified is the principal diagnosis on an inpatient stay, it groups to MS-DRG 640, 641, with relative weights from 0.7782 to 1.3356 depending on complications. Higher weights mean higher Medicare reimbursement.

Does E66.89 justify an inpatient admission?

Not on its own. The Medicare Code Editor lists this code as a questionable admission because other obesity not elsewhere classified is not usually sufficient justification for admission to an acute care hospital.

Footnotes

[1] Chronic - a chronic condition code indicates a condition lasting 12 months or longer and its effect on the patient based on one or both of the following criteria:

  • The condition results in the need for ongoing intervention with medical products,treatment, services, and special equipment
  • The condition places limitations on self-care, independent living, and social interactions.