What change in management is recommended for a patient with poorly controlled diabetes and impaired renal function, currently on metformin and losartan?

Management Changes Required

You must immediately discontinue metformin and add an SGLT2 inhibitor to this patient's regimen. With a creatinine of 227.2 μmol/L (approximately 2.57 mg/dL), this patient's eGFR is approximately 25-29 mL/min/1.73m², which is below the 30 mL/min/1.73m² threshold where metformin becomes contraindicated due to lactic acidosis risk 1, 2.

Immediate Actions Required

Discontinue Metformin

• Metformin must be stopped immediately as the patient's eGFR is <30 mL/min/1.73m², which is an absolute contraindication 1, 2.
• The FDA label explicitly states metformin is contraindicated when eGFR <30 mL/min/1.73m² due to risk of metformin accumulation and lactic acidosis 2.
• Continuing metformin at this level of renal function significantly increases lactic acidosis risk, which can be fatal 2.

Add SGLT2 Inhibitor (If eGFR ≥30 mL/min/1.73m²)

• If the calculated eGFR is ≥30 mL/min/1.73m², immediately add an SGLT2 inhibitor (empagliflozin, dapagliflozin, or canagliflozin) as this is a Grade 1A recommendation for patients with diabetes and CKD 1, 3.
• SGLT2 inhibitors provide cardiorenal protection independent of glycemic control and should be prioritized over other glucose-lowering agents 1, 3.
• Choose agents with documented cardiovascular and kidney benefits: empagliflozin, dapagliflozin, or canagliflozin 1, 3.

Continue Losartan

• Continue losartan 100mg as renin-angiotensin system blockade is essential for renoprotection in diabetic nephropathy 4, 5.
• The current blood pressure of 130/80 mmHg is at target for diabetic patients with CKD 5.

Alternative Glucose-Lowering Options

If eGFR <30 mL/min/1.73m² (SGLT2i contraindicated)

• Add insulin as the primary glucose-lowering agent since both metformin and SGLT2 inhibitors are contraindicated at eGFR <30 mL/min/1.73m² 1.
• Consider adding a GLP-1 receptor agonist (long-acting preferred: dulaglutide, semaglutide, or liraglutide) for additional glycemic control and cardiovascular benefits 1, 3.
• GLP-1 receptor agonists can be used at eGFR >15 mL/min/1.73m² with appropriate dose adjustments 1.

If eGFR ≥30 mL/min/1.73m² but glycemic targets not met with SGLT2i alone

• Add a long-acting GLP-1 receptor agonist as third-line therapy if HbA1c remains >7-8% despite SGLT2 inhibitor 1, 3.
• Start with low doses and titrate slowly to minimize gastrointestinal side effects 1.
• Prioritize agents with documented cardiovascular benefits 1.

Critical Monitoring Requirements

Renal Function Monitoring

• Monitor eGFR every 3-6 months given the patient's eGFR <60 mL/min/1.73m² 1, 6, 7.
• More frequent monitoring may be needed if renal function is declining rapidly 1.

If SGLT2 Inhibitor Started

• Temporarily withhold SGLT2 inhibitor during prolonged fasting, surgery, or critical illness due to increased ketoacidosis risk 3.
• Monitor for volume depletion, especially in the first few weeks of therapy 1.

Vitamin B12 Monitoring

• Check vitamin B12 levels if the patient has been on metformin for >4 years prior to discontinuation 1, 6, 7.

Common Pitfalls to Avoid

• Do not continue metformin at any dose when eGFR <30 mL/min/1.73m² - this is a hard contraindication, not a dose-reduction scenario 1, 2.
• Do not add sulfonylureas or insulin before trying SGLT2 inhibitor and GLP-1 RA (if eGFR permits), as these have superior cardiorenal outcomes 3.
• Do not delay SGLT2 inhibitor initiation if eGFR ≥30 mL/min/1.73m² - the cardiorenal benefits are independent of glycemic control and should be started immediately 1, 3.

Summary Algorithm

1. Calculate exact eGFR from creatinine 227.2 μmol/L
2. Stop metformin immediately (eGFR <30 contraindication)
3. If eGFR ≥30: Add SGLT2 inhibitor + consider GLP-1 RA if needed for glycemic control
4. **If eGFR <30**: Start insulin ± GLP-1 RA (if eGFR >15)
5. Continue losartan 100mg
6. Monitor eGFR every 3-6 months