An elderly diabetic who has been maintained on metformin (Glucophage) is scheduled for a cardiac catheterization. Which instruction should be given to the client? A. Take the medication as ordered prior to the exam B. Limit the amount of protein in the diet prior to the exam C. Discontinue the medication prior to the exam D. Take the medication with only water prior to the exam

Metformin is an oral medication used to manage diabetes, specifically type 2 diabetes. It works by reducing the amount of glucose absorbed by the body and increasing the body's sensitivity to insulin. This helps to control blood sugar levels, which is essential for diabetic patients. In this situation, the elderly patient must rely on this medication for maintaining optimal blood sugar levels.

Cardiac catheterization is a procedure used to diagnose and treat certain heart conditions. It involves inserting a long, thin tube (called a catheter) through a blood vessel in the arm or leg and guiding it towards the heart. This procedure may require the use of a contrast agent (dye) to visualize the blood vessels. Some potential risks of this procedure include blood vessel damage, heart rhythm problems, infection, and allergic reaction to the contrast agent.

Now that we have a general understanding of metformin and cardiac catheterization, we can assess each answer choice provided: A. Take the medication as ordered prior to the exam - This option may not be advisable, as the contrast agent used in cardiac catheterization can negatively interact with metformin, increasing the risk of a rare but serious condition called lactic acidosis. B. Limit the amount of protein in the diet prior to the exam - This option is not directly relevant to the metformin or the specific procedure, and therefore is not the most appropriate instruction. C. Discontinue the medication prior to the exam - This is the correct option. It is generally recommended that patients stop taking metformin before undergoing cardiac catheterization to minimize the risk of lactic acidosis and other potential complications. D. Take the medication with only water prior to the exam - This option does not address the potential risks associated with taking metformin before the procedure, and therefore is not the appropriate instruction.

Based on our analysis, the correct instruction that should be given to the elderly diabetic patient scheduled for a cardiac catheterization is: C. Discontinue the medication prior to the exam.