NICE vs SIGN: Management of Type 1 Diabetes in Adults (2025) - A Clinical Comparison
This guide provides a detailed, factual comparison of the National Institute for Health and Care Excellence (NICE) NG17 (updated 2022, with 2025 amendments under review) and the Scottish Intercollegiate Guidelines Network (SIGN) 154 (2024) guidelines for the management of type 1 diabetes in adults. It is designed to help UK clinicians understand the nuances, similarities, and key differences between these two authoritative sources to inform their practice.
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Diagnosis and Initial Assessment
NICE NG17
NICE provides a comprehensive pathway for diagnosis, strongly emphasising the use of laboratory tests (plasma glucose, HbA1c) to confirm hyperglycaemia. A key feature is the recommendation to measure diabetes-specific autoantibodies (e.g., islet cell, GAD, IA-2, ZnT8) to confirm a diagnosis of type 1 diabetes in adults where there is clinical uncertainty, particularly to distinguish from type 2 or monogenic diabetes. This is a significant step towards precision in diagnosis.
- Key Tests: Laboratory glucose, HbA1c, autoantibodies (if doubt exists), C-peptide (if doubt persists).
- Initial Assessment: A full assessment of physical and psychological health, complications risk, and education needs is mandated at diagnosis.
SIGN 154
SIGN aligns with NICE on the core diagnostic criteria but presents its recommendations with a slightly different emphasis. While it acknowledges the role of autoantibodies, its guidance is more focused on the clinical presentation (e.g., rapid symptom onset, ketosis) as the primary indicator. The measurement of C-peptide is highlighted as a practical tool to assess endogenous insulin secretion, especially in cases where the classification is unclear after initial presentation.
- Key Tests: Laboratory glucose, HbA1c. C-peptide is prominently recommended for diagnostic clarification.
- Initial Assessment: Similar holistic assessment, with a strong focus on immediately connecting the individual with a specialist multidisciplinary team.
Key Difference & Practical Takeaway
Diagnostic Certainty: NICE more actively promotes the use of autoantibody testing to definitively classify type 1 diabetes at diagnosis. SIGN, while not contradictory, places greater immediate emphasis on clinical presentation and C-peptide. The practical takeaway is that in England and Wales, autoantibody testing may be more readily utilised, whereas in Scotland, C-peptide might be the first-line test in ambiguous cases. Both are valid approaches to reduce diagnostic misclassification.
Glycaemic Management and Technology
NICE NG17
NICE is highly technology-focused, with clear, sequential criteria for accessing advanced diabetes technologies. Its guidance on insulin pumps (CSII) and continuous glucose monitoring (CGM) is detailed and structured.
- HbA1c Target: < 48 mmol/mol (6.5%) for most adults, but individualise based on patient factors (e.g., risk of hypoglycaemia).
- Flash Glucose Monitoring (Flash GM): Recommended as an option for all adults with type 1 diabetes.
- Real-time CGM (rtCGM): Recommended if the person has frequent severe hypoglycaemia, impaired hypoglycaemia awareness, or if HbA1c is > 75 mmol/mol (9%) despite insulin therapy.
- Insulin Pumps (CSII): Consider if MDI therapy fails to achieve HbA1c < 69 mmol/mol (8.5%) or disabling hypoglycaemia occurs, following a structured education programme.
SIGN 154
SIGN's recommendations are broadly similar but are often expressed with a focus on clinical need rather than strict HbA1c thresholds. It strongly advocates for the use of technology to improve quality of life and reduce hypoglycaemia.
- HbA1c Target: < 53 mmol/mol (7.0%) for many adults, emphasising individualisation and the avoidance of hypoglycaemia.
- Glucose Monitoring: Recommends that all adults should be offered CGM or Flash GM. The distinction between the two technologies is less hierarchical than in NICE, focusing more on patient choice and appropriateness.
- Insulin Pumps (CSII): Recommended for individuals who are unable to achieve target glycaemic control or who experience problematic hypoglycaemia on MDI therapy.
Key Difference & Practical Takeaway
Technology Access and HbA1c Targets: The most notable difference lies in the HbA1c target (NICE <48 mmol/mol vs SIGN <53 mmol/mol for many), which reflects a slightly different risk-benefit balance. Furthermore, while both endorse technology, NICE provides a more tiered and criteria-based access pathway for rtCGM and pumps, often linked to specific HbA1c levels or clinical events. SIGN's approach is more universally supportive of offering CGM/Flash GM to all and bases pump eligibility more squarely on clinical need. The practical takeaway is that the threshold for initiating advanced technologies may be perceived as lower in Scotland based on SIGN guidance.
Special Situations
Driving
Both guidelines reference the Driver and Vehicle Licensing Agency (DVLA) standards. NICE includes a specific recommendation to advise people to check blood glucose before driving and every 2 hours during long journeys. SIGN reinforces the legal requirements but integrates the advice within broader safety and education discussions.
Pregnancy
Both guidelines defer to specific antenatal diabetes management guidelines. NICE Signpost to its own NG3 (Diabetes in pregnancy) guideline. SIGN 154 provides more detailed interim advice within the type 1 diabetes document itself, emphasising the need for preconception counselling and tight glycaemic targets (HbA1c < 48 mmol/mol) before conception and during pregnancy, closely aligning with NICE NG3.
Hospital Inpatient Management
This is a major area of difference. NICE has a dedicated guideline (NG18) for diabetes in adults in hospital, which recommends Variable Rate Intravenous Insulin Infusion (VRIII) for most inpatients, with clear protocols. SIGN 154 incorporates inpatient advice directly, strongly advocating for the continuation of the patient's home insulin regimen (especially pumps) where possible, to avoid the risks associated with VRIII. This is a more patient-centred and pragmatic approach for stable inpatients.
Key Difference & Practical Takeaway
Inpatient Management Philosophy: The significant difference is in the approach to hospital care. NICE is more protocol-driven (default to VRIII), while SIGN is more flexible, encouraging the continuation of basal-bolus or pump therapy for clinically stable patients. The practical takeaway for clinicians in England and Wales is to consult NG18 for inpatient care, whereas in Scotland, SIGN 154 provides the direct framework, potentially supporting greater use of patient's own technology during hospital stays.
Practical Clinical Flow: From Diagnosis to Ongoing Management
1. Diagnosis & Referral: Suspect type 1 diabetes → Confirm with lab glucose/HbA1c → Immediate referral to multidisciplinary specialist team. (NICE: Consider autoantibodies; SIGN: Consider C-peptide if unclear).
2. Initial Education & Insulin Start: Provide structured education (e.g., DAFNE, BERTIE) alongside initiation of a basal-bolus insulin regimen.
3. Technology Assessment (at diagnosis and annually): Offer Flash GM to all (per NICE/SIGN). Assess need for rtCGM or pump therapy based on guidelines:
- NICE-focused pathway: Check for severe hypoglycaemia, impaired awareness, or high HbA1c (>75 mmol/mol) for rtCGM; check for failure to achieve HbA1c <69 mmol/mol on MDI for pump.
- SIGN-focused pathway: Offer CGM/Flash GM to all. Consider pump therapy for any significant clinical need related to glycaemic control or hypoglycaemia.
4. Ongoing Review: Annual review for complications (eyes, feet, kidneys, cardiovascular risk). Individualise HbA1c target (NICE: aim for <48 mmol/mol; SIGN: aim for <53 mmol/mol for many), prioritising hypoglycaemia avoidance.
Frequently Asked Questions (FAQs)
1. Which guideline should I follow if I practice in Wales or Northern Ireland?
NICE guidelines are the standard for England and Wales. Northern Ireland typically adopts NICE guidelines, though local health trusts may provide specific adaptations. For practice in Scotland, SIGN is the standard.
2. The HbA1c targets differ. Which one is correct?
Both are correct within their context. The more intensive NICE target (<48 mmol/mol) is based on long-term microvascular benefit but requires careful management to avoid hypoglycaemia. The SIGN target (<53 mmol/mol for many) reflects a slightly greater emphasis on safety and individualisation. The key principle from both is to agree on an individualised target with the patient.
3. Does SIGN recommend insulin pumps more freely than NICE?
Not necessarily "more freely," but based on slightly different criteria. SIGN focuses on "failure to achieve target control" or "problematic hypoglycaemia," which can be interpreted more broadly than NICE's specific HbA1c threshold of <69 mmol/mol for pump consideration. The clinical assessment of "problematic hypoglycaemia" is central to the SIGN approach.
4. A patient is on a pump and is admitted to my hospital in Scotland. Can they continue it?
Yes, SIGN 154 actively supports this where the patient is competent, the diabetes team is familiar with pump therapy, and the patient is clinically stable (e.g., not peri-operative or critically ill). Local hospital policies should be developed to facilitate this.
5. Are there cost implications behind the technological differences?
Both guidelines are developed with cost-effectiveness in mind. The differences likely stem from varying interpretations of clinical trial evidence and health economic modelling by the respective committees, rather than explicit budgetary constraints. The overarching goal of both is to improve outcomes and quality of life.
Source Links
- NICE NG17 (Type 1 diabetes in adults: diagnosis and management): [https://www.nice.org.uk/guidance/ng17]
- SIGN 154 (Management of Diabetes: A national clinical guideline): [https://www.sign.ac.uk/media/1091/sign-154-management-of-diabetes.pdf]
- NICE NG18 (Diabetes in adults): [https://www.nice.org.uk/guidance/ng18] (For inpatient management in England/Wales).
- DVLA Medical Guidance (Diabetes): [https://www.gov.uk/diabetes-driving]