Prednisone, a corticosteroid medication, is frequently prescribed to reduce inflammation and suppress the immune system in various conditions. Metformin, on the other hand, is a widely used medication primarily to manage high blood sugar levels in individuals with type 2 diabetes. While these two medications serve different purposes, they are sometimes prescribed together to address a specific metabolic challenge that can arise from prednisone use.
Prednisone and Blood Sugar Elevation
Prednisone belongs to a class of drugs known as glucocorticoids, which mimic cortisol, a natural hormone produced by the body in response to stress. When prednisone is introduced, it can significantly alter the body’s glucose metabolism. One primary effect is to stimulate the liver to produce and release more glucose into the bloodstream, a process called gluconeogenesis. This increased glucose production contributes directly to higher blood sugar levels.
Prednisone can also induce insulin resistance, meaning cells become less responsive to insulin. Insulin helps glucose move from the blood into cells for energy. When cells resist insulin, glucose remains in the bloodstream, further elevating blood sugar. This combined effect can lead to “steroid-induced hyperglycemia” or “steroid-induced diabetes.” Blood sugar levels often spike 4 to 8 hours after taking prednisone, with higher doses having a more pronounced effect.
Metformin’s Mechanism for Lowering Blood Sugar
Metformin works through several pathways to lower elevated blood sugar levels. Its main action involves reducing glucose production by the liver, by inhibiting gluconeogenesis.
Metformin also improves the body’s sensitivity to insulin. This means cells become more receptive to insulin, absorbing more glucose from the bloodstream. Metformin also reduces glucose absorption from the intestines. These mechanisms allow metformin to manage blood glucose without directly increasing insulin secretion from the pancreas, which helps reduce the risk of low blood sugar when used alone.
Why Prednisone and Metformin Are Prescribed Together
Prednisone and metformin are prescribed together to counteract metabolic disturbances caused by prednisone. Metformin directly addresses the increased liver glucose production and insulin resistance caused by prednisone. This co-administration helps maintain more stable blood glucose levels, particularly when prednisone is used for extended periods or at higher doses.
For individuals who already have type 2 diabetes, prednisone can make their existing condition more challenging to manage, often requiring an increase in their current diabetes medication or the addition of metformin. For patients without a prior diagnosis of diabetes, metformin is prescribed to prevent or reduce the development of steroid-induced hyperglycemia. This preventive measure helps avoid high blood sugar symptoms and reduces the risk of developing new-onset diabetes during and after prednisone therapy. Studies show metformin can maintain stable glucose levels in non-diabetic patients receiving glucocorticoid treatment, contrasting with significant increases seen in placebo groups.
Managing Treatment and Potential Side Effects
When taking both prednisone and metformin, careful monitoring of blood sugar levels is advised. This is important when starting prednisone, changing its dose, or discontinuing it, as blood sugar fluctuations are likely. Regular checks help healthcare professionals adjust medication doses as needed to maintain glycemic control and prevent complications.
Metformin can cause gastrointestinal side effects, such as nausea, vomiting, diarrhea, and stomach discomfort, especially when treatment begins. These symptoms often lessen as the body adjusts, and taking metformin with meals can help reduce their severity. Prednisone also has its own side effects, including increased appetite, mood changes, and fluid retention. A rare but serious side effect of metformin is lactic acidosis, where too much lactic acid builds up in the blood. Symptoms include unusual fatigue or weakness, severe muscle pain, trouble breathing, stomach pain, dizziness, or a slow heartbeat. This condition is more likely in individuals with kidney or liver disease.
It is important to communicate any concerning side effects to a doctor immediately. Patients should never stop either medication without consulting their healthcare provider. The need for metformin may decrease or be discontinued once the prednisone course is completed and blood sugar levels stabilize.