GPAtlas🧭 When to suspect (and when to screen)
Non-diabetic hyperglycaemia (NDH) – commonly called prediabetes, and historically impaired fasting glucose or impaired glucose tolerance – is a blood glucose above normal but below the diabetic range.
NICE PH38 defines it as either:
• A glycated haemoglobin (HbA1c) of 42–47 mmol/mol (6.0–6.4%).
• A fasting plasma glucose (FPG) of 5.5–6.9 mmol/L.
NDH is usually asymptomatic, found incidentally or through structured risk screening.
NDH matters for two reasons:
• It carries a high risk of progression to type 2 diabetes mellitus (T2DM).
• It is a marker of raised cardiovascular disease (CVD) risk.
NDH is also often reversible. In primary care:
• Confirm the band.
• Refer to structured lifestyle support.
• Manage the whole cardiovascular risk.
• Recognise when the result has actually crossed into diabetes.
| HbA1c | Classification | Action |
|---|---|---|
| < 42 mmol/mol (< 6.0%) | Normal | • Lifestyle advice • Reassess by risk (low risk 5-yearly, moderate 3-yearly) |
| 42–47 mmol/mol (6.0–6.4%) | Non-diabetic hyperglycaemia (high risk) | • Refer to the NHS Diabetes Prevention Programme • Annual HbA1c + weight check |
| 44–47 mmol/mol (6.2–6.4%) or FPG 6.5–6.9 | Highest-risk subgroup | Prioritise for the intensive lifestyle programme where places are limited |
| ≥ 48 mmol/mol (≥ 6.5%) | Diabetes range | • Asymptomatic → repeat to confirm • Symptomatic → diagnose now • Manage as T2DM (NG28) |
Raise suspicion and offer a blood test in those with risk factors:
• Overweight or obesity (body mass index [BMI] ≥ 25, or ≥ 23 if South Asian or Chinese) and central adiposity.
• Physical inactivity.
• Age ≥ 40 (or ≥ 25 in South Asian, Chinese, African-Caribbean and black African groups).
• A first-degree family history of T2DM.
• Previous gestational diabetes mellitus (GDM).
• Polycystic ovary syndrome (PCOS).
• Hypertension or established CVD.
• Metabolic dysfunction-associated steatotic liver disease (MASLD, formerly non-alcoholic fatty liver disease [NAFLD]).
• Treatment with antipsychotics.
Use a validated tool (e.g. the Diabetes UK Know Your Risk score) to direct who to test.
|
🧠 Clinical pearl • Read the result, not just the band. • A single asymptomatic HbA1c of ≥ 48 mmol/mol is not a diabetes diagnosis – it must be repeated before labelling. • The same ≥ 48 with osmotic symptoms (thirst, polyuria, weight loss) is diabetes: diagnose and act on the single result, do not wait for a repeat. |
Source: NICE PH38 · NHS Diabetes Prevention Programme
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