Certified Diabetes Care and Education Specialist (CDCES) Practice Exam

What medication is most likely responsible for an increase in serum creatinine in a man with diabetes?

1. Metoprolol

2. Atorvastatin

3. Metformin

4. Irbesartan

The correct answer is: Irbesartan

Irbesartan is an angiotensin II receptor blocker (ARB) commonly used in the management of hypertension and diabetic kidney disease. One of the pharmacological effects of this medication is its influence on renal function. Specifically, ARBs can lead to a decrease in glomerular filtration rate (GFR) shortly after initiation due to their action on the renal vasculature. This can result in an increase in serum creatinine levels, especially in individuals with pre-existing renal impairment or in those who are volume depleted. In patients with diabetes, particularly those with diabetic nephropathy, kidney function is often already compromised, making them more susceptible to changes in serum creatinine when starting an ARB. While creatinine levels may stabilize or even improve over time as the drug exerts its long-term protective effects against renal decline, the initial increase is a recognized response. In contrast, medications like metoprolol (a beta-blocker), atorvastatin (a statin), and metformin (a biguanide) do not typically cause significant acute increases in serum creatinine in the same way that ARBs can. Metformin, in particular, is often contraindicated in cases of significant renal impairment due to the risk of lactic acidosis,