NPI registry status
Active
2026 NPPES data Internal Medicine Physician NPI 1356704795 MD
Verify on CMS → Diane Mar, MD
Internal Medicine Physician in Stanford, California.
This profile is drawn from the federal National Provider Identifier Registry (CMS NPPES), which lists more than 7 million U.S. healthcare providers - including 172,737 in Internal Medicine Physician, and covers specialty classification, practice address, and Medicare Part D prescribing data when reported. According to CMS, every field reflects the provider's official federal registration, see our methodology.
Federal data, no proprietary rating.
We show these CMS records as-is - no composite score, no star rating, no editorial opinion layered on top.
Prescribing volume
279
Medicare Part D claims · 44 beneficiaries · Internal Medicine Physician avg: 3K
Generic prescribing
86%
generic claims · 14% brand-name · higher generic rates reduce patient out-of-pocket costs
MIPS score
76.5/100
▼ 7 pts below national avg 83.5 · Above neutral
Source: CMS Medicare Part D Prescriber Public Use File, 2023
What the federal data shows
Diane Mar, MD reported a CMS MIPS final score of 76.5/100 - below the 83.5 national average - and filed 279 Medicare Part D claims in 2023.
- 76.5/100
- MIPS score · -7 vs avg
- 279
- Part D claims, 2023
- 86%
- generic prescribing
- Likely
- board-certified (heuristic)
Every figure on this page comes straight from federal CMS records (NPPES, Medicare Part D, MIPS, Open Payments) - no proprietary rating or editorial opinion is applied.
Diane Mar, MD's MIPS score vs every measured U.S. clinician
CMS Merit-based Incentive Payment System (MIPS) final score, 2023, the federal quality measure. Clinicians whose score CMS assigned without scoring any category are excluded.
77 ≥ 17th percentile 17% of 454,083 measured providers are in lower value bands
Each bar is a band; taller bars hold more measured providers. The dashed line + filled bar mark this entry. Hover or tap any bar for its full count, share, and where it sits relative to this entry.
The percentile is a conservative whole-score-point band: it counts only measured clinicians in lower score bands. A CMS MIPS metric is not a recommendation or a clinical-quality rating by PlainDoctor. See methodology § corpus placement.
Source CMS Merit-based Incentive Payment System (MIPS) · 2023
Where Diane Mar, MD sits
This provider among internal medicine physician peers
Across the 34,612 internal medicine physician providers who report both Medicare Part D prescribing and a MIPS quality score, Diane Mar, MD writes more Part D claims than 32% of them and scores higher on MIPS quality than 17% - placing this provider in the lower-volume, lower-quality quadrant. Volume reflects patient-panel size and specialty, not quality; the two axes are independent.
Part D claim volume vs MIPS quality, by specialty percentile
Each dot is one internal medicine physician peer from a representative sample of 60; the gold marker is Diane Mar, MD. Source: CMS Medicare Part D Prescriber data and the CMS Merit-based Incentive Payment System, 2023.
✓
Board certification likely (heuristic, not verified)
Diane Mar, MD practices in an ABMS-board-eligible specialty and shows active CMS Medicare participation + MIPS quality reporting + 1 hospital affiliation - signals consistent with board-certified status. For verified board certification, see CertificationMatters.org (the official ABMS public lookup).
What does the federal data show about Diane Mar, MD?
Below national averagePrimary specialty
Internal Medicine Physician
Medicare Part D claims
279 90% vs specialty avg
MIPS final score
76.5/100 7 pts vs avg
Specialty distribution in California
How Internal Medicine Physician compares to other specialties among California providers
Medicare quality performance, MIPS
Diane Mar, MD's 2023 MIPS final score plotted against the Internal Medicine Physician national average
- MIPS Final Score
- 76.5/100
- vs 83.5 national avg · 2023 performance year
MIPS final score (Internal Medicine Physician) - 76.5/100 vs national avg 83.5
How MIPS and board certification work
The Merit-based Incentive Payment System (MIPS) scores providers 0–100 across four performance categories: Quality, Cost, Promoting Interoperability, and Improvement Activities, weighted under 42 CFR §414.1380. Reporting is voluntary for many small practices, so absence of a MIPS score is not a quality signal.
Board certification through an ABMS or AOA member board signals voluntary post-licensure examination plus continuous Maintenance of Certification cycles. Verify any individual provider's status through certificationmatters.org (ABMS) or osteopathic.org (AOA).
Diane Mar, MD appears in the CMS NPPES registry as an Internal Medicine Physician provider holding MD credentials at 300 PASTEUR DR, Stanford, CA, 94305, with a listed phone of (650) 723-4000. NPI 1356704795 was issued on 04/02/2016.
Medicare Part D records for calendar year 2023 show 279 prescription claims written by this provider, covering 44 Medicare beneficiaries and totaling roughly $383K in drug spend, split 14% brand-name and 86% generic by claim count. On the CMS Merit-based Incentive Payment System, this provider earned a Final Score of 76.5/100 for the 2023 performance year (Quality 74.3, Cost 44), compared with the 83.5 average among clinicians with a measured score.
Internal Medicine Physician is a high-volume specialty nationwide, with 172,737 enrolled providers across 56 states and an average of 2,716 Part D claims per prescriber, so the context for interpreting these metrics differs meaningfully from a primary-care baseline.
Important: PlainDoctor is a directory of publicly available government data, not medical advice, a malpractice database, or a quality rating. Inclusion here does not imply a recommendation, and absence of complaints or sanctions on this page does not mean none exist, always verify credentials through the NPPES NPI Registry, your state medical board, and the ABMS or AOA before making healthcare decisions.
Practice Address
Provider Details
| NPI | 1356704795 |
|---|---|
| Specialty | Internal Medicine Physician |
| Credentials | MD |
| Gender | Female |
| NPI Issued | 04/02/2016 |
CMS Quality Score (MIPS)
Merit-based Incentive Payment System (MIPS) scores from CMS, 2023 performance year.
76.5025
Final Score
Measured-score avg: 83.5
74.3195
Quality
43.9595
Cost
100
Promoting Interoperability
Reporting: Group practice
Hospital and facility affiliations
Facilities where Diane Mar, MD bills Medicare from. Star ratings (1-5) are CMS Hospital Compare's "Hospital overall rating" - a composite of mortality, readmission, patient experience, safety, timely care, and efficient use of medical imaging measures. Source: CMS Care Compare.
County OF Santa Clara
San Jose, CA
Affiliations sourced from CMS Doctors and Clinicians National Downloadable File; hospital ratings from CMS Hospital General Information dataset (cross-referenced by facility name + state).
License & disciplinary context - California MBC 2023 annual report
Aggregate state board data only, NOT a determination of any individual provider's status. The figures below describe statewide disciplinary activity across all ~150K California medical licensees in 2023 - they are NOT specific to Diane Mar, MD. To verify Diane Mar, MD's current license status, search the MBC public license lookup directly, or check the Federation of State Medical Boards (FSMB) verification service.
576
Total board actions, California 2023
Across 556 cases
3.84
Actions per 1,000 licensees
California statewide rate
probation
Most common action type
186 cases
MBC publishes annual disciplinary statistics as part of public-record reporting under each state's Administrative Procedure Act. See the full breakdown by action type and year on the California disciplinary trends page. Cross-checked against FSMB U.S. Medical Regulatory Trends.
Brand vs generic prescribing mix · Typical
Diane Mar, MD - brand share 14.0%
Internal Medicine Physician average
14% brand-name claims vs 86% generic, on 279 2023 Medicare Part D claims.
The federal Medicare Part D Generic Dispensing Rate national benchmark sits near 90% generic / 10% brand for primary-care prescribers, per CMS Office of the Actuary 2024 estimates. Higher brand share is common in specialty prescribing where generic equivalents are not available.
Medicare Part D Prescribing Data
CMS Medicare Part D prescriber-level data for calendar year 2023.
279
Total Claims
$383K
Total Drug Cost
44
Medicare Beneficiaries
Prescribing Breakdown
- 30-Day Fills
- 492
- Total Day Supply
- 13,871
- Brand vs Generic
- 14% brand / 86% generic
- Brand Drug Cost
- $363K
- Generic Drug Cost
- $20K
Patient Demographics
- Average Patient Age
- 66.9 years
- Avg HCC Risk Score
- 2.77
- Age Distribution
- <65: 11, 65-74: 21, 75-84: N/A, 85+: N/A
Top Prescribed Drugs (Medicare Part D)
Top drugs by claim count for calendar year 2023. Based on Medicare Part D data only.
What Diane Mar, MD prescribes most
Top Medicare Part D drugs by claim count, 2023
- Prednisone
Prednisone
60 claims
- Hydroxychloroquine…
Hydroxychloroquine Sulfate
32 claims
- Allopurinol
Allopurinol
31 claims
- Methotrexate 21
Methotrexate
21 claims
- Leflunomide 16
Leflunomide
16 claims
- Rinvoq 12
Rinvoq
12 claims
| Drug | Claims |
|---|---|
| Prednisone | 60 |
| Hydroxychloroquine Sulfate | 32 |
| Allopurinol | 31 |
| Methotrexate Methotrexate Sodium | 21 |
| Leflunomide | 16 |
| Rinvoq Upadacitinib | 12 |
* Counts below 11 are suppressed by CMS for patient privacy. Generic names shown where available from CMS Part D data.
Internal Medicine Physician Overview
How Diane Mar, MD fits within the Internal Medicine Physician landscape nationally.
172,737
Internal Medicine Physician Providers in US
56
States with Internal Medicine Physician
2,716
Avg Claims per Provider
Diane Mar, MD's 279 claims are below the specialty average of 2,716.
Nearby Internal Medicine Physician Providers in California
Other clinicians with the same primary specialty enrolled in California, drawn from the same CMS NPPES roster as Mar.
Dr. Jacob Aaron
MD
San Francisco, CA
Dr. Alistair Aaronson
MD
Stanford, CA
Dr. Jose Abad.
MD
Sacramento, CA
Dr. Donna Abare
MD
Oakland, CA
Marce Abare
Scotts Valley, CA
Compare Internal Medicine Physician nationally: see state-by-state distribution →
Before you book an appointment
Use this federal record as your verification checklist, not as a recommendation.
- Confirm the NPI record is current in the official CMS registry, providers update their own NPPES details, and moves can lag. Verify this NPI
- Check the active license and any disciplinary history with the California medical board, federal registration is not a license check. Credential verification guide
- Weigh a second option: compare this provider with a nearby Internal Medicine Physician peer on Medicare volume and prescribing patterns. Compare providers
Medicare Part D and MIPS figures describe practice patterns in federal programs only, they are not quality ratings, and PlainDoctor does not rate, rank, or recommend providers.
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Frequently Asked Questions
What is Diane Mar, MD's specialty? ▼
Diane Mar, MD specializes in Internal Medicine Physician and practices in Stanford, California. Credentials: MD.
How much does Diane Mar, MD prescribe under Medicare Part D? ▼
In 2023, Diane Mar, MD wrote 279 Medicare Part D claims totaling $383K in drug costs for 44 beneficiaries.
What is Diane Mar, MD's Medicare quality score? ▼
Diane Mar, MD has a CMS MIPS Final Score of 76.5/100 (Quality: 74.3, Cost: 44). The average MIPS Final Score across the 454,083 clinicians with at least one published category score is 83.5; clinicians whose score CMS assigned without scoring any category are excluded from that average. Source: CMS Merit-based Incentive Payment System (MIPS) 2023.
Where is Diane Mar, MD located? ▼
Diane Mar, MD is located at 300 PASTEUR DR, Stanford, CA, 94305. Phone: (650) 723-4000.
What is Diane Mar, MD's NPI number? ▼
Diane Mar, MD's National Provider Identifier (NPI) is 1356704795, issued on 04/02/2016.
Does Diane Mar, MD prescribe more brand-name or generic drugs? ▼
Diane Mar, MD's prescribing is 14% brand-name and 86% generic drugs by claim count, with $363K in brand drug costs.
How many Internal Medicine Physician providers are there in the US? ▼
There are 172,737 Internal Medicine Physician providers across 56 states in the US. The average Internal Medicine Physician provider writes 2,716 Medicare Part D claims per year.
What drugs does Diane Mar, MD prescribe most often? ▼
Based on 2023 Medicare Part D data, Diane Mar, MD's most frequently prescribed drugs include Prednisone, Hydroxychloroquine Sulfate, Allopurinol. This reflects Medicare Part D prescriptions only and does not include commercial insurance or other payer types.
Does Diane Mar, MD accept Medicare? ▼
Diane Mar, MD appears in CMS Medicare data with 279 Part D claims and 44 Medicare beneficiaries in 2023. Contact the provider's office directly to confirm current Medicare enrollment and accepted plans.
How can I verify Diane Mar, MD's credentials? ▼
Diane Mar, MD's NPI is 1356704795 with credentials MD. You can verify this through the NPPES NPI Registry, check state medical board records, and confirm board certification through the ABMS or AOA.
Data Sources
View source datasets and methodology notes
- Provider Directory
- CMS National Plan and Provider Enumeration System (NPPES), download.cms.gov/nppes, updated monthly. Contains NPI, specialty, credentials, and practice location.
- Specialty Classification
- NUCC Health Care Provider Taxonomy (nucc.org), the industry standard for classifying provider specialties in Medicare and Medicaid billing.
- Prescribing Data
- CMS Medicare Part D Prescriber Public Use File (2023). Includes claims, drug costs, beneficiaries, and opioid prescribing rates.
- Quality Performance
- CMS Merit-based Incentive Payment System (MIPS) - 2023 performance year.
- Limitations
- Provider data is self-reported to CMS. Prescribing data reflects Medicare Part D only and does not include commercial insurance, Medicaid, or cash prescriptions. Claims below 11 beneficiaries are suppressed by CMS for privacy.
See our complete data methodology for details on how we collect and process government data.
Data as of April 2026 (NPPES) / 2023 (Medicare Part D). Source: Centers for Medicare & Medicaid Services (CMS).
Disclaimer: Data from CMS NPPES and Medicare Part D. PlainDoctor does not rate or rank providers. Provider information is self-reported and may not be current. Always verify information directly with the provider. About · Methodology
Every figure on PlainDoctor is rendered directly from the federal CMS NPPES registry, Medicare Part D, MIPS, and Open Payments records, no number is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. Data current as of May 2026.