NPI registry status
Active
2026 NPPES data Internal Medicine Physician NPI 1225171754 MD
Verify on CMS → Pei Sun, MD
Internal Medicine Physician in Wallingford, Connecticut.
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
5K
Medicare Part D claims · 803 beneficiaries · Internal Medicine Physician avg: 3K
Generic prescribing
88%
generic claims · 11% brand-name · higher generic rates reduce patient out-of-pocket costs
Industry payments
$55.15
2 payments · CMS Open Payments (Sunshine Act)
Source: CMS Medicare Part D Prescriber Public Use File, 2023
What the federal data shows
Pei Sun, MD filed 5,491 Medicare Part D claims in 2023 as an Internal Medicine Physician in Wallingford, Connecticut, prescribing 88% generic.
- 5K
- Part D claims, 2023
- 88%
- 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.
Pei Sun, MD's Medicare Part D volume vs every U.S. prescriber
Total Medicare Part D claims, 2023, across all CMS prescribers nationally
5,491 Top 6% higher than 94% of 1,370,886 prescribers
Each bar is a band; taller bars hold more prescribers. 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.
Source CMS Medicare Part D Prescriber Public Use File · 2023
✓
Board certification likely (heuristic, not verified)
Pei Sun, MD practices in an ABMS-board-eligible specialty and shows active CMS Medicare participation + 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 Pei Sun, MD?
Quality data not reportedPrimary specialty
Internal Medicine Physician
Medicare Part D claims
5,491 102% vs specialty avg
Specialty distribution in Connecticut
How Internal Medicine Physician compares to other specialties among Connecticut providers
Board certification
Not published by CMS
CMS does not publish a per-provider board-certification field in NPPES. PlainDoctor does not have a reliable per-specialty certification rate to show for Internal Medicine Physician. Verify directly:
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).
Pei Sun, MD appears in the CMS NPPES registry as an Internal Medicine Physician provider holding MD credentials at 850 N MAIN STREET EXT, Wallingford, CT, 06492, with a listed phone of (203) 269-4353. NPI 1225171754 was issued on 02/15/2007.
Medicare Part D records for calendar year 2023 show 5,491 prescription claims written by this provider, covering 803 Medicare beneficiaries and totaling roughly $419K in drug spend, split 11% brand-name and 88% generic by claim count, with an opioid prescribing rate of 0.2%.
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 | 1225171754 |
|---|---|
| Specialty | Internal Medicine Physician |
| Credentials | MD |
| Gender | Female |
| NPI Issued | 02/15/2007 |
Hospital and facility affiliations
Facilities where Pei Sun, 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.
Pei Sun Md.llc
Wallingford, CT
Affiliations sourced from CMS Doctors and Clinicians National Downloadable File; hospital ratings from CMS Hospital General Information dataset (cross-referenced by facility name + state).
Industry payments received (2024) - CMS Open Payments transparency data
The federal Physician Payments Sunshine Act (part of the Affordable Care Act) requires drug and medical-device manufacturers + group purchasing organizations to publicly report payments and other transfers of value to physicians and teaching hospitals. The data below covers 2024 for Pei Sun, MD. Source: openpaymentsdata.cms.gov.
Total received
$55
Largest payer
Exact Sciences Corporation
Most common payment type
Food and Beverage
Industry payments are not necessarily indicators of bias, they include research funding, consulting fees for evidence-based work, royalties for inventions, food at conferences, and similar items. The disclosure exists for transparency. Read our methodology for how we interpret this data.
Brand vs generic prescribing mix · Typical
Pei Sun, MD - brand share 11.0%
Internal Medicine Physician average
11% brand-name claims vs 88% generic, on 5,491 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.
5,491
Total Claims
$419K
Total Drug Cost
803
Medicare Beneficiaries
Prescribing Breakdown
- 30-Day Fills
- 12,995
- Total Day Supply
- 382,451
- Brand vs Generic
- 11% brand / 88% generic
- Brand Drug Cost
- $310K
- Generic Drug Cost
- $107K
- Opioid Claims
- 13 (0.2% rate)
- Antibiotic Claims
- 139
Patient Demographics
- Average Patient Age
- 74.3 years
- Avg HCC Risk Score
- 0.94
- Gender Split
- 64% female / 36% male
- Age Distribution
- <65: 53, 65-74: 380, 75-84: 264, 85+: 106
Top Prescribed Drugs (Medicare Part D)
Top drugs by claim count for calendar year 2023. Based on Medicare Part D data only.
What Pei Sun, MD prescribes most
Top Medicare Part D drugs by claim count, 2023
- Amlodipine Besylate
Amlodipine Besylate
340 claims
- Levothyroxine Sodium
Levothyroxine Sodium
285 claims
- Atorvastatin Calcium
Atorvastatin Calcium
260 claims
- Rosuvastatin Calcium
Rosuvastatin Calcium
217 claims
- Metformin Hcl
Metformin Hcl
197 claims
- Lisinopril
Lisinopril
171 claims
- Losartan Potassium
Losartan Potassium
170 claims
- Simvastatin
Simvastatin
145 claims
| Drug | Claims |
|---|---|
| Amlodipine Besylate | 340 |
| Levothyroxine Sodium | 285 |
| Atorvastatin Calcium | 260 |
| Rosuvastatin Calcium | 217 |
| Metformin Hcl | 197 |
| Lisinopril | 171 |
| Losartan Potassium | 170 |
| Simvastatin | 145 |
| Gabapentin | 143 |
| Pantoprazole Sodium | 135 |
* 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 Pei Sun, 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
Pei Sun, MD's 5,491 claims are above the specialty average of 2,716.
Nearby Internal Medicine Physician Providers in Connecticut
Other clinicians with the same primary specialty enrolled in Connecticut, drawn from the same CMS NPPES roster as Sun.
Christina Abavana
Bridgeport, CT
Dr. Hoda Abdel Salam
M.D.
New Britain, CT
Dr. Gada Abdelhafiz
MD
New London, CT
Dr. Mahmoud Abdelrahman
MD
Bridgeport, CT
Dr. Safiyya Abdulkadir
MD
Norwalk, CT
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 Connecticut 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 Pei Sun, MD's specialty? ▼
Pei Sun, MD specializes in Internal Medicine Physician and practices in Wallingford, Connecticut. Credentials: MD.
How much does Pei Sun, MD prescribe under Medicare Part D? ▼
In 2023, Pei Sun, MD wrote 5,491 Medicare Part D claims totaling $419K in drug costs for 803 beneficiaries.
Where is Pei Sun, MD located? ▼
Pei Sun, MD is located at 850 N MAIN STREET EXT, Wallingford, CT, 06492. Phone: (203) 269-4353.
What is Pei Sun, MD's NPI number? ▼
Pei Sun, MD's National Provider Identifier (NPI) is 1225171754, issued on 02/15/2007.
Does Pei Sun, MD prescribe more brand-name or generic drugs? ▼
Pei Sun, MD's prescribing is 11% brand-name and 88% generic drugs by claim count, with $310K in brand drug costs.
Does Pei Sun, MD prescribe opioids? ▼
Yes, Pei Sun, MD had 13 opioid claims in 2023 with an opioid prescribing rate of 0.2%.
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 Pei Sun, MD prescribe most often? ▼
Based on 2023 Medicare Part D data, Pei Sun, MD's most frequently prescribed drugs include Amlodipine Besylate, Levothyroxine Sodium, Atorvastatin Calcium. This reflects Medicare Part D prescriptions only and does not include commercial insurance or other payer types.
Does Pei Sun, MD accept Medicare? ▼
Pei Sun, MD appears in CMS Medicare data with 5,491 Part D claims and 803 Medicare beneficiaries in 2023. Contact the provider's office directly to confirm current Medicare enrollment and accepted plans.
How can I verify Pei Sun, MD's credentials? ▼
Pei Sun, MD's NPI is 1225171754 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.
- 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.