Dr. Matthew Patrick Diaz, DO
- Part D claims, 2024
- 6,403
- Hospital affiliations
- 1
- Industry payments
- $140
- Medical group
- 1
- Insurance carriers
- 2
- Practice address
- 9961 Sierra Ave, Fontana, CA 92335
- Practice phone
- Call (909) 427-3910
- Professional email
- Get professional email
- Personal email
- Get personal email
- Mobile number
- Get mobile number
Primary practice
Fontana Medical Center
Fontana, California
Find Dr. Diaz's professional email, personal email and mobile number
Dmand AI checks each channel through healthcare-specific waterfall enrichment. See what is on file with a free account, with practice phones, licenses and affiliations.
Dr. Matthew Patrick Diaz is a family medicine physician in Fontana, California
Dr. Diaz practices at Fontana Medical Center in Fontana, California.
Dr. Diaz's NPI, 1235492943, was assigned on June 18, 2012. Dr. Diaz graduated from WesternU College of Osteopathic Medicine of the Pacific in 2012. Dr. Diaz holds California license 20A12957.
- NPI
- 1235492943NPI Registry (opens in a new tab)
- Medicare PAC ID
- 7810204617
- NPI enumeration date
- June 18, 2012
- NPI status
- Active
- Accepts Medicare assignment
- Yes
- Practice phone
- (909) 427-3910
- Professional email
- Get email
- Personal email
- Get email
- Mobile number
- Get number
- Sex
- Male
- Estimated age
- 40
- Medical school graduation
- 2012
Sources: NPPES NPI Registry (CMS); Dmand AI Professional Profile Data; Dmand AI Practice Data; and Doctors and Clinicians National Downloadable File (CMS)
Dr. Matthew Patrick Diaz practices at Fontana Medical Center in Fontana, California
Dr. Diaz's primary practice is Fontana Medical Center, at 9961 Sierra Ave, Fontana, CA 92335 in San Bernardino County. The practice phone is (909) 427-3910.
- Fontana Medical Center9961 Sierra Ave, Fontana, CA 92335 · San Bernardino CountyPhone(909) 427-3910
Sources: NPPES NPI Registry (CMS); and Dmand AI Practice Data
Dr. Matthew Patrick Diaz is affiliated with 2 sites of care and 1 medical group
Dr. Diaz's primary practice is Fontana Medical Center in Fontana, California. Dr. Diaz is also affiliated with Arrowhead Regional Medical Center. The medical group on file is Southern California Permanente Medical Group.
Sources: NPPES NPI Registry (CMS); Dmand AI Practice Data; Dmand AI Affiliation Data; and Dmand AI Org Hierarchy Data
Dmand AI tracks the EHR system at Dr. Matthew Patrick Diaz's practice
Dmand AI tracks the electronic health record (EHR) system at each site where Dr. Diaz practices. Vendor and product names are available with a free account.
| Site | EHR vendor and product |
|---|---|
| Fontana Medical Center | Available with a free account |
| +1 more affiliated site | Available with a free account |
Source: Dmand AI Technology Install Data
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Dr. Matthew Patrick Diaz is one of 15,680 family medicine physicians in California
Family medicine is Dr. Diaz's primary specialty in the NPI Registry, under taxonomy code 207Q00000X. Dr. Diaz is board certified in family medicine by the American Board of Family Medicine. Dr. Diaz is licensed in California.
Specialties and state licenses
- Family medicine, CaliforniaPrimary
Family medicine physicians near Dr. Diaz
Counts of family medicine physicians with a Dmand AI profile, by place and practice. Each opens the list.
Sources: NPPES NPI Registry (CMS); Dmand AI Professional Profile Data; and Dmand AI Peer Benchmarks
Dr. Matthew Patrick Diaz's patients have a median age of 49
Across all payers, Dmand AI patient panel data puts Dr. Diaz's median patient age at 49, with 56% women.
Dr. Diaz's patients across all payers
Dmand AI patient panel data covers Medicare, Medicaid and commercial patients.
Patient panel by age, all payers
Median age 49
Patient panel by sex, all payers
- Women56%
- Men43%
Source: Dmand AI Patient Panel Data
Dr. Matthew Patrick Diaz wrote 6,403 Medicare Part D claims in 2024
In 2024, Dr. Diaz wrote 6,403 Medicare Part D claims for 1,212 patients. 86% of them were for generic drugs. CMS names the drug for 5,806 of them, across 106 drugs with 11 or more claims each, at $297,536 in total drug cost. In 2023, CMS named 4,333 claims across 83 drugs.
Dr. Diaz's Part D claims by kind of drug, 2024
- Generic5,506 claims86%
- Brand-name713 claims11%
- Other184 claims3%
Dr. Diaz's most prescribed drugs by claims, 2024
CMS names a drug when it has 11 or more claims. Share is of the claims for drugs CMS names.
Drug classes CMS tracks in Dr. Diaz's Part D claims, 2024
- Opioids3%208 of 6,403 claims
- Antibiotics2%122 of 6,403 claims
Share of all Part D claims for each drug class CMS reports on. Classes with no claims are left out.
Part D claims for drugs CMS names, 2023 to 2024
- 2023
- 2024
- Claims for drugs CMS names
- 2023: 4,3332024: 5,80634%
Drugs named by CMS: 106 in 2024, 83 in 2023.
Sources: Medicare Part D Prescribers - by Provider and Drug (CMS), 2024 data, released May 6, 2026; and Medicare Part D Prescribers - by Provider (CMS), 2024 data
How Dr. Matthew Patrick Diaz takes part in Medicare
Dr. Diaz accepts Medicare assignment, so Medicare's approved amount is taken as full payment.
- Accepts Medicare assignment
- Yes
Source: Doctors and Clinicians National Downloadable File (CMS)
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Dr. Matthew Patrick Diaz received $140 in industry payments from 2017 to 2025
CMS Open Payments shows 2 general payments to Dr. Diaz from 2 drug and device companies from 2017 to 2025. Food and beverage make up the largest share, 100% of the total. Gilead Sciences, Inc. paid the most, $100.
General payments to Dr. Diaz by program year, 2017 to 2025
Companies that paid Dr. Diaz the most, 2017 to 2025
Share is of all general payments to this clinician.
Source: Open Payments (CMS), 2025 data, released July 7, 2026
Dr. Matthew Patrick Diaz graduated from WesternU College of Osteopathic Medicine of the Pacific
Dr. Diaz graduated from WesternU College of Osteopathic Medicine of the Pacific in 2012.
- Medical school
- Board certified in family medicine
Source: Dmand AI Professional Profile Data
Dr. Matthew Patrick Diaz accepts plans from 2 insurance carriers
Dr. Diaz is in network with 2 carriers, including Kaiser Permanente and CMS Medicare. EPO plans come from the most carriers, 1. Check the plan with the practice before a visit.
- Kaiser Permanente
- CMS Medicare
Plan types Dr. Diaz accepts, by number of carriers
- EPO1
- HMO1
- Medicare1
- POS1
Source: Dmand AI Insurance Network Data
Sources for Dr. Matthew Patrick Diaz's profile data
| Data on this page | Source |
|---|---|
| NPI, name, sex, specialty and licenses | NPPES NPI Registry (CMS) (opens in a new tab)Dmand AI Professional Profile Data |
| Practice locations and phone | NPPES NPI Registry (CMS) (opens in a new tab)Dmand AI Practice Data |
| Primary practice, affiliations and health system | NPPES NPI Registry (CMS) (opens in a new tab)Dmand AI Practice DataDmand AI Affiliation DataDmand AI Org Hierarchy Data |
| Medicare patients and the all-payer patient panel | Dmand AI Patient Panel Data |
| Part D prescribing | Medicare Part D Prescribers - by Provider and Drug (CMS) (opens in a new tab)Medicare Part D Prescribers - by Provider (CMS) (opens in a new tab) |
| MIPS scores, telehealth, assignment and procedure percentiles | Doctors and Clinicians National Downloadable File (CMS) (opens in a new tab) |
| Industry payments | Open Payments (CMS) (opens in a new tab) |
| Training, board certification and memberships | Dmand AI Professional Profile Data |
| Insurance carriers and plan types | Dmand AI Insurance Network Data |
| EHR at each practice site | Dmand AI Technology Install Data |
| Similar physicians | Dmand AI Affiliation Data |
Data last refreshed October 2026Report an inaccuracyRemove my information
FAQ
Frequently asked questions about Dr. Matthew Patrick Diaz
Spotted something out of date? Email hello@dmand.ai and we will check the record. Contact details live in the free trial.
What is Dr. Matthew Patrick Diaz's NPI number?
Dr. Matthew Patrick Diaz's NPI number is 1235492943. It was assigned on June 18, 2012, and it is active in the NPI Registry.
What kind of doctor is Dr. Matthew Patrick Diaz?
Dr. Matthew Patrick Diaz is a family medicine physician in Fontana, California. The primary specialty in the NPI Registry is Family Medicine Physician (taxonomy code 207Q00000X).
Where does Dr. Matthew Patrick Diaz practice?
Dr. Diaz practices at 9961 Sierra Ave, Fontana, CA 92335. Dr. Diaz's primary practice is Fontana Medical Center in Fontana, California.
What is Dr. Matthew Patrick Diaz's office phone number?
The practice phone on file for Dr. Diaz is (909) 427-3910.
What is Dr. Matthew Patrick Diaz's medical license number?
Dr. Diaz holds California license 20A12957.
Which hospitals is Dr. Matthew Patrick Diaz affiliated with?
Dr. Diaz is affiliated with Arrowhead Regional Medical Center.
What medical group is Dr. Matthew Patrick Diaz part of?
Dr. Diaz is linked to Southern California Permanente Medical Group.
Does Dr. Matthew Patrick Diaz accept Medicare?
Yes. CMS lists Dr. Diaz as accepting Medicare assignment.
Is Dr. Matthew Patrick Diaz board certified?
Yes. Dr. Diaz is board certified in family medicine by the American Board of Family Medicine.
Where did Dr. Matthew Patrick Diaz go to medical school?
Dr. Diaz graduated from WesternU College of Osteopathic Medicine of the Pacific in 2012.
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What drugs does Dr. Matthew Patrick Diaz prescribe most?
In 2024 Medicare Part D data, Dr. Diaz's most prescribed drugs by claims were Atorvastatin Calcium, Amlodipine Besylate and Losartan Potassium.
Has Dr. Matthew Patrick Diaz received payments from drug or device companies?
CMS Open Payments shows $140 in general payments to Dr. Diaz from 2 companies from 2017 to 2025. The largest total came from Gilead Sciences, Inc.
How long has Dr. Matthew Patrick Diaz been practicing?
Dr. Diaz graduated from medical school in 2012, 14 years ago.
What insurance does Dr. Matthew Patrick Diaz accept?
Dr. Diaz is in network with 2 carriers, including Kaiser Permanente and CMS Medicare. EPO plans come from the most carriers, 1. Check the plan with the practice before a visit.
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