2026 NPPES data Endocrinology, Diabetes & Metabolism Physician NPI 1639290083 MD
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JANET LO, MD

Endocrinology, Diabetes & Metabolism Physician in BOSTON, Massachusetts. CMS National Plan and Provider Enumeration System profile including specialty classification, practice address, and Medicare prescribing data when reported.

Federal data — no proprietary rating. PlainDoctor publishes the actual CMS NPPES and Medicare records — NPI registration, specialty, practice location, and prescribing data — without a composite score or editorial opinion on top. Every field traces to a federal source.
Prescribing volume
464
Medicare Part D claims · 97 beneficiaries · Endocrinology, Diabetes & Metabolism Physician avg: 3K
Generic prescribing
58%
generic claims · 42% brand-name · higher generic rates reduce patient out-of-pocket costs

What the federal data shows

JANET LO, MD filed 464 Medicare Part D claims in 2023 as a Endocrinology, Diabetes & Metabolism Physician in BOSTON, Massachusetts, prescribing 58% generic.

464
Part D claims, 2023
58%
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.

JANET LO, MD's Medicare Part D volume vs every U.S. prescriber

Total Medicare Part D claims, 2023 — across all CMS prescribers nationally

464 Top 38% higher than 62% of 1,370,886 prescribers

0–200: 670,926 prescribers (49%). Below this entry. 200–400: 182,923 prescribers (13%). Below this entry. 400–600: 90,619 prescribers (7%). This entry sits in this band. 600–800: 56,224 prescribers (4%). Above this entry. 800–1,000: 40,919 prescribers (3%). Above this entry. 1,000–1,200: 31,827 prescribers (2%). Above this entry. 1,200–1,400: 26,224 prescribers (2%). Above this entry. 1,400–1,600: 21,710 prescribers (2%). Above this entry. 1,600–1,800: 19,072 prescribers (1%). Above this entry. 1,800–2,000: 16,451 prescribers (1%). Above this entry. 2,000–2,200: 213,991 prescribers (16%). Above this entry. This provider 0 2K+ every Part D prescriber (claims/yr), bucketed by value

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)

JANET LO, MD practices in an ABMS-board-eligible specialty and shows active CMS Medicare participation + 2 hospital affiliations — 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 JANET LO, MD?

Quality data not reported

NPI registry status

Active

Issued 04/03/2007

NPI 1639290083

Primary specialty

Endocrinology, Diabetes & Metabolism Physician

Mid-sized

7,852 US NPIs in this specialty

Medicare Part D claims

464 82% vs specialty avg

2023 prescription claims

Specialty avg: 2,639

Specialty distribution in Massachusetts

How Endocrinology, Diabetes & Metabolism Physician compares to other specialties among Massachusetts providers

Massachusetts providers

Endocrinology, Diabetes & Metabolism Physician share within Massachusetts

1. Endocrinology, Diabetes & Metabolism Physician42%2. Internal medicine21%3. Family medicine17%4. Surgical12%5. Pediatric8%
Endocrinology, Diabetes & Metabolism Physician share within Massachusetts

Specialty board-certification context

Estimated specialty board-certified rate — Endocrinology, Diabetes & Metabolism Physician (ABMS / AOA reference)

Quality data not reported
Est. board-certified rate
78%
Endocrinology, Diabetes & Metabolism Physician ABMS/AOA estimate

Est. board-certified rate (Endocrinology, Diabetes & Metabolism Physician) — ABMS / AOA estimate

0%100%78%
Est. board-certified rate (Endocrinology, Diabetes & Metabolism Physician) — ABMS / AOA estimate

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).

JANET LO, MD appears in the CMS NPPES registry as a Endocrinology, Diabetes & Metabolism Physician provider holding MD credentials at MASSACHUSETTS GENERAL HOSPITAL, BOSTON, MA, 02114, with a listed phone of (617) 724-9109. NPI 1639290083 was issued on 04/03/2007. Because NPPES data is self-reported by the provider and refreshed monthly, the address, phone, and specialty reflect what LO most recently submitted to CMS rather than a vetted directory listing, which is why patients should always confirm the practice is still at this location before scheduling.

Medicare Part D records for calendar year 2023 show 464 prescription claims written by this provider, covering 97 Medicare beneficiaries and totaling roughly $280K in drug spend, split 42% brand-name and 58% generic by claim count. These figures capture only Medicare Part D — commercial insurance, Medicaid, and cash-pay prescriptions are not included, and any drug-beneficiary cell under 11 is suppressed by CMS for patient privacy.

Endocrinology, Diabetes & Metabolism Physician is a mid-sized specialty nationwide, with 7,852 enrolled providers across 54 states and an average of 2,639 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

MASSACHUSETTS GENERAL HOSPITAL
BOSTON, MA 02114

Provider Details

NPI 1639290083
Specialty Endocrinology, Diabetes & Metabolism Physician
Credentials MD
Gender Female
NPI Issued 04/03/2007

Hospital and facility affiliations

Facilities where JANET LO, 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.

MASSACHUSETTS GENERAL PHYSICIANS ORGANIZATION INC
BOSTON, MA
THE GENERAL HOSPITAL CORPORATION
BOSTON, MA

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 — Massachusetts BORIM 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 ~38K Massachusetts medical licensees in 2023 — they are NOT specific to JANET LO, MD. To verify JANET LO, MD's current license status, search the BORIM public license lookup directly, or check the Federation of State Medical Boards (FSMB) verification service.

80
Total board actions, Massachusetts 2023
Across 78 cases
2.11
Actions per 1,000 licensees
Massachusetts statewide rate
probation
Most common action type
29 cases

BORIM 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 Massachusetts disciplinary trends page. Cross-checked against FSMB U.S. Medical Regulatory Trends.

Brand vs generic prescribing mix · Above average

JANET LO, MD — brand share 42.0%
Specialty average (est.)

42% brand-name claims vs 58% generic, on 464 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.

464
Total Claims
$280K
Total Drug Cost
97
Medicare Beneficiaries

Prescribing Breakdown

30-Day Fills
1,088
Total Day Supply
32,513
Brand vs Generic
42% brand / 58% generic
Brand Drug Cost
$262K
Generic Drug Cost
$18K

Patient Demographics

Average Patient Age
71.2 years
Avg HCC Risk Score
1.35
Gender Split
52% female / 48% male

Top Prescribed Drugs (Medicare Part D)

Top drugs by claim count for calendar year 2023. Based on Medicare Part D data only.

What JANET LO, MD prescribes most

Top Medicare Part D drugs by claim count, 2023

claims
Source CMS Medicare Part D Prescriber Public Use File As of 2023
Drug Claims
Praluent Pen
Alirocumab
100
Levothyroxine Sodium
49
Ezetimibe
36
Repatha Sureclick
Evolocumab
35
Atorvastatin Calcium
29
Rosuvastatin Calcium
29
Livalo
Pitavastatin Calcium
21
Prednisone
21
Testosterone
21
Metformin Hcl
16

* Counts below 11 are suppressed by CMS for patient privacy. Generic names shown where available from CMS Part D data.

Endocrinology, Diabetes & Metabolism Physician Overview

How JANET LO, MD fits within the Endocrinology, Diabetes & Metabolism Physician landscape nationally.

7,852
Endocrinology, Diabetes & Metabolism Physician Providers in US
54
States with Endocrinology, Diabetes & Metabolism Physician
2,639
Avg Claims per Provider

JANET LO, MD's 464 claims are below the specialty average of 2,639.

Nearby Endocrinology, Diabetes & Metabolism Physician Providers in Massachusetts

Other clinicians with the same primary specialty enrolled in Massachusetts, drawn from the same CMS NPPES roster as LO.

Compare Endocrinology, Diabetes & Metabolism Physician nationally: see state-by-state distribution →

Frequently Asked Questions

What is JANET LO, MD's specialty?
JANET LO, MD specializes in Endocrinology, Diabetes & Metabolism Physician and practices in BOSTON, Massachusetts. Credentials: MD.
How much does JANET LO, MD prescribe under Medicare Part D?
In 2023, JANET LO, MD wrote 464 Medicare Part D claims totaling $280K in drug costs for 97 beneficiaries.
Where is JANET LO, MD located?
JANET LO, MD is located at MASSACHUSETTS GENERAL HOSPITAL, BOSTON, MA, 02114. Phone: (617) 724-9109.
What is JANET LO, MD's NPI number?
JANET LO, MD's National Provider Identifier (NPI) is 1639290083, issued on 04/03/2007.
Does JANET LO, MD prescribe more brand-name or generic drugs?
JANET LO, MD's prescribing is 42% brand-name and 58% generic drugs by claim count, with $262K in brand drug costs.
How many Endocrinology, Diabetes & Metabolism Physician providers are there in the US?
There are 7,852 Endocrinology, Diabetes & Metabolism Physician providers across 54 states in the US. The average Endocrinology, Diabetes & Metabolism Physician provider writes 2,639 Medicare Part D claims per year.
What drugs does JANET LO, MD prescribe most often?
Based on 2023 Medicare Part D data, JANET LO, MD's most frequently prescribed drugs include Praluent Pen, Levothyroxine Sodium, Ezetimibe. This reflects Medicare Part D prescriptions only and does not include commercial insurance or other payer types.
Does JANET LO, MD accept Medicare?
JANET LO, MD appears in CMS Medicare data with 464 Part D claims and 97 Medicare beneficiaries in 2023. Contact the provider's office directly to confirm current Medicare enrollment and accepted plans.
How can I verify JANET LO, MD's credentials?
JANET LO, MD's NPI is 1639290083 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

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