What is the management plan for an 84-year-old female with type 2 diabetes mellitus, HbA1c of 6.7%, and mild impaired renal function on metformin 500mg bid?

From the Guidelines

The patient's current metformin dose of 500 mg twice daily can be continued, given the GFR of 62 ml/min is above the threshold of 45 ml/min, as recommended by the KDIGO 2022 clinical practice guideline for diabetes management in chronic kidney disease 1. The patient's diabetes management appears adequate with an A1c of 6.7. However, the reduced GFR of 62 ml/min requires attention.

• Regular kidney function monitoring should be performed every 3-6 months given the patient's age and mild renal impairment, as suggested by the KDIGO 2022 guideline 1.
• The current A1c target of 6.7 is appropriate for this 84-year-old patient, balancing glycemic control with avoiding hypoglycemia risks, in line with the recommendations for older adults with type 2 diabetes 1.
• If GFR declines below 45, metformin dose reduction to 500 mg once daily should be considered, and if it falls below 30, metformin should be discontinued, as per the KDIGO 2022 guideline 1.
• Additionally, ensure the patient receives annual eye exams, foot examinations, and cardiovascular risk assessment. Metformin remains effective in this case by reducing hepatic glucose production and improving insulin sensitivity, while its renal clearance explains why kidney function monitoring is essential to prevent lactic acidosis risk, which increases with declining renal function.
• Monitoring of vitamin B12 levels is also recommended, especially if the patient has been on metformin for more than 4 years, as indicated in the KDIGO 2022 guideline 1.

From the FDA Drug Label

Before initiating metformin hydrochloride tablets, obtain an estimated glomerular filtration rate (eGFR). Metformin hydrochloride tablets are contraindicated in patients with an eGFR less than 30 mL/min/1.73 m 2 Initiation of metformin hydrochloride tablets is not recommended in patients with eGFR between 30 to 45 mL/min/1. 73 m 2. Obtain an eGFR at least annually in all patients taking metformin hydrochloride tablets.

The patient has a GFR of 62, which is above the threshold where metformin is contraindicated or not recommended.

• The patient can continue taking metformin.
• However, it is recommended to monitor the patient's renal function at least annually.
• The patient's A1c of 6.7 and current metformin dose of 500 bid should be assessed by the healthcare provider to determine if any adjustments are needed. 2

From the Research

Patient Profile

• Age: 84 years
• Type 2 Diabetes Mellitus (T2DM)
• Medication: Metformin 500 mg twice daily
• A1c: 6.7%
• GFR: 62 mL/min/1.73 m2

Metformin Use in Patients with T2DM and Kidney Disease

• A study published in JAMA in 2014 3 found that metformin can be safely used in patients with mild to moderate chronic kidney disease (CKD), with an estimated glomerular filtration rate (eGFR) of 30-60 mL/min/1.73 m2.
• Another study published in Oncotarget in 2018 4 found that continuous metformin treatment may have an adverse effect on renal function in patients with T2DM and moderate CKD.
• A review published in The Medical Journal of Australia in 2019 5 suggested that metformin can be safely used in patients with mild to moderate renal impairment (eGFR 30-60 mL/min/1.73 m2), but its use in patients with severe renal impairment (eGFR < 30 mL/min/1.73 m2) remains a controversial issue.

Dosing and Safety of Metformin in Patients with CKD

• A study published in Diabetes Care in 2018 6 found that metformin can be safely used in patients with moderate and severe CKD (stages 3A, 3B, and 4) when the dose is adjusted for renal function.
• The study suggested the following daily dosing schedules: 1,500 mg for CKD stage 3A, 1,000 mg for CKD stage 3B, and 500 mg for CKD stage 4.
• A study published in Clinical Therapeutics in 2003 7 found that switching from twice-daily immediate-release metformin to a once-daily extended-release formulation did not affect glycemic control in patients with T2DM.

Considerations for the Patient

• The patient's GFR is 62 mL/min/1.73 m2, which is considered mild CKD.
• The patient is currently taking metformin 500 mg twice daily, which is a common dosing regimen for patients with T2DM.
• Based on the available evidence, metformin can be safely continued in this patient, but regular monitoring of kidney function and A1c levels is recommended.