Raised HbA1c or High Blood Glucose Algorithm

Safety

Red flags — DKA, HHS, new type 1 and the cancer flag

Done

Diabetic ketoacidosis Vomiting, abdominal pain, deep rapid (Kussmaul) breathing, drowsiness, ketotic breath → check capillary glucose and blood ketones now. Ketones ≥3.0 mmol/L (or urine ketones ≥2+) or clinically unwell → 999. Do not wait for glucose to be very high: on an SGLT2 inhibitor DKA can occur with near-normal glucose.

Hyperosmolar hyperglycaemic state (HHS) Usually an older person with type 2 diabetes: very high glucose (often >30 mmol/L), profound dehydration, confusion or drowsiness, without marked ketosis; mixed DKA/HHS occurs → 999.

Possible new type 1 diabetes Hyperglycaemia with weight loss, marked thirst and polyuria, ketones, rapid onset over weeks, younger age or low BMI — at any age or BMI → same-day diabetes-team assessment (blood ketones 1.6–2.9 mmol/L: same-day; ≥3.0 or vomiting/unwell: 999). Do not start metformin and review in 3 months.

Pancreatic cancer — NICE NG12 Aged 60 or over with new-onset diabetes and weight loss → urgent direct-access CT abdomen (within 2 weeks; ultrasound if CT unavailable) for pancreatic cancer. Also consider a pancreatic cause with steatorrhoea, jaundice or persistent upper abdominal or back pain.

Hyperglycaemia in pregnancy Pregnant, or planning pregnancy, with raised glucose → same-day discussion with the antenatal diabetes team; HbA1c is not used to diagnose gestational diabetes.

Active foot disease or sepsis New diabetes found with a hot, swollen foot, ulcer or spreading infection → same-day foot protection/MDT service; with systemic sepsis → 999.

A raised HbA1c in a well, overweight middle-aged adult is almost always type 2 diabetes, but the dangerous minority hide in the same result. DKA kills through dehydration, acidosis and potassium shifts, and ketones are measured, not guessed. The site's type 2 diabetes protocol stresses that up to 20% of DKA episodes occur in people later labelled type 2, and that classifying type 1 as type 2 and starting metformin can be fatal. NICE NG12 makes new diabetes with weight loss over 60 a trigger for urgent pancreatic imaging, because pancreatic cancer often presents first as diabetes.

Diagnose

Confirm the diagnosis — the numbers

Done

HbA1c ≥48 mmol/mol

Diagnostic of diabetes. Asymptomatic: repeat to confirm (a second HbA1c ≥48, ideally within 2 weeks). Symptomatic (thirst, polyuria, weight loss, recurrent infections): one result is enough.

HbA1c 42–47 mmol/mol

Non-diabetic hyperglycaemia (pre-diabetes) — high risk, not diabetes. Refer to the NHS Diabetes Prevention Programme and recheck HbA1c at least annually.

HbA1c <42

Normal; if symptoms persist or HbA1c may be unreliable, check fasting glucose.

Fasting plasma glucose

≥7.0 mmol/L diagnostic (confirm with a second result if asymptomatic); 5.5–6.9 = non-diabetic hyperglycaemia (NICE PH38); the WHO definition of impaired fasting glucose is 6.1–6.9.

Random plasma glucose

≥11.1 mmol/L diagnostic only with symptoms; if asymptomatic, confirm with HbA1c or fasting glucose. Capillary meter readings are not diagnostic.

When HbA1c is unreliable — use glucose

Symptoms for less than 2 months or rapid onset; suspected type 1 at any age; children; pregnancy (current or within 2 months postpartum); acute illness; drugs causing rapid rises (steroids, antipsychotics); acute pancreatic damage or surgery; anaemia (iron, B12 or folate deficiency — direction depends on cause), haemolysis, recent transfusion or blood loss, haemoglobinopathy; advanced CKD (especially on erythropoietin) and HIV treatment. Use venous plasma glucose and seek laboratory advice.

NICE NG28 and the WHO accept HbA1c 48 mmol/mol as diagnostic. Because the test has an analytical variation of a few mmol/mol, a single borderline result in an asymptomatic person must be repeated; in someone with classical symptoms one result is enough. HbA1c reflects the average glucose over the previous 8–12 weeks, so anything that changes red cell lifespan, or a glucose rise too recent to show, makes it misleading — which is why rapid onset, suspected type 1, pregnancy, haemoglobinopathy and anaemia need a glucose-based diagnosis. Results of 42–47 identify non-diabetic hyperglycaemia, a risk state for which the Diabetes Prevention Programme reduces progression.

Diagnose

History and examination — is it type 2?

Done

Symptoms and pace

Thirst, polyuria, nocturia, blurred vision, tiredness, recurrent thrush or skin infections, weight loss. Weeks rather than months, or rapid weight loss, points to insulin deficiency.

Type 1 / LADA clues

Weight loss, ketones, low or normal BMI, rapid deterioration, personal or family autoimmune disease (thyroid, coeliac, vitiligo, pernicious anaemia), poor response to tablets. LADA presents in adults and progresses to insulin need over months to years.

MODY clues

Diagnosis under about 25–30 years, non-obese, strong family history in two or more generations, no ketosis, antibody negative.

Pancreatic clues

Pancreatitis, alcohol excess, pancreatic surgery, cystic fibrosis, haemochromatosis; steatorrhoea, back or upper abdominal pain, jaundice, weight loss.

Drugs

Corticosteroids, antipsychotics (olanzapine, clozapine), thiazides at high dose, tacrolimus/ciclosporin, HIV protease inhibitors, statins (small rise).

Endocrine causes

Cushing's (proximal weakness, striae, bruising, central obesity, hypertension), acromegaly, phaeochromocytoma, hyperthyroidism; haemochromatosis (arthropathy, raised ferritin, liver disease, bronze skin).

Pregnancy and gestational history

Previous gestational diabetes; plans for pregnancy (needs pre-conception care).

Examination

Weight, BMI, waist, BP, hydration and mental state if unwell; feet (pulses, monofilament, ulcers); fundi or retinal screening referral; signs of Cushing's, acromegaly or haemochromatosis; acanthosis nigricans.

Type 2 diabetes is a diagnosis of exclusion after the history has been asked properly. The clues to insulin deficiency are weight loss, speed of onset and ketones, not age or BMI — type 1 and LADA occur in overweight adults. MODY matters because the right treatment is often a sulfonylurea rather than insulin, and it has genetic implications for the family. Secondary causes — pancreatic disease, steroids and other drugs, Cushing's and haemochromatosis — change management and in the case of pancreatic cancer are time-critical.

Diagnose

Investigations at diagnosis

Done

Today if symptomatic

Capillary glucose and blood ketones; urine dipstick for ketones, glucose, protein and infection.

Confirm and baseline

HbA1c (repeat if asymptomatic) or venous plasma glucose; U&E and eGFR (drug choice), urine ACR, lipids, LFTs (fatty liver), FBC; TSH, ECG where clinically indicated.

Cardiovascular risk

QRISK3 (≥10% → offer atorvastatin 20 mg; established CVD → atorvastatin 80 mg), BP, smoking status.

If type 1 or LADA suspected

Islet autoantibodies (usually GAD first) — but never delay same-day diabetes-team assessment or insulin waiting for results; C-peptide later if classification is still uncertain.

Secondary causes (targeted)

Ferritin and transferrin saturation (haemochromatosis); faecal elastase if steatorrhoea; overnight dexamethasone suppression test or late-night salivary cortisol if Cushing's suspected; MODY — diabetes team for genetic testing.

Pancreas (NG12)

Aged 60 or over with new diabetes and weight loss → urgent direct-access CT abdomen.

Eyes and feet

Refer to the NHS Diabetic Eye Screening Programme at diagnosis; foot risk assessment.

The investigation set does three jobs at once: confirms the diagnosis, tests for the alternatives that change treatment, and establishes the baseline for drug choice — kidney function gates both metformin and SGLT2 inhibitors. Ketones are checked on the day in anyone symptomatic because a normal glucose meter reading does not exclude ketoacidosis. Antibodies help confirm type 1 or LADA but are slow and imperfect, so the clinical picture drives same-day action.

Diagnose

Differential — classify the hyperglycaemia

Done

Type 2 diabetes (commonest)

Gradual, overweight or central adiposity, family history, South Asian or African-Caribbean heritage, metabolic syndrome, no ketosis.

Type 1 / LADA — Do not miss

Weight loss, ketones, rapid onset, autoimmunity; antibody positive. Same-day diabetes team.

Pancreatic (type 3c) — Do not miss

Pancreatitis, alcohol, surgery, haemochromatosis, cystic fibrosis — and pancreatic cancer (60+ with weight loss → urgent CT).

Drug-induced

Steroids (afternoon/evening hyperglycaemia; HbA1c may lag), antipsychotics, immunosuppressants. Often reversible.

Endocrine

Cushing's, acromegaly, phaeochromocytoma, hyperthyroidism.

MODY

Young, non-obese, autosomal dominant family history, antibody negative.

Stress hyperglycaemia

Raised glucose during acute illness, infection or surgery with a normal HbA1c — recheck HbA1c after 3 months.

Gestational diabetes

First found in pregnancy — antenatal pathway (NICE NG3).

Uncertain

Treat as possible type 1 if unwell or ketotic; otherwise discuss with the diabetes team before labelling.

Classifying correctly at the first consultation prevents the two classic harms — DKA in someone with insulin deficiency labelled as type 2, and a missed pancreatic cancer. Most people will turn out to have type 2 diabetes, but the label should be reviewed if the course is atypical: rapid failure of tablets, weight loss despite treatment, or ketosis.

Refer

Referral and urgency

Done

999

DKA (ketones ≥3.0 mmol/L or unwell with vomiting, abdominal pain, Kussmaul breathing, drowsiness) · HHS (very high glucose, dehydration, confusion) · sepsis or acute foot infection with systemic illness.

Same-day

Suspected type 1 diabetes or LADA with symptoms, weight loss or ketones (blood ketones 1.6–2.9 mmol/L) → diabetes team / acute medical take · hyperglycaemia in pregnancy → antenatal diabetes team · active foot disease → foot protection/MDT service.

Urgent direct-access CT

Aged 60 or over with new-onset diabetes and weight loss → urgent CT abdomen for pancreatic cancer (NICE NG12); jaundice → suspected cancer pathway referral.

Diabetes team — urgent

Severe symptomatic hyperglycaemia unresponsive to treatment; catabolic weight loss; possible LADA in a well patient.

Diabetes team — routine

Possible MODY (genetic testing), possible pancreatic diabetes, steroid-induced diabetes that is hard to manage, diagnostic doubt.

Endocrinology

Suspected Cushing's syndrome, acromegaly or phaeochromocytoma.

Everyone with diabetes

Structured education (DESMOND or local equivalent) within 3 months; NHS Diabetic Eye Screening Programme at diagnosis; dietitian if needed.

Non-diabetic hyperglycaemia

NHS Diabetes Prevention Programme (or Healthier You digital option).

The urgency ladder is driven by insulin deficiency and the cancer flag. DKA and HHS are 999 emergencies; possible new type 1 in a patient who is not yet in DKA needs same-day specialist input because deterioration can happen in hours. The NG12 pancreatic flag is a direct-access test, not a referral, and it is easily missed if the new diagnosis is treated reflexively with metformin.

Treat

Management at this consultation (type 2 diabetes)

Done

For confirmed type 2 diabetes in a well patient — NICE NG28 (updated February 2026): dual first-line for most people, matched to the site's type 2 diabetes protocol.

First-line for most (unless contraindicated)

Modified-release metformin

Usual adult dose: 500 mg once daily with food, increased weekly as tolerated to 1–2 g daily (maximum 2 g daily). Needs eGFR ≥30; review the dose below 45. Introduce first to check tolerability (NICE NG28; SPC).

Add once metformin tolerated

SGLT2 inhibitor

Usual adult dose: dapagliflozin 10 mg or empagliflozin 10 mg once daily — eGFR threshold depends on the drug and licence (check the SPC). Before starting: check for previous DKA, dehydration or volume depletion, and a very-low-carbohydrate or ketogenic diet; do not start while unwell; give MHRA ketone and sick-day advice with a restart plan. Avoid or use caution in frailty with risk of volume depletion; counsel on genital thrush. Metformin not tolerated → SGLT2 inhibitor alone (DPP-4 inhibitor if frailty makes an SGLT2i unsafe).

Established cardiovascular disease

Triple first-line

MR metformin + SGLT2 inhibitor + subcutaneous semaglutide up to 1 mg weekly (NICE NG28 2026) — usually started stepwise; see the protocol for titration. Heart failure → the SGLT2 inhibitor is the priority agent.

Very symptomatic but well, no ketones

Consider faster control

Markedly symptomatic type 2 diabetes with high glucose but no ketosis: consider a sulfonylurea (works within days) or insulin with diabetes-team advice, then rationalise. Any ketones or doubt about type → same-day diabetes team instead.

Steroid-induced hyperglycaemia

Monitor afternoon glucose

Check capillary glucose before the evening meal; a morning sulfonylurea (e.g. gliclazide) or insulin may be needed while on steroids — follow local/JBDS steroid guidance.

Non-diabetic hyperglycaemia (42–47)

No medication as routine

Diabetes Prevention Programme referral, lifestyle advice, annual HbA1c, cardiovascular risk assessment. Metformin is only considered if HbA1c keeps rising despite intensive lifestyle change (NICE PH38).

Agree a target

Usually HbA1c 48 mmol/mol on lifestyle ± a single drug not causing hypoglycaemia; 53 mmol/mol on drugs that can cause hypoglycaemia; relax for frailty, limited life expectancy or hypoglycaemia risk.

Alongside glucose

Atorvastatin 20 mg if QRISK3 ≥10% (80 mg if established CVD); BP target; ACEi/ARB if ACR ≥3 mg/mmol; stop smoking; foot and eye screening.

Driving and work

Advise on hypoglycaemia and DVLA rules if a sulfonylurea or insulin is started; tablets alone usually need no DVLA notification for car drivers.

Next steps: see Type 2 diabetes · Type 1 diabetes · DKA · Sick day rules

In February 2026 NICE NG28 changed first-line treatment: metformin monotherapy is no longer the default, and most people needing medication are offered modified-release metformin with an SGLT2 inhibitor, introduced stepwise. The site's type 2 diabetes protocol follows this, so the algorithm does too. The SGLT2 inhibitor brings cardiorenal protection but a small risk of euglycaemic DKA, which is why the pre-initiation DKA check and sick-day advice are part of the prescription. Established cardiovascular disease moves a GLP-1 receptor agonist into first-line. The detailed ladder, phenotype branches and monitoring stay on the protocol.

Lifestyle

Structured education and self-care

Done

Structured education Offer DESMOND or a local equivalent to everyone within 3 months of diagnosis (NICE NG28); DAFNE for type 1. Record the offer.

Diet and weight Individualised dietary advice; weight loss of 5–10% improves HbA1c, and greater loss can bring remission (NHS low-calorie diet programme where eligible).

Activity At least 150 minutes a week of moderate activity plus strength work twice a week; break up sitting time.

Smoking and alcohol Stop smoking; keep alcohol within 14 units a week and avoid on an empty stomach if on a sulfonylurea or insulin.

Sick-day rules On an SGLT2 inhibitor or metformin: pause during vomiting, diarrhoea or poor intake and restart when eating and drinking normally for 24–48 hours.

Feet and eyes Check feet daily; attend eye screening; report foot wounds the same day.

Emotional health A new diagnosis can be distressing — ask, and signpost Diabetes UK and peer support.

Lifestyle and education are treatments in their own right. Structured education within 3 months improves HbA1c and self-management, and weight loss can produce remission in some people with recent type 2 diabetes. The sick-day message belongs at the first prescription because SGLT2 inhibitors and metformin are among the drugs paused during dehydrating illness.

Safety

Follow-up and safety-netting

Done

Repeat tests

Asymptomatic HbA1c ≥48 → repeat to confirm before labelling. Non-diabetic hyperglycaemia → annual HbA1c. Stress hyperglycaemia → HbA1c 3 months after recovery.

Early review

Review metformin tolerability once titrated, before adding the SGLT2 inhibitor; HbA1c at 3 months; U&E after starting if renal function is borderline.

Results to chase

Antibodies, CT abdomen, ferritin, ACR, eye screening invitation.

Rethink the type

Rapid failure of tablets, ongoing weight loss, or ketones at any point → reconsider type 1/LADA or pancreatic disease.

Remote consultations

Telephone, video or online consultation with any 999 feature → convert to a 999 call, not a later appointment; if examination is needed to decide, see the patient the same day.

SCA safety-net wording

"If you start vomiting, get tummy pain, very fast or deep breathing, or become drowsy or confused, call 999 — on the 'flozin' tablet this can happen even when your sugar isn't very high. If you are very thirsty, passing lots of urine and losing weight, or you can't keep fluids down, contact us the same day; stop the flozin and metformin until you are eating and drinking again. A new sore or redness on your foot — call us the same day."

Audit checklist

Diagnosis confirmed correctly · type considered (type 1, LADA, pancreatic, drugs) · NG12 pancreatic flag checked if 60+ · ketones checked if symptomatic · DKA check before SGLT2i · education, eye screening and DPP referrals made · safety-net documented.

The safety-net covers the two emergencies that can follow a new diagnosis — DKA (including euglycaemic DKA on an SGLT2 inhibitor) and an evolving type 1 picture — and the foot. A diagnosis is not fixed: if the course does not fit type 2 diabetes the label should be revisited, because LADA and pancreatic diabetes often reveal themselves only over months.