The man whose diabetes tablets 'are damaging his kidneys'
A 58-year-old man with type 2 diabetes for 9 years, hypertension and obesity (BMI 32.4) attends his annual review. He takes metformin 1 g twice daily, modified-release gliclazide 60 mg each morning, ramipril 5 mg daily and atorvastatin 20 mg nightly. He smokes 10 cigarettes daily and walks rarely. He reports two episodes of sweating and confusion in the last month, both mid-morning, one of which required his wife to give him glucose. HbA1c is 9.2%. Creatinine 178 µmol/L, eGFR 36 mL/min/1.73 m², urine albumin-to-creatinine ratio 480 mg/g. Potassium 4.9 mmol/L. Blood pressure 148/86 mmHg. He has no retinopathy and a normal foot examination. He asks whether he should start 'the injection everyone is talking about' for weight loss, and whether his kidneys are 'failing' because a relative told him his tablets are damaging them.
1. Which of this patient's current medicines require change today, and what would you prescribe instead? Justify each decision.
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Stop the gliclazide. Sulfonylureas and their active metabolites are cleared renally and accumulate once eGFR falls below about 45. His two mid-morning episodes are a hypoglycaemia signal; continuing the drug is the single most dangerous element of his regimen.
Reduce metformin, do not stop it. eGFR 36 sits in the 30–44 band: continue at a maximum total daily dose of 1000 mg (for example 500 mg twice daily), with explicit sick-day rules - hold during vomiting, diarrhoea, dehydration, sepsis, before contrast and before surgery. It is contraindicated below eGFR 30.
Keep and titrate the ramipril. ACE inhibition is the cornerstone of renoprotection with A3 albuminuria. Uptitrate to the maximum tolerated dose, checking potassium and creatinine after 1–2 weeks; a creatinine rise of up to 30% is expected and is not a reason to stop.
Add an SGLT2 inhibitor. Dapagliflozin 10 mg daily is licensed for CKD with eGFR ≥25 and slows progression while reducing heart failure and mortality in albuminuric CKD. Warn about a reversible early eGFR dip of a few mL/min, genital mycotic infection, volume depletion and euglycaemic ketoacidosis.
Use the incretin rather than insulin. His question about the 'weight-loss injection' is an opening: a GLP-1 receptor agonist such as semaglutide addresses HbA1c, weight and cardiovascular risk with low hypoglycaemia risk, especially once the sulfonylurea is gone.
Intensify the statin to atorvastatin 40 mg. Diabetes plus CKD is high cardiovascular risk and 20 mg is not high-intensity therapy.
2. What targets and monitoring would you set for the next three months?
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A reasonable HbA1c target is about 7.5–8.0%, not the 6.5% often quoted. The driver is not his age but the combination of CKD G3b, established albuminuria and demonstrated hypoglycaemia: a tighter target buys little and risks a fall, a fracture or a road traffic collision. A safe, non-hypoglycaemic regimen is worth more than a low number.
Monitoring plan:
- eGFR and potassium 1–2 weeks after the ramipril increase and after starting dapagliflozin, then at least every 3–6 months.
- HbA1c at 3 months; urine albumin-to-creatinine ratio at least annually, more often during therapy changes.
- Home blood pressure readings, aiming below 130/80 if tolerated.
- Weight, foot examination (monofilament, pulses, skin) and annual retinal screening.
- Lipids and review of statin intensity.
- Education: sick-day rules, recognition of hypoglycaemia (much less likely once off gliclazide), avoidance of NSAIDs, holding metformin for contrast.
He now meets nephrology referral criteria because ACR exceeds 300 mg/g (A3) alongside eGFR 36, so arrange a shared-care review even though the numbers are stable. Referral is not an admission of failure - it is what preserves the kidney.
3. How would you explain the kidney problem to him, addressing his belief that his tablets are damaging his kidneys?
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Start from what he already believes and correct it explicitly, because that belief is the main threat to adherence.
Explain that the kidney filters blood through millions of tiny filters, and after nine years of high glucose and high blood pressure those filters have become thickened and leaky. The leak is what the urine albumin measures: 480 mg/g means protein is escaping that should stay in the blood. An eGFR of 36 means the kidney is working at roughly a third of normal; it does not mean dialysis is imminent, and most people with these numbers stay stable for years with good control.
Address the pills directly. Metformin did not damage the kidney - the dose simply has to be reduced because the kidney clears it, exactly as we adjust the dose of any drug eliminated by that route; small doses remain safe and useful. The blood pressure tablet is protecting the kidney, not harming it, and the new tablet is licensed specifically to slow the decline.
Avoid absolute risk percentages unless he asks; offer them if he does. Close the loop by asking him to explain back what he will do if he develops a vomiting illness, and give written sick-day instructions.