Type 2 Diabetes Mellitus
A disease of insulin resistance plus progressive beta-cell failure that raises glucose enough to cause osmotic symptoms and long-term vascular damage; treatment lowers glucose while attacking the cardiovascular risk that actually kills patients.
In a nutshell
Insulin resistance that the beta cells compensate for until they cannot. Glucose rises, spills past the renal threshold and causes osmotic symptoms; over years it damages small vessels and large ones. Macrovascular disease, not glucose itself, is what kills patients.
Classic presentation
An overweight adult with cardiovascular risk factors, found on screening bloods, or presenting with thirst, polyuria, fatigue and recurrent thrush.
Key points
- The classic symptoms are all osmotic: glucose spills into the urine and drags water with it (polyuria), and the resulting fluid loss drives thirst.
- Microvascular complications (retinopathy, nephropathy, neuropathy) track glycaemic control. Macrovascular complications track the whole cardiovascular risk profile.
- HbA1c reflects average glycaemia over the preceding weeks. It is both the diagnostic test and the monitoring target.
- Metformin is first-line because it lowers hepatic glucose output and improves insulin sensitivity without hypoglycaemia or weight gain: it treats the resistance rather than flogging a failing beta cell.
- SGLT2 inhibitors and GLP-1 receptor agonists are added for cardiovascular and renal protection, particularly with established cardiovascular disease, heart failure or chronic kidney disease.
- Blood pressure and lipids are treated in parallel, because macrovascular disease is the leading cause of death.
- Annual retinal screening, foot checks and urine albumin:creatinine ratio catch microvascular complications while they are still modifiable.
First-line investigation
HbA1c (or a fasting/random glucose) to confirm the diagnosis, with urine albumin:creatinine ratio, renal function, lipids and blood pressure to stage risk.
First-line management
Structured education, dietary change, weight management and physical activity, plus metformin unless contraindicated.
Exam traps
- Rapid unexplained weight loss should make you reconsider type 1 diabetes or malignancy rather than assume type 2.
- Metformin does not cause hypoglycaemia. If the stem features a hypo, look at the sulfonylurea or the insulin.
- Tight glucose control prevents microvascular disease, but it is treating the cardiovascular risk factors that prevents death.
Educational content pending clinical review. Not medical advice.