DR. ALEJANDRO ERNESTO DIAZ MD
NPI 1437591104
Internal Medicine in Oakland, CA

Q: What is Alejandro Diaz's NPI number?

The NPI number for Alejandro Diaz is 1437591104. It was assigned to this individual provider in the NPPES registry on July 23, 2013.

Q: What is Alejandro Diaz's specialty?

The primary specialty registered for this NPI is Internal Medicine with taxonomy code 207R00000X.

Q: When was this NPI record last updated?

The NPPES record for Alejandro Diaz was last updated on April 13, 2016. NPI Profile syncs weekly with the NPPES registry data releases published by CMS. This NPI record was last updated 10 years ago. If this record has changed at CMS more recently, you can request an on-demand re-check against the live CMS registry, directly from this page.

Active since July 23, 2013PECOS EnrolledAccepts Medicare Assignment

91.04/100

CMS Quality Rating

1411 E 31ST ST, OAKLAND, CA 94602(510) 437-4887 Get Directions Write a Review

NPPES record last updated: April 13, 2016. Verified against the NPPES registry weekly; last sync: October 25, 2026.

On this page

About Dr. Alejandro Ernesto Diaz Md NPPES

Official registry information on file with the National Plan and Provider Enumeration System.

DR. ALEJANDRO ERNESTO DIAZ MD (NPI 1437591104) is an individual internal medicine provider in Oakland, California, licensed in California (132627) and active in the NPI registry since July 2013. He is enrolled in Medicare PECOS and is a graduate of Other (2012).

NPPES Registry Identity

NPI1437591104

Entity TypeIndividualMale

Primary Taxonomy207R00000X

Provider Legal NameDR. ALEJANDRO ERNESTO DIAZCredential: MD

Location Address1411 E 31ST STOakland, CA 94602-1018

Mailing Address1411 E 31st StOakland, CA 94602-1018 · (510) 437-4887

Phone(510) 437-4887

Sole ProprietorNo

Medical School CMSOtherGraduated 2012

Enumeration DateJuly 23, 2013

Last NPPES UpdateApril 13, 2016

✔ NPI 1437591104 is a valid, active identifier and passes the ISO check-digit test.

Specialties & Licenses

★ Primary SpecialtyInternal MedicineAllopathic & Osteopathic Physicians

Taxonomy Code207R00000X

License✔ Licensed in CA · 132627

Definition

A physician who provides long-term, comprehensive care in the office and the hospital, managing both common and complex illness of adolescents, adults and the elderly. Internists are trained in the diagnosis and treatment of cancer, infections and diseases affecting the heart, blood, kidneys, joints and digestive, respiratory and vascular systems. They are also trained in the essentials of primary care internal medicine, which incorporates an understanding of disease prevention, wellness, substance abuse, mental health and effective treatment of common problems of the eyes, ears, skin, nervous system and reproductive organs.

1411 E 31ST ST, Oakland, CA 94602

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Medicare Participation & PECOS CMS

Medicare enrollment, assignment, billing reassignment, and ordering and referring status from CMS.

Medicare Enrollment Status

✔

Enrolled in Medicare and accepts Medicare assignment

Dr. Alejandro Ernesto Diaz Md is registered in PECOS and agrees to accept the Medicare-approved amount as full payment. Medicare patients are not billed beyond the standard deductible and coinsurance.

PECOS PAC ID8224338736

PECOS Enrollment IDI20151204000660

Eligible to Order & Refer✔ Part B Labs & Imaging✔ Durable Medical Equipment✔ Home Health Agency✔ Power Mobility DevicesPer the CMS Ordering and Referring file. Eligibility means Medicare pays claims that this provider orders or refers for these categories.

Medicare Billing Reassignment

Medicare enrollment records show Alejandro Diaz reassigns Medicare billing to 1 organization. The organization bills Medicare for the services this provider delivers there.

Alameda Health System

Same address

Surgery

1411 E 31ST STREET
Oakland, CA 94602

Reassigned Medicare billing, California enrollment
900 clinicians in this Medicare group

NPI 1740332931 (510) 437-4800

Source: CMS Revalidation Reassignment List, October 2026 release. Reassignment records can lag staffing changes; confirm a current affiliation with the organization.

Physician Visit Costs CMS claims · ZIP area

Typical Medicare office-visit costs in the 94602 ZIP code area, from fee-for-service claims. These are area statistics, not this provider’s prices; actual charges vary by service and coverage.

New Patient

$153.83 typical visit price

range $69.00 – $202.35

Typical copayment $38.45 (range $17.25 – $50.58)

Most-billed visit code 99204

Established Patient

$119.48 typical visit price

range $23.44 – $166.46

Typical copayment $29.87 (range $5.86 – $41.61)

Most-billed visit code 99214

Amounts reflect what Medicare beneficiaries in this ZIP area are typically charged for office visits. Patients with other coverage should check their individual plans.

Medicare Quality Performance CMS QPP · MIPS

Performance in the CMS Quality Payment Program: the MIPS final score across four weighted categories, and the individual quality measures reported to Medicare.

91.04/100

MIPS Final ScoreMerit-based Incentive Payment System · CMS Quality Payment Program

Scored as part of a group practice

Quality

82.13

Promoting Interoperability

100

Improvement Activities

Cost

64.1

Referred Medical Equipment & Supplies CMS DME claims 5

Durable medical equipment, devices and supplies this provider ordered from DME suppliers for patients, from Medicare fee-for-service claims.

Blood glucose test or reagent strips for home blood glucose monitor, per 50 strips A4253

DME-Other DME · category DE017N

9 suppliers21 claims69 services$4.13 avg. paid by Medicare

Oxygen concentrator, single delivery port, capable of delivering 85 percent or greater oxygen concentration at the prescribed flow rate E1390

DME-Oxygen and Supplies · category DC002N

2 suppliers11 claims11 services$69.24 avg. paid by Medicare

Mycophenolic acid, oral, 180 mg J7518

Treatment-Treatment - Miscellaneous · category RX029N

1 supplier11 claims1,320 services$0.90 avg. paid by Medicare

Supply allowance for therapeutic continuous glucose monitor (cgm), includes all supplies and accessories, 1 month supply = 1 unit of service K0553

DME-Other DME · category DE017N

3 suppliers26 claims26 services$206.22 avg. paid by Medicare

Pharmacy supply fee for oral anti-cancer, oral anti-emetic or immunosuppressive drug(s); for a subsequent prescription in a 30-day period Q0512

Treatment-Chemotherapy · category RH012N

1 supplier11 claims12 services$11.57 avg. paid by Medicare

Dollar amounts are the average Medicare paid the supplier per service. They are not the cost to the patient.

Other Providers at the Same Location NPPES 20

Providers registered at the same practice address, or within the immediate area, according to the NPPES registry.

MS. YVONNE DIANE ESCARSEGA MSW

Social Worker (Clinical)

1411 E 31ST ST
OAKLAND, CA 94602

Alameda County (510) 437-4373

MR. JUAN CASILLAS JR. NP

Nurse Practitioner (Family)

1411 E 31ST ST
OAKLAND, CA 94602

Alameda County (510) 437-4800

SADHANA SAMANT MD

Obstetrics & Gynecology

1411 E 31ST ST, OAKCARE MEDICAL GROUP
OAKLAND, CA 94602

Alameda County (510) 437-4323

PATRICIA SCOTT MEYER PA

Clinical Nurse Specialist (Emergency)

1411 E 31ST ST
OAKLAND, CA 94602

Alameda County (209) 342-2300

NATHALIE BALOGUN MSW MPH

Social Worker (Clinical)

1411 E 31ST ST, ALAMEDA COUNTY MEDICAL CENTER - MEDICAL SOCAL WORK SRVC
OAKLAND, CA 94602

Alameda County (510) 437-4949

CYNTHIA MARIE ROWDEN RN

Registered Nurse (Ambulatory Care)

1411 E 31ST ST
OAKLAND, CA 94602

Alameda County (510) 437-4373

DR. KAYLA ENRIQUEZ MD

Emergency Medicine

1411 E 31ST ST
OAKLAND, CA 94602

Alameda County (510) 437-4564

DR. CHERYL LIN PARK M.D.

Surgery

1411 E 31ST ST
OAKLAND, CA 94602

Alameda County (510) 437-4743

Frequently Asked Questions NPPES & CMS

Common questions about this NPI record, answered from the official NPPES registry and CMS datasets shown on this page.

What is Alejandro Diaz's NPI number?

The NPI number for Alejandro Diaz is 1437591104. It was assigned to this individual provider in the NPPES registry on July 23, 2013.

Where is Alejandro Diaz located?

Alejandro Diaz practices at 1411 E 31st St, Oakland, CA 94602. The listed phone number is (510) 437-4887.

What is Alejandro Diaz's specialty?

The primary specialty registered for this NPI is Internal Medicine with taxonomy code 207R00000X.

Is Alejandro Diaz enrolled in Medicare?

Yes. Alejandro Diaz is registered in the Medicare PECOS system and accepts Medicare assignment, which means accepting the Medicare-approved amount as payment in full for covered services.

Which organization bills Medicare for Alejandro Diaz's services?

According to the CMS Revalidation Reassignment List (October 2026 release), Alejandro Diaz reassigns Medicare benefits to Alameda Health System (Oakland, CA). The reassignment is filed with Medicare on form CMS-855R, signed by both the clinician and the organization, and lets the organization bill Medicare and receive payment for Alejandro Diaz's services. Reassignment records can lag staffing changes; confirm current arrangements with the organization.

When was this NPI record last updated?

The NPPES record for Alejandro Diaz was last updated on April 13, 2016. NPI Profile syncs weekly with the NPPES registry data releases published by CMS. This NPI record was last updated 10 years ago. If this record has changed at CMS more recently, you can request an on-demand re-check against the live CMS registry, directly from this page.