Diabetic Kidney Disease — Written Clinical Reasoning

SAQ 1 — Integrated Diabetic Kidney Disease Management (20 marks, 30 minutes)

Prompt: Outline your integrated management plan for this patient, addressing each problem with evidence-based therapy and a clear rationale. Address the decision points where the examiner will probe. ^[1]

Case vignette: A 66-year-old man with type 2 diabetes for 18 years complicated by retinopathy, and a prior NSTEMI. eGFR 32 (falling 14 points in 14 months), urine ACR 92 mg/mmol, BP 148/90 on perindopril, HbA1c 68 mmol/mol, Hb 101 g/L, ferritin 52 micrograms/L, TSAT 17%, PTH 16 pmol/L, 25-OH vitamin D 32 nmol/L, bicarbonate 21 mmol/L, K+ 5.1 mmol/L. Eight regular medications. ^[1]

Model Answer

Problem list (4 marks):

1. Progressive diabetic kidney disease — CKD G3b A3, eGFR falling 14 points in 14 months (rapid decline), very high progression risk
2. Suboptimal blood pressure (148/90) and persistent macroalbuminuria despite ACE inhibitor
3. Suboptimal glycaemic control (HbA1c 68 mmol/mol) — contributing to progression
4. Renal anaemia with iron deficiency (Hb 101, ferritin 52, TSAT 17%)
5. Early CKD-MBD — secondary hyperparathyroidism (PTH 16), vitamin D deficiency (25-OH D 32)
6. Mild metabolic acidosis (bicarbonate 21)
7. High cardiovascular risk — prior NSTEMI, diabetes, CKD (coronary risk equivalent), obesity
8. Polypharmacy (8 medications) and sick-day medication risk ^[1]

Step 1 — Confirm this is DKD and assess for atypical features (2 marks): ^[1]

The clinical picture is classic diabetic kidney disease: long-standing T2DM with retinopathy, progressive macroalbuminuria, bland urine (no haematuria reported), and a typical trajectory. Retinopathy is the strongest correlate of classic DKD and its presence here strongly supports the clinical diagnosis — renal biopsy is NOT indicated unless atypical features emerge (haematuria, active sediment, rapid decline beyond expectation, or signs of systemic disease). I would document the rate of eGFR decline and apply the Kidney Failure Risk Equation (Tangri) to quantify his 2- and 5-year risk of kidney failure — with eGFR 32, ACR 92 and a steep decline, his risk is high and dialysis planning must begin. ^[1]

Step 2 — Progression-slowing therapy: the four-pillar approach (6 marks): ^[1]

Step 3 — Complication management (4 marks): ^[1]

• Anaemia: Iron first. Give IV ferric carboxymaltose (weight-based, e.g. 1 g) to correct iron deficiency before any ESA. Target ferritin greater than 100, TSAT greater than 20%. Recheck Hb in 4 weeks; if still under 100 g/L after iron repletion, start an ESA (darbepoetin) targeting Hb 100 to 110 g/L — never above 115 (TREAT showed harm: stroke, thromboembolism).
• CKD-MBD: Optimise 25-OH vitamin D — increase cholecalciferol to 1000 to 2000 units daily. Dietary phosphate counselling. If PTH continues to rise, consider calcitriol or paricalcitol. Use a non-calcium phosphate binder (sevelamer) if phosphate rises — avoid calcium-based binders given his vascular disease.
• Metabolic acidosis: Start oral sodium bicarbonate 600 mg TDS, titrate to bicarbonate 22 to 26 mmol/L. Correcting acidosis slows progression and reduces muscle wasting. Watch the sodium load — adjust diuretics.
• Hyperkalaemia (K+ 5.1): Bicarbonate corrects acidosis and lowers potassium; uptitrate loop diuretic (kaliuretic). If K+ remains above 5.5 despite these, consider a potassium binder (patiromer or sodium zirconium cyclosilicate) to permit finerenone and continued ACEi. The goal is to keep him on the disease-modifying drugs, not to stop them. ^[1]

Step 4 — Cardiovascular risk reduction and glycaemic strategy (2 marks): ^[1]

He is a coronary risk equivalent and cardiovascular disease is his dominant mortality risk. Continue atorvastatin 80 mg (high-intensity; atorvastatin is hepatically cleared so safe in CKD), aspirin, metoprolol. Adjust glycaemic therapy for his eGFR 32: reduce metformin to 500 mg BD (eGFR less than 45 — halve the dose; stop below 30), stop gliclazide (hypoglycaemia risk in CKD; sulfonylurea clearance falls), add a GLP-1 receptor agonist (semaglutide weekly) for residual cardiovascular protection, weight loss and additional albuminuria reduction. Target HbA1c 53 to 58 mmol/mol — avoid over-tight control (ACCORD harm in older high-risk patients). The SGLT2 inhibitor also provides cardiovascular protection. ^[1]

Step 5 — Dialysis and transplant planning (1 mark): ^[1]

His Kidney Failure Risk Equation risk is high given eGFR 32, ACR 92 and the steep decline. Refer now for dialysis modality education (home-first — PD and home HD). Initiate transplant workup now — pre-emptive living-donor transplant is the best survival option; discuss with family. Refer for vascular surgery at eGFR 15 to 20 (creation plus a minimum 6 to 12 weeks maturation, plus revision time if needed — so referral runs roughly 6 to 12 months ahead). Protect the non-dominant arm from cannulae from today. Offer a conservative care pathway discussion if he is unlikely to benefit. ^[1]

Step 6 — Communication and safety (1 mark): ^[1]

Provide written sick-day rules: hold ACEi, SGLT2i, diuretics, metformin during any acute illness with reduced intake, vomiting, diarrhoea or fever; resume when recovered for 24 to 48 hours. Permanent NSAID avoidance (including over-the-counter). Vaccinations (influenza, COVID-19, pneumococcal, hepatitis B, herpes zoster). Document and share the integrated plan with the GP. Address his understanding and goals. Smoking cessation if applicable. The Steno-2 model ^[6] is the evidence that this integrated approach halves cardiovascular events over the long term.