Type 2 diabetes is one of the most examined chronic conditions in UK medicine, and its drug treatment has shifted decisively towards protecting the heart and kidneys rather than chasing glucose alone. This guide covers type 2 diabetes as examiners frame them, to the current NICE standard (NG28, with a significant 2026 update). Follow current guidance and local protocols in practice; this reflects guidance as of mid-2026.
What type 2 diabetes is
Type 2 diabetes is a chronic metabolic disorder of insulin resistance with progressive beta-cell dysfunction, leading to hyperglycaemia. It is strongly associated with obesity, physical inactivity and a genetic predisposition, and it drives both microvascular complications (retinopathy, nephropathy, neuropathy) and macrovascular disease (coronary disease, stroke, peripheral arterial disease). The exam focus is increasingly on the cardiovascular and renal stakes, not just the blood sugar. Many people are diagnosed incidentally on screening or are asymptomatic, while others present with thirst, polyuria, fatigue, recurrent infections or blurred vision, and a small number present acutely with a hyperosmolar hyperglycaemic state. Distinguishing type 2 from type 1 matters: type 1 tends to present younger, leaner and more acutely with ketosis, and where the distinction is unclear, antibody and C-peptide testing helps.
Diagnosis
Diagnosis rests on demonstrating hyperglycaemia. In an asymptomatic person, two abnormal results are needed; in a symptomatic person, one suffices. The thresholds are an HbA1c of 48 mmol/mol (6.5%) or above, a fasting plasma glucose of 7.0 mmol/L or above, or a random or two-hour glucose of 11.1 mmol/L or above. HbA1c is unreliable in certain situations — pregnancy, recent acute illness, haemoglobinopathies, and rapid-onset diabetes — where glucose-based testing is used instead. A single abnormal HbA1c in an asymptomatic person should be repeated to confirm, and an HbA1c between 42 and 47 mmol/mol identifies someone at high risk who should be offered lifestyle intervention.
Monitoring and targets
Glycaemic control is tracked with HbA1c, but targets are individualised. For a person managed by lifestyle or a single drug not associated with hypoglycaemia, aim for 48 mmol/mol; for a person on a drug that can cause hypoglycaemia (such as a sulfonylurea), aim for 53 mmol/mol (7.0%). Intensify treatment if HbA1c rises to 58 mmol/mol (7.5%). Relax the target for those who are older or frail, or who have a reduced life expectancy or a high risk of hypoglycaemia. HbA1c reflects average glucose over roughly the preceding three months, which is why it is checked every three to six months until stable.
Management: the cardiorenal-first shift
This is the heart of the topic, and it has changed. Lifestyle — diet, weight management, physical activity and smoking cessation — underpins everything, and structured education is offered at diagnosis.
Drug treatment now leads with cardiorenal protection. Metformin remains the foundation, with modified-release metformin favoured in the 2026 update for better gastrointestinal tolerability. Crucially, an SGLT2 inhibitor with proven cardiovascular benefit is added to metformin — and the 2026 update recommends starting both together as standard care for the prevention of complications, rather than waiting for metformin to fail. An SGLT2 inhibitor is particularly indicated for those with heart failure, established atherosclerotic cardiovascular disease, or chronic kidney disease, where the benefit is independent of glucose control. For a person who already has established atherosclerotic disease, the update positions triple therapy — metformin, an SGLT2 inhibitor and subcutaneous semaglutide — as first-line.
Beyond this, further glucose lowering can use a GLP-1 receptor agonist (favoured where weight loss is a priority), a DPP-4 inhibitor, a sulfonylurea, or pioglitazone, with insulin added when oral and injectable therapies are insufficient. Throughout, the choice of agent weighs glucose lowering against weight, hypoglycaemia risk, renal function and cardiovascular benefit, and treatment is reviewed and intensified rather than left static. Where metformin is contraindicated, an SGLT2 inhibitor is used as the foundation instead.
Complications and reviews
Annual review covers the complications that drive morbidity: retinal screening, foot checks (for neuropathy and vascular disease), urine ACR and eGFR for nephropathy, and cardiovascular risk-factor control with blood pressure management and a statin. Sick-day rules are essential — certain drugs, including metformin and SGLT2 inhibitors, are held during acute illness with poor oral intake.
High-yield exam points and traps
- Metformin remains first-line, but an SGLT2 inhibitor is now added early — and started alongside metformin in the 2026 update for complication prevention.
- SGLT2 inhibitors protect the heart and kidneys independent of glucose, so they are indicated in heart failure, atherosclerotic disease and chronic kidney disease.
- HbA1c targets are individualised: 48 mmol/mol on lifestyle or a low-hypoglycaemia drug, 53 mmol/mol on a drug that causes hypoglycaemia.
- Diagnosis needs two abnormal results if asymptomatic, one if symptomatic.
- HbA1c is unreliable in pregnancy, haemoglobinopathies and acute or rapid-onset illness.
- Hold metformin and SGLT2 inhibitors during acute illness (sick-day rules), and be alert to euglycaemic ketoacidosis with SGLT2 inhibitors.
- Distinguish type 2 from type 1 and from a hyperosmolar hyperglycaemic state, both of which change management.
A few common questions
Which drug is first-line for type 2 diabetes? Metformin, with an SGLT2 inhibitor added early — and the 2026 NICE update recommends starting both together for the prevention of complications.
What HbA1c level diagnoses diabetes? An HbA1c of 48 mmol/mol (6.5%) or above — two abnormal results if the person is asymptomatic, one if symptomatic.
Why are SGLT2 inhibitors used so early now? SGLT2 inhibitors are used early because they reduce cardiovascular and kidney events independent of glucose control, with particular benefit in heart failure, established atherosclerotic disease and chronic kidney disease.
What are the HbA1c targets? 48 mmol/mol for a person on lifestyle or a drug not causing hypoglycaemia; 53 mmol/mol for a person on a drug that can, with intensification considered at 58 mmol/mol.
What are sick-day rules? Guidance to temporarily hold certain drugs — metformin, SGLT2 inhibitors and others — during acute illness with reduced oral intake, restarting on recovery.
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