How to manage an elderly female patient with diabetes and impaired renal function, currently on Metformin (metformin) ER and Jardiance (empagliflozin), with an estimated glomerular filtration rate (eGFR) of 39?

Management of Elderly Female with Diabetes and CKD Stage 3b

Reduce metformin to 500 mg daily immediately, continue Jardiance 10 mg daily, and refer to nephrology for CKD management and medication optimization. 1, 2

Immediate Medication Adjustments Required

Metformin Dose Reduction

• Your patient's eGFR of 39 mL/min/1.73m² places her in CKD Stage 3b, requiring mandatory metformin dose reduction to a maximum of 1000 mg daily 1, 2
• The FDA label explicitly states that when eGFR falls below 45 mL/min/1.73m², clinicians must assess the benefit-risk of continuing therapy and adjust dosing 2
• Given her current dose of 750 mg daily is already below the 1000 mg maximum for this eGFR range, you could maintain this dose, but consider reducing to 500 mg daily given her excellent glycemic control (A1c 6.7%) and elderly status with increased lactic acidosis risk 1, 2
• The 2022 ADA/KDIGO consensus strongly recommends metformin for eGFR ≥30 mL/min/1.73m² but emphasizes dose adjustment when eGFR is <45 mL/min/1.73m² 1
• Critical caveat: Elderly patients have reduced muscle mass, which can falsely elevate eGFR estimates based on creatinine alone; her true renal function may be worse than calculated 1

Jardiance (Empagliflozin) Management

• Continue Jardiance 10 mg daily without dose adjustment - this is the appropriate dose for her eGFR range 1
• Empagliflozin is FDA-approved and guideline-recommended for use down to eGFR 20 mL/min/1.73m² for cardiovascular and kidney protection, though glycemic efficacy diminishes as eGFR declines 1
• The 2022 KDIGO guideline gives a strong 1A recommendation for SGLT2 inhibitors in patients with T2D and CKD with eGFR ≥20 mL/min/1.73m² 1
• Do not increase the dose - while 25 mg is available, it offers no additional clinical benefit at this eGFR level and the 10 mg dose provides full cardiovascular and renal protection 1
• Monitor for volume depletion, urinary tract infections, and genital mycotic infections, which are more common in elderly females 3, 4

Nephrology Referral Indications

Refer to nephrology now - this patient meets multiple criteria for specialist evaluation 1:

• eGFR 39 mL/min/1.73m² represents CKD Stage 3b, approaching Stage 4 1
• BUN 36 with BUN/creatinine ratio of 24 suggests possible prerenal component or inadequate protein intake 1
• Elderly patient requiring optimization of medications with narrow therapeutic windows in renal impairment 1
• Need for comprehensive CKD management including evaluation for progression, cardiovascular risk reduction, and potential complications 1

Monitoring Requirements

Renal Function Surveillance

• Recheck eGFR and creatinine in 3 months given CKD Stage 3b 1, 2
• In elderly patients with diabetes and CKD, renal function should be assessed more frequently than annually due to higher risk of progression 1, 2
• If eGFR falls below 30 mL/min/1.73m², metformin must be discontinued entirely per FDA contraindication 2
• Consider cystatin C-based eGFR calculation for more accurate assessment in elderly patients with reduced muscle mass 1

Glycemic Monitoring

• Her A1c of 6.7% (improved from 8.5%) indicates excellent control, potentially allowing for less aggressive glucose-lowering to reduce hypoglycemia risk 1
• C-peptide of 4.0 suggests preserved beta-cell function 1
• Fructosamine 301 provides additional glycemic assessment less affected by anemia or hemoglobinopathies that may occur in CKD 1

Lactic Acidosis Risk Assessment

• Elderly patients have increased risk of metformin-associated lactic acidosis due to higher likelihood of hepatic, renal, or cardiac impairment 2
• Monitor for nonspecific symptoms: malaise, myalgias, abdominal pain, respiratory distress, or increased somnolence 2
• Educate patient to discontinue metformin and seek immediate care if these symptoms develop 2

Additional Considerations for CKD Management

Cardiovascular Risk Reduction

• The combination of metformin and empagliflozin provides cardiovascular protection, which is critical given diabetes and CKD are major ASCVD risk factors 1
• Consider adding a GLP-1 receptor agonist (dulaglutide, liraglutide, or semaglutide) if additional glycemic control or cardiovascular protection is needed - these require no dose adjustment at her eGFR 1, 5

Vitamin B12 Monitoring

• Check vitamin B12 levels given chronic metformin use, as deficiency occurs in approximately 7% of patients and is more common with longer duration of therapy 2
• Measure hematologic parameters annually and vitamin B12 every 2-3 years 2

Contrast Imaging Precautions

• If any iodinated contrast imaging is planned, metformin must be held at the time of or prior to the procedure given her eGFR 30-60 mL/min/1.73m² range 2
• Recheck eGFR 48 hours post-procedure before restarting metformin 2

Common Pitfalls to Avoid

• Do not continue metformin at current dose without reassessment - failure to adjust dosing in renal impairment is the most common cause of adverse drug reactions in CKD patients 1, 6, 7
• Do not discontinue empagliflozin - despite reduced glycemic efficacy at lower eGFR, kidney and cardiovascular benefits persist and are particularly important in this population 1
• Do not delay nephrology referral - studies show that 46% of patients with severe renal impairment have non-adherence to dosing guidelines at discharge, potentially causing moderate to severe harm in 71% of cases 7
• Do not assume creatinine-based eGFR is accurate - elderly patients may have falsely reassuring eGFR values due to reduced muscle mass 1