From the Guidelines
For a patient with impaired renal function (GFR 29), a reasonable alternative to metformin would be a sodium-glucose cotransporter-2 (SGLT2) inhibitor or a glucagon-like peptide-1 (GLP-1) receptor agonist. SGLT2 inhibitors like empagliflozin (Jardiance) at 10-25 mg daily or dapagliflozin (Farxiga) at 5-10 mg daily are good options as they provide cardiovascular and renal protection 1. GLP-1 receptor agonists such as semaglutide (Ozempic) starting at 0.25 mg weekly and titrating up to 0.5-1 mg weekly, or dulaglutide (Trulicity) 0.75-1.5 mg weekly are also excellent choices 1. These medications are preferred because they don't accumulate in renal impairment like metformin does, which can cause lactic acidosis when GFR falls below 30. Additionally, both drug classes have demonstrated cardiovascular benefits and SGLT2 inhibitors specifically slow the progression of kidney disease. Dipeptidyl peptidase-4 (DPP-4) inhibitors like linagliptin (Tradjenta) 5 mg daily are also safe as they require no dose adjustment in renal impairment 1. Some key points to consider when choosing an alternative to metformin include:
- The patient's individual characteristics, such as the presence of cardiovascular disease or heart failure
- The potential for hypoglycemia with certain medications
- The need for dose adjustments based on renal function
- The potential for adverse effects, such as genital infections with SGLT2 inhibitors or gastrointestinal symptoms with GLP-1 agonists Blood glucose monitoring should be increased when switching medications, and the patient should be educated about potential side effects. It's also important to note that the choice of medication should be individualized based on the patient's specific needs and circumstances. Overall, the goal is to choose a medication that will provide effective glucose control while minimizing the risk of adverse effects and slowing the progression of kidney disease.
From the Research
Alternatives to Metformin
In patients with impaired renal function, such as a GFR of 29, metformin may not be suitable due to the increased risk of lactic acidosis 2.
- Dipeptidyl peptidase-4 inhibitors (gliptins) may be considered as an alternative to metformin in patients with renal impairment, especially in those without obesity or severe hyperglycaemia, elderly patients, or those with a frailty profile 3.
- Sodium-glucose cotransporters type 2 (gliflozins) may also be an option, but their use may be limited in patients with advanced renal insufficiency due to the increased risk of urinary/genital infections or events linked to dehydration such as hypotension 3.
- Other classes of agents, such as sulphonylureas, may be considered, but their use may be associated with a higher risk of hypoglycaemia and weight gain 4, 5.
Considerations for Alternative Therapies
When selecting an alternative to metformin, clinicians should consider factors such as: