Metformin is considered a “first-line” drug for people who have type 2 diabetes. While there are a growing number of classes of drugs to help treat type 2 diabetes, most clinical guidelines suggest that metformin be prescribed first. Why? Metformin is safe, effective and inexpensive. In addition, metformin may provide other health benefits besides helping to lower blood sugar. But metformin remains somewhat shrouded in mystery and controversy. Not everyone understands how it works, and many people claim that it’s dangerous and should be avoided like the plague (we can thank the internet for perpetuating some of these unfounded “facts”). While metformin isn’t for everyone, there’s a lot about this drug that’s helpful and important to know.
Metformin contains a substance called guanidine, which can lower blood sugars. Guanidine is found in an herb called goat’s rue (also known as French lilac), and this herb has been used to treat diabetes since the early 1900s. The FDA approved metformin in 1995, although it’s been used in the UK since 1958.
About 88 million people in the U.S. have prediabetes. Most of them don’t know they have it. And without intervention, about 70% of them will go on to develop type 2 diabetes. The Diabetes Prevention Program (DPP), a landmark clinical trial, showed that lifestyle changes (weight loss, healthy eating, physical activity) can lower the risk of getting type 2 diabetes by close to 60%. It also showed that taking metformin can lower the risk by 31%. Data from the ongoing DPP study indicates that lifestyle changes or metformin could reduce or delay the onset of type 2 diabetes by up to 15 years.
Metformin comes as a tablet that is typically taken once or twice a day. There’s an extended-release tablet that is taken once a day with the evening meal. If swallowing pills isn’t for you, you can use a liquid form of metformin, called Riomet, taken one to three times a day with meals. Metformin is available as a generic drug, but the brand-name versions include Glucophage, Glucophage XR, Glumetza, Fortamet and Riomet. In addition, metformin is available in combination with other types of diabetes medicines.
Vitamin B12 is necessary for the brain and nervous system to function properly. It’s also needed for red blood cell formation, DNA production and metabolism. Research shows that taking metformin for an extended period of time raises the risk of developing a B12 deficiency. Why? Metformin appears to limit the absorption of B12 in the stomach and from the bloodstream into cells. A B12 deficiency can lead to megaloblastic anemia, neuropathy, memory loss and fatigue. If you take metformin, check with your doctor about getting your B12 level checked. If it’s on the low side or if you’re deficient, you may need to take a B12 supplement or get B12 injections.
PCOS (polycystic ovary syndrome) is a hormonal disorder that affects women of childbearing age. Symptoms include irregular menstrual periods, an excess of androgen (a male hormone) and numerous cysts on the ovaries. The ovaries may fail to release eggs, so becoming pregnant is often difficult. PCOS is also associated with obesity, hirsutism (excessive body hair growth) and insulin resistance. Hormones may be prescribed to help regulate the menstrual cycle and encourage ovulation. Lifestyle changes, such as losing weight and being physically active, can help. In addition, metformin may be prescribed to improve insulin resistance, which not only decreases the risk of type 2 diabetes but also helps to balance hormone levels, which helps regulate menstruation and ovulation.
If you take metformin and are due to have a CT scan, MRI or angiogram that involves the use of IV contrast dye, talk with your doctor about stopping your metformin before the procedure. The contrast dye may cause minor, short-term changes to your kidney function. According to the American College of Radiology, you may not need to stop your metformin if you have normal kidney function. However, if you have acute or chronic kidney issues, you will likely need to stop taking your metformin prior to the procedure, and 48 hours afterwards. Make sure you let all of your doctors know which medicines you take, and be sure to ask about taking metformin if you will be having any procedure that involves use of a contrast dye.
Metformin isn’t a weight-loss drug. But studies show that some people who take this medicine lose weight — as long as they are eating healthfully and being active. How does metformin work to cause weight loss? Researchers aren’t entirely clear, but weight loss may result from a reduced appetite. Metformin may also affect how the body stores fat. And metformin lowers insulin resistance, which can make it easier to lose weight. On a side note, metformin is sometimes prescribed to people who take antipsychotic medicines to prevent or reduce weight gain. Keep in mind that metformin is not a magic diet pill, and if you take it, you may not notice any effect on your weight.
Metformin has shown some promise in improving survival in breast cancer patients and those with endometrial hyperplasia, a condition that can lead to cancer if not treated. According to the National Cancer Institute, numerous trials are underway to find out if metformin can prevent a number of different cancers, including breast, prostate, colorectal and endometrial cancers. Stay tuned!
One of the main complications of diabetes is heart disease. Research on more than one million people with diabetes shows that metformin can reduce the risk of dying from heart disease by 30% to 40%, compared with sulfonylurea drugs (another class of diabetes pills). Results from a newer study, called REMOVAL, showed that metformin lowered LDL cholesterol, plaque accumulation and weight in more than 400 people with type 1 diabetes, indicating that this drug may be helpful for preventing heart disease in those with type 1 diabetes.
The smell of a dead fish is one of the worst smells around. Understandably, if your medicine smells like this, it’s going to be hard to swallow. And many people find that fishy metformin increases the chances of nausea. What gives with the fishy smell? Apparently, generic metformin has a higher likelihood of smelling bad. If you notice a bad smell when you open your metformin container, you can try a couple of things: hold your nose when you take it, or talk to your doctor about switching to another type of metformin, including an extended-release version.
There are definitely pros and cons to taking metformin. Talk with your doctor or diabetes educator if you have concerns or questions about this drug, and find out if it’s a good choice for you.
Want to learn more about metformin? Read “Diabetes Medicine: Metformin” and “Metformin: The Unauthorized Biography.”
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Amy Campbell: Amy Campbell is the author of Staying Healthy with Diabetes: Nutrition and Meal Planning and a frequent contributor to Diabetes Self-Management and Diabetes & You. She has co-authored several books, including the The Joslin Guide to Diabetes and the American Diabetes Association’s 16 Myths of a “Diabetic Diet,” for which she received a Will Solimene Award of Excellence in Medical Communication and a National Health Information Award in 2000. Amy also developed menus for Fit Not Fat at Forty Plus and co-authored Eat Carbs, Lose Weight with fitness expert Denise Austin. Amy earned a bachelor’s degree in nutrition from Simmons College and a master’s degree in nutrition education from Boston University. In addition to being a Registered Dietitian, she is a Certified Diabetes Educator and a member of the American Dietetic Association, the American Diabetes Association, and the American Association of Diabetes Educators. Amy was formerly a Diabetes and Nutrition Educator at Joslin Diabetes Center, where she was responsible for the development, implementation, and evaluation of disease management programs, including clinical guideline and educational material development, and the development, testing, and implementation of disease management applications. She is currently the Director of Clinical Education Content Development and Training at Good Measures. Amy has developed and conducted training sessions for various disease and case management programs and is a frequent presenter at disease management events.
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