Type 2 Diabetes — HbA1c Target-Setting and Intensification Triggers
Based on: Type 2 Diabetes in Adults: Management (NG28) — NICE (last updated February 2026)
Reference: https://www.nice.org.uk/guidance/ng28
PURPOSE
Use this skill at any structured diabetes review to answer three questions in sequence:
- What is the right HbA1c target for this individual?
- Is the current HbA1c result actionable — does it require intensification?
- How frequently should HbA1c be monitored going forward?
The skill applies the NICE NG28 Section 1.5 framework, which is built on the principle that
HbA1c targets must be individualised — agreed with the patient — rather than applied
universally.
STEP 1 — GATHER INFORMATION
Current glycaemic status
- Most recent HbA1c (mmol/mol), date of measurement, and method used (IFCC-calibrated?)
- Has an individualised HbA1c target previously been agreed with this patient?
- Frequency of recent HbA1c monitoring — is it in keeping with clinical need?
- Any unexplained discrepancy between HbA1c and self-monitored blood glucose readings
Current treatment
- Current glucose-lowering medicines: names, doses, duration
- Is the current regimen associated with hypoglycaemia risk? (Sulfonylureas and insulin are; metformin, SGLT-2 inhibitors, DPP-4 inhibitors, and GLP-1 receptor agonists generally are not)
- Recent adherence — has the person been taking medicines as prescribed?
- Recent diet and lifestyle changes
Factors relevant to target-setting
- Age and frailty status
- Hypoglycaemia awareness — is it intact or impaired?
- Risk of harm from hypoglycaemia: falls risk, driving or operating machinery, lives alone
- Comorbidities and life expectancy — is long-term risk reduction the primary goal?
- Quality of life impact of intensive management
- Patient preference and health literacy
Factors that invalidate HbA1c
- Conditions causing disturbed erythrocyte turnover: haemolytic anaemia, iron deficiency anaemia, haemoglobinopathy, recent blood transfusion, pregnancy
- If any are present, HbA1c is unreliable — alternative monitoring required (see Step 2)
STEP 2 — RULE IN / RULE OUT
Confirm HbA1c is a valid measure for this patient:
If any of the following apply, HbA1c monitoring is unreliable — do NOT use it to set or
assess targets. Use an alternative (see below):
- Haemolytic anaemia or other cause of shortened red cell survival
- Iron deficiency anaemia (falsely elevates HbA1c)
- Haemoglobin variant (e.g., HbS, HbC, HbE) — use total glycated haemoglobin if variant present
- Recent blood transfusion
- Pregnancy (refer to NICE NG3 — different monitoring and targets apply)
Alternatives if HbA1c is unreliable:
- Quality-controlled plasma glucose profiles
- Total glycated haemoglobin (if abnormal haemoglobin type present)
- Fructosamine estimation
Investigate unexplained discrepancies between HbA1c and glucose measurements — seek
specialist advice from diabetes or clinical biochemistry if the discrepancy cannot be explained.
Acute action triggers — do not use routine target-setting pathway if:
- Patient has symptoms of hyperglycaemia (polyuria, polydipsia, weight loss) → consider
insulin or sulfonylurea acutely (Section 1.8), review when stable
- Patient is acutely unwell → apply sick day rules first; defer routine target review until recovered
STEP 3 — CLASSIFY OR STRATIFY
Assign the patient to one of three target categories based on their current treatment and
clinical profile:
Category A — Standard target: 48 mmol/mol (6.5%)
Applies to: Adults managed by lifestyle alone, OR on medicines NOT associated with
hypoglycaemia risk (e.g., metformin, SGLT-2 inhibitor, DPP-4 inhibitor, GLP-1 receptor agonist,
tirzepatide).
Category B — Hypoglycaemia-risk target: 53 mmol/mol (7.0%)
Applies to: Adults on any medicine associated with hypoglycaemia (primarily sulfonylureas
and insulin-based regimens). The higher target reduces the risk of treatment-related hypoglycaemia.
Category C — Relaxed target (agreed individually — higher than 53 mmol/mol)
Applies to: Adults in whom tighter control would cause net harm or where intensive
management is not appropriate. Consider relaxation if ONE OR MORE of the following apply:
- Reduced life expectancy where long-term risk-reduction benefit is unlikely
- High risk of harm from hypoglycaemia: falls risk, impaired hypoglycaemia awareness, driving
or operating machinery as an occupational requirement
- Significant comorbidities making intensive management inappropriate
- Older or frailer adults (with particular — though not exclusive — consideration for this group)
Target in Category C is set by shared decision with the patient — there is no single number.
Document the agreed target and the clinical rationale.
STEP 4 — DECIDE
Setting the Target
| Category | Target | Condition |
|---|
| A | 48 mmol/mol (6.5%) | Lifestyle or non-hypoglycaemia-risk medicines |
| B | 53 mmol/mol (7.0%) | On sulfonylurea or insulin |
| C | Relaxed — agreed individually | Frailty, reduced life expectancy, high hypo risk, significant comorbidity |
If the patient is already below their agreed target without hypoglycaemia, encourage them
to maintain it — do not automatically increase their target.
If HbA1c is unexpectedly lower than the target without hypoglycaemia, consider other
explanations before celebrating: deteriorating renal function (reduces HbA1c artificially),
recent acute illness, or sudden weight loss.
Intensification Trigger
Act when HbA1c rises to ≥58 mmol/mol (7.5%) on the current regimen, regardless of
which category the patient is in (Category C patients may have a different agreed ceiling —
apply the individually agreed level for them).
When the intensification trigger is met, take all three steps together:
- Reinforce — revisit diet, lifestyle, and medicine adherence before adding a new drug
- Reset the target — support the person to aim for 53 mmol/mol (7.0%)
- Intensify medicines — proceed to the comorbidity-stratified further medicine framework
(NICE NG28 Sections 1.25–1.31; see the T2DM Comorbidity Medicine Selector skill)
Monitoring Frequency
| Clinical situation | HbA1c frequency |
|---|
| HbA1c not yet stable on current therapy | Every 3–6 months (tailored to individual need) |
| HbA1c stable on stable therapy | Every 6 months |
STEP 5 — CLINICAL GUARDRAILS
Common Mistakes
-
Using 53 mmol/mol as the universal target: The guideline specifies 48 mmol/mol (6.5%) for
patients not on hypoglycaemia-risk medicines. Defaulting to 53 for everyone leads to
systematic under-treatment of low-risk patients on metformin or SGLT-2 inhibitors alone.
-
Not documenting a shared decision on the target: Category C (relaxed target) is only valid
if it is explicitly agreed with the patient and recorded, with the clinical rationale stated.
An undocumented relaxed target is not clinically or medicolegally defensible.
-
Missing a false-low HbA1c: An HbA1c that is unexpectedly on or below target should
prompt consideration of: declining eGFR (reduced red cell lifespan), iron deficiency
anaemia (can falsely lower or raise depending on context), haemolytic anaemia, or recent
blood transfusion. Acting on a falsely reassuring result leads to under-treatment.
-
Skipping the intensification trigger check: If HbA1c is ≥58 mmol/mol (7.5%) and the
clinician only reinforces lifestyle without changing medicines, that is non-concordant with
the guideline. All three actions — reinforce, reset target, intensify — should be taken together.
-
Changing medicines without first checking adherence: Before intensifying, confirm the
patient is actually taking their existing medicines at the prescribed dose. Poor adherence
is a common and treatable cause of rising HbA1c that does not require a new prescription.
-
Not addressing quality of life when setting targets: The guideline explicitly requires
that if efforts to achieve the target, or adverse effects of treatment, impair quality of life,
the target should be reconsidered. This is a positive obligation — not an optional note.
Mimics and Measurement Traps
-
Haemoglobin variants: In populations with a high prevalence of sickle cell trait, thalassaemia, or other haemoglobin variants (common in South Asian, Black African, and Black Caribbean patients), HbA1c may be unreliable depending on the assay method used. If in doubt, check the assay type and consider fructosamine.
-
Rapidly falling HbA1c without clinical explanation: Consider: newly initiated SGLT-2
inhibitor or GLP-1 receptor agonist with unexpected efficacy; significant unintentional weight
loss (check for occult illness); remission following bariatric surgery; or worsening renal function.
-
Steroid-induced hyperglycaemia: HbA1c is not a reliable guide to glycaemic control in
patients on fluctuating corticosteroid doses — blood glucose profiles are more informative.
Do not apply standard T2DM HbA1c targets in this context.
What NOT To Do
- Do NOT use HbA1c as the primary monitoring tool in pregnancy — refer to NICE NG3
- Do NOT interpret a low HbA1c as automatically good news — investigate if unexplained
- Do NOT set or relax a target without involving the patient in a documented shared decision
- Do NOT defer intensification when the trigger is met — acting on all three steps together
(reinforce, reset, intensify) is the guideline standard
- Do NOT check HbA1c more frequently than every 3 months — it reflects 2–3 month average
glucose and more frequent testing does not add information
Special Populations
-
Older adults and frailty: The guideline singles out older and frailer adults as the group
in whom target relaxation most commonly applies, but relaxation is not automatic — it requires
individual assessment and a shared decision. HbA1c targets that are tight enough to cause
hypoglycaemia in a frail 80-year-old who falls are clinically harmful.
-
Drivers and occupational machinery operators: Hypoglycaemia risk from sulfonylureas
or insulin must be discussed explicitly. If a person's occupation places them or others at risk,
this is a specific indication for a higher (safer) HbA1c target and for structured self-monitoring.
-
CKD: As eGFR falls, erythrocyte lifespan shortens, and HbA1c may underestimate true
glycaemia. In advanced CKD, plasma glucose profiles or fructosamine may be more reliable.
-
Patients aiming for remission: Adults pursuing a very low calorie or dietary remission
programme (NHS Type 2 Diabetes Path to Remission) may achieve HbA1c below target —
support them to maintain it while reviewing medicines to avoid hypoglycaemia.
SOURCE
National Institute for Health and Care Excellence. Type 2 Diabetes in Adults: Management (NG28).
London: NICE; 2015, last updated February 2026.
Available from: https://www.nice.org.uk/guidance/ng28