Chronic hyperglycaemia from insulin resistance with relative insulin deficiency. Major driver of CV, renal, ophthalmic, and neurological complications.
⚠ Red flags
- DKA: vomiting, abdominal pain, Kussmaul breathing, ketones
- HHS: profound dehydration, altered consciousness, glucose >30
- Hypoglycaemia <3.9 mmol/L (especially recurrent or unawareness)
- Diabetic foot infection with systemic features — admit
Diagnostic criteria
Clinical
- Symptoms: polyuria, polydipsia, weight loss, fatigue, recurrent infection
- Asymptomatic in many — diagnose on screening of high-risk groups
Investigations
- FBG ≥7.0 mmol/L (126 mg/dL) on two occasions
- HbA1c ≥6.5% (48 mmol/mol)
- 2h OGTT ≥11.1 mmol/L
- Random glucose ≥11.1 mmol/L plus symptoms (single test sufficient)
Scoring tools
- QDiabetes risk score
- FINDRISC questionnaire
Investigations
Essential
- HbA1c (diagnosis and monitoring)
- U&E, creatinine, eGFR
- Lipid profile
- Urine ACR (microalbuminuria)
- LFTs (NAFLD screen)
Optional
- C-peptide and GAD antibodies if MODY/LADA suspected
- Fundoscopy (annual)
- Foot exam: monofilament + pulses (annual)
- TSH (if symptoms or T1DM suspected)
Management
Acute
- DKA or HHS: see dedicated emergency pathway
- Symptomatic hyperglycaemia with HbA1c >9%: consider early insulin or GLP-1 RA
Long-term
- Individualised HbA1c target (typically <7%; 7.5–8% if elderly/comorbid)
- Structured education programme (DESMOND, X-PERT)
- Annual review: retinal screening, foot check, urine ACR, lipids
Non-pharmacological
- Mediterranean or low-carbohydrate dietary pattern
- Weight loss ≥5–10% (consider DiRECT-style very-low-calorie diet for remission)
- Aerobic + resistance exercise ≥150 min/week
- Smoking cessation; alcohol within recommended limits
Pharmacological
| Drug | Dose | Notes |
|---|---|---|
| Metformin | 500 mg PO BD → 1 g BD | First-line. Hold if eGFR <30. GI side effects mitigated by MR formulation. |
| Empagliflozin (SGLT2i) | 10–25 mg PO once daily | Add if CVD, HF, or CKD (eGFR ≥20). Counsel on DKA, genital infection, ketosis on sick days. |
| Semaglutide (GLP-1 RA) | 0.25 mg SC weekly → 1 mg | Add if obesity or established CVD. GI side effects; pause if pancreatitis. |
| Gliclazide (sulfonylurea) | 40–160 mg PO once or twice | Cheap; risk of hypoglycaemia and weight gain. |
| Basal insulin (glargine) | 0.1–0.2 units/kg SC at night | Add when HbA1c remains above target despite oral therapy. |
Monitoring
- HbA1c every 3 months until stable, then every 6 months
- Annual U&E, urine ACR, lipids, LFTs
- Annual diabetic eye screening and foot exam
- Self-monitoring of blood glucose if on insulin or sulfonylurea
Referral criteria
- Suspected T1DM, MODY, LADA, or pancreatic diabetes
- Pregnancy / preconception planning
- Severe or frequent hypoglycaemia
- Diabetic foot ulceration or critical limb ischaemia
- Stage 3b CKD or worse
Complications
- Macrovascular: MI, stroke, peripheral arterial disease
- Microvascular: retinopathy, nephropathy, neuropathy
- Diabetic foot ulceration / Charcot arthropathy
- Erectile dysfunction, gastroparesis
Special populations
- Pregnancy
- Pre-conception HbA1c <6.5% if possible. Stop ACEi/ARB and statin. Use insulin or metformin; avoid SGLT2i/GLP-1 RA/sulfonylureas in pregnancy.
- Renal impairment
- Stop metformin if eGFR <30. SGLT2i still beneficial down to eGFR ≥20. Adjust insulin (reduced clearance).
- Hepatic impairment
- Avoid pioglitazone in active liver disease. Sulfonylurea risk of hypoglycaemia higher.
- Elderly
- Relax HbA1c target (7.5–8%). Avoid sulfonylureas if recurrent hypos. Simplify regimens.
- Paediatric
- T1DM far more common than T2DM — refer to paediatric endocrinology.