Understanding DM01

Making sense of NHS diagnostic waiting time reporting 

In the world of NHS performance targets, TLAs rule the roost — RTTs, PTLs, EPRs… the list goes on. But there’s one acronym that often flies under the radar, despite being key to keeping patient flow moving and diagnostics on track: DM01.

Not sure what it means? You’re not alone.

But whether you’re trying to clear a backlog, hit your performance KPIs, or just figure out where all your patients have gone — DM01 could be the key to unlocking it all.

What is DM01?

Well firstly, it stands for Diagnostics Waiting Times and Activity.

DM01 is a national NHS data collection that tracks:

1. How many patients are waiting for key diagnostic tests

2. How many diagnostic procedures are being carried out each month

It applies to 15 core test types, including:

• MRI and CT scans

• Endoscopy (e.g. colonoscopy, gastroscopy)

• Ultrasound and DEXA scans

• Sleep studies, audiology, echocardiography and more

This data is reported by NHS diagnostic service providers, and is used by local and national decision-makers to monitor performance, manage resources, and forecast demand.

Why is DM01 so important?

Although it might sound like a technical return, DM01 is a critical indicator of system health. It impacts:

Patient Outcomes: Long diagnostic waits can delay life-saving treatment — particularly in cancer, cardiac, and respiratory pathways.

Performance Targets: RTT (Referral to Treatment) targets begin with diagnostics. Inaccurate or delayed DM01 data can distort RTT performance, risking missed targets and regulatory concern.

Operational and Capacity Planning: Commissioners and ICBs rely on DM01 to understand diagnostic pressure points and allocate funding and workforce accordingly.

Clinical Safety: When patients are not accurately recorded on waiting lists, their care may be delayed, duplicated or entirely missed — creating clinical and governance risks.

What’s New in 2025?

The 2025 updates to NHS England’s DM01 guidance introduce several important changes:

1. Community Diagnostic Centres (CDCs) Reported Separately

CDCs — facilities that provide diagnostics closer to home — are now reported separately from traditional NHS Trust data. While CDC activity is still counted, it doesn’t yet include formal waiting time reporting.

Why it matters:
Systems must now reconcile two streams of diagnostic activity — from acute settings and from CDCs — to get a full picture of capacity and waiting lists.

2. OPCS Codes Updated 

The procedure codes that underpin DM01 reporting have been revised to reflect clinical practice and new technologies.

Why it matters:
Trusts must ensure their coding systems are up to date, or they risk under-reporting activity and reducing the visibility of diagnostic demand.

3. Alignment with the Waiting List Minimum Data Set (WLMDS)

DM01 is now more closely aligned with WLMDS, a standard dataset for managing elective care waiting lists.

Why it matters:
This tighter integration improves visibility of patients moving between diagnostics and treatment — supporting a more joined-up approach to pathway management and improving RTT accuracy.

Why is DM01 Reporting So Challenging?

Getting DM01 data right is easier said than done. Here’s why:

• Diagnostic data is often scattered across departments, systems, and even providers (e.g. insourcing, CDCs).

• Much of the data is unstructured, living in scanned documents, letters, or untagged fields in the EPR.

• Definitions can be complex, especially around planned vs active waits, zero-day waits, and follow-up procedures.

• Manual processes persist, leading to variable practices and delayed updates.

• The ‘rules’ are different to RTT – patient choice and clock resets are treated differently, leading to variation in application and reporting

Together, these challenges mean that under-reporting or misreporting is common — which in turn can lead to performance dips, missed safety flags, and planning blind spots.

Whether you’re in a clinical, operational, or informatics role, DM01 affects your world.

In a system facing increasing demand, workforce constraints and pressure to deliver against performance metrics, robust diagnostics reporting isn’t a luxury — it’s a necessity.