Recurrent hypoglycaemia in an older woman with advancing kidney disease
A 76-year-old woman with type 2 diabetes for 18 years, ischaemic cardiomyopathy (LVEF 32%) and CKD stage 4 attends with her daughter. HbA1c is 71 mmol/mol (8.7%). She has had three hypoglycaemic episodes in two months, one needing paramedic treatment, and last week her daughter found her confused on the kitchen floor. She lives alone, weighs 54 kg, BMI 22, and eGFR is 24 mL/min/1.73 m² (38 a year ago). Medications: metformin 1 g twice daily, gliclazide MR 60 mg each morning (increased from 30 mg six weeks ago), furosemide 40 mg, bisoprolol, sacubitril–valsartan, atorvastatin and ferrous sulphate. She has peripheral neuropathy and one healed foot ulcer. She insists on 'keeping her sugar low' because her late sister needed dialysis.
1. Explain why she is now having severe hypoglycaemia and set out your medication changes in priority order, with justification.
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Why now. Three factors converged: (1) gliclazide was doubled six weeks ago; (2) her eGFR has fallen from 38 to 24, and sulphonylureas and their metabolites accumulate as renal clearance falls, while reduced renal gluconeogenesis and reduced insulin clearance further lower her defences; (3) she is small (54 kg), 76 years old, lives alone and takes a beta-blocker, which blunts adrenergic warning symptoms so she cannot self-treat.
Priority order.
- Stop gliclazide immediately - the single intervention most likely to prevent another severe episode. It is the clear proximate cause.
- Stop metformin - contraindicated below an eGFR of 30 (lactic acidosis risk), and of no benefit at this eGFR with her comorbidities.
- Review furosemide and sacubitril–valsartan for volume depletion and falls contribution; do not stop them reflexively, as they are treating heart failure, but check lying and standing blood pressure.
- Do not simply add insulin. Starting insulin in a woman living alone with cognitive blunting and a beta-blocker would trade one hazard for another unless she has structured education and support.
Recheck renal function, HbA1c, thyroid function and B12 after the changes; a fall in HbA1c without drug change would raise other causes.
2. What glucose-lowering regimen would you use instead, and how would you justify it to her?
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Her remaining options must be low-hypoglycaemia agents with a dose appropriate to an eGFR of 24.
- Linagliptin 5 mg daily - no renal dose adjustment, weight-neutral, essentially no hypoglycaemia when used without a sulphonylurea. This is the safest first step to cover post-prandial excursions.
- An SGLT2 inhibitor would give the largest cardiovascular and renal benefit, and efficacy for heart-failure hospitalisation and CKD progression is preserved at low eGFR. Initiation thresholds differ by drug and licence (empagliflozin is licensed from eGFR 20 for heart failure), so choose an agent she is actually eligible for, counsel on genital mycotic infection, volume depletion, sick-day rules and euglycaemic ketoacidosis, and hold it during acute illness or before surgery.
- Basal insulin at a low dose (e.g. 6–8 units) only if she remains above target on the above, with a district nurse, pen technique teaching and a clear hypo plan.
How to frame it. She equates tight control with kidney protection. Explain that at her age and eGFR the kidney protection now comes from blood pressure, the SGLT2 inhibitor, avoiding NSAIDs and contrast, and not from a low HbA1c - and that the immediate threat to her independence is a fractured hip or a head injury from a fall she cannot remember.
3. What glycaemic target and safety plan would you agree with her and her daughter?
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Target. Given frailty, a previous severe hypoglycaemic episode, living alone and cardiac disease, aim for an HbA1c of roughly 58–69 mmol/mol (7.5–8.5%), avoiding symptomatic or biochemical hypoglycaemia (<4 mmol/L) altogether. Do not chase a 'normal' HbA1c: at this eGFR the risk of harm from hypoglycaemia exceeds the microvascular benefit of tight control.
Safety plan.
- Teach recognition and treatment of hypoglycaemia to her and her daughter; supply glucose gel and consider a continuous glucose monitor with an alarm, which is particularly useful in someone with beta-blocker-blunted symptoms.
- Sick-day rules: hold metformin (stopped), SGLT2 inhibitor and ACE inhibitor/ARNI during vomiting or diarrhoea; seek advice early.
- Foot care and annual retinal screening, given neuropathy and previous ulceration.
- Review driving status and advise her to check glucose before driving and not to drive with glucose <5 mmol/L.
- Deprescribe and simplify where possible; a single daily tablet plus heart-failure therapy is a realistic regimen for someone with mild cognitive blunting.
- Arrange a follow-up in 4–6 weeks with repeat HbA1c and electrolytes, and a falls/occupational therapy assessment at home.