Med unsafe with kidney problems

Dear Dr. Roach: I took Glucovance (metformin and glyburide) for more than 30 years. Then, because of worsening kidney function (high creatinine), I have been switched to just glyburide alone. I am also on Actos for my diabetes. I just joined Medicare Part D; however, there were only one or two plans that covered glyburide. Why do drug companies push metformin if it worsens kidney function?

Answer:

C.S.

Metformin and glyburide are both older medications for Type 2 diabetes, and both are quite inexpensive — less than $5 per month in the U.S. using one of the online discount programs, without needing insurance. (This is often less than insurance co-pays.) Part D providers are generally happy to pay for these less-expensive alternatives to newer medications, but the newer medicines are much better for some people.

Glyburide, for example, tends to promote weight gain and stops working in many people after several years, especially when used by itself. Metformin remains a first-line oral medication for many, but it is not safe in people with more-than-mild kidney problems — and is not responsible for the kidney problems itself. Diabetes, especially if not well-controlled, accelerates the normal loss of kidney function with age. Metformin in someone with poor kidney function can cause a dreaded complication called lactic acidosis.

Pioglitazone (Actos) is another older drug that is not recommended for first-line use, due to a small increase in risk of heart failure, weight gain, and possibly bladder cancer. Most diabetes experts choose a type of medication called a GLP-1 agonist, such as semaglutide, in people with diabetes who do not reach their blood sugar control goals with metformin alone. GLP-1 agonists show benefit in helping people losing weight and have also demonstrated the ability to reduce heart disease risk.

Unfortunately, these types of drugs are much more expensive, and there have been recent shortages due to their use as weight-loss drugs.